RCT2011 · PNAS · Erickson KI, Kramer AF et al.
Erickson: a year of walking grows the hippocampus 2% after 65
Who, how long
120 healthy, inactive older US adults (mean age 67), 1 year
What they found
Three 40-minute moderate walks a week grew hippocampal volume 2% (reversing 1–2 years of age-related shrinkage) while the stretching control lost 1.4%; spatial memory improved in proportion to BDNF levels.
⚠ Caveat
Small sample; memory improved in both groups (practice effect); MRI volume is a surrogate endpoint, not dementia.
Related in the knowledge base
Last reviewed: 6 September 2026
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