Commentary: The use and misuse of life course models

Testing lifecourse theories characterising associations between maternal depression and offspring depression in emerging adulthood: the Avon Longitudinal Study of Parents and Children

BACKGROUND

Maternal depression is a major determinant of offspring mental health. Yet, little is understood about how the duration and timing of maternal depression shapes youth risk for depressive symptoms, which if understood could inform when best to intervene. This study aimed to determine how the timing and duration of maternal depression was related to offspring depression in emerging adulthood, and if these associations varied by sex.

METHODS

We analysed data from the Avon Longitudinal Study of Parents and Children (a prenatal cohort in the Avon area of England, 1991-2003), n = 3,301. We applied the structured lifecourse modelling approach to maternal depression (assessed at 13 points from prenatal period to adolescence) and emerging adult depressive symptoms (age 21). Lifecourse models assessed were accumulation (sum of timepoints when maternal depression was reported), sensitive periods (each period assessed as one during which maternal depression has a stronger effect) and instability (frequent fluctuations in maternal depression).

RESULTS

Female adolescents (n = 2,132) had higher SMFQ scores (mean = 6.15, SD = 5.90) than males (n = 1,169, mean = 4.87, SD = 4.82). Maternal depression was most common in the infancy period (21.2% males; 21.4% females). For males, accumulation was the most appropriate lifecourse model; for each additional period of maternal depression, depressive symptoms in emerging adulthood increased by 0.11 (95% CI: 0.07, 0.15, one-sided p value ≤ .001). For females, exposure to maternal depression was associated with increasing depressive symptoms in emerging adulthood, with the largest effect in mid-childhood (increase of 0.27 units, 95% CI 0.03-0.50, p = .015 for difference between mid-childhood and other time-periods) and a smaller, equal effect at all other time-periods (increase of 0.07 units per time-period, 95% CI: 0.03-0.12, p = .002).

CONCLUSIONS

This study highlights the importance of ongoing maternal depression for the development of depression in offspring through to emerging adulthood. Because long-term exposure to maternal depression was particularly important, early interventions are warranted.

Parents' awareness and perceptions of the Change4Life 100 cal snack campaign, and perceived impact on snack consumption by children under 11 years

Background

Childhood obesity is a pertinent public health problem in the UK. Consumption of free sugars has been associated with the development of obesity. In 2018, the Change 4Life (C4L) 100 cal snack campaign was launched with the slogan ‘100 calorie snacks, two a day max’, aiming to encourage parents to choose lower sugar, fat and calorie snacks for their children. This study aimed to examine how the campaign has been perceived by parents.

Methods

An online survey was developed to explore parent awareness, perceptions and understanding of the C4L 100 cal snack campaign. Respondents were recruited via Leeds City Council, posters displayed at primary schools and children’s centres across Leeds and via social media. Paper surveys were also shared with voluntarily led playgroups. Survey data was analysed using descriptive statistics. Thematic analysis was performed on open text responses.

Results

Three hundred forty-two 342 respondents completed the survey. Just over half of the respondents had come across the campaign, most seeing the leaflet or a television advert. Over two-thirds of respondents ‘agreed’ or ‘strongly agreed’ that the campaign caught their attention. A similar proportion ‘agreed’ or ‘strongly agreed’ that the campaign informed them about 100 cal snacks and just over a half thought it was memorable. Most respondents used positive language to describe the campaign, but there was no clear consensus of a perceived positive impact on healthier snack purchasing, nor preparing more 100 cal snacks at home. Respondents provided examples of how the campaign could be improved to positively impact eating behaviours: better publicity and information delivery; healthier snack examples made more visible; improved nutritional labelling and access to healthier products in supermarkets (availability, promotion, display, choice).

Conclusions

The C4L 100 cal snack campaign was perceived positively by parents and carers, with many agreeing that the campaign was informative and memorable. However, there was no agreement in terms of the parents reporting an impact of the campaign on behaviour change and healthier snack habits. Future social marketing campaigns could be improved through more formal pilot testing to assess the understanding and acceptance of the campaign amongst the target audience.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-12789-7.

