Marcus Richards

Birth weight and cognitive function in the British 1946 birth cohort: longitudinal population based study

OBJECTIVE To examine the association between birth weight and cognitive function in the normal population. DESIGN A longitudinal, population based, birth cohort study. PARTICIPANTS 3900 males and females born in 1946. MAIN OUTCOME MEASURES Cognitive function from childhood to middle life (measured at ages 8, 11, 15, 26, and 43 years). RESULTS Birth weight was significantly and positively associated with cognitive ability at age 8 (with an estimated standard deviation score of 0.44 (95% confidence interval 0.28 to 0.59)) between the lowest and highest birthweight categories after sex, fathers social class, mothers education, and birth order were controlled for. This association was evident across the normal birthweight range (>2.5 kg) and so was not accounted for exclusively by low birth weight. The association was also observed at ages 11, 15, and 26, and weakly at age 43, although these associations were dependent on the association at age 8. Birth weight was also associated with education, with those of higher birth weight more likely to have achieved higher qualifications, and this effect was accounted for partly by cognitive function at age 8. CONCLUSIONS Birth weight was associated with cognitive ability at age 8 in the general population, and in the normal birthweight range. The effect at this age largely explains associations between birth weight and cognitive function at subsequent ages. Similarly, the association between birth weight and education was accounted for partly by earlier cognitive scores.

Lifetime antecedents of cognitive reserve

We used path analysis on data from the British 1946 birth cohort to model lifetime antecedents of cognitive reserve, represented by the NARTat 53 years, and compared this model for verbal memory and psychomotor function at this age, cognitive outcomes that are sensitive to age-associated decline. We showed independent paths from childhood cognition, educational attainment and adult occupation to cognitive reserve, with that from childhood cognition the strongest, and that from adult occupation the weakest. A similar pattern was found for the verbal memory and psychomotor outcomes, although the pathways were weaker than those to the NART. The pattern was also mirrored by the paths from paternal occupation to childhood cognition, educational attainment and adult occupation, with that to childhood cognition the strongest, and that to adult occupation the weakest. The direct influence of paternal occupation on cognitive reserve was negligible, and almost entirely mediated by childhood cognitive ability and educational attainment.

Does active leisure protect cognition? Evidence from a national birth cohort

Social, physical and intellectual activities are thought to facilitate cognitive performance and slow the rate of age associated cognitive decline, but little is known about this association in younger adulthood. We used multiple regression to test the association between two kinds of activity at 36 years-physical exercise and spare-time activity-and verbal memory at 43 and 53 years in 1919 males and females enrolled in the MRC National Survey of Health and Development (the British 1946 birth cohort). Both kinds of activities were significantly and positively associated with memory performance at 43 years, after controlling for sex, education, occupational social class, IQ at 15 years, and recurrent ill health and significant mental distress. Furthermore, physical exercise at 36 years (but not spare-time activity) was associated with a significantly slower rate of decline in memory from 43 to 53 years, after controlling for the same factors, with evidence that continuing physical exercise after 36 years was important for protection. We conclude that physical exercise and spare-time activity are significantly associated with benefit to memory in midlife, although these two kinds of voluntary activity may exert their effects on cognition via different paths.

Mortality in adults aged 26-54 years related to socioeconomic conditions in childhood and adulthood: post war birth cohort study

