• physical activity;
  • exercise;
  • cognition;
  • cognitive impairment;
  • life course

OBJECTIVE: To determine how physical activity at various ages over the life course is associated with cognitive impairment in late life.

DESIGN: Cross-sectional study.

SETTING: Four U.S. sites.

PARTICIPANTS: Nine thousand three hundred forty-four women aged 65 and older (mean 71.6) who self-reported teenage, age 30, age 50, and late-life physical activity.

MEASUREMENTS: Logistic regression was used to determine the association between physical activity status at each age and likelihood of cognitive impairment (modified Mini-Mental State Examination (mMMSE) score >1.5 standard deviations below the mean, mMMSE score≤22). Models were adjusted for age, education, marital status, diabetes mellitus, hypertension, depressive symptoms, smoking, and body mass index.

RESULTS: Women who reported being physically active had a lower prevalence of cognitive impairment in late life than women who were inactive at each time (teenage: 8.5% vs 16.7%, adjusted odds ratio (AOR)=0.65, 95% confidence interval (CI)=0.53–0.80; age 30: 8.9% vs 12.0%, AOR=0.80, 95% CI=0.67–0.96); age 50: 8.5% vs 13.1%, AOR=0.71, 95% CI=0.59–0.85; old age: 8.2% vs 15.9%, AOR=0.74, 95% CI=0.61–0.91). When the four times were analyzed together, teenage physical activity was most strongly associated with lower odds of late-life cognitive impairment (OR=0.73, 95% CI=0.58–0.92). However, women who were physically inactive as teenagers and became active in later life had lower risk than those who remained inactive.

CONCLUSIONS: Women who reported being physically active at any point over the life course, especially as teenagers, had a lower likelihood of cognitive impairment in late life. Interventions should promote physical activity early in life and throughout the life course.