Study protocol: MyoFit46-the cardiac sub-study of the MRC National Survey of Health and Development

BACKGROUND

The life course accumulation of overt and subclinical myocardial dysfunction contributes to older age mortality, frailty, disability and loss of independence. The Medical Research Council National Survey of Health and Development (NSHD) is the world's longest running continued surveillance birth cohort providing a unique opportunity to understand life course determinants of myocardial dysfunction as part of MyoFit46-the cardiac sub-study of the NSHD.

METHODS

We aim to recruit 550 NSHD participants of approximately 75 years+ to undertake high-density surface electrocardiographic imaging (ECGI) and stress perfusion cardiovascular magnetic resonance (CMR). Through comprehensive myocardial tissue characterization and 4-dimensional flow we hope to better understand the burden of clinical and subclinical cardiovascular disease. Supercomputers will be used to combine the multi-scale ECGI and CMR datasets per participant. Rarely available, prospectively collected whole-of-life data on exposures, traditional risk factors and multimorbidity will be studied to identify risk trajectories, critical change periods, mediators and cumulative impacts on the myocardium.

DISCUSSION

By combining well curated, prospectively acquired longitudinal data of the NSHD with novel CMR-ECGI data and sharing these results and associated pipelines with the CMR community, MyoFit46 seeks to transform our understanding of how early, mid and later-life risk factor trajectories interact to determine the state of cardiovascular health in older age.

TRIAL REGISTRATION

Prospectively registered on ClinicalTrials.gov with trial ID: 19/LO/1774 Multimorbidity Life-Course Approach to Myocardial Health- A Cardiac Sub-Study of the MCRC National Survey of Health and Development (NSHD).

Physical Inactivity From Childhood to Adolescence and Incident Depression

INTRODUCTION

The long-term impact of physical activity during early life on the risk of depression in later stages of adulthood remains unclear. This study examines the association between physical activity during childhood and adolescence and the incidence of depressive symptoms in early, middle, and late adulthood.

METHODS

Data from a birth cohort (the 1958 National Child Development Survey), including births (N=17,415) in England, Wales, and Scotland, were used. After birth, 11 more follow-ups were carried out between ages 7 and 62 years (2020). Leisure-time physical activity was assessed through a self-reported questionnaire. Psychological measures were assessed with the teacher-rated Bristol Social Adjustment Guide, the teacher-rated Rutter scale, and the self-rated Malaise Inventory. Leisure-time physical activity and psychological symptoms were examined in all the 11 follow-up assessments included in this study. Best-fit model was used to obtain hazard ratios and 95% CIs of depression symptoms by physical activity status in different ages, including demographic, behavioral, and health-related variables as potential confounders.

RESULTS

After multivariate analysis, being physically active at age 16 years reduced the risk of incident elevated depressive symptoms (hazard ratio=0.73, 95% CI=0.62, 0.85) throughout adulthood. The long-term impacts of physical activity practiced at age 16 years persisted throughout adulthood up to age 62 years.

CONCLUSIONS

Adolescence is a critical early-life period to promote physical activity for reducing the incidence of elevated depressive symptoms throughout adulthood. Public health policies should promote healthy lifestyles during the lifespan to reduce both the burden of physical inactivity and depressive symptoms at the population level.

Childhood growth and development and DNA methylation age in mid-life

BACKGROUND

In the first study of its kind, we examine the association between growth and development in early life and DNAm age biomarkers in mid-life.

METHODS

Participants were from the Medical Research Council National Survey of Health and Development (n = 1376). Four DNAm age acceleration (AgeAccel) biomarkers were measured when participants were aged 53 years: AgeAccelHannum; AgeAccelHorvath; AgeAccelLevine; and AgeAccelGrim. Exposure variables included: relative weight gain (standardised residuals from models of current weight z-score on current height, and previous weight and height z-scores); and linear growth (standardised residuals from models of current height z-score on previous height and weight z-scores) during infancy (0-2 years, weight gain only), early childhood (2-4 years), middle childhood (4-7 years) and late childhood to adolescence (7-15 years); age at menarche; and pubertal stage for men at 14-15 years. The relationship between relative weight gain and linear growth and AgeAccel was investigated using conditional growth models. We replicated analyses from the late childhood to adolescence period and pubertal timing among 240 participants from The National Child and Development Study (NCDS).

