All peer reviewed publications are listed below. Other publications will be uploaded shortly.

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Sligo, J., McAnally, H.M., Tansley, J.E., Baxter, J., Bolton, A.E., Skillander, K.M., Hancox, R. J. | 2016

The dynamic, complex and diverse living and care arrangements of young New Zealanders: implications for policy

Kotuitui: New Zealand Journal of Social Sciences Online, 2016, DOI: 10.1080/1177083X.2016.1196715.
DOI: 10.1080/1177083X.2016.1196715

Our ref: NZ94

Show abstract » The living arrangements of young people in New Zealand are diverse and often complex. In this article we report the range of care and living arrangements of 209 15-year-old New Zealanders, 47 of whom identified as Maori. These young people were participants in the second generation of a cohort study. Data were collected from their parents via a life history calendar and analysed for variety and consistency of care arrangements, household membership and transitions. Few participants had a consistent pattern of parental care arrangements and most had experienced multiple changes in household composition and frequent changes of address. We conclude that the whanau/family lives of many young New Zealanders are complex and dynamic. These observations contrast with the conventional notions of family life that form the basis for New Zealand's family policies. We argue that social policies and services impacting on young people need to reflect the lived reality of young people if they are to meet young people's needs.
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Moffitt, Terrie E., Belsky, Daniel W., Danese, Andrea, Poulton, Richie, Caspi, Avshalom | 2016

The Longitudinal Study of Aging in Human Young Adults: Knowledge Gaps and Research Agenda

The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 2016, first published online October 7, 2016 doi:10.1093/gerona/glw191 .

Our ref: RO690

Show abstract » Background: To prevent onset of age-related diseases and physical and cognitive decline, interventions to slow human aging and extend health span must eventually be applied to people while they are still young and healthy. Yet most human aging research examines older adults, many with chronic disease, and little is known about aging in healthy young humans.Method: This article explains how this knowledge gap is a barrier to extending health span and puts forward the case that geroscience should invest in researching the pace of aging in young adults. As one illustrative example, we describe an initial effort to study the pace of aging in a young-adult birth cohort by using repeated waves of biomarkers collected across the third and fourth decades to quantify the pace of coordinated physiological deterioration across multiple organ systems (eg, pulmonary, periodontal, cardiovascular, renal, hepatic, metabolic, and immune function).Results: Findings provided proof of principle that it is possible to quantify individual variation in the pace of aging in young adults still free of age-related diseases.Conclusions: This article articulates research needs to improve longitudinal measurement of the pace of aging in young people, to pinpoint factors that slow or speed the pace of aging, to compare pace of aging against genomic clocks, to explain slow-aging young adults, and to apply pace of aging in preventive clinical trials of antiaging therapies. This article puts forward a research agenda to fill the knowledge gap concerning lifelong causes of aging.
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Shearer, D.M., Thomson, W. M., Broadbent, J. M. , McLean, R., Poulton, R., Mann, J. | 2016

High risk glycated hemoglobin trajectories established by mid-20s: findings from a birth cohort study

BMJ Open Diabetes Research and Care, 2016, 4(e000243), doi:10.1136/bmjdrc-2016-000243.

Our ref: RO689

Show abstract » Objective To describe the natural history of glycemia (as measured by glycated hemoglobin (HbA1c)) over 12 years using group-based trajectory modeling (GBTM), and to examine baseline predictors of trajectory. Research design and methods HbA1c data collected at ages 26, 32 and 38 in the long-running, prospective Dunedin Multidisciplinary Health and Development Study were used to assign study members (n=893) to trajectories applying GBTM. A generalization of the model allowed the statistical linking of baseline demographic, smoking and anthropometric characteristics to group membership probability. Results Mean HbA1c increased with age, as did prevalence of prediabetes, diabetes and dysglycemia. The greatest increase occurred between ages 26 and 32. Glycemic health status at age 26 predicted glycemic health status at age 38. 3 HbA1c trajectory groups were identified: ślow' (n=98, 11.0%); śmedium' (n=482, 54.0%); and śhigh' (n=313, 35.0%) with mean HbA1c of 29.6, 34.1, and 38.7 mmol/mol, respectively, at age 38. High waist circumference (=880 mm for women and =1020 mm for men), high waist-height ratio (=0.50), and being a smoker at age 26 predicted membership of the least favorable trajectory over the next 12 years. High body mass index (=30) at age 26 did not predict of trajectory. Conclusions Trajectories of HbA1c are established relatively early in adulthood. HbA1c levels, waist circumference, waist-height ratio, and smoking status at age 26 are valid clinical predictors for future dysglycemic risk. The identification of HbA1c trajectories and their predictors introduces the possibility of an individualized approach to prevention at an earlier stage than is currently done.
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Meier, M.H., Hall, W., Caspi, A., Belsky, D.W., Cerda, M., Harrington, H. L., Houts, R., Poulton, R. , Moffitt, T. E. | 2016

Which adolescents develop persistent substance dependence in adulthood? Using population-representative longitudinal data to inform universal risk assessment

Psychological Medicine, 2016, 46(4), 877-889.

Our ref: RO688

Show abstract » Importance: Longitudinal studies have shown that youth exposed to particular risks are more likely to develop substance dependence, and these studies point to potential targets for prevention. They do not, however, directly address the pressing public health question of how accurately we can predict the development of persistent substance dependence in the general population. Objective: To determine how accurately childhood and adolescent risk factors can predict persistent substance dependence. Design: A 38-year, prospective, longitudinal study of a representative birth cohort. Setting: The Dunedin Multidisciplinary Health and Development Study of New Zealand. Participants: The study included 1,037 male and female participants. Exposure: Prospectively assessed predictors included family history of substance dependence, childhood psychopathology (conduct disorder, depression), early exposure to substances, frequent substance use in adolescence, sex, and childhood socioeconomic status. Main Outcome Measures: Persistent substance dependence was defined as dependence on one or more of alcohol, tobacco, cannabis, or hard-drugs at three or more assessment ages: ages 21, 26, 32, and 38. Results: An ROC curve analysis showed that a cumulative index of childhood and adolescent risk predicted persistent adult substance dependence with an AUC (area-under-the-curve) of 0.80 a large effect. Daily tobacco use in adolescence was the single best predictor of later persistent substance dependence, accurately identifying 68% of those who developed persistent substance dependence in adulthood. Nearly 1 in 2 adolescents who used tobacco on a daily basis developed severe substance dependence that persisted through early midlife. Conclusions and Relevance: We can predict with considerable accuracy which individuals will develop persistent substance dependence in adulthood based on information obtained in childhood and adolescence. By ascertaining adolescent tobacco use, clinicians, parents, and teachers, can efficiently identify the majority of individuals who will struggle with persistent substance dependence in adulthood.
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Lynch, S.J., Sears, M.R., Hancox, R. J. | 2016

Thumb-sucking, nail-biting and atopic sensitisation, asthma, and hay fever

Pediatrics, 2016, 138(2), e20160443; DOI: 10.1542/peds.2016-0443.

Our ref: RO687

Show abstract » Background: The hygiene hypothesis suggests that early-life exposure to microbial organisms reduces the risk of developing allergies. Thumb-sucking and nail-biting are common childhood habits that may increase microbial exposures. We tested the hypothesis that children who suck their thumbs or bite their nails have a lower risk of developing atopy, asthma, and hay fever in a population-based birth-cohort followed to adulthood. Methods: Parents reported children's thumb-sucking and nail-biting habits when their children were ages 5, 7, 9, and 11 years. Atopic sensitisation was defined as a positive skin prick test (>2mm weal) to at least one common allergen at 13 and 32 years. Associations between thumb-sucking and nail-biting in childhood, and atopic sensitisation, asthma, and hay fever at these ages were assessed using logistic regression with adjustments for sex and other potential confounding factors: parental atopy, breastfeeding, pet ownership, household crowding, socio-economic status, and parental smoking. Results: 31% of children were frequent thumb-suckers or nail-biters at at least one age. These children had a lower risk of atopic sensitisation at age 13 years (OR=0.67 [95%CI: 0.48, 0.92], p=0.013) and age 32 years (OR=0.61 [95%CI: 0.46, 0.81], p=0.001). These associations persisted when adjusted for multiple confounding factors. Children who had both habits had a lower risk of atopic sensitisation than those who only had one. No associations were found for nail-biting, thumb-sucking and asthma or hay fever at either age. Conclusion: Children who suck their thumbs or bite their nails are less likely to have atopic sensitisation in childhood and adulthood.
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Sutherland, T.J.T., McLachlan, C. R. , Sears, M.R., Poulton, R., Hancox, R. J. | 2016

The relationship between body fat and respiratory function in young adults

European Respiratory Journal, 2016, 48(3), 734-747.

