The purpose of this study is to determine the safety and effectiveness of 2,000 international units of Vitamin E (alpha tocopherol)on cognitive function of aging persons with Down syndrome. It is a randomized, double-blind, placebo-controlled trial lasting 36 months. It is expected that Vitamin E will slow the deterioration in cognitive functions associated with Alzheimer disease.
Alzheimer disease (AD) continues to be the most serious health problem faced by aging persons with Down syndrome. AD is also a major public health concern in the aging general population. With increasing life expectancy there will be a dramatic increase in the prevalence of AD cases, which will pose a significant increased burden on the health care system and individual providers of care. Persons with Down syndrome are uniquely vulnerable to a form of Alzheimer disease indistinguishable from the sporadic variety that affects aging individuals from the general population. Oxidative damage is a highly plausible mechanism in the pathogenesis of this disease due to the overexpression of superoxide dismutase, associated with a gene located on chromosome 21, which is present in triplicate in the Down syndrome genotype. For the last six years, we have been conducting a clinical trial to determine the safety and efficacy of the anti-oxidant Vitamin E in slowing the cognitive and functional decline associated with the dementia of AD among individuals with DS. The study is a randomized, double-blind trial, stratified in a two-arm parallel design. The subjects are medically stable individuals who are 50 years of age or older at the time of screening. Among those randomized to the treatment arm, vitamin E is taken in the form of 1000 IU capsules for 36 months. Each subject is evaluated every 6 months for 3 years. The primary outcome is is the Brief Praxis Test (BPT), which is well-suited to quantifying cognitive decline in this population. The target enrollment of 350 persons is estimated to be sufficient to provide adequate statistical power to detect a slowing by one-third in the rate of cognitive decline with vitamin E treatment. The Data and Safety Monitoring Board (DSMB) for this trial includes 4 physicians, and a statistician with expertise in clinical trials. Each DSMB member receives a report on each serious adverse event (SAE) on a flow basis, and statistically summaries of unblinded safety data--including deaths, adverse events and vital signs--prior to each meeting of the DSMB. The most recent DSMB meeting took place on February 23,2010. The timeline for study completion is: recruitment of the study sample (N=350) was completed on 12/31/2008; the final 36-month evaluation will take place in 04/2010; statistical analysis and final report of results is expected to be completed by 12/31/2010.
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