RESULTS

A 1SD increase in relative weight gain in late childhood to adolescence was associated with 0.50 years (95% CI 0.20, 0.79) higher AgeAccelGrim. Although the CI includes the null, the estimate was similar in NCDS [0.57 years (95% CI - 0.01, 1.16)] There was no strong evidence that relative weight gain and linear growth in childhood was associated with any other AgeAccel biomarker. There was no relationship between pubertal timing in men and AgeAccel biomarkers. Women who reached menarche ≥ 12 years had 1.20 years (95% CI 0.15, 2.24) higher AgeAccelGrim on average than women who reached menarche < 12 years; however, this was not replicated in NCDS and was not statistically significant after Bonferroni correction.

CONCLUSIONS

Our findings generally do not support an association between growth and AgeAccel biomarkers in mid-life. However, we found rapid weight gain during pubertal development, previously related to higher cardiovascular disease risk, to be associated with older AgeAccelGrim. Given this is an exploratory study, this finding requires replication.

Body Mass Index Mediates the Association between Growth Trajectories and Cardiometabolic Risk in Children

Background: Few studies have published mediation analyses to quantify the role concurrent BMI plays in the relationship between growth and cardiometabolic risk (CMR) outcomes. Methods: We used data from a longitudinal cohort study conducted in children aged 0-60 months through The Applied Research Group for Kids (TARGet Kids!) in Canada. Four age and sex standardized BMI (zBMI) trajectories were identified using latent class mixed models. CMR were assessed using a CMR score. Concurrent zBMI was the zBMI measured on the same visit as CMR. Mediation analyses were performed comparing each trajectory with the reference trajectory. Results: One thousand one hundred sixty-five children were included. On average, compared with being in the stable low trajectory, being in the catch-up trajectory was associated with an increased CMR score of 0.42, 0.28 of which was mediated through concurrent zBMI [95% confidence interval (CI) 0.17 to 0.41, p = 0.001]; being in the stable high trajectory was associated with an increased CMR score of 0.23, 0.24 through concurrent zBMI (95% CI 0.18 to 0.31, p < 0.001). Similarly, being in the rapid accelerating trajectory was associated with an increased CMR score of 1.43, 1.18 of which was through concurrent zBMI (95% CI 0.89 to 1.50, p < 0.001). Conclusions: There was a strong evidence that the effect of BMI trajectories on CMR was indirect via concurrent BMI. It is important for researchers to choose the most appropriate analytic method based on the study hypothesis to understand the total or direct effect of growth patterns on cardiometabolic disease risk in children.

Associations Between Vascular Risk Across Adulthood and Brain Pathology in Late Life: Evidence From a British Birth Cohort

Question

When is vascular risk during adulthood (early adulthood, midlife, or late life) most strongly associated with late-life brain structure and pathology?

Findings

In a propective cohort of 463 participants free of dementia from the population-based Insight 46 study, higher vascular risk in early adulthood was most strongly associated with smaller whole-brain volumes and greater white matter–hyperintensity volumes at age 69 to 71 years. There were no associations at any age with amyloid status.

Meaning

These findings are consistent with vascular risk influencing late-life brain health via cerebral small-vessel disease and lower brain volumes but not amyloidosis; vascular risk screening and modification may need to be considered from early adulthood.

Importance

Midlife vascular risk burden is associated with late-life dementia. Less is known about if and how risk exposure in early adulthood influences late-life brain health.

Objective

To determine the associations between vascular risk in early adulthood, midlife, and late life with late-life brain structure and pathology using measures of white matter–hyperintensity volume, β-amyloid load, and whole-brain and hippocampal volumes.