Our ref: RO686

Show abstract » The relationship between adiposity and respiratory function is poorly understood. Most studies investigating this have used indirect measures of body fat and few have assessed how changes in adiposity influence lung function. Body fat measured by bio-electrical impedance analysis, body mass index, waist circumference, spirometry, body plethysmography and transfer factor were measured at ages 32 and 38 years in 361 non-smoking, non-asthmatic participants from a population-based birth cohort. Higher percentage body fat was associated with lower spirometric and plethysmographic lung volumes, but not with airflow obstruction, or transfer factor at 32 years. Changes in adiposity between ages 32 and 38 years were inversely associated with changes in lung volumes. These associations were generally stronger in men than women, but an association between increasing adiposity and lower airway function (forced expiratory volume in 1 s/forced vital capacity) was only found in women. Similar associations were found for body mass index and waist circumference. Higher percentage body fat is associated with lower lung volumes. Direct and indirect measures of adiposity had similar associations with lung function. Adiposity had a greater effect on lung volumes in men than women but was associated with airway function only in women. There was little evidence that adiposity influenced transfer factor.
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Cerda, M., Moffitt, T.E., Meier, M.H., /Harrington, H. L., Houts, R., Ramrakha, S., Hogan, S., Poulton, R., Caspi, A. | 2016

Persistent cannabis dependence and alcohol dependence represent risks for midlife economic and social problems: A longitudinal cohort study

Clinical Psychological Science, 2016, Published online before print 22 March 2016, DOI: 10.1177/2167702616630958.
DOI: 10.1177/2167702616630958

Our ref: RO685

Show abstract » With the increasing legalization of cannabis, understanding the consequences of cannabis use is particularly timely. We examined the association between cannabis use and dependence, prospectively assessed between ages 18 and 38, and economic and social problems at age 38. We studied participants in the Dunedin Longitudinal Study, a cohort (N = 1,037) followed from birth to age 38. Study members with regular cannabis use and persistent dependence experienced downward socioeconomic mobility, more financial difficulties, workplace problems, and relationship conflict in early midlife. Cannabis dependence was not linked to traffic-related convictions. Associations were not explained by socioeconomic adversity, childhood psychopathology, achievement orientation, or family structure; cannabis-related criminal convictions; early onset of cannabis dependence; or comorbid substance dependence. Cannabis dependence was associated with more financial difficulties than was alcohol dependence; no difference was found in risks for other economic or social problems. Cannabis dependence is not associated with fewer harmful economic and social problems than alcohol dependence.
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Hancox, R. J., Gray, A.R., Sears, M.R., Poulton, R. | 2016

Systemic inflammation and lung function: A longitudinal analysis

Respiratory Medicine, 2016, 111 54-59.

Our ref: RO684

Show abstract » Abstract: Background. Systemic inflammation is associated with impaired lung function in healthy adults as well as in patients with lung disease. The mechanism for this association is unknown and it is unclear if systemic inflammation leads to impaired lung function or if poor lung function leads to inflammation. We explored the temporal associations between blood C-reactive protein (CRP), fibrinogen, and white blood cells, and lung function in young adults. Methods. Spirometry, plethysmography, and diffusion capacity were measured in a population-based cohort at ages 32 and 38 years. Highsensitivity CRP, fibrinogen, and white blood cells were measured at the same ages. Results. Higher levels of CRP and, to a lesser extent, fibrinogen were associated with lower lung volumes in cross-sectional analyses at both ages 32 and 38 years. Higher CRP and fibrinogen at age 32 were associated with higher FEV1 and FEV1/FVC at age 38, but not other measures of lung function. Lower lung volumes (total lung capacity, functional residual capacity, and residual volume) but not airflow obstruction (FEV1/FVC) at age 32 were associated with higher CRP at age 38. Associations between age 32 lung function and fibrinogen at follow-up were weaker, but consistent. There were no longitudinal associations between white blood cells and lung function. Conclusions. We found no evidence that systemic inflammation causes a decline in lung function. However, lower lung volumes were associated with higher CRP and fibrinogen at follow-up indicating that pulmonary restriction may be a risk factor for systemic inflammation. The mechanism for this association remains unclear.
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Meier, M.H., Caspi, A., Cerda, M., Hancox, R. J., Harrington, H. L., Houts, R., Poulton, R., Ramrakha, S., Thomson, W. M., Moffitt, T.E. | 2016

Associations between cannabis use and physical health problems in early midlife: a longitudinal comparison of persistent cannabis versus tobacco users

JAMA Psychiatry, 2016, Published online first June 01, 2016. doi:10.1001/jamapsychiatry.2016.0637.

Our ref: RO683

Show abstract » Importance: After major policy changes in the United States, policymakers, health care professionals, and the general public seek information about whether recreational cannabis use is associated with physical health problems later in life. Objective: To test associations between cannabis use over 20 years and a variety of physical health indexes at early midlife.
Design, Setting, and Participants: Participants belonged to a representative birth cohort of 1037 individuals born in Dunedin, New Zealand, in 1972 and 1973 and followed to age 38 years, with 95% retention (the Dunedin Multidisciplinary Health and Development Study). We tested whether cannabis use from ages 18 to 38 years was associated with physical health at age 38, even after controlling for tobacco use, childhood health, and childhood socioeconomic status. We also tested whether cannabis use from ages 26 to 38 years was associated with within-individual health decline using the same measures of health at both ages. Exposures: We assessed frequency of cannabis use and cannabis dependence at ages 18, 21, 26, 32, and 38 years. Main Outcomes and Measures: We obtained laboratory measures of physical health (periodontal health, lung function, systemic inflammation, and metabolic health), as well as self-reported physical health, at ages 26 and 38 years. Results: The 1037 study participants were 51.6% male (n = 535). Of these, 484 had ever used tobacco daily and 675 had ever used cannabis. Cannabis use was associated with poorer periodontal health at age 38 years and within-individual decline in periodontal health from ages 26 to 38 years. For example, cannabis joint-years from ages 18 to 38 years was associated with poorer periodontal health at age 38 years, even after controlling for tobacco pack-years (├č = 0.12; 95% CI, 0.05-0.18; P <.001). Additionally, cannabis joint-years from ages 26 to 38 years was associated with poorer periodontal health at age 38 years, even after accounting for periodontal health at age 26 years and tobacco pack-years (├č = 0.10; 95% CI, 0.05-0.16; P <.001) However, cannabis use was unrelated to other physical health problems. Unlike cannabis use, tobacco use was associated with worse lung function, systemic inflammation, and metabolic health at age 38 years, as well as within-individual decline in health from ages 26 to 38 years. Conclusions and Relevance: Cannabis use for up to 20 years is associated with periodontal disease but is not associated with other physical health problems in early midlife.
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Belsky, D.W., Moffitt, T.E., Corcoran, D.L., Domingue, B., Harrington, H. L., Houts, R., Ramrakha, S., Sugden, K., Williams, B.S., Poulton, R., Caspi, A. | 2016

The Genetics of Success: How single nucleotide polymorphisms associated with educational attainment relate to life-course development

Psychological Science, 2016, OnlineFirst, published on June 1, 2016, doi:10.1177/0956797616643070.

Our ref: RO682

Show abstract » A previous genome-wide association study (GWAS) of more than 100,000 individuals identified molecular-genetic predictors of educational attainment. We undertook in-depth life-course investigation of the polygenic score derived from this GWAS using the four-decade Dunedin Study (N = 918). There were five main findings. First, polygenic scores predicted adult economic outcomes even after accounting for educational attainments. Second, genes and environments were correlated: Children with higher polygenic scores were born into better-off homes. Third, children's polygenic scores predicted their adult outcomes even when analyses accounted for their social-class origins; social-mobility analysis showed that children with higher polygenic scores were more upwardly mobile than children with lower scores. Fourth, polygenic scores predicted behavior across the life course, from early acquisition of speech and reading skills through geographic mobility and mate choice and on to financial planning for retirement. Fifth, polygenic-score associations were mediated by psychological characteristics, including intelligence, self-control, and interpersonal skill. Effect sizes were small. Factors connecting DNA sequence with life outcomes may provide targets for interventions to promote population-wide positive development.
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Thomson, W. M., Zeng, J., Broadbent, J. M. , Foster-Page, L.A. , Shalev, I., Moffitt, T.E., Caspi, A., Williams, S.M., Braithwaite, A., Robertson, S. P. , Poulton, R. | 2016

Telomere length and periodontal attachment loss: a prospective cohort study

Journal of Clinical Periodontology, 2016, 43(2), 121-127.

