Study evaluated the ability of vitamin E and Aricept, to delay the progression of mild cognitive impairment to Alzheimer's disease

Researchers in the neurology department in the University of Arizona College of Medicine in Tucson participated in a study that evaluated the ability of vitamin E and donepezil hydrochloride, marketed as Aricept, to delay the progression of mild cognitive impairment to Alzheimer's disease.

Study results were presented July 18 at the Ninth International Conference on Alzheimer's Disease and Related Disorders in Philadelphia.

The study found, for the first time, that a drug has a limited slowing effect on the progression from mild cognitive impairment (MCI) - a memory disorder considered a strong early predictor of Alzheimer's disease (AD) -- to full-blown dementia of the Alzheimer's type.

Headed by Dr. Geoffrey Ahern, a UA professor of neurology, psychology and psychiatry, the UA clinical research group was one of 69 sites in the United States and Canada.

Seven-hundred and sixty-nine patients with MCI participated in the three-year trial, titled "A Randomized, Double-Blind, Placebo-Controlled Trial to Evaluate the Safety and Efficacy of Vitamin E and Donepezil HCl (Aricept) to Delay Clinical Progression from Mild Cognitive Impairment (MCI) to Alzheimer's Disease (AD). The study was led by Dr. Ronald Petersen of the Mayo Clinic in Rochester, Minn., and Dr. Leon Thal, of the University of California, San Diego.

Study participants were divided into three groups: one treated with vitamin E, one with Aricept and one with a placebo. The study investigators found that vitamin E did not slow the progression to AD. During the first 18 months of the trial, patients treated with Aricept had a reduced risk of progressing to AD compared to patients who took the placebo; the average delay in disease progression was about six months in those patients who progressed to AD.

Although patients treated with Aricept initially progressed to AD at a slower rate than patients treated with vitamin E or placebo, this risk-reduction effect was short term. By the end of the study, the risk of progression to AD was the same among all three groups.

Previous studies have shown that without treatment about 10 to 15 percent of individuals with MCI progress to AD each year. Study participants developed AD at a rate of 13 percent per year. Among those who progressed to AD, patients treated with Aricept averaged 661 days until diagnosed with AD. Those treated with vitamin E averaged 540 days and those treated with placebo averaged 484 days to AD diagnosis.

Patients with MCI are often - but not always - in a transitional state between early aging and AD. They have greater-than-normal memory problems for their age, but they do not show other symptoms of AD or other types of dementia and they can think and reason well. Researchers have found that MCI patients show atrophy in the hippocampus -- the area of the brain that controls the sorting, storage and recall of information.

The study was was sponsored by the National Institute on Aging (NIA) as part of its Alzheimer's Disease Cooperative Study (ADCS) clinical trials consortium at the University of California, San Diego, with additional support from Pfizer Inc. and Eisai Inc., the two pharmaceutical companies that market Aricept in the United States. DSM Nutritional Products of Switzerland donated the vitamin E used in the study.