Design, Setting, and Participants

This prospective longitudinal cohort study, Insight 46, is part of the Medical Research Council National Survey of Health and Development, which commenced in 1946. Participants had vascular risk factors evaluated at ages 36 years (early adulthood), 53 years (midlife), and 69 years (early late life). Participants were assessed with multimodal magnetic resonance imaging and florbetapir-amyloid positron emission tomography scans between May 2015 and January 2018 at University College London. Participants with at least 1 available imaging measure, vascular risk measurements at 1 or more points, and no dementia were included in analyses.

Exposures

Office-based Framingham Heart study–cardiovascular risk scores (FHS-CVS) were derived at ages 36, 53, and 69 years using systolic blood pressure, antihypertensive medication usage, smoking, diabetic status, and body mass index. Analysis models adjusted for age at imaging, sex, APOE genotype, socioeconomic position, and, where appropriate, total intracranial volume.

Main Outcomes and Measures

White matter–hyperintensity volume was generated from T1/fluid-attenuated inversion recovery scans using an automated technique and whole-brain volume and hippocampal volume were generated from automated in-house pipelines; β-amyloid status was determined using a gray matter/eroded subcortical white matter standardized uptake value ratio threshold of 0.61.

Results

A total of 502 participants were assessed as part of Insight 46, and 463 participants (236 male [51.0%]) with at least 1 available imaging measure (mean [SD] age at imaging, 70.7 [0.7] years; 83 β-amyloid positive [18.2%]) who fulfilled eligibility criteria were included. Among them, FHS-CVS increased with age (36 years: median [interquartile range], 2.7% [1.5%-3.6%]; 53 years: 10.9% [6.7%-15.6%]; 69 years: 24.3% [14.9%-34.9%]). At all points, these scores were associated with smaller whole-brain volumes (36 years: β coefficient per 1% increase, −3.6 [95% CI, −7.0 to −0.3]; 53 years: −0.8 [95% CI, −1.5 to −0.08]; 69 years: −0.6 [95% CI, −1.1 to −0.2]) and higher white matter–hyperintensity volume (exponentiated coefficient: 36 years, 1.09 [95% CI, 1.01-1.18]; 53 years, 1.02 [95% CI, 1.00-1.04]; 69 years, 1.01 [95% CI, 1.00-1.02]), with largest effect sizes at age 36 years. At no point were FHS-CVS results associated with β-amyloid status.

Conclusions and Relevance

Higher vascular risk is associated with smaller whole-brain volume and greater white matter–hyperintensity volume at age 69 to 71 years, with the strongest association seen with early adulthood vascular risk. There was no evidence that higher vascular risk influences amyloid deposition, at least up to age 71 years. Reducing vascular risk with appropriate interventions should be considered from early adulthood to maximize late-life brain health.

Lifecourse body mass index trajectories and cardio-metabolic disease risk in Guatemalan adults

Little is known about body size over the life-course and non-communicable disease risk in low- and middle-income country populations. Our study explored the role of body mass index (BMI) trajectories from infancy through mid-adulthood on cardio-metabolic disease (CMD) risk factors in a prospective cohort of Guatemalan adults. Study participants were born in Guatemala from 1962-77 and have been followed prospectively since participating in a nutrition supplementation trial as children. Sex-specific BMI latent class trajectories were derived using latent class growth modeling from up to 22 possible BMI values from age 1 month to 42 years measured between 1969 and 2004. CMD risk factors were assessed in 2015-17 (at age 37-54 years) using anthropometry, blood glucose and lipids, and blood pressure. We used logistic regression to assess the role of BMI trajectory on CMD risk factors in 510 women and 346 men (N = 856). We identified two BMI latent classes for women (low [n = 287, 56.3%] and high [n = 223, 43.7%]) and three classes for men (low [n = 141, 40.8%], medium [n = 160, 46.2%], and high [n = 45, 13.0%]). Given the small percentage of men in the high BMI latent class, we collapsed the medium and high BMI latent classes for men (n = 205, 59.1%). Among the most prevalent CMD risk factors at ages 37-54 years were abdominal obesity defined by waist-height ratio (99.6% of women and 87.3% of men), obesity defined by percent body fat (96.6% of women and 75.9% of men), low HDL-c (87.5% of women and 74.5% of men), and elevated triglycerides (78.3% of women and 73.6% of men). Except for obesity defined by BMI, we found no associations between BMI latent class and CMD risk factors in women. Among men, BMI latent class was not associated with CMD risk factors after controlling for current BMI. For the CMD risk factors we analyzed, the role of early life BMI on adult CMD appeared to be mediated by adult BMI among men-highlighting the need to establish and maintain healthy body weight over the life course.

