July 18, 2006
Alzheimer’s Drug Slows Brain Shrinkage
WASHINGTON -- The Alzheimer's drug Aricept not only improves memory and understanding in patients but appears to slow the characteristic shrinkage of the brain, researchers reported on Monday.
Magnetic resonance imaging or MRI images of the brains of 131 patients with mild cognitive impairment showed less shrinkage of the hippocampus, a structure key to memory function, in patients who got the drug compared to those who got a placebo, researchers told a meeting.
"No drug has been shown to slow brain atrophy for patients with mild cognitive impairment," said Dr. Clifford Jack of the Mayo Clinic in Rochester, Minnesota.
Aricept, which is known generically as donepezil, is marketed by Pfizer and Japan's Eisai Co. Ltd..
"Our study results seem to imply that donepezil does more than provide symptom relief -- it has an effect on a measure of brain health. Our findings also show that MRI measures can have usefulness in future studies of mild cognitive impairment."
Mild cognitive impairment can lead to Alzheimer's disease, but not always.
Jack's team found the effects only in people with the apolipoprotein E4 (APOE 4) gene, a genetic variation that has long been known to put people at higher risk of Alzheimer's.
Why is unclear, he said.
"One possibility is that APOE 4 carriers were more likely to have definite Alzheimer's disease than noncarriers in the study who appear to have symptoms of early Alzheimer's disease, yet turn out to have a different diagnosis when an autopsy is performed after death," he said.
Jack's study was presented to the International Conference on Alzheimer's Disease and Related Disorders in Madrid, Spain.
An estimated 12 million people worldwide suffer from Alzheimer's disease, but international researchers predict the number of people suffering from dementia worldwide could reach 81 million by 2040 as the "baby boom" generation ages.
There is no cure for Alzheimer's, which begins as mild memory loss and can progress quickly to complete loss of any ability to care for oneself.
The brain becomes clogged with proteins known as plaques and tangles of nerve fibers. And it shrinks.
"In extreme cases, the brain of an Alzheimer's patient might weigh half of what a normal person's brain does at peak health," Jack said.
Experts are looking for ways to prevent Alzheimer's from developing, or to slow its fatal progression. They are also looking for better ways to diagnose the disease in patients using imaging scans such as MRI or PET.