BACKGROUND AND PURPOSE:

• Marino et al. (JAMA Network Open, 2025) examined whether higher physical activity levels in early adult life, midlife, or late life are associated with lower risk of all-cause or Alzheimer disease (AD) dementia

METHODS:

• Prospective cohort study
  • Data derived from the Framingham Heart Study
• Population
  • Dementia Free
  • Had physical activity measured at baseline
• Exposures
  • Self-reported physical activity using the physical activity index
    • Composite score weighted by hours spent sleeping and in sedentary, slight, moderate, or heavy activity
  • Time in adult life course participants entered the study
    • Early adult life (1979 to 1983)
    • Midlife (1987 to 1991)
    • Late life (1998 to 2001)
• Study design
  • Follow-up was for 37.2 (SD, 7.1) years for those who entered in early adult life to 14.5 (SD, 6.6) years for those who entered in late life
• Primary outcome
  • All-cause and AD dementia

RESULTS:

• Early life: 1526 participants
  • Mean age: 36.7 (SD, 4.7) years | 53.8% female
• Midlife: 1943 participants
  • Mean age: 54.0 (SD, 5.8) years | 52.0% female
• Late life: 885 participants
  • Mean age: 71.0 (SD, 4.5) years | 53.4% female
• Cases of incident all-cause dementia during follow-up: 567
• Higher levels of midlife and late-life physical activity (quintile 4 or 5) were associated with lower risk of all-cause dementia, compared to lower levels (quintile 1)
  • Midlife
    • Q4 vs Q1: HR 0.60 (95% CI, 0.41 to 0.89)
    • Q5 vs Q1: HR 0.59 (95% CI, 0.40 to0.88)
  • Late life
    • Q4 vs Q1: HR 0.64 (95% CI, 0.42 to 1.00)
    • Q5 to Q1: HR 0.55 (95% CI, 0.35 to 0.87)
• There were no associations between early adult–life physical activity and dementia risk
• Findings were similar for Alzheimer’s-specific dementia

CONCLUSION:

• Higher levels of physical activity in midlife and late life were associated with reduced risk of incident dementia
  • Physical activity in early adult life was not associated with dementia risk reductions
• The authors state

This study is among the first to evaluate the potential critical periods for physical activity in association with dementia risk

These findings may inform future efforts to delay or prevent dementia through timing interventions and public health promotion efforts during the most relevant stages of the adult life course

Learn More – Primary Sources:

Physical Activity Over the Adult Life Course and Risk of Dementia in the Framingham Heart Study