Our ref: RO680

Show abstract » Aim: To examine the association between telomere erosion and periodontitis in a longstanding prospective cohort study of New Zealand adults. Specific hypotheses tested were: (1) that exposure to periodontitis at ages 26 and 38 was associated with accelerated leucocyte telomere erosion; and (2) that accelerated leucocyte telomere erosion was associated with higher rates of periodontitis by ages 26 and 38. Materials and Methods: Periodontal attachment loss data were collected at ages 26 and 38. Blood samples taken at the same ages were analysed to obtain estimates of leucocyte telomere length and erosion over a 12-year period. Results: Overall, mean telomere length reduced by 0.15 TS ratio (adjusted) from age 26 to 38 among the 661 participants reported on here. During the same period, the mean attachment loss increased by 10%, after adjusting for sex, socio-economic status and smoking. Regression models showed that attachment loss did not predict telomere length, and that telomere erosion did not predict attachment loss. Conclusions: Although both periodontitis and telomere length are age-dependent, they do not appear to be linked, suggesting that determination of leucocyte telomere length may not be a promising clinical approach for identifying people who are at risk for periodontitis.
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Beckley, A.L., Caspi, A., Harrington, H. L., Houts, R., McGee, T.R., Morgan, N., Schroeder, F., Ramrakha, S., Poulton, R. , Moffitt, T. E. | 2016

Adult-onset offenders: Is a tailored theory warranted?

Journal of Criminal Justice, 2016, 46 64-81. doi:10.1016/j.jcrimjus.2016.03.001.

Our ref: RO681

Show abstract » Purpose: To describe official adult-onset offenders, investigate their antisocial histories and test hypotheses about their origins. Methods: We defined adult-onset offenders among 931 Dunedin Study members followed to age 38, using criminal-court conviction records. Results: Official adult-onset offenders were 14% of men, and 32% of convicted men, but accounted for only 15% of convictions. As anticipated by developmental theories emphasizing early-life influences on crime, adult-onset offenders' histories of antisocial behavior spanned back to childhood. Relative to juvenile-offenders, during adolescence they had fewer delinquent peers and were more socially inhibited, which may have protected them from conviction. As anticipated by theories emphasizing the importance of situational influences on offending, adult-onset offenders, relative to non-offenders, during adulthood more often had schizophrenia, bipolar disorder, and alcohol-dependence, had weaker social bonds, anticipated fewer informal sanctions, and self-reported more offenses. Contrary to some expectations, adult-onset offenders did not have high IQ or high socioeconomic-status families protecting them from juvenile conviction. Conclusions: A tailored theory for adult-onset offenders is unwarranted because few people begin crime de novo as adults. Official adult-onset offenders fall on a continuum of crime and its correlates, between official non-offenders and official juvenile-onset offenders. Existing theories can accommodate adult-onset offenders.
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Broadbent, J. M. , Zeng, J., Foster Page, L.A. , Baker, S.R., Thomson, W. M. | 2016

Oral-health-related beliefs, behaviours, and outcomes through the life course

Journal of Dental Research, 2016, First published online 2 March 2016 , doi: 10.1177/0022034516634663.

Our ref: RO679

Show abstract » Complex associations exist among socioeconomic status (SES) in early life, beliefs about oral health care (held by individuals and their parents), and oral health"related behaviors. The pathways to poor adult oral health are difficult to model and describe, especially due to a lack of longitudinal data. The study aim was to explore possible pathways of oral health from birth to adulthood (age 38 y). We hypothesized that higher socioeconomic position in childhood would predict favorable oral health beliefs in adolescence and early adulthood, which in turn would predict favorable self-care and dental attendance behaviors; those would lead to lower dental caries experience and better self-reported oral health by age 38 y. A generalized structural equation modeling approach was used to investigate the relationship among oral health"related beliefs, behaviors in early adulthood, and dental health outcomes and quality of life in adulthood (age, 38 y), based on longitudinal data from a population-based birth cohort. The current investigation utilized prospectively collected data on early (up to 15 y) and adult (26 and 32 y) SES, oral health"related beliefs (15, 26, and 32 y), self-care behaviors (15, 28, and 32 y), oral health outcomes (e.g., number of carious and missing tooth surfaces), and oral health"related quality of life (38 y). Early SES and parental oral health"related beliefs were associated with the study members' oral health"related beliefs, which in turn predicted toothbrushing and dental service use. Toothbrushing and dental service use were associated with the number of untreated carious and missing tooth surfaces in adulthood. The number of untreated carious and missing tooth surfaces were associated with oral health"related quality of life. Oral health toward the end of the fourth decade of life is associated with intergenerational factors and various aspects of people's beliefs, SES, dental attendance, and self-care operating since the childhood years.
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Sugden, K., Moffitt, T.E., Pinto, L., Poulton, R., Williams, B.S., Caspi, A. | 2016

Is Toxoplasma Gondii Infection Related to Brain and Behavior Impairments in Humans? Evidence from a Population-Representative Birth Cohort

PlosOne, 2016, 11(2), e0148435.

Our ref: RO678

Show abstract » Toxoplasma gondii (T. gondii) is a protozoan parasite present in around a third of the human population. Infected individuals are commonly asymptomatic, though recent reports have suggested that infection might influence aspects of the host's behavior. In particular, Toxoplasma infection has been linked to schizophrenia, suicide attempt, differences in aspects of personality and poorer neurocognitive performance. However, these studies are often conducted in clinical samples or convenience samples. In a population-representative birth-cohort of individuals tested for presence of antibodies to T. gondii (N=837) we investigated the association between infection and four facets of human behavior: neuropsychiatric disorder (schizophrenia and major depression), poor impulse control (suicidal behavior and criminality), personality, and neurocognitive performance. Suicide attempt was marginally more frequent among individuals with T. gondii seropositivity (p = .06). Seropositive individuals also performed worse on one out of 14 measures of neuropsychological function. On the whole, there was little evidence that T. gondii was related to increased risk of psychiatric disorder, poor impulse control, personality aberrations or neurocognitive impairment.
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Hancox, R. J., Poulton, R., Caspi, A., Sears, M.R. | 2016

The effect of cigarette smoking on lung function in young adults with asthma

American Journal of Respiratory and Critical Care Medicine, 2016, First published online 11 Feb 2016 as DOI: 10.1164/rccm.201512-2492OC.

Our ref: RO677

Show abstract » Rationale. Life-course persistent asthma and tobacco smoking are risk factors for irreversible airflow obstruction. It is often assumed that smoking and asthma have additive or multiplicative effects on the risk for airflow obstruction, but this has not been demonstrated in prospective studies of children with persistent asthma. Objective. To investigate the effects of smoking and asthma on the development of airflow obstruction in a population-based birth-cohort followed to age 38 years. Measurements and Main Results. Reports of childhood asthma from ages 9, 11, and 13 and self-reports of adult asthma at ages 32 and 38 years were used to define childhood-onset persistent (n=91), late-onset (n=93), asthma in remission (n=85), and non-asthmatic (n=572) phenotypes. Cumulative tobacco smoking histories and spirometry were obtained at ages 18, 21, 26, 32, and 38 years. Analyses were by generalised estimating equations (GEEs) adjusting for childhood spirometry, body mass index, age, and sex. Smoking history and childhood-onset persistent asthma were both associated with lower FEV1/FVC ratios. Associations between smoking and FEV1/FVC ratios were different between asthma phenotypes (interaction p<0.001). Smoking was associated with lower pre- and post-bronchodilator FEV1/FVC ratios among non-asthmatics and those with late-onset or remittent asthma, but smoking was not associated with lower FEV1/FVC ratios among those with childhood-onset persistent asthma. Conclusions. Childhood-onset persistent asthma is associated with airflow obstruction by mid adult life, but this does not appear to be made worse by tobacco smoking. We found no evidence that smoking and childhood-persistent asthma have additive or multiplicative effects on airflow obstruction.
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Theodore, R., Broadbent, J. M. , Nagin, D.S., Ambler, A., Hogan, S., Ramrakha, S., Cutfield, W., Williams, M. J. A., Harrington, H. L., Moffitt, T.E., Caspi, A., Poulton, R. | 2015

Systolic blood pressure trajectories from childhood to early mid-life: early life predictors, effect modifiers, and adult cardiovascular outcomes

Hypertension, 2015, 66 1108-1115.