Trajectories of childhood adversity and mortality in early adulthood: a population-based cohort study

BACKGROUND

Childhood is a sensitive period with rapid brain development and physiological growth, and adverse events in childhood might interfere with these processes and have long-lasting effects on health. In this study, we aimed to describe trajectories of adverse childhood experiences and relate these to overall and cause-specific mortality in early adult life.

METHODS

For this population-based cohort study, we used unselected annually updated data from Danish nationwide registers covering more than 1 million children born between 1980 and 1998. We distinguished between three different dimensions of childhood adversities: poverty and material deprivation, loss or threat of loss within the family, and aspects of family dynamics such as maternal separation. We used a group-based multi-trajectory clustering model to define the different trajectories of children aged between 0 and 16 years. We assessed the associations between these trajectories and mortality rates between 16 and 34 years of age using a Cox proportional hazards model and an Aalen hazards difference model.

FINDINGS

Between Jan 1, 1980 and Dec 31, 2015, 2 223 927 children were included in the Danish Life Course cohort. We excluded 1 064 864 children born after 1998, 50 274 children who emigrated before their 16th birthday, and 11 161 children who died before their 16th birthday, resulting in a final sample of 1 097 628 children. We identified five distinct trajectories of childhood adversities. Compared with children with a low adversity trajectory, those who had early-life material deprivation (hazard ratio 1·38, 95% CI 1·27-1·51), persistent deprivation (1·77, 1·62-1·93), or loss or threat of loss (1·80, 1·61-2·00) had a moderately higher risk of premature mortality. A small proportion of children (36 081 [3%]) had multiple adversities within all dimensions and throughout the entire childhood. This group had a 4·54 times higher all-cause mortality risk (95% CI 4·07-5·06) than that of children with a low adversity trajectory, corresponding to 10·30 (95% CI 9·03-11·60) additional deaths per 10 000 person-years. Accidents, suicides, and cancer were the most common causes of death in this high adversity population.

INTERPRETATION

Almost half of Danish children in our study experienced some degree of adversity, and this was associated with a moderately higher risk of mortality in adulthood. Among these, a small group of children had multiple adversities across social, health, and family-related dimensions. This group had a markedly higher mortality risk in early adulthood than that of other children, which requires public health attention.

FUNDING

None.

The feasibility and acceptability of a primary school-based programme targeting diet and physical activity: the PhunkyFoods Programme

Background

This study aims to evaluate the feasibility and acceptability of the PhunkyFoods Programme, a primary school-based intervention to promote healthy nutrition and physical activity knowledge and behaviours to assess outcomes to inform a phase 3 trial.

Methods

The cluster randomised feasibility trial recruited eight primary schools from the North of England. Elibility criteria included all primary schools in one town, excluding independent and special schools and schools that comprised of only key stage 2 pupils (years 3–6). Eight schools agreed to participate. Randomisation to intervention or control arms was in a 1:1 ratio. Intervention schools received PhunkyFoods over 17 months. Control schools continued with usual curriculum. Assessors were blinded to group assignment. Measures comprised of a Healthy Lifestyle Knowledge Questionnaire and Synchronised Nutrition and Activity Program to assess diet and physical activity, height, weight, and psychological wellbeing. Feasibility outcomes were recruitment, attrition rates, interviews with teaching staff, focus groups with pupils to explore the acceptability of outcome measures, implementation, intervention content, and programme fidelity.

