NEW YORK (Reuters Health) - There is considerable variation in the rate of decline associated with various drugs prescribed for patients with Alzheimer's disease. Drugs licensed to treat dementia tend to correlate with a slower decline, while antipsychotics and benzodiazepines tend to speed the rate of deterioration.

"Prescribed drugs in patients with Alzheimer's disease may affect the symptomatic progression of their disease, both positively and negatively," Dr. J. Ellul, of the University of Patras, Greece, and colleagues write in the March issue of the Journal of Neurology, Neurosurgery and Psychiatry.

The researchers examined the effects of drugs prescribed for a community cohort of 224 patients (mean age 82.3 years) with a diagnosis of probable Alzheimer's disease. The drugs prescribed were recorded at initial assessment and then correlated in logistic regression analysis with disease progression, defined as an increase of at least one point in the Global Deterioration Scale over the next 12-month period.

Thirty-four patients (15%) were taking antipsychotics, 54 (24%) were taking antidepressants, and 30 (13%) were taking benzodiazepines or benzodiazepines-related drugs. Subjects with more advanced disease were more likely to be prescribed older antipsychotics, tricyclic antidepressants, hypnotics or anxiolytics.

A total of 87 patients (39%) were taking drugs for dementia, one (0.4%) was taking vitamin E, and 20 (9%) were taking vitamin B12 or folic acid. These patients tended to be younger and in earlier stages of the disease.

Dr. Ellul's group found that risk of deterioration was significantly higher among patients who were taking antipsychotics or sedatives compared with those who were not (odds ratio 2.74 and 2.77, respectively). Patients who were taking both antipsychotics and sedatives had an even higher risk of rapid deterioration (OR 3.86).

"On the other hand, patients on acetylcholinesterase inhibitors or NMDA antagonists, drugs affecting the renin-angiotensin system and statins had a significantly lower risk of rapid deterioration than those who did not take any of these drugs (ORs 0.49, 0.31, and 0.12, respectively)," Dr. Ellul's team reports. However, the investigators observed no additive effect in patients taking two or more of these drugs.

"These observations have important implications for both clinicians and trialists," the researchers conclude. "Most importantly, clinicians should be aware that antipsychotics and benzodiazepines, especially in combination, may hasten decline."