Oxidative damage by free radicals may be involved in causing Alzheimer's disease (AD). Free radicals may lead to death of nerve cells and decline in brain function. Certain antioxidants may suppress this free radical damage associated with AD. Carotenoids are a family of naturally occurring antioxidants that have important functions for human health. Carotenoids are known to reduce oxidative damage, but their effects have not been studied in AD patients.