One hypothesis for mechanisms underlying development of Alzheimer disease states that free radicals initiate the chain of events resulting in disease by damaging neurons. If so, antioxidants might reduce cellular damage and decrease risk for the disease.

Jose A Luchsinger, M.D., and his American colleagues tested the hypothesis by studying the relationship between intake of carotenes, vitamin C, and vitamin E and development of the disease in 980 elderly subjects who were free of dementia at baseline and were followed for an average of 4 years. The participants answered questionnaires about their eating habits at the beginning of the study and at follow-up visits.

The researchers reported 242 cases of the disease in their study population over the course of the follow-up period. They found that consumption of carotenes or vitamins A and E either through the diet or by supplements was not related to a decreased risk for development of the disease.

"Higher intake of antioxidant vitamins at the usual levels, reported in our sample of elderly individuals without dementia at baseline, was not associated with a decrease in the risk of incident Alzheimer disease," the authors concluded.

Because the study did not include dietary information from earlier in life, it was not possible to assess whether long-term diet might have an effect on risk for dementia.