Abstract Objective: To examine premature mortality in adults in relation to socioeconomic conditions in childhood and adulthood. Design: Nationally representative birth cohort study with prospective information on socioeconomic conditions. Setting: England, Scotland, and Wales. Study members: 2132 women and 2322 men born in March 1946 and followed until age 55 years. Main outcome measures: Deaths between 26 and 54 years of age notified by the NHS central register. Results: Study members whose fathers occupation was manual at age 4, or who lived in the worst housing, or who received the poorest care in childhood had double the death rate during adulthood of those living in the best socioeconomic conditions. All indicators of socioeconomic disadvantage at age 26 years, particularly lack of home ownership, were associated with a higher death rate. Manual origins and poor care in childhood remained associated with mortality even after adjusting for social class in adulthood or home ownership. The hazard ratio was 2.6 (95% confidence interval 1.5 to 4.4) for those living in manual households as children and as adults compared with those living in non-manual households at both life stages. The hazard ratio for those from manual origins who did not own their own home at age 26 years was 4.9 (2.3 to 10.5) compared with those from non-manual origins who were home owners. Conclusions: Socioeconomic conditions in childhood as well as early adulthood have strongly influenced the survival of British people born in the immediate post war era. What is already known on this topic Associations between socioeconomic conditions in childhood and mortality in adulthood suggest that risks to survival begin in early life Studies have been generally retrospective, been unrepresentative, used only one marker of childhood conditions, controlled inadequately for adult conditions, or not included women What this study adds The death rate for women and men between 26 and 54 years living in poor socioeconomic conditions in childhood was double that of those living in the best conditions Those for whom socioeconomic disadvantage continued into early adulthood were between three and five times more likely to die than those in the most advantageous conditions

The life course prospective design: an example of benefits and problems associated with study longevity

Although the life course prospective study design has many benefits, and information from such studies is in increasing demand for scientific and policy purposes, it has potential inherent design problems associated with its longevity. These are in particular the fixed sample structure and the data collected in early life, which are each determined by the scientific principles of another time and the risk over time of increased sample loss and distortion through loss. The example of a national birth cohort in Britain, studied from birth so far to age 53 years is used to address these questions. Although the response rate is high, avoidable loss, which was low in childhood, increased in adulthood, and was highest in those in adverse socio-economic circumstances and those with low scores on childhood cognitive measures. Recent permanent refusal rate rises may be the result of better tracing and/or a response to increased requests for biological measurement. Nevertheless, the responding sample continues in most respects to be representative of the national population of a similar age. Consistency of response over the studys 20 data collections has been high. The size of the sample responding in adulthood is adequate for the study of the major costly diseases, and for the study of functional ageing and its precursors. This studys continuation has depended not only on scientific value but also policy relevance. Although the problems inherent in the prospective design are unavoidable they are not, in the study described, a barrier to scientific and policy value. That seems also likely in Britains two later born national birth cohort studies that have continued into adulthood.

A life course approach to cognitive reserve: a model for cognitive aging and development?

The concept of reserve in neuroscience maintains that there are aspects of brain structure and function that can buffer the effects of neuropathology such that the greater the reserve, the more severe the pathology must be to cause functional impairment. This article provides a concise overview of structural and functional approaches to reserve and shows how reserve may be conceived as the sum of its lifetime input. In this context, reserve therefore provides an empirical yet general model of cognitive aging and development. Ann Neurol 2005;58:617–622

Effect of 2-y n−3 long-chain polyunsaturated fatty acid supplementation on cognitive function in older people: a randomized, double-blind, controlled trial

BACKGROUND Increased consumption of n-3 (omega-3) long-chain polyunsaturated fatty acids (LC PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may maintain cognitive function in later life. OBJECTIVE We tested the hypothesis that n-3 LC PUFA supplementation would benefit cognitive function in cognitively healthy older people. DESIGN At total of 867 cognitively healthy adults, aged 70-79 y, from 20 general practices in England and Wales were randomly assigned into a double-blind controlled trial of daily capsules providing 200 mg EPA plus 500 mg DHA or olive oil for 24 mo. Treatment-allocation codes were obtained from a central computerized randomization service. Trained research nurses administered a battery of cognitive tests, including the primary outcome, the California Verbal Learning Test (CVLT), at baseline and 24 mo. Intention-to-treat analysis of covariance, with adjustment for baseline cognitive scores, age, sex, and age at leaving full-time education, included 748 (86%) individuals who completed the study. RESULTS The mean age of participants was 75 y; 55% of the participants were men. Withdrawals and deaths were similar in active (n = 49 and n = 9, respectively) and placebo (n = 53 and n = 8, respectively) arms. Mean (+/-SD) serum EPA and DHA concentrations were significantly higher in the active arm than in the placebo arm at 24 mo (49.9 +/- 2.7 mg EPA/L in the active arm compared with 39.1 +/- 3.1 mg EPA/L in the placebo arm; 95.6 +/- 3.1 mg DHA/L in the active arm compared with 70.7 +/- 2.9 mg DHA/L in the placebo arm). There was no change in cognitive function scores over 24 mo, and intention-to-treat analysis showed no significant differences between trial arms at 24 mo in the CVLT or any secondary cognitive outcome. CONCLUSIONS Cognitive function did not decline in either study arm over 24 mo. The lack of decline in the control arm and the relatively short intervention period may have limited our ability to detect any potential beneficial effect of fish oil on cognitive function in this study. The Older People And n-3 Long-chain polyunsaturated fatty acids (OPAL) Study was registered at www.controlled-trials.com as ISRCTN 72331636.

