https://www.medpagetoday.org/neurology/ ... ve&vpass=1
Notably, the number of mentally stimulating activities participants engaged in at midlife (from the ages of 50 through 65) showed no significant association with the risk of new onset of MCI. But in late life (ages ≥66), engaging in more activities was tied to a significantly reduced risk of incident MCI. Engaging in any two activities in late life showed an HR for MCI of 0.72 (95% CI 0.53-0.99). Engaging in any three late-life activities had an HR of 0.55 (95% CI 0.40-0.77), four activities showed an HR of 0.44 (95% 0.30-0.65), and five had an HR of 0.57 (95% CI 0.34-0.96).