Results

Three hundred fifty-eight pupils, aged 6–9 years from eight schools were recruited at baseline (control n = 170, intervention n = 188); 337 (94.1%) at 6 months (control n = 163, intervention n = 181); and 331 (92.5%) at 18 months (control n = 152, intervention n = 179), and 6 pupils opted out. Trends in increased knowledge of healthy lifestyle behaviours, healthier eating, and liking of fruit and vegetables were reported in the intervention compared to the control group. Year 4 intervention pupils had significantly higher healthy balanced diet knowledge scores compared to control pupils, mean difference 5.1 (95% CI 0.1 to 10.1, p=0.05). At 18 months, the mean percentage of vegetables liked was higher (intervention 53.9% vs. 43.0% control). Similarly, percentage of fruits liked was also higher (intervention 76.9% vs. 67.2% control). Qualitative data showed that delivery of the intervention was feasible and acceptable to teachers and pupils. Lessons were learned to inform the phase 3 trial around the dietary assessment measure and timing of recruitment.

Conclusions

Whilst the study was not powered to detect a definitive effect, results suggest a potential to increase knowledge of healthy lifestyle behaviours and dietary behaviours, suggesting that with minor changes, a phase 3 trial is likely to be deliverable.

Trial registration

ISRCTN, ISRCTN15641330. Registered 8 May 2015—retrospectively registered, 10.1186/ISRCTN15641330

Effective implementation of primary school-based healthy lifestyle programmes: a qualitative study of views of school staff

Background

Primary schools are valuable settings to implement healthy lifestyle (healthy eating and physical activity) interventions, aimed at targeting childhood obesity. This study explored school staff perceptions of factors that hinder and enable successful implementation and sustainability of healthy lifestyle interventions in primary schools. Qualitative data was pooled and analysed from two evaluations carried out in primary schools in North England: a feasibility study of a nutrition and physical activity educational programme (PhunkyFoods Feasibility Study), and an evaluation of a healthy eating programme (The Food Dudes Evaluation).

Methods

Sixty-five qualitative semi-structured interviews were conducted with head teachers, teachers, catering managers, designated school-based programme coordinators and programme staff supporting schools with programme delivery, at 14 schools involved in both evaluations. Thematic analysis was undertaken and emergent themes categorised using a framework for successful implementation by Durlak and Dupre (2008).

Results

Overall, all schools were delivering a range of healthy lifestyle programmes, often with overlapping content. Perceived challenges to implementation of individual programmes included: limited time, timing of implementation, limited training and support, insufficient resources, capacity and facilities, staff perceptions of intervention and perceived skill-proficiency (for cooking and physical activities). Short-term funding, lack of external and internal support were perceived to hinder sustainability. Staff recommendations for successful implementation of future programmes included: extended training and planning time, sufficient capacity, external support for delivery, good resources (interactive, practical and adaptable), and facilities for cooking, healthy eating, gardening and physical activities. Head teachers need to prioritise delivery of a few key healthy lifestyle programmes, in an overcrowded curriculum. Schools need to employ strategies to engage participation of staff, pupils and parents long term.

Conclusions

Effective implementation of school-based healthy lifestyle programmes was thought to be aided by flexible and adaptable programmes, enabling good contextual fit, well-resourced programmes and effective leadership at multiple levels, pupil (pupils support delivery) and parent involvement. To facilitate sustainability, it was perceived that programmes need to be integrated within the curriculum and school policies long term, with sustained support from head teachers and staff. These findings are relevant to programme developers, policy makers and those involved in delivering interventions.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7550-2) contains supplementary material, which is available to authorized users.

Life course epidemiology: Modeling educational attainment with administrative data

Background

Understanding the processes across childhood and adolescence that affect later life inequalities depends on many variables for a large number of individuals measured over substantial time periods. Linkable administrative data were used to generate birth cohorts and to study pathways of inequity in childhood and early adolescence leading to differences in educational attainment. Advantages and disadvantages of using large administrative data bases for such research were highlighted.

