Overview
- Participants with higher step counts saw slower decline, with 3,000–5,000 steps associated with an average three-year delay and 5,000–7,500 steps with about seven years, with benefits plateauing in the moderate range.
- Researchers tracked daily steps via waistband pedometers and measured amyloid-beta and tau with PET scans, alongside annual cognitive testing over a median of roughly nine years.
- The associations were most pronounced in people already showing elevated amyloid-beta, while those with low baseline amyloid had little decline and no measurable benefit from activity.
- Analyses indicate the cognitive benefits were mediated by slower amyloid-related tau accumulation, particularly in the inferior temporal cortex, rather than changes in amyloid itself.
- Authors stress the findings are observational in a relatively small, demographically narrow U.S. cohort, underscoring the need for randomized trials and further mechanistic research.