CHICAGO--Continuous use of antidementia drugs is associated with a decreased risk of death in Alzheimer's patients. Specifically, those who took the medications for more than 70% of the time since being diagnosed with dementia lived an average of 3 years longer than did those who took them for shorter

"These drugs work better than we thought they would in the long term, not only in terms of cognition and function, but also in survival," noted Dr. Susan Rountree, a neurologist at the Alzheimer's disease and memory disorders center at Baylor College of Medicine, Houston.

Speaking at the International Conference on Alzheimer's Disease, Dr. Rountree presented a prospective observational study of 641 patients with Alzheimer's. All the patients were enrolled at the center and seen during a 16-year period (1989-2005). Patients were evaluated annually until their deaths.

For assessment of the impact of antidementia drugs on lifespan, patients were assigned a medication persistency score, Dr. Rountree said in an interview. "This was a measure of how much time the person spent on medication, compared to the duration of illness. For example, if the illness was 10 years in duration and the patient took medication for 5 years, the persistency score was 50%."

She divided the patients into quartiles depending on the persistency score. Quartile 1 consisted of those who took medication for up to 33% of their illness (including the 12% of the cohort who never took antidementia medication). Patients in quartile 2 took medication for 34%-55% of their illness; the third quartile was made up of people who took medications for 56%-70% of their illness; and those in quartile 4 took their medications for at least 71% of the illness.

All of the antidementia drugs available during the study period (tacrine donepezil, rivastigmine, galantamine, and memantine) were considered, Dr. Rountree said. By the end of the study period, 53% of the cohort had died.

There was an inverse, statistically significant relationship between the overall risk of death and the consistency of drug use, she said. Compared with those in quartile 4, who took medication with the highest consistence, those in quartiles 1 and 2 were more than twice as likely to die. Those in quartile 3 were at a 1.5 times increased risk of death. Patients in quartile 4 lived an average of 3 years longer than did those in quartile 1.

Since the study was observational in nature, Dr. Rountree said she was unable to draw any conclusions about cause and effect. But, the lengthened lifespan probably is related to the long-term benefit that antidementia drugs provide in both cognition and function, she said.

"We previously reported from this cohort that cognitive and functional benefits continue over many years for patients who persist in their treatment even among those with an advanced disease."

The study is a bit of good news, Dr. Rountree said, coming as it does on the heels of the failure of two highly anticipated phase III trials of potential disease-modifying agents (tramiprosate and tarenflurbil). She hopes her results will encourage families to view the existing medications more positively.

"These drugs have been beaten up recently. Yes, they don't cure the disease. But there are many diseases we can't cure. There is a therapeutic nihilism when it comes to this disease," Dr. Rountree said at the meeting, which was sponsored by the Alzheimer's Association.

Dr. Rountree noted that she has received financial support from Forest Pharmaceuticals Inc. and Novartis, and is a paid speaker for Pfizer Inc.

ARTICLES BY MICHELE G. SULLIVAN Mid-Atlantic Bureau