Our ref: ro675

Show abstract » Previous studies examining blood pressure change over time have modelled an 'average' population trajectory. Recent research among older adults suggests there may be subgroups with different blood pressure trajectories. Identifying subgroups at risk of developing adult hypertension early in life can inform effective risk reduction efforts. We sought to identify different systolic blood pressure trajectories from childhood, their correlated risk factors and early midlife cardiovascular outcomes. Blood pressure data at ages 7, 11, 18, 26, 32 and 38 years from a longitudinal, representative birth cohort study (n=975) were used to identify four distinct trajectory groups via group-based trajectory modeling: 'normal' (21.8%), 'high-normal' (43.3%), 'prehypertensive' (31.6%), and 'hypertensive' (4.2%). The categories refer to blood pressure beginning at age 7 and most recently measured at age 38. Family history of high blood pressure (OR=43.23, 95% CI 5.27, 354.65), male gender (OR=109.48, 95% CI=26.82, 446.96), being first born (OR=2.5 95% CI=1.00, 8.69) and low birthweight (OR=2.79, 95% CI 2.49, 3.09) were associated with hypertensive group membership (compared to the normal group). Higher body mass index and cigarette smoking resulted in increasing blood pressure across trajectories, particularly for the higher blood pressure groups. Prehypertensive and hypertensive trajectory groups had worse cardiovascular outcomes by early midlife. Harmful blood pressure trajectories are identifiable in childhood, associated with both antecedent and modifiable risk factors over time, and predict adult cardiovascular disease risk. Early detection, subsequent targeted prevention and/or intervention may reduce the lifecourse burden associated with higher blood pressure.
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Dickson, N. , Righarts, A., van Roode, T. , Cameron, C., Connor, J. | 2015

Do reports of age and circumstances of first intercourse differ in a birth cohort when asked seventeen years apart?

Journal of Sex Research, 2015, First Published Online 15 Oct 2015,

Our ref: RO676

Show abstract » Conclusions about temporal changes in age and circumstances of first intercourse are generally derived from retrospective reports by people of various ages in cross-sectional studies, with an inherent assumption of no bias stemming from time since the event. We examined this assumption through repeated questions on age and circumstances of first heterosexual intercourse (FHI) at ages 21 and 38 in a birth cohort. Despite considerable movement in individual reports, there was no bias in reported age of FHI. However, a greater proportion of both men and women stated at the later assessment both partners had been equally willing (versus persuading or persuaded). The distribution of current views of the appropriateness of the timing did not differ markedly between assessments, although there were many individual changes. Reports of contraceptive usage were similar at the two assessments for men but differed among women, mainly through more reporting that they could not remember. These findings imply that among cohorts born in the 1970s, there is no bias in reports of age of FHI many years after the event, and views on the appropriateness of timing persist. However, time biases reports in favor of a more mutual willingness.
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Robertson, L.A., Iosua, E., McGee, R., Hancox, R. J. | 2015

Non-daily, low-rate daily and high-rate daily smoking in young adults: A 17 year follow-up

Nicotine & Tobacco Research, 2015, Advance access online August 17, 2015, doi: 10.1093/ntr/ntv167.

Our ref: RO674

Show abstract » Introduction: While overall tobacco consumption is declining in many countries, patterns of low-frequency smoking"such as nondaily and low-rate daily smoking"appear to be increasing. We aimed firstly to describe differences in demographic, smoking- and quitting-related characteristics between nondaily and daily smokers in young adults; secondly, to determine the proportion of low-frequency smokers who transition to a higher rate of smoking by age 38 and factors associated with this. Methods: We assessed a cohort of individuals born in Dunedin, New Zealand, in 1972"1973, at regular intervals from age 21 to age 38 years. Smokers were categorized as either nondaily, low-rate daily (ie, defined as five or less cigarettes per day) or high-rate daily smokers (six or more cigarettes per day). Descriptive statistics, linear and logistic regression were used. Results: Nondaily smokers at age 21 tended to self-identify as nonsmokers. Both nondaily smokers and low-rate daily smokers reported higher readiness and confidence in quitting compared to high-rate daily smokers. Around 40% of the age 21 low-rate daily smokers reported smoking daily at age 38, compared to 13% of the nondaily smokers and 4% of the nonsmokers. Nondaily smoking at age 21 was associated with increased odds of being a daily smoker by age 38 (OR: 3.6; 95% CI = 1.7% to 7.8%) compared to nonsmokers. Conclusions: Different patterns of smoking are associated with differences in readiness to quit and confidence in quitting ability. For a considerable proportion of smokers, low-frequency smoking in young adulthood develops into daily smoking by adulthood. Implications: Low-frequency smoking, including nondaily smoking, in early adulthood is a significant risk factor for being a daily smoker in the long-term. Cessation interventions should be tailored to low-frequency smokers, taking into account differences between them and heavier smokers in terms of smoking motivation and quitting-related cognitions.
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Connor, J., Kydd, R.M., Dickson, N. | 2015

Alcohol involvement in sexual behaviour and adverse sexual health outcomes from 26 to 38 years of age

PLOS ONE, 2015, Available online, doi:10.1371/journal.pone.0135660.

Our ref: RO673

Show abstract » Background: Research on alcohol and sexual behaviour has focused on young adults or high-risk groups, showing alcohol use contributing to riskier sexual choices. Adults now in their late thirties have been exposed to heavier drinking norms than previously, raising questions about effects on sexual wellbeing. We examined self-reported use and consequences of alcohol in sexual contexts, and its association with usual drinking pattern at age 38, and also associations of heavy drinking occasion (HDO) frequency with number of sexual partners, sexually transmitted infections (STIs), and terminations of pregnancy (TOPs), from 26"32 and 32"38 years of age.
Methods: Members of the Dunedin Study birth cohort answered computer-presented questions about sexual behaviour and outcomes, and interviewer-administered alcohol consumption questions, at age 26, 32 and 38 years.
Results: Response level was >90% at each assessment. At 38, drinking before or during sex in the previous year was common (8.2% of men; 14.6% of women reported usually/alwaysŁ), and unwanted consequences were reported by 13.5% of men and 11.9% of women, including regretted sex or failure to use contraception or condoms. Frequent heavy drinkers were more likely to use alcohol to make it easier to have sexŁ and regret partner choice, particularly women. Heavy drinking frequency was strongly associated with partner numbers for men and women at 32, but only for women at 38. Significantly higher odds of STIs amongst the heaviest drinking men, and TOPs amongst the heaviest drinking women were seen at 32"38.
Conclusions: Alcohol involvement in sex continues beyond young adulthood where it has been well documented, and is common at 38. Women appear to be more affected than men, and heavy drinking is associated with poorer outcomes for both. Improving sexual health and wellbeing throughout the life course needs to take account of the role of alcohol in sexual behaviour.
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Foster Page, L.A. , Thomson, W. M., Broadbent, J. M. | 2015

Validity of self-reported periodontal questions in a New Zealand cohort

Clinical Oral Investigations, 2015, Published online 24 July 2015, DOI 10.1007/s00784-015-1526-0.

Our ref: RO672

Show abstract » Methods: Full-mouth periodontal examinations (three sites/tooth) were undertaken at age 38 in a complete birth cohort born in 1972/1973 in New Zealand. Four self-reported periodontal screening questions were included (Do you think you have gum diseaseŁ; Has a dental professional ever told you that you have lost bone around your teethŁ; Have you ever had scaling, root planing, surgery, or other treatment for gum diseaseŁ and Have you ever had any teeth that have become loose by themselves without some injuryŁ), and the sensitivity and specificity of those self-reported items were calculated for individual questions and using a multivariable binary logistic regression model. Generalised linear models were used to compare relative risks for periodontitis and smoking, using the (a) clinical measures and (b) self-reported questions. Results: Among the 895 who had periodontal examinations, the prevalence of periodontitis was 43.7, 22.8 and 12.0 %, respectively, for one or more sites with =4, =5 and =6 mm clinical attachment loss (AL). The specificity of the four self-reported questions was high (82"94 %), but the sensitivity was low for all, except the question: Do you think you have gum diseaseŁ. The four questions' highest combined sensitivity?+?specificity value was 1.33 for one or more sites with =4 mm AL, with the area under the receiver operating characteristic (ROC) curve being greatest for one or more sites with =6 mm AL, at 0.84. For the smoking"periodontitis association, the estimates of relative risk for periodontitis among smokers were as follows: (a) 1.81, 2.88 and 5.79, respectively, clinically determined to have one or more sites with =4, =5 and =6 mm AL and (b) 2.19, 2.17, 1.23 and 1.89, respectively, for the four self-reported questions. Conclusion: The four self-reported periodontal screening questions performed adequately in identifying clinically determined periodontal disease, and they showed moderate validity when used together as a set. However, the strength of the association between smoking and periodontitis was underestimated when they were used instead of clinically determined periodontal disease. Clinical relevance: These findings suggest that clinical examinations remain to be the desired approach for periodontal surveys, but where resource constraints preclude those, self-reported methods can provide useful information; after all, some periodontal information is better than none at all.
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Goldman-Mellor, S., Caspi, A., Gregory, A. M., Harrington, H. L., Poulton, R., Moffitt, T.E. | 2015

Is insomnia associated with deficits in neuropsychological functioning? Evidence from a population-based study

Sleep, 2015, 38(4), 623-631.

