The Food and Drug Administration asked drug makers in April to add warnings to the labels of newer anti-psychotics because studies showed the drugs nearly doubled the risk of death for older patients with dementia.
These drugs are widely used to treat the aggressive behavior, delusions and hallucinations sometimes experienced by those with dementia, including Alzheimer's disease.
Researchers at Harvard's Brigham and Women's Hospital in Boston worried that doctors would just switch elderly patients to older medications like Thorazine and Haldol.
The researchers analyzed prescription and death records for nearly 23,000 older patients who took anti-psychotics. They found that 18 percent of patients on the old drugs died in the first six months, compared with 15 percent on the new drugs.
"If confirmed, our results suggest that conventional anti-psychotic medications should be included in the FDA's public health advisory," the researchers said. Their findings appear in Thursday's New England Journal of Medicine.
Dr. Philip Wang, lead author of the study, said studies to determine the best way to treat behavior problems in the elderly are sorely needed. Doctors now rely heavily on tests done in younger people.
"All we can do is encourage clinicians to be thoughtful — to balance whatever benefits there are with what appears to be risk," Wang said.
The study was funded by two federal health agencies.
William Thies, scientific director of the Alzheimer's Association, said he has not seen any evidence that doctors are switching to the older drugs. One of the concerns with the older drugs, he said, is their more severe side effects, including Parkinson's-like tremors and involuntary movements.
While there may be a slight increase in the risk of dying, "these medications are being used to treat a problem which is not trivial," Thies said.
The newer anti-psychotics, such as Risperdal and Seroquel, came out in the 1990s and now account for 95 percent of the prescriptions for anti-psychotics, according to IMS Health, a pharmaceutical information and consulting company.
The drugs were approved by the FDA for treating mental illnesses such as schizophrenia and manic depression, but doctