Longitudinal studies generally show the anticipated results when it comes to physical activity and age-related decline - if you are more active, you tend to exhibit a slower pace of decline. Education, intelligence, and wealth are also correlated with longer life and slower onset of frailty and disability, but unlike physical activity it is less clear as to what the root causes of these correlations might be:
[Data on] one thousand nine hundred fifty-four healthy participants aged 35 to 85 at baseline from the Betula Project [was used] to reveal distinct longitudinal trajectories in episodic memory over 15 years and to identify demographic, lifestyle, health-related, and genetic predictors of stability or decline.
Memory was assessed according to validated episodic memory tasks in participants from a large population-based sample. ... Of 1,558 participants with two or more test sessions, 18% were classified as maintainers and 13% as decliners, and 68% showed age-typical average change. More educated and more physically active participants, women, and those living with someone were more likely to be classified as maintainers, as were carriers of the met allele of the catechol-O-methyltransferase gene. Less educated participants, those not active in the labor force, and men were more likely to be classified as decliners, and the apolipoprotein E ɛ4 allele was more frequent in decliners.