Studies show that increased oxidative stress (from excess free radicals) may damage brain cells and is linked with Alzheimer's disease (AD). Many studies show increased oxidation of brain lipids (fats), proteins, carbohydrates (sugars) and DNA in AD. Although the causes of AD are not known, it is believed that oxidative stress is part of what damages brain cells in AD and probably other brain diseases. Animal and tissue culture studies of vitamin E and selenium suggest that they can protect brain cells from damage. This research study is being done to see how safe and effective vitamin E and selenium may be in preventing AD and other brain illnesses. These illnesses are more common in people over the age of 60 to 65. A potential benefit of participating in the PREADVISE study is that early detection of memory changes can lead to early diagnosis and treatment. Also, some participants may decrease their risk of getting AD if the supplements are effective. The findings of this study may also help in the research and understanding of AD.