Associations of vegetable and fruit consumption with age-related cognitive change

Abstract

Objective: To examine the association between rates of cognitive change and dietary consumption of fruits and vegetables among older persons.

Methods: The authors conducted a prospective cohort study of 3,718 participants, aged 65 years and older of the Chicago Health and Aging Project. Participants completed a food frequency questionnaire and were administered at least two of three cognitive assessments at baseline, 3-year, and 6-year follow-ups. Cognitive function was measured using the average z-score of four tests: the East Boston Tests of immediate memory and delayed recall, the Mini-Mental State Examination, and the Symbol Digit Modalities Test.

Results: The mean cognitive score at baseline for the analyzed cohort was 0.18 (range: -3.5 to 1.6), and the overall mean change in score per year was a decline of 0.04 standardized units. In mixed effects models adjusted for age, sex, race, and education, compared with the rate of cognitive decline among persons in the lowest quintile of vegetable intake (median of 0.9 servings/day), the rate for persons in the fourth quintile (median, 2.8 servings/day) was slower by 0.019 standardized units per year (p = 0.01), a 40% decrease, and by 0.018 standardized units per year (p = 0.02) for the fifth quintile (median, 4.1 servings/day), or a 38% decrease in rates. The association remained significant (p for linear trend = 0.02) with further control of cardiovascular-related conditions and risk factors. Fruit consumption was not associated with cognitive change.

Conclusion: High vegetable but not fruit consumption may be associated with slower rate of cognitive decline with older age.

Figure

Annual rates of change and differences in the rates (p value) by quintile of fruit and vegetable intake based on random effects models of 3,718 persons with cognition measured at three time points over 6 years, Chicago Health and Aging Project, 1993–2002. (A) The age-adjusted model includes terms for age, age², total energy intake (linear, squared, and cubic terms), quintiles of fruit/vegetable intake, time, and the interaction between time and each of age, total energy intake (all terms), and quintiles of fruit/vegetable intake. (B) The multiple-adjusted model included terms from the age-adjusted model plus sex, race (black/white), education (years), participation in cognitive activities, physical activity, alcohol consumption (linear and squared terms), interaction terms between sex and age, sex and education, and race and education, two-way interaction terms between time and each covariate, and a three-way interaction term between time, race, and education.