Among 4,397 women in the NYU Women's Health Study (mean age 46 at baseline, 79 at follow-up), those in the top tertile of midlife physical activity had 20% lower odds of reporting two or more subjective cognitive complaints nearly 30 years later (OR 0.80; 95% CI 0.68-0.95). The association appeared for moderate and vigorous activity but not mild activity, and was stronger in never smokers (OR 0.68). Results held across sensitivity analyses and inverse probability weighting.
The 30-year gap is the study's real strength: most exercise-cognition work spans a decade or less, which invites reverse causation, since early dementia changes can reduce activity. Starting in midlife largely sidesteps that problem. The moderate-to-vigorous pattern matches existing guidance, which favors activity that raises heart rate over light movement. Still, caveats are substantial. Activity was self-reported once at baseline, so it cannot capture how habits changed across three decades. Subjective complaints are a soft outcome, shaped by mood, personality and health worries rather than measured cognition or diagnosed dementia. Only about a third of the original cohort was analyzed, and residual confounding by education, diet and socioeconomic status is likely despite adjustment. The stronger effect in never smokers may reflect smoking noise or competing mortality. An odds ratio of 0.80 is modest and observational, so it cannot prove causation. Editorially, this is confirmatory rather than paradigm-shifting: it adds long-horizon, women-specific support for the established advice to exercise at moderate-to-vigorous intensity from midlife onward, a recommendation that carries cardiovascular benefits regardless.