Cohort Profile: Updating the cohort profile for the MRC National Survey of Health and Development: a new clinic-based data collection for ageing research

MRC Unit for Lifelong Health and Ageing, Research Department of Epidemiology and Public Health, University College London, London, UK, Clinical Radiology, Manchester Royal Infirmary, Oxford Road, Manchester, UK, Vascular Physiology Unit, Institute of Child Health, University College London, London, UK, MRC Epidemiology Unit, Cambridge, UK, Cardiovacular Institute, Sahlgrenska University Hospital, Göteborg, Sweden, Wellcome Trust Clinical Research Facility Manchester, Manchester, UK, International Centre for Circulatory Health, National Heart and Lung Institute, Imperial College London, London, UK, Institute of Cardiovascular & Medical Sciences, University of Glasgow, Glasgow, UK, Department of Echocardiography, The Heart Hospital, London, UK and MRC Human Nutrition Research, Cambridge, UK

Cigarette Smoking and Cognitive Decline in Midlife: Evidence From a Prospective Birth Cohort Study

OBJECTIVES The authors investigated the effects of cigarette smoking on midlife cognitive performance. METHODS Multiple regression was used to test the association between cigarette smoking and changes in cognitive test scores among male and female members of the British 1946 birth cohort aged between 43 and 53 years. RESULTS Smoking was associated with faster declines in verbal memory and with slower visual search speeds. These effects were largely accounted for by individuals who smoked more than 20 cigarettes per day and were independent of sex, socioeconomic status, previous (adolescent) cognitive ability, and a range of health indicators. CONCLUSIONS The present results show that heavy smoking is associated with cognitive impairment and decline in midlife. Smokers who survive into later life may be at risk of clinically significant cognitive declines.

Cognitive ability in childhood and cognitive decline in mid-life: longitudinal birth cohort study

Abstract Objective To examine the association between cognitive ability in childhood and mid-life cognitive decline in the normal population. Design Longitudinal, population based, birth cohort study. Participants 2058 men and women born in 1946. Main study measures Ability in childhood measured by AH4 and test of verbal comprehension at age 15 years. Ability in adulthood measured by the national adult reading test (NART) at age 53 years. Outcome measures were decline in memory (word list learning) and speed and concentration (timed visual search) from age 43 to 53 years. Results Ability in childhood was significantly and negatively associated with decline in memory (β = 0.09, P = 0.005, for men; 0.10, P < 0.001, for women) and search speed (β = 0.13, P < 0.001, for men; 0.08, P = 0.01, for women), independent of educational attainment, occupational social class, and a range of health indicators. The adult reading test was also significantly and negatively associated with decline in these outcomes (for memory β = 0.21, P < 0.001, for men; 0.17, P < 0.001, for women; and for search speed β= −0.05 for men; 0.10, P = 0.008 for women) independent of educational attainment, social class, and childhood ability. Conclusions Ability in childhood can protect against cognitive decline in mid-life and beyond. Results for the adult reading test indicate that the protective effect of ability may also be acquired in adulthood.