The Effect of Midlife Physical Activity on Cognitive Function Among Older Adults: AGES—Reykjavik Study

REGULAR physical activity (PA) provides benefits for cardiovascular health and helps improve or maintain physical function among older adults (1–3). Numerous epidemiological studies suggest that regular PA may reduce the risk of cognitive decline and dementia in older adults (4–6). This may reflect lifestyle factors (7–10) or underlying modulation of neurotrophic and vascular health factors demonstrated in clinical and experimental research (1,10). Although the evidence suggests that PA is beneficial for maintaining cognitive function and reducing risk of dementia in later life, most previous epidemiological studies report data on PA collected close to the time at which cognitive function was assessed or dementia diagnosed (5,6,9,11). With short intervals between PA and dementia, it is difficult to determine whether what is reported regarding PA is a risk factor for cognitive decline and dementia or an indicator of incipient disease. Findings from two studies that examined midlife PA and risk of dementia were mixed (12,13). Furthermore, most previous studies examined either global cognitive performance (11,14,15) or dementia risk related to PA (5,6,9,12,13) but not both. In the current study, we examine the association of midlife PA and to late-life domain-specific cognitive performance and dementia. Following reports of APOE ϵ4 allele, a risk factor for Alzheimer’s disease, modifying the association between PA and dementia (6,11,12), we examined the interaction of PA and APOE ϵ4 allele on dementia in a subsample of the total cohort.