Bidirectional associations between quality of life and cognitive function over 17 years: Evidence from the English Longitudinal Study of Ageing (ELSA)

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AbstractBackgroundDepression and anxiety are well recognised as risk factors for dementia and poorer cognitive outcomes. However, considerably less is known about the relationship between quality of life and cognitive function over time. Quality of life is not simply the absence of mental health problems, but instead is a related but distinct construct. In particular, it is unclear whether poorer quality of life precedes cognitive decline, or vice versa or whether there is a bidirectional relationship. This is of import because understanding directionality allows us to start to plan interventions around dementia risk reduction. The aim of this study was to test bidirectionality between quality of life and memory in a large, nationally representative sample of people aged 50+ without cognitive impairment.MethodData were used from the English Longitudinal Study of Ageing (ELSA), a longitudinal cohort comprising 12,099 people over the age of 50 and their partners. Repeated measures of quality of life and memory (immediate and delayed) were available nine times over a 17‐year period. Cross‐lagged models were fitted to test for bidirectionality between quality of life and memory function.ResultThe fully adjusted model revealed that higher quality of life was significantly associated with higher subsequent immediate memory scores at all time‐points, and with higher subsequent delayed memory scores at all except the final time‐point. There was no consistent evidence that memory was significantly associated with subsequent quality of life.ConclusionThese results extend previous research by providing evidence for the temporal association between quality of life and memory in a population‐based sample of people aged 50+. Specifically, results suggest that quality of life is consistently associated with later memory function over nearly two decades, though the study did not provide evidence that the association operates in the opposite direction. The lack of consistent evidence for a relationship between cognitive function and subsequent quality of life may be due to the exclusion of people with cognitive impairment and adjustment for depressive symptoms. Better quality of life may act as a protective factor in retaining memory function from middle to later adulthood.