Changes in Diet Quality from Mid- to Late Life Are Associated with Cognitive Impairment in the Singapore Chinese Health Study.

BACKGROUND Although higher diet quality at mid-life has been associated with better cognitive function in late adulthood, it is unclear whether dietary improvement after mid-life may reduce the risk of cognitive impairment. OBJECTIVES We examined associations between changes in diet quality and risk of cognitive impairment in the Singapore Chinese Health Study cohort. METHODS We used data from 14,683 Chinese men and women who were recruited at ages 45 to 74 y from 1993 to 1998 and re-interviewed after 20 y at ages 61 to 96 y during follow-up 3 (2014-2016). Diet quality was measured using the Dietary Approaches to Stop Hypertension (DASH) scores at baseline and follow-up 3 interviews. Cognitive impairment was defined using scores from the Singapore-modified Mini-Mental State Examination at the follow-up 3 interview. Multivariable logistic regression models were used to estimate ORs and 95% CIs for the associations between change in DASH scores and cognitive impairment. RESULTS Higher quintiles in DASH scores at baseline and follow-up 3 interviews were associated with lower odds of cognitive impairment in a dose-dependent manner (both: P-trend < 0.001). Compared with participants with consistently low DASH scores, the OR (95% CI) of cognitive impairment was lowest, at 0.64 (0.51, 0.79), in those with consistently high DASH scores. Those with small (OR: 0.80, 95% CI: 0.65, 0.98) or moderate-large (OR: 0.72, 95% CI: 0.59, 0.86) increases in DASH scores were associated with significantly lower odds of cognitive impairment than those with consistently low DASH scores. Associations were consistent across subgroups by sex, BMI (kg/m2; <23 or ≥23), and age (<60 y, ≥60 y) at baseline. CONCLUSIONS Although maintaining high diet quality confers the lowest risk, improving diet quality from mid- to late life was still associated with a lower risk of cognitive impairment in late adulthood.