Alzheimer's Research Brings Progress, Setbacks

"This is a medication that has not previously been studied in Alzheimer's disease," Doody said. In the trial, patients were randomly assigned to 20 milligrams of dimebon three times a day, or a placebo.

After six months, Doody's team found that patients on dimebon had significant improvement in cognitive ability, compared with those receiving placebo.

"We found treated patients were improved in their thinking abilities, their behavioral symptoms [and] their daily skills abilities, compared to people who took placebo," she said.

The patients were evaluated using ADAS-cog, a battery of tests that assesses a person's ability to track dates, comprehend instructions, follow commands, memorize word lists, and complete simple tasks such as copying drawings or addressing an envelope.

At six months, patients receiving dimebon showed an improvement of 1.9 points on the ADAS-cog scale from the beginning of the study, while those on placebo continued to decline. After a year, those receiving dimebon showed a 6.9 point increase on the ADAS-cog scale, the researchers report.

"This first trial was promising," Doody said. "This is not a cure for Alzheimer's disease, but the benefits could last for a long time. The drug appears to slow the clinical progression of the disease."

The study was done in Russia because dimebon had been approved there as an antihistamine. Dimebon is made by the San Francisco-based biopharmaceutical company Medivation. Doody is on the Scientific and Clinical Advisory Board of Medivation and has stock options in the company.

Another phase III trial has just started, Doody said. This six-month trial is being conducted in the United States, Europe and South America and is now in the process of recruiting several hundred patients, she noted.

"We are anxiously awaiting the completion of the next study, so that we can see if this drug could potentially be approved for treating Alzheimer's patients," Doody said.

Gandy said the drug does appear to be superior to the currently approved medicines for Alzheimer's.

"This is the first new promising symptomatic therapy in a long time," Gandy said. "This drug could potentially add to the effects of other drugs such as Aricept, Namenda and Exelon," he said. "I think it's a pretty exciting development."

More information

For more information on Alzheimer's disease, visit the Alzheimer's Association.

SOURCES: Clive Holmes, M.D., Ph.D., Memory Assessment and Research Centre, Moorgreen Hospital, Southampton, UK; Rachelle S. Doody, M.D., Ph.D., professor, neurology, Alzheimer's Disease and Memory Disorders Center, Baylor College of Medicine, Houston; Sam Gandy, M.D., chairman, Alzheimer's Association National Medical and Scientific Advisory Council; July 19, 2008,The Lancet