Our ref: RO671

Show abstract » Study Objectives: People with insomnia complain of cognitive deficits in daily life. Results from empirical studies examining associations between insomnia and cognitive impairment, however, are mixed. Research is needed that compares treatment-seeking and community-based insomnia study samples, measures subjective as well as objective cognitive functioning, and considers participants' pre-insomnia cognitive function. Design and Participants: We used data from the Dunedin Study, a representative birth cohort of 1,037 individuals, to examine whether insomnia in early midlife was associated with subjective and objective cognitive functioning. We also tested whether individuals with insomnia who reported seeking treatment for their sleep problems (treatment-seekers) showed greater impairment than other individuals with insomnia (non-treatment-seekers). The role of key confounders, including childhood cognitive ability and comorbid health conditions, was evaluated. Measurements: Insomnia was diagnosed at age 38 according to DSM-IV criteria. Objective neuropsychological assessments at age 38 included the WAIS-IV IQ test, the Wechsler Memory Scale, and the Trail-Making Test. Childhood cognitive functioning was assessed using the Wechsler Intelligence Scale for Children-Revised (WISC-R). Results: A total of 949 cohort members were assessed for insomnia symptoms and other study measures at age 38. Although cohort members with insomnia (n = 186, 19.6%) had greater subjective cognitive impairment than their peers at age 38, they did not exhibit greater objective impairment on formal testing. Treatment-seekers, however, exhibited significant objective impairment compared to non-treatment-seekers. Controlling for comorbidity, daytime impairment, and medications slightly decreased this association. Childhood cognitive deficits antedated the adult cognitive deficits of treatment-seekers.
Conclusions: Links between insomnia and cognitive impairment may be strongest among individuals who seek clinical treatment. Clinicians should take into account the presence of complex health problems and lower premorbid cognitive function when planning treatment for insomnia patients.
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Ramrakha, S., Fergusson, D.M., Horwood, L.J., Dalgard, F., Ambler, A., Kokaua, J., Milne, B.J., Poulton, R. | 2015

Cumulative mental health consequences of acne: 23-year follow-up in a general population birth cohort study

British Journal of Dermatology, 2015, Accepted article published online 27 March, doi:10.1111/bjd.13786.

Our ref: RO670

Show abstract » Acne is a highly prevalent condition during adolescence and young adulthood worldwide. School and university samples indicate rates between 12% and 99%, depending on how acne was classified. General population surveys report rates between 14% and 88%.Acne remains a problem in adulthood with rates ranging from 20 to 54%. The effects of acne, regardless of severity, can be debilitating. Studies have shown a range of psychosocial and interpersonal impacts including feelings of shame and loneliness, anger, impaired self-image, attitude and esteem, lack of pride and body satisfaction. It can also affect interpersonal relationships including poor attachment to friends, and not having romantic or sexual relationships. Finally, it has been associated with impaired functioning in other life domains, for example, not thriving at school, decreased participation in sport and exercise and employment problems. Although acne has been associated with negative emotion, impaired ability to function in daily life and a decreased quality of life only a small number of cross-sectional studies have reported an association between acne and specific psychological problems, including symptoms of anxiety and depression and suicide ideation when compared to those with little or no acne. However, no study has examined the relationship of acne and with psychiatric disorder (i.e. psychological distress of greatest severity and clinical interest), nor has research ascertained the cumulative lifecourse effects of acne on psychiatric disorder. In the present study, prospective-longitudinal data from a general population sample was used to determine whether acne preceded poor mental health at the disorder level from adolescence to adulthood. The specific aim of this study was to examine the association between acne and the development of the most common psychiatric disorders of anxiety, depression, alcohol and cannabis dependence.
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Belsky, D.W., Caspi, A., Houts, R., Corcoran, D.L., Danese, A., Harrington, H. L., Israel, S., Levine, M., Schaefer, J., Sugden, K., Williams, B.S., Yashin, A.I., Poulton, R., Moffitt, T.E. | 2015

Quantification of biological aging in young adults

PNAS (Proceedings of the National Academy of Sciences of the USA) , 2015, 112(30), E4104-E4110.

Our ref: RO669

Show abstract » Antiaging therapies show promise in model organism research. Translation to humans is needed to address the challenges of an aging global population. Interventions to slow human aging will need to be applied to still-young individuals. However, most human aging research examines older adults, many with chronic disease. As a result, little is known about aging in young humans. We studied aging in 954 young humans, the Dunedin Study birth cohort, tracking multiple biomarkers across three time points spanning their third and fourth decades of life. We developed and validated two methods by which aging can be measured in young adults, one cross-sectional and one longitudinal. Our longitudinal measure allows quantification of the pace of coordinated physiological deterioration across multiple organ systems (e.g., pulmonary, periodontal, cardiovascular, renal, hepatic, and immune function). We applied these methods to assess biological aging in young humans who had not yet developed age-related diseases. Young individuals of the same chronological age varied in their biological agingŁ (declining integrity of multiple organ systems). Already, before midlife, individuals who were aging more rapidly were less physically able, showed cognitive decline and brain aging, self-reported worse health, and looked older. Measured biological aging in young adults can be used to identify causes of aging and evaluate rejuvenation therapies.
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Schaefer, J., Caspi, A., Belsky, D.W., Harrington, H. L., Houts, R., Israel, S., Levine, M., Sugden, K., Williams, B.S., Poulton, R., Moffitt, T.E. | 2015

Early-life intelligence predicts midlife biological age

Journal of Gerontology, Series B: Psychological Sciences and Social Sciences, 2015, First published online May 26, 2015, doi: 10.1093/geronb/gbv035.

Our ref: RO668

Show abstract » Objectives. Early-life intelligence has been shown to predict multiple causes of death in populations around the world. This finding suggests that intelligence might influence mortality through its effects on a general process of physiological deterioration (i.e., individual variation in 'biological age'). We examined whether intelligence could predict measures of aging at midlife before the onset of most age-related disease. Methods. We tested whether intelligence assessed in early childhood, middle childhood, and midlife predicted midlife biological age in members of the Dunedin Study, a population-representative birth cohort. Results. Lower intelligence predicted more advanced biological age at midlife as captured by perceived facial age, a 10-biomarker algorithm based on data from the National Health and Nutrition Examination Survey (NHANES), and Framingham heart age (r = 0.1"0.2). Correlations between intelligence and telomere length were less consistent. The associations between intelligence and biological age were not explained by differences in childhood health or parental socioeconomic status, and intelligence remained a significant predictor of biological age even when intelligence was assessed before Study members began their formal schooling. Discussion. These results suggest that accelerated aging may serve as one of the factors linking low early-life intelligence to increased rates of morbidity and mortality.
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Moffitt, T.E., Houts, R., Asherson, P., Belsky, D.W., Corcoran, D.L., Hammerle, M., Harrington, H. L., Hogan, S., Meier, M.H., Polanczyk, G., Poulton, R., Ramrakha, S., Sugden, K., Williams, B.S., Rohde, L.A., Caspi, A. | 2015

Is adult ADHD a childhood-onset neurodevelopmental disorder? Evidence from a four-decade longitudinal cohort study.

American Journal of Psychiatry, 2015, AJP in Advance May 2015 (doi: 10.1176/appi.ajp.2015.14101266).

Our ref: RO667

Show abstract » Objective: Despite a prevailing assumption that adult ADHD is a childhood-onset neurodevelopmental disorder, no prospective longitudinal study has described the childhoods of the adult ADHD population. The authors report follow-back analyses of ADHD cases diagnosed in adulthood, alongside follow-forward analyses of ADHD cases diagnosed in childhood, in one cohort. Method: Participants belonged to a representative birth cohort of 1,037 individuals born in Dunedin, New Zealand, in 1972 and 1973 and followed to age 38, with 95% retention. Symptoms of ADHD, associated clinical features, comorbid disorders, neuropsychological deficits, genome-wide association study-derived polygenic risk, and life impairment indicators were assessed. Data sources were participants, parents, teachers, informants, neuropsychological test results, and administrative records. Adult ADHD diagnoses used DSM-5 criteria, apart from onset age and cross-setting corroboration, which were study outcome measures. Results: As expected, childhood ADHD had a prevalence of 6% (predominantly male) and was associated with childhood comorbid disorders, neurocognitive deficits, polygenic risk, and residual adult life impairment. Also as expected, adult ADHD had a prevalence of 3% (gender balanced) and was associated with adult substance dependence, adult life impairment, and treatment contact. Unexpectedly, the childhood ADHD and adult ADHD groups comprised virtually nonoverlapping sets; 90% of adult ADHD cases lacked a history of childhood ADHD. Also unexpectedly, the adult ADHD group did not show tested neuropsychological deficits in childhood or adulthood, nor did they show polygenic risk for childhood ADHD.
Conclusions: The findings raise the possibility that adults presenting with the ADHD symptom picture may not have a childhood-onset neurodevelopmental disorder. If this finding is replicated, then the disorder's place in the classification system must be reconsidered, and research must investigate the etiology of adult ADHD.
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Belsky, D.W., Caspi, A., Israel, S., Blumenthal, J.A., Poulton, R., Moffitt, T.E. | 2015

Cardiorespiratory fitness and cognitive function at midlife: Neuroprotection or Neuroselection?

