Causes of heterogeneity in ageing - the Whitehall II study
Lead Research Organisation:
University College London
Department Name: Epidemiology and Public Health
Abstract
When the Whitehall II study started in 1985 its aim was to put social class differences in health on the map and investigate the causes of social inequalities in disease during work life. This it has achieved with outstanding success. Subsequent to the WHO Commission on Social Determinants of Health, launched by the Prime Minister in November 2008, Professor Sir Michael Marmot was invited by the Secretary of State for Health to undertake a national review of the evidence. The Marmot Commission, due to report early in 2010, will propose the most effective strategies for reducing health inequalities in England from 2010 on.
Our current proposal marks a change of direction for the study, namely to combine our existing wealth of data on social inequalities and chronic disease with new clinical measures of cognitive function, mental disorders and physical functioning to build Whitehall II into a world-class, interdisciplinary study of ageing. Ageing is not characterised by universal decline, rather variations in the speed of ageing result in people of the same age becoming increasingly dissimilar in terms of cognitive, mental and physical health and functioning over time. Using existing self-reported measures we have shown physical functioning to decline faster with age in low socioeconomic groups, suggesting that inequalities in functioning will become an important public health issue as the population ages. Understanding the causes of this age-related individual heterogeneity and its distribution by social group will be the core focus of our future work. By the proposed next medical screening, our eleventh wave of data collection, Whitehall II will be optimal for studying outcomes in the elderly. Ninety percent of participants will be 65+, more than 30% 75-85, and our data will span an age range of 50 years. In addition to providing insights into individual and social difference in the development of frailty, disability, dependence, and dementia, our work will enable the determination of optimal time windows and targets for interventions that lower risk and optimise healthy-ageing and independent living.
Our current proposal marks a change of direction for the study, namely to combine our existing wealth of data on social inequalities and chronic disease with new clinical measures of cognitive function, mental disorders and physical functioning to build Whitehall II into a world-class, interdisciplinary study of ageing. Ageing is not characterised by universal decline, rather variations in the speed of ageing result in people of the same age becoming increasingly dissimilar in terms of cognitive, mental and physical health and functioning over time. Using existing self-reported measures we have shown physical functioning to decline faster with age in low socioeconomic groups, suggesting that inequalities in functioning will become an important public health issue as the population ages. Understanding the causes of this age-related individual heterogeneity and its distribution by social group will be the core focus of our future work. By the proposed next medical screening, our eleventh wave of data collection, Whitehall II will be optimal for studying outcomes in the elderly. Ninety percent of participants will be 65+, more than 30% 75-85, and our data will span an age range of 50 years. In addition to providing insights into individual and social difference in the development of frailty, disability, dependence, and dementia, our work will enable the determination of optimal time windows and targets for interventions that lower risk and optimise healthy-ageing and independent living.
Technical Summary
Whitehall II is a cohort of 10,308 men and women followed since 1985-88 when they were aged 35-55 and employed by the Civil Service. It has fulfilled its original aim of understanding the contribution of psychosocial, behavioural and biological factors to socioeconomic inequalities in health during work-life. Our current proposal marks a change of direction, namely to build Whitehall II into a world-class, interdisciplinary study of the determinants of ageing, both individual and socioeconomic.
The main advantage of Whitehall II is that the baseline data collection predates that for most studies of ageing by 20-30 years. High quality, repeated measures of environmental exposures and pathophysiological changes over the entire adult life-course bring the advantages of a prospective study of chronic disease aetiology to the study of ageing. These data, augmented by new measures of cognitive function and mental disorders at the next sweep, combined with the age profile of the Whitehall II participants at phase 11 (90% 65+, 30% 75-85) provide a study design and cohort optimal for studying outcomes in the elderly.
Ageing is not characterised by ubiquitous decline, rather variations in the speed of ageing result in contemporaries becoming increasingly dissimilar in terms of cognitive, mental and physical health and functioning over time. Understanding the causes of this age-related individual heterogeneity and its distribution by social group will be the core focus of our future work, addressed via three key cross-cutting aims.
Our first aim is to determine causes of age-related heterogeneity, its origins in midlife and the relative importance of cumulative exposure to risk factors over the adult life course versus factors predominantly operating at older ages.
The second aim is to examine biological and behavioural mechanisms underlying age-related heterogeneity in cognitive, mental and physical health and functioning, and disentangle the temporal relationships, beginning in midlife, between mental health, cognitive and physical functioning and cardiovascular health.
Our third, longer-term aim for Whitehall II, is to use the findings generated by aims 1 and 2 to build up a model of the determinants and the mechanisms that generate individual and social heterogeneity in healthy ageing and its converse; frailty, disability, dependence, and dementia.
Our application requests funding primarily to undertake the phase 11 data collection. In addition we seek funding to maintain the cohort, prepare for phase 11, contribute to genetic collaborations, and make Whitehall II data available to the international research community.
The main advantage of Whitehall II is that the baseline data collection predates that for most studies of ageing by 20-30 years. High quality, repeated measures of environmental exposures and pathophysiological changes over the entire adult life-course bring the advantages of a prospective study of chronic disease aetiology to the study of ageing. These data, augmented by new measures of cognitive function and mental disorders at the next sweep, combined with the age profile of the Whitehall II participants at phase 11 (90% 65+, 30% 75-85) provide a study design and cohort optimal for studying outcomes in the elderly.
Ageing is not characterised by ubiquitous decline, rather variations in the speed of ageing result in contemporaries becoming increasingly dissimilar in terms of cognitive, mental and physical health and functioning over time. Understanding the causes of this age-related individual heterogeneity and its distribution by social group will be the core focus of our future work, addressed via three key cross-cutting aims.
Our first aim is to determine causes of age-related heterogeneity, its origins in midlife and the relative importance of cumulative exposure to risk factors over the adult life course versus factors predominantly operating at older ages.
The second aim is to examine biological and behavioural mechanisms underlying age-related heterogeneity in cognitive, mental and physical health and functioning, and disentangle the temporal relationships, beginning in midlife, between mental health, cognitive and physical functioning and cardiovascular health.
Our third, longer-term aim for Whitehall II, is to use the findings generated by aims 1 and 2 to build up a model of the determinants and the mechanisms that generate individual and social heterogeneity in healthy ageing and its converse; frailty, disability, dependence, and dementia.
Our application requests funding primarily to undertake the phase 11 data collection. In addition we seek funding to maintain the cohort, prepare for phase 11, contribute to genetic collaborations, and make Whitehall II data available to the international research community.
