Longitudinal evaluation of total tau and physical activity on cognitive decline in a population‐based study

Abstract

AbstractBackgroundLittle is known about the longitudinal relationships of physical activity (PA) and serum total tau (tau) on cognitive decline. We examined if PA moderated the association of tau and cognitive decline in a biracial, population‐based sample of older adults.MethodWe studied 1,159 participants in the Chicago Health and Aging Project (CHAP), who provided blood and completed neuropsychological tests of episodic memory, perceptual speed, and the Mini‐Mental State Examination (MMSE). A standardized global cognitive function test score was computed using individual tests. Self‐report PA was categorized into three groups‐ No PA (responded to at least four of five specified activity items and reported no activity for all responses), low PA (< 150 minutes/week), and high PA ( > 150 minutes/week). Tau concentrations were measured by ultrasensitive immunoassay and classified as low (<0.40 pg/mL) and high (>0.40 pg/mL).ResultThe average age of study participants (63% females and 60% African Americans) was 77 years, with a mean education of 13 years. After adjusting for demographic characteristics and APOE‐ε4 allele, among participants with high tau concentrations, the rate of cognitive decline for participants with high PA (β= ‐0.047, 95% CI= ‐0.067, ‐0.027) was 70% slower than for participants with no PA (β= ‐0.080, 95% CI= ‐0.101, ‐0.058). Similar associations were observed for individual cognitive tests. Specifically, comparing participants with high PA to no PA among those with high tau concentrations, the rate of annual decline in episodic memory was slower by 92%, perceptual speed by 62%, and MMSE by 80%. Among participants with low tau concentrations, high PA (β= ‐0.035, 95% CI= ‐0.052, ‐0.019) was associated with a 77% slower cognitive decline in annual rate compared to no PA (β= ‐0.046, 95% CI= ‐0.066, ‐0.026). Individual tests of those with low tau concentrations showed the annual rate of decline in episodic memory was slower by 76%, perceptual speed by 78%, and MMSE by 68% for high versus low PA.ConclusionPA significantly slowed cognitive decline in participants with high and low concentrations of tau. These findings may inform the development of prevention trials tailored to at‐risk characteristics with long‐term follow‐up measurement.