MONDAY, July 17, 2006 (HealthDay News) -- The Alzheimer's drug Aricept (donepezil) slows the rate of brain shrinkage in some people with mild cognitive impairment, a pre-Alzheimer's disease condition, U.S. researchers report.
However, this benefit was seen only in patients carrying a copy of the apolipoprotein (APOE 4) gene, which increases the risk of Alzheimer's disease. Experts estimate that about 25 percent of the population carries the APOE 4 gene.
The finding is significant because, so far, "No drug has been shown to slow brain atrophy for patients with mild cognitive impairment," Mayo Clinic radiologist and lead investigator Dr. Clifford Jack Jr. said in a prepared statement.
"Our study results seem to imply that donepezil does more than provide symptom relief -- it has an effect on measures of brain health," Jack said. "Our findings also show that MRI measures can have usefulness in future studies of mild cognitive impairment."
His team presented the findings Monday at the International Conference on Alzheimer's Disease and Related Disorders in Madrid.
The study included 131 people with mild cognitive impairment. They were divided into three groups that took either Aricept, vitamin E, or a placebo. A series of MRIs were used to assess brain shrinkage.
Brain shrinkage in Aricept-treated APOE 4 carriers was 4.5 percent a year, compared to 6.14 percent for those who took the placebo. Vitamin E had no effect on brain shrinkage in any of the patients in the study.
The researchers also noted that brain-shrinkage rates were greater among patients who were diagnosed with Alzheimer's disease during the study.
"Though the MRI findings with donepezil were measurable, this is still a very small effect. It's not like this drug stopped the disease from progressing -- it just slightly slowed the rate," Jack said.
The study received partial funding from the Institute for the Study of Aging.
The Alzheimer's Association has more about the stages of Alzheimer's disease.