Annals of Neurology, 2015, 77(4), 607-617.

Our ref: RO666

Show abstract » Objective: A study was undertaken to determine whether better cognitive functioning at midlife among more physically fit individuals reflects neuroprotection, by which fitness protects against age-related cognitive decline, or neuroselection, by which children with higher cognitive functioning select more active lifestyles. Methods: Children in the Dunedin Longitudinal Study (N?=?1,037) completed the Wechsler Intelligence Scales and the Trail Making, Rey Delayed Recall, and Grooved Pegboard tasks as children and again at midlife (age?=?38 years). Adult cardiorespiratory fitness was assessed using a submaximal exercise test to estimate maximum oxygen consumption adjusted for body weight in milliliters/minute/kilogram. We tested whether more fit individuals had better cognitive functioning than their less fit counterparts (which could be consistent with neuroprotection), and whether better childhood cognitive functioning predisposed to better adult cardiorespiratory fitness (neuroselection). Finally, we examined possible mechanisms of neuroselection. Results: Participants with better cardiorespiratory fitness had higher cognitive test scores at midlife. However, fitness-associated advantages in cognitive functioning were already present in childhood. After accounting for childhood baseline performance on the same cognitive tests, there was no association between cardiorespiratory fitness and midlife cognitive functioning. Socioeconomic and health advantages in childhood and healthier lifestyles during young adulthood explained most of the association between childhood cognitive functioning and adult cardiorespiratory fitness. Interpretation: We found no evidence for a neuroprotective effect of cardiorespiratory fitness as of midlife. Instead, children with better cognitive functioning are selecting healthier lives. Fitness interventions may enhance cognitive functioning. However, observational and experimental studies testing neuroprotective effects of physical fitness should consider confounding by neuroselection.
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Hancox, R. J., Shin, H.H., Gray, A.R., Poulton, R. , Sears, M.R. | 2015

Effects of quitting cannabis on respiratory symptoms

European Respiratory Journal, 2015, Published ahead of print 2 April 2015, doi: 10.1183/09031936.00228914.
doi: 10.1183/09031936.00228914

Our ref: RO665

Show abstract » Smoking cannabis is associated with symptoms of bronchitis. Little is known about the persistence of symptoms after stopping cannabis use. We assessed associations between changes in cannabis use and respiratory symptoms in a population-based cohort of 1037 young adults. Participants were asked about cannabis and tobacco use at ages 18, 21, 26, 32 and 38 years. Symptoms of morning cough, sputum production, wheeze, dyspnoea on exertion and asthma diagnoses were ascertained at the same ages. Frequent cannabis use was defined as .52 occasions over the previous year. Associations between frequent cannabis use and respiratory symptoms were analysed using generalised estimating equations with adjustments for tobacco smoking, asthma, sex and age. Frequent cannabis use was associated with morning cough (OR 1.97, p<0.001), sputum production (OR 2.31, p<0.001) and wheeze (OR 1.55, p<0.001). Reducing or quitting cannabis use was associated with reductions in the prevalence of cough, sputum and wheeze to levels similar to nonusers. Frequent cannabis use is associated with symptoms of bronchitis in young adults. Reducing cannabis use often leads to a resolution of these symptoms.

Media Report:
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Poulton, R. , Moffitt, T.E., Silva, P.A. | 2015

The Dunedin Multidisciplinary Health and Development Study: Overview of the first 40 years, with an eye to the future

Social Psychiatry and Psychiatric Epidemiology , 2015, 50(5), 679-693.
DOI 10.1007/s00127-015-1048-8

Our ref: RO664

Show abstract » The Dunedin Multidisciplinary Health and Development Study began more than four decades ago. Unusual at the time, it was founded as a multidisciplinary research enterprise, and was strongly supported by the Dunedin community, both professional and lay, in its early years. Seven research themes have evolved over the last 40 years focusing on: mental and neuro-cognition, cardiovascular risk, respiratory health, oral health, sexual and reproductive health and psychosocial functioning. A seventh, more applied theme, seeks to maximise the value of the Study findings for New Zealand's indigenous people M├óori (or tangata whenua transl people of the land). The Study has published over 1200 papers and reports to date, with almost 2/3 of these being in peer reviewed journals. Here we provide an overview of the study, its history, leadership structure, scientific approach, operational foci, and some recent examples of work that illustrates: (i) the value of multidisciplinary data; (ii) how the Study is well positioned to addresses contemporary issues; and (iii) how research can simultaneously address multiple audiences - from researchers and theoreticians to policy makers and practitioners. Near future research plans are described, and we end by reflecting upon the core aspects of the Study that portend future useful contributions.
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Kydd, R.M., Connor, J. | 2015

Inconsistency in Reporting Abstention and Heavy Drinking Frequency: Associations with Sex and Socioeconomic Status, and Potential Impacts

Alcohol and Alcoholism, 2015, 50(3), 333-345.
doi: 10.1093/alcalc/agu106

Our ref: RO663

Show abstract » Aims: To describe inconsistencies in reporting past-year drinking status and heavy drinking occasions (HDOs) on single questions from two different instruments, and to identify associated characteristics and impacts. Methods: We compared computer-presented Alcohol Use Disorder Identification Test-Consumption (AUDIT-C) with categorical response options, and mental health interview (MHI) with open-ended consumption questions, completed on the same day. Participants were 464 men and 459 women aged 38 (91.7% of surviving birth cohort members). Differences in dichotomous single-item measures of abstention and HDO frequency, associations of inconsistent reporting with sex, socioeconomic status (SES) and survey order, and impacts of instrument choice on associations of alcohol with sex and SES were examined. Results: The AUDIT-C drinking frequency question estimated higher past-year abstention prevalence (AUDIT = 7.6%, MHI = 5.4%), with one-third of AUDIT-C abstainers being MHI drinkers. Only AUDIT-C produced significant sex differences in abstainer prevalence. Inconsistencies in HDO classifications were bidirectional, but with fewer HDOs reported on the MHI than AUDIT-C question. Lower SES was associated with inconsistency in abstention and weekly+ HDOs. Abstention and higher HDO frequency were associated with lower SES overall, but sex-specific associations differed by instrument. Conclusions: In this context, data collection method affected findings, with inconsistencies in abstention reports having most impact. Future studies should: (a) confirm self-reported abstention; (b) consider piloting data collection methods in target populations; (c) expect impacts of sex and SES on measurements and analyses.
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van Roode, T., Dickson, N., Righarts, A., Gillett, W. | 2015

Cumulative incidence of infertility in a New Zealand birth cohort to age 38 by sex, and the relationship with family formation

Fertility and Sterility, 2015, Available online first 27 January 2015,

Our ref: RO662

Show abstract » Objective: To estimate the cumulative incidence of infertility for men and women in a population-based sample. Design: Longitudinal study of a birth cohort. Setting: Research unit. A population-based birth cohort of 1,037 men and women born in Dunedin, New Zealand, between 1972 and1973. Main Outcome Measure(s): Cumulative incidence of infertility by age 32 and 38, distribution of causes and service use for infertility, live birth subsequent to infertility, and live birth by age38. Result(s): The cumulative incidence of infertility by age 38 ranged from 14.4% to 21.8% for men and from 15.2% to 26.0% for women depending on the infertility definition and data used. Infertility, defined as having tried to conceive for 12months or more or having sought medical help to conceive, was experienced by 21.8% (95% confidence interval [CI], 17.726.2) of men and 26.0% (95% CI, 21.830.6) of women by age 38. For those who experienced infertility, 59.8% (95% CI, 48.370.4) of men and 71.8% (95% CI, 62.180.3) of women eventually had a live birth. Successful resolution of infertility and entry into parenthood by age 38 were much lower for those who first experienced infertility in their mid to late thirties compared with at a younger age. Conclusion(s): Comparison of reports from two assessments in this cohort study suggests infertility estimates from a single cross-sectional study may underestimate lifetime infertility. The lower rate of resolution and entry into parenthood for those first experiencing infertility in their mid to late thirties highlights the consequences of postponing parenthood and could result in involuntary childlessness and fewer children than desired.
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Parsons, M.J., Moffitt, T.E., Gregory, A. M., Goldman-Mellor, S., Nolan, P.M., Poulton, R., Caspi, A. | 2015

Social Jetlag, Obesity and Metabolic Disorder: Investigation in a Cohort Study

International Journal of Obesity, 2015, Advance online publication 20 January 2015; doi: 10.1038/ijo.2014.201.

