A long-running study involving 454 older adults who were given physical exams and cognitive tests every year for 20 years has found that those who moved more than average maintained more of their cognitive skills than people who were less active than average, even if they have brain lesions or biomarkers linked to dementia.
Participants wore an activity monitor for a week, an average of two years before death. The range of physical activity was extreme, with the average being 155,000 counts/day and the standard deviation being 116,000 counts. Daily physical activity was affected by age (unsurprisingly) and education.
For every increase in physical activity by one standard deviation, participants were 31% less likely to develop dementia. For every increase in motor ability by one standard deviation, participants were 55% less likely to develop dementia.
191 had dementia and 263 did not. The participants donated their brains for research upon their deaths. The average age at death was 91 years. Almost all (95.6%) showed at least one brain pathology, with 85% having at least two, and the average being three. Pathologies include Alzheimer's pathology, Lewy Bodies, nigral neuronal loss, TDP-43, hippocampal sclerosis, micro- and macro-infarcts, atherosclerosis, arteriolosclerosis, and cerebral amyloid angiopathy.
Buchman, Aron S. et al. 2019. Physical activity, common brain pathologies, and cognition in community-dwelling older adults. Neurology, 92 (8), e811-e822; DOI: 10.1212/WNL.0000000000006954