Life course influence of early life adversity on physical capability in late life

Life course influence of early life adversity on physical capability in late life: evidence from high and mid-income countries

Background:
Early life circumstances have an enduring effect on health in late life, including physical capability (a person’s capacity to undertake the physical tasks of everyday life). Physical capability is important as poorer performance on commonly used objective measures of physical capability (e.g. grip strength and walking speed) was associated with a higher risk of developing health problems later on in life, including fractures and cognitive decline, and higher rates of death. Recent studies have shown that low socio-economic position (SEP) and stressful experiences in early life are associated with lower levels of physical capability in adulthood, and the associations may be direct and/or mediated through various life course pathways. While studies have shown consistent evidence of an association between lower childhood SEP and modest reductions in physical capability levels after adjusting for adult SEP and adult body size, these associations vary by population.  Studies have also shown that associations of childhood SEP with measures of physical capability in midlife persisted, whereas associations of own education and occupation with these measures disappeared after adjustment for possible mediators, highlighting the potential importance of early life factors. The existing evidence on childhood factors associations with adult physical capability is based mainly on populations in Western countries such as the UK. Understanding the long term relationships between childhood factors and adult physical capability in different settings is crucial, in order to provide insight into the potential contextual influences and mechanisms of the relationships. China is a country experiencing marked and rapid changes in demographics and health as the growth of the older population becomes more prominent. Until recently, but limited attention has been paid to ageing-related outcomes. A recent study showed that socio-demographic determinants (e.g. female gender, lower education, rural residence, low earning, less coverage in medical insurance), and physical and mental health were all associated with increased risk of functional limitations in older Chinese adults.

Aims and Methods:
The aim of this PhD project is to compare the long-term association of early life adversity with physical capability in England and China where exposures (early life circumstances) differ substantially. The project will use data from two large national surveys: the English Longitudinal Study of Ageing (ELSA) and the China Health and Retirement Longitudinal Study (CHARLS). Many aspects of these two studies are purposefully comparable and therefore provide remarkable opportunities for cross-country comparisons. The student will use a life course approach to investigate (1) the association between a range of early life adversity measures and objective measures of physical capability in mid- and late adulthood (such as grip strength, chair rising, standing balance time, walking speed) and (2) to what extent the associations can be explained by potential mediators across adult life.