Our ref: RO661

Show abstract » Background: Obesity is one of the leading causes of preventable death worldwide. Circadian rhythms are known to control both sleep timing and energy homeostasis, and disruptions in circadian rhythms have been linked with metabolic dysfunction and obesity-associated disease. In previous research, social jetlag, a measure of chronic circadian disruption caused by the discrepancy between our internal versus social clocks, was associated with elevated self-reported body mass index, possibly indicative of a more generalized association with obesity and metabolic dysfunction. Methods: We studied participants from the population-representative Dunedin Longitudinal Study (N=1037) to determine whether social jetlag was associated with clinically assessed measurements of metabolic phenotypes and disease indicators for obesity-related disease, specifically, indicators of inflammation and diabetes. Results: Our analysis was restricted to N=815 non-shift workers in our cohort. Among these participants, we found that social jetlag was associated with numerous clinically assessed measures of metabolic dysfunction and obesity. We distinguished between obese individuals who were metabolically healthy versus unhealthy, and found higher social jetlag levels in metabolically unhealthy obese individuals. Among metabolically unhealthy obese individuals, social jetlag was additionally associated with elevated glycated hemoglobin and an indicator of inflammation. Conclusions: The findings are consistent with the possibility that śliving against our internal clock' may contribute to metabolic dysfunction and its consequences. Further research aimed at understanding that the physiology and social features of social jetlag may inform obesity prevention and have ramifications for policies and practices that contribute to increased social jetlag, such as work schedules and daylight savings time.
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Broadbent, J. M. , Thomson, W. M., Ramrakha, S., Moffitt, T.E., Zeng, J., Foster-Page, L.A. , Poulton, R. | 2015

Community water fluoridation and intelligence: Prospective Study in New Zealand

American Journal of Public Health, 2015, 105(1), 72-76.

Our ref: RO653

Show abstract » Objectives.This study aimed to clarify the relationship between community water fluoridation (CWF) and IQ. Methods. We conducted a prospective study of a general population sample of those born in Dunedin, New Zealand, between April 1, 1972, and March 30, 1973 (95.4% retention of cohort after 38 years of prospective follow-up). Residence in a CWF area, use of fluoride dentifrice and intake of 0.5-milligram fluoride tablets were assessed in early life (prior to age 5 years); we assessed IQ repeatedly between ages 7 to 13 years and at age 38 years. Results. No significant differences in IQ because of fluoride exposure were noted. These findings held after adjusting for potential confounding variables, including sex, socioeconomic status, breastfeeding, and birth weight (as well as educational attainment for adult IQ outcomes). Conclusions. These findings do not support the assertion that fluoride in the context of CWF programs is neurotoxic. Associations between very high fluoride exposure and low IQ reported in previous studies may have been affected by confounding, particularly by urban or rural status.
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Goldman-Mellor, S., Gregory, A. M., Caspi, A., Harrington, H. L., Parsons, M.J., Poulton, R., Moffitt, T.E. | 2014

Mental health antecedents of early midlife insomnia: Evidence from a four-decade longitudinal study

Sleep, 2014, 37(11), 1767-1775.

Our ref: RO660

Show abstract » Study objectives. Insomnia is a highly prevalent condition that constitutes a major public health and economic burden. However, little is known about the developmental etiology of adulthood insomnia. Design. We examined whether indicators of psychological vulnerability across multiple developmental periods (psychiatric diagnoses in young adulthood and adolescence, childhood behavioral problems, and familial psychiatric history) predicted subsequent insomnia in adulthood. Setting and participants. We used data from the ongoing Dunedin Multidisciplinary Health and Development Study, a population-representative birth cohort study of 1,037 children in New Zealand who were followed prospectively from birth (19721973) through their fourth decade of life with a 95% retention rate. Measurements. Insomnia was diagnosed at age 38 according to DSM-IV criteria. Psychiatric diagnoses, behavioral problems, and family psychiatric histories were assessed between ages 5 and 38. Results. In cross-sectional analyses, insomnia was highly comorbid with multiple psychiatric disorders. After controlling for this concurrent comorbidity, our results showed that individuals who have family histories of depression or anxiety, and who manifest lifelong depression and anxiety beginning in childhood, are at uniquely high risk of age-38 insomnia. Other disorders did not predict adulthood insomnia. Conclusions. The link between lifelong depression and anxiety symptoms and adulthood insomnia calls for further studies to clarify the neurophysiological systems or behavioral conditioning processes that may underlie this association.
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Shalev, I., Caspi, A., Ambler, A., Belsky, D.W., Chapple, S., Cohen, H., Israel, S., Poulton, R. , Ramrakha, S., Rivera, C., Sugden, K., Williams, B.S., Wolke, D., Moffitt, T.E. | 2014

Perinatal Complications and Aging Indicators by Midlife

Pediatrics, 2014, 134 e1315-e1323. Available early view online DOI: 10.1542/peds.2014-1669.

Our ref: RO658

Show abstract » BACKGROUND: Perinatal complications predict increased risk for morbidity and early mortality. Evidence of perinatal programming of adult mortality raises the question of what mechanisms embed this long-term effect. We tested a hypothesis related to the theory of developmental origins of health and disease: that perinatal complications assessed at birth predict indicators of accelerated aging by midlife. METHODS: Perinatal complications, including both maternal and neonatal complications, were assessed in the Dunedin Multidisciplinary Health and Development Study cohort (N = 1037), a 38-year, prospective longitudinal study of a representative birth cohort. Two aging indicators were assessed at age 38 years, objectively by leukocyte telomere length (TL) and subjectively by perceived facial age. RESULTS: Perinatal complications predicted both leukocyte TL (b =20.101; 95% confidence interval, 20.169 to 20.033; P = .004) and perceived age (b = 0.097; 95% confidence interval, 0.029 to 0.165; P = .005) by midlife. We repeated analyses with controls for measures of family history and social risk that could predispose to perinatal complications and accelerated aging, and for measures of poor health taken in between birth and the age-38 follow-up. These covariates attenuated, but did not fully explain the associations observed between perinatal complications and aging indicators. CONCLUSIONS: Our findings provide support for early-life developmental programming by linking newborns' perinatal complications to accelerated aging at midlife. We observed indications of accelerated aging inside,Ł as measured by leukocyte TL, an indicator of cellular aging, and outside,Ł as measured by perceived age, an indicator of declining tissue integrity. A better understanding of mechanisms underlying perinatal programming of adult aging is needed.
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Israel, S., Caspi, A., Belsky, D.W., Harrington, H. L., Hogan, S., Houts, R., Ramrakha, S., Sanders, S., Poulton, R. , Moffitt, T.E. | 2014

Credit Scores, Cardiovascular Disease Risk and Human Capital

PNAS, 2014, Available Early Edition online DOI: 10.1073.

Our ref: RO659

Show abstract » Credit scores are the most widely used instruments to assess whether or not a person is a financial risk. Credit scoring has been so successful that it has expanded beyond lending and into our everyday lives, even to inform how insurers evaluate our health. The pervasive application of credit scoring has outpaced knowledge about why credit scores are such useful indicators of individual behavior. Here we test if the same factors that lead to poor credit scores also lead to poor health. Following the Dunedin (New Zealand) Longitudinal Study cohort of 1,037 study members, we examined the association between credit scores and cardiovascular disease risk and the underlying factors that account for this association. We find that credit scores are negatively correlated with cardiovascular disease risk. Variation in household income was not sufficient to account for this association. Rather, individual differences in human capital factors educational attainment, cognitive ability, and self-control predicted both credit scores and cardiovascular disease risk and accounted for ~45% of the correlation between credit scores and cardiovascular disease risk. Tracing human capital factors back to their childhood antecedents revealed that the characteristic attitudes, behaviors, and competencies children develop in their first decade of life account for a significant portion (~22%) of the link between credit scores and cardiovascular disease risk at midlife. We discuss the implications of these findings for policy debates about data privacy, financial literacy, and early childhood interventions.
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Shin, H.H., Sears, M.R., Hancox, R. J. | 2014

Prevalence and correlates of a 'knee' pattern on the maximal expiratory flow volume loop in young adults

Respirology, 2014, 19(7), 1052-1058.

