Use of vitamin E and vitamin C supplements in combination is associated with reduced prevalence and incidence of AD. Antioxidant supplements merit further study as agents for the primary prevention of AD.
The public health threat of Alzheimer disease (AD) will grow as people live longer. Consequently, strategies for the prevention of AD are important. Because judicious doses of antioxidant vitamin supplements are relatively nontoxic and may have wide-ranging health benefits, antioxidants may offer an attractive prevention strategy.
Antioxidants scavenge free radicals and other reactive oxygen species that damage cellular membranes, organelles, and macromolecules. Accumulation of reactive oxygen species may overwhelm the protective reserves of antioxidants in cells (oxidative stress). In neurons, which are especially vulnerable to free radical–mediated damage, these processes may be important in aging of the brain and the pathogenesis of AD. Thus, intake of antioxidants in the diet or, more powerfully, in nutritional supplements may be neuroprotective.
Antioxidants may mitigate age-related cognitive decline, and a randomized trial showed that selegiline hydrochloride or vitamin E may slow the progression of AD However, few epidemiologic studies have examined whether antioxidants may delay AD onset. Three prospective studies found lower risks of dementia or AD in participants consuming more dietary antioxidants. Another study of 633 participants found no incident AD cases during 4 years among individuals who reported use of vitamin E or vitamin C (ascorbic acid) supplements at baseline,while an investigation of 3385 men found reduced prevalence of vascular and mixed dementias, but not AD, among users of both vitamin E and C supplements.These results contrast with a recent study showing no association between AD and antioxidant vitamin consumption in either dietary or supplement form.
To extend these findings, we examined data from the Cache County Study, a large, population-based investigation of the prevalence and incidence of AD and other dementias in relation to genetic and environmental antecedents. Using both prevalence and incidence data, we analyzed the association of antioxidant supplement use and occurrence of AD.