Is antioxidant use protective of cognitive function in the community-dwelling elderly?

The role of oxidative stress in the pathogenesis of diseases such as macular degeneration, certain types of cancer, and Alzheimer's disease has received much attention. Thus, there is considerable interest in the potential contribution of antioxidants to the prevention of these diseases.

The objective of this study was to determine whether use of supplemental antioxidants (vitamins A, C, or E, plus selenium or zinc) was associated with a reduced risk of development of cognitive impairment or cognitive decline in a representative sample of the community-dwelling elderly.

The sample consisted of 2082 nonproxy subjects from the Duke Established Populations for Epidemiologic Studies of the Elderly who were not cognitively impaired at the 1989-1990 interview (baseline for the present analysis). Medication use was determined during in-home interviews. Cognitive function was assessed 3 and 7 years from baseline in terms of incident cognitive impairment, as measured on the Short Portable Mental Status Questionnaire (SPMSQ) using specific cut points (number of errors) based on race and education, and cognitive decline, defined as an increase of > or = 2 errors on the SPMSQ. Multivariate analyses were performed using weighted data adjusted for sampling design and controlled for sociodemographic characteristics, health-related behaviors, and health status.

At baseline, 224 (10.8%) subjects were currently taking a supplement containing an antioxidant. During the follow-up period, 24.0% of subjects developed cognitive impairment and 34.5% experienced cognitive decline. Current antioxidant users had a 34.0% lower risk of developing cognitive impairment compared with non-antioxidant users (adjusted relative risk [RR], 0.66; 95% CI, 0.44-1.00) and a 29.0% lower risk of experiencing cognitive decline (adjusted RR, 0.71; 95% CI, 0.49-1.01).

The results of this analysis suggest a possible beneficial effect of antioxidant use in terms of reducing cognitive decline among the community-dwelling elderly.