Social connections, cognitive reserve, and cognitive function in later life

Abstract

Background: Good social connections have been identified as a factor that may be associated with healthy cognitive function in later life. In line with cognitive reserve theory, good social connections may provide mental stimulation through complex interaction with others and hence build cognitive reserve and maintain healthy cognitive function. However, there is considerable inconsistency in findings reported by studies that examine this association. Inconsistency in findings may be attributed to the heterogeneity of concepts potentially associated with social connections and to the variation in approaches to measuring and defining these concepts. Aims: To assess the association between aspects of social connections and cognitive function in later life. This thesis introduces a novel element by considering the moderating role of cognitive reserve in this association. Method: A scoping review was conducted to establish which concepts are used within the literature to describe social connections and how these are measured and defined. Next, a systematic review and meta-analysis was conducted to identify evidence regarding the association between social isolation and cognitive function in published studies. Empirical work was conducted using cross-sectional and longitudinal data from the Cognitive Function and Ageing Study–Wales (CFAS-Wales) to determine the associations between social isolation, cognitive reserve, and cognitive function in healthy older people. Extending this approach further, these associations were examined in two groups potentially at risk of social isolation: older people with depression or anxiety and older people living alone. Finally, empirical work was completed using the Platform for Research Online to investigate Genetics and Cognition in Ageing (PROTECT) to assess how satisfaction with social contact may be associated with cognitive function compared to a structural measure of isolation. Results: A lack of social connections was associated with poor cognitive function in later life. For people with depression or anxiety, these associations may be better explained by mood-related symptoms than social connections. People who live alone in later life were at no greater risk of poor cognitive function compared to those living with others. Satisfaction with social contact was associated with poor cognitive function but a structural measure of social isolation was not. Conclusions: Social connections play an important role in building cognitive reserve and protecting people against poor cognitive function in later life. People who are vulnerable to social isolation have different needs to those who are less vulnerable. Satisfaction with social contact is often neglected in measures that assess structural aspects of social connections but may be a better predictor of cognitive function.