Our ref: RO657

Show abstract » Background and objective: Visual inspection of the maximal flow-volume curve is an important step in interpreting spirometry. Many young people have a convex inflection or 'knee' on the expiratory part of the loop. This is thought to be a normal variant, but this view is based on theoretical grounds, and the epidemiology of the knee pattern has never been reported. Methods: Flow-volume loops from an unselected birth cohort of 1037 individuals at ages 18, 26, 32 and 38 years were visually inspected for a knee pattern. Associations with asthma diagnoses, smoking history, body mass index (BMI) and spirometry were assessed. Results: The knee pattern was found in approximately two thirds of men and women at age 18. The prevalence decreased with age, but it was more likely to persist in women. The knee was more common after bronchodilator and was associated with higher forced expiratory volume in 1 s/forced vital capacity ratios and mid-expiratory flow rates. There was no association with smoking, except for an inverse correlation in men at age 18. No association was found with BMI. Women with asthma were less likely to have a knee at both ages 18 and 38, whereas men with asthma showed an inverse association at age 18. Conclusions: A knee is a very common pattern on flow-volume loop in young adults. In accordance with theoretical predictions, the prevalence of the knee declines with age, but it is more likely to persist in women. It is associated with less airflow obstruction and is less common in people with asthma.
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Belsky, D.W., Shalev, I., Sears, M.R., Hancox, R. J., Harrington, H. L., Houts, R., Moffitt, T.E., Sugden, K., Williams, B.S., Poulton, R., Caspi, A. | 2014

Is Chronic Asthma Associated with Shorter Leukocyte Telomere Length at Midlife?

American Journal of Respiratory and Critical Care Medicine, 2014, First published online 23 Jun 2014 as DOI: 10.1164/rccm.201402-0370OC.

Our ref: RO656

Show abstract » Background. Asthma is prospectively associated with age-related chronic diseases and mortality, suggesting the hypothesis that asthma may relate to a general, multi-system phenotype of accelerated aging. Objective. To test whether chronic asthma is associated with a proposed biomarker of accelerated aging, leukocyte telomere length. Method. Asthma was ascertained prospectively in the Dunedin Multidisciplinary Health and Development Study cohort (N=1,037) at 9 in-person assessments spanning ages 9 to 38 years. Leukocyte telomere length was measured at ages 26 and 38 years. Asthma was classified as life-course-persistent, childhood-onset not meeting criteria for persistence, and adolescent/adult onset. We tested associations between asthma and leukocyte telomere length using regression models. We tested for confounding of asthma-leukocyte telomere length associations using covariate adjustment. We tested serum C-reactive protein and white blood cell counts as potential mediators of asthma-leukocyte telomere length associations. Results. Study members with life-course-persistent asthma had shorter leukocyte telomere length as compared to sex- and age-matched peers with no reported asthma. In contrast, leukocyte telomere length in study members with childhood-onset and adolescent/adult-onset asthma was not different from leukocyte telomere length in peers with no reported asthma. Adjustment for life histories of obesity and smoking did not change results. Study members with life-course-persistent asthma had elevated blood eosinophil counts. Blood eosinophil count mediated 29% of the life-course-persistent asthma-leukocyte telomere length association. Conclusions. Life-course-persistent asthma is related to a proposed biomarker of accelerated aging, possibly via systemic eosinophilic inflammation. Life histories of asthma can inform studies of aging.
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Iosua, E., Gray, A.R., McGee, R., Landhuis, C.E., Keane, R., Hancox, R. J. | 2014

Employment among schoolchildren and its associations with adult substance use, psychological wellbeing, and academic achievement

Journal of Adolescent Health, 2014, 55(4), 542-548.

Our ref: RO655

Show abstract » Purpose: To examine the association between paid part-time employment among schoolchildren, and adult substance use, psychological wellbeing, and academic achievement. Methods: Longitudinal data from the Dunedin Multidisciplinary Health and Development Study were used to evaluate the association between employment at each of 11, 13, and 15 years, and adult smoking, regular alcohol binge drinking, regular cannabis use, Sense of Coherence, social participation, positive coping style, prosociality, no formal qualifications, and university degree. Associations were initially assessed using unadjusted regression analyses and then adjusted for the potential childhood confounders IQ, reading development, Student's Perception of Ability Scale, socioeconomic disadvantage, family climate, harsh parent-child interaction, parental opinion of their child's attitude to school, and child's personal attitude to school. Results: Employment at 11 years of age was associated with a lower odds of adult smoking; the odds of subsequent regular alcohol binge drinking were greater for those who were employed at age 13; and higher adult rates of social participation and prosociality were identified for adolescents who were employed at 15 years of age. When the potential confounders were con- trolled, employment at age 13 was predictive of both adult smoking and regular binge drinking, and working at 15 years of age was protective against regular cannabis use and associated with greater social participation. Conclusion: There is no consistent evidence that exposing schoolchildren to part-time employment compromised subsequent health, wellbeing, and education in a developed country.
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Breslau, N., Koenen, K., Swanson, S., Agnew-Blais, M.A., Houts, R., Poulton, R., Moffitt, T.E. | 2014

Childhood maltreatment, juvenile disorders and adult post-traumatic stress disorder: A prospective investigation

Psychological Medicine, 2014, 44(9), 1937ÔÇô1945.

Our ref: RO654

Show abstract » Background We examine prospectively the influence of two separate but potentially inter-related factors in the etiology of post-traumatic stress disorder (PTSD): childhood maltreatment as conferring a susceptibility to the PTSD response to adult trauma and juvenile disorders as precursors of adult PTSD. Method The Dunedin Multidisciplinary Health and Development Study (DMHDS) is a birth cohort (n = 1037) from the general population of New Zealand's South Island, with multiple assessments up to age 38 years. DSM-IV PTSD was assessed among participants exposed to trauma at ages 26"38. Complete data were available on 928 participants. Results Severe maltreatment in the first decade of life, experienced by 8.5% of the sample, was associated significantly with the risk of PTSD among those exposed to adult trauma [odds ratio (OR) 2.64, 95% confidence interval (CI) 1.16"6.01], compared to no maltreatment. Moderate maltreatment, experienced by 27.2%, was not associated significantly with that risk (OR 1.55, 95% CI 0.85"2.85). However, the two estimates did not differ significantly from one another. Juvenile disorders (ages 11"15), experienced by 35% of the sample, independent of childhood maltreatment, were associated significantly with the risk of PTSD response to adult trauma (OR 2.35, 95% CI 1.32"4.18). Conclusions Severe maltreatment is associated with risk of PTSD response to adult trauma, compared to no maltreatment, and juvenile disorders, independent of earlier maltreatment, are associated with that risk. The role of moderate maltreatment remains unresolved. Larger longitudinal studies are needed to assess the impact of moderate maltreatment, experienced by the majority of adult trauma victims with a history of maltreatment.
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Dickson, N., Righarts, A., van Roode, T., Paul, C., Taylor, J., Cunningham, A.L. | 2014

HSV-2 incidence by sex over four age periods to age 38 in a birth cohort

Sexually Transmitted Infections, 2014, 90(3), 143-145.

Our ref: R0652

Show abstract » Objectives: To examine herpes simplex virus type 2 (HSV-2) incidence over four periods to age 38 in a birth cohort, and to compare risks for men and women, taking into account sexual behaviour. Methods: At ages 21, 26, 32 and 38, participants in the Dunedin Multidisciplinary Health and Development Study were invited to provide serum for HSV-2 serology, and information on sexual behaviour. HSV-2 incidence rates were calculated for four age periods, and comparisons made by sex and period, taking into account number of sexual partners. Results: By age 38, 17.3% of men and 26.8% of women had ever been seropositive for HSV-2. Incidence peaked for women from age 21 to 26 (19.1 per 1000 person-years) and men from age 26 to 32 (14.1 per 1000 person-years); it fell markedly for both from age 32 to 38 (5.1 and 6.8 per 1000 person-years for men and women, respectively). Overall risk was significantly higher for women: adjusted incidence rate ratio 1.9 (95% CI 1.4 to 2.7); the sex difference was most marked from age 21 to 26 (3.4, 95% CI 1.9 to 6.3). Conclusions: Our findings are consistent with a greater biological susceptibility to HSV-2 among women, and with the increasing risk to the early/mid-20s for women and late 20s/early 30s for men, being driven by an increasing pool of prevalent infection. The reduced risk in the mid-30s is consistent with declining infectivity of long-term prevalent infections.
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