 The growing success of therapeutic interventions including the antioxidant Vitamin E for Alzheimers disease in the general population requires a solution to the methodological problems so that therapeutic trials can be conducted in the aging population with Down syndrome which will ultimately improve their quality of life as well as that of their families and caregivers. The experience gained in this trial will be useful to the design of appropriate cognitive measures of Alzheimers disease in persons with Down syndrome in subsequent trials. 