Only participants who are taking part in the SELECT study (a study that looks at the use of vitamin E and selenium for preventing prostate cancer) may apply to participate in the PREADVISE study about how useful vitamin E and selenium might be for preventing memory changes with age (including Alzheimer's disease and other disease that can affect the brain). African American and Hispanic men who are age 60 or older may take part. Men of other ethnic groups aged 62 or older may take part. The SELECT doctors or staff will review the applicant's medical history and drugs to verify that they have no conditions that would exclude them from this study. About 10,000 men will take part in this study.