Table 4.

Estimated proportion of association between midlife exposure to residential greenness [normalized difference vegetation index (NDVI), 1986–1994] and baseline cognitive function (1995–2001) explained by physical activity, air pollution exposure, social engagement, and mental health ($n=\mathrm{16,962}$).

Mediator	Proportion of association of cumulative average greenness and global cognition explained by mediator (95% CI)	Proportion of association of cumulative average greenness and verbal memory explained by mediator (95% CI)
Total physical activity	0.02 ($-0.01$, 0.06)	0.04 ($-0.17$, 1.36)
Air pollution	$-0.01$ ($-0.16$, 0.08)	$-0.03$ ($-4.02$, 0.50)
Social engagement	0.00 ($-0.01$, 0.01)	0.00 ($-0.04$, 0.04)
Mental health	0.18 (0.07, 0.29)	0.33 ($-0.445$, 1.16)

Note: Participants average age ranged from 61 to 69 y at midlife exposure to residential greenness and cognitive function was assessed at age $70+$ years. Mediation analyses assume that there is no unmeasured exposure–outcome confounding, no unmeasured mediator–outcome confounding, no unmeasured exposure–mediator confounding, and no mediator–outcome confounder affected by exposure. CI, confidence interval.