Lifestyle activities contribute to cognitive reserve in mid‐life, independently of education, in cognitively healthy middle‐aged individuals at risk for late‐life Alzheimer’s disease

Background It is now acknowledged that Alzheimer’s Disease (AD) processes are present decades before the onset of clinical symptoms, but it remains unknown whether lifestyle factors can protect against these early AD processes in mid‐life. Intellectually, physically, and socially stimulating lifestyle activities are associated with maintenance of late‐life cognitive abilities (Chan et al., 2018), and lower cognitive impairment in AD (Livingston et al., 2020). We asked whether such activities contribute to cognitive reserve (CR) from mid‐life, in cognitively healthy individuals who are at risk for late‐life AD. Method Middle‐aged individuals (aged 40‐59 years, mean = 52 years) from the PREVENT Dementia study (www.preventdementia.co.uk) were assessed at baseline (N = 210, 62/148 male/female) and two‐year follow‐up (N = 188, 55/133 male/female), with cognitive ability (multidomain battery) and brain health (total grey matter volume, functional brain network segregation) measures. Mid‐life activities were measured using the Lifetime of Experiences Questionnaire, which comprises occupational as well as intellectually, physically, and socially stimulating leisure activities. Dementia risk was assessed with the Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) score. Result Multivariable linear regression showed that intellectual, physical, and social activities undertaken in mid‐life made a unique contribution to episodic and relational memory in mid‐life, independent of occupation and CAIDE at baseline (β (se) = 0.04 (0.02), p = 0.02, Figure 1a) and follow‐up (β (se) = 0.07 (0.02), p = 0.002, Figure 1b). Furthermore, these activities moderated the relationship between cognitive ability and brain health at follow‐up (β (se) = 3.47 (1.40), p = 0.01), with verbal and visuospatial functions, and short‐term (conjunctive) memory of people with higher activity levels less dependent on their brain functional integrity (Figure 2), consistent with the concept of CR (Brayne et al., 2010). Such a moderation by these mid‐life activities was more prominent in individuals with higher CAIDE scores (β (se) = 4.28 (1.83), p = 0.02, Figure 3). Conclusion These findings suggest that modifiable lifestyle activities contribute uniquely to CR and may offset cognitive decrements due to AD risk in mid‐life. They support the targeting of modifiable lifestyle activities for the prevention of Alzheimer’s disease.