Methods

Children born in Manitoba, Canada between 1982 and 1995 were followed until age 19 (N = 89,763), with many time-invariant measures serving as controls. Five time-varying predictors of high school graduation—three social and two health—were modelled using logistic regression and a framework for examining predictors across the life course. For each time-varying predictor, six temporal patterns were tested: full, accumulation of risk, sensitive period, and three critical period models.

Results

Predictors measured in early adolescence generated the highest odds ratios, suggesting the importance of adolescence. Full models provided the best fit for the three time-varying social measures. Residence in a low-income neighborhood was a particularly influential predictor of not graduating from high school. The transmission of risk across developmental periods was also highlighted; exposure in one period had significant implications for subsequent life stages.

Conclusion

This study advances life course epidemiology, using administrative data to clarify the relationships among several measures of social behavior, cognitive development, and health. Analyses of temporal patterns can be useful in studying such other outcomes as educational achievement, teen pregnancy, and workforce participation.

Maternal gestational weight gain and DNA methylation in young women: application of life course mediation methods

AIM

To investigate the role of maternal gestational weight gain (GWG) and prepregnancy BMI on programming offspring DNA methylation.

METHODS

Among 589 adult (age = 32) women participants of the Jerusalem Perinatal Study, we quantified DNA methylation in five candidate genes. We used inverse probability-weighting and parametric g-formula to estimate direct effects of maternal prepregnancy BMI and GWG on methylation.

RESULTS

Higher maternal GWG, but not prepregnancy BMI, was inversely related to offspring ABCA1 methylation (β = -1.1% per quartile; 95% CI: -2.0, -0.3) after accounting for ancestry, parental and offspring exposures. Total and controlled direct effects were nearly identical suggesting included offspring exposures did not mediate this relationship. Results were robust to sensitivity analyses for missing data and model specification.

CONCLUSION

We find some support for epigenetic programming and highlight strengths and limitations of these methods relative to other prevailing approaches.

Study protocol: Insight 46 - a neuroscience sub-study of the MRC National Survey of Health and Development

BACKGROUND

Increasing age is the biggest risk factor for dementia, of which Alzheimer's disease is the commonest cause. The pathological changes underpinning Alzheimer's disease are thought to develop at least a decade prior to the onset of symptoms. Molecular positron emission tomography and multi-modal magnetic resonance imaging allow key pathological processes underpinning cognitive impairment - including β-amyloid depostion, vascular disease, network breakdown and atrophy - to be assessed repeatedly and non-invasively. This enables potential determinants of dementia to be delineated earlier, and therefore opens a pre-symptomatic window where intervention may prevent the onset of cognitive symptoms.

METHODS/DESIGN

This paper outlines the clinical, cognitive and imaging protocol of "Insight 46", a neuroscience sub-study of the MRC National Survey of Health and Development. This is one of the oldest British birth cohort studies and has followed 5362 individuals since their birth in England, Scotland and Wales during one week in March 1946. These individuals have been tracked in 24 waves of data collection incorporating a wide range of health and functional measures, including repeat measures of cognitive function. Now aged 71 years, a small fraction have overt dementia, but estimates suggest that ~1/3 of individuals in this age group may be in the preclinical stages of Alzheimer's disease. Insight 46 is recruiting 500 study members selected at random from those who attended a clinical visit at 60-64 years and on whom relevant lifecourse data are available. We describe the sub-study design and protocol which involves a prospective two time-point (0, 24 month) data collection covering clinical, neuropsychological, β-amyloid positron emission tomography and magnetic resonance imaging, biomarker and genetic information. Data collection started in 2015 (age 69) and aims to be completed in 2019 (age 73).

DISCUSSION

Through the integration of data on the socioeconomic environment and on physical, psychological and cognitive function from 0 to 69 years, coupled with genetics, structural and molecular imaging, and intensive cognitive and neurological phenotyping, Insight 46 aims to identify lifetime factors which influence brain health and cognitive ageing, with particular focus on Alzheimer's disease and cerebrovascular disease. This will provide an evidence base for the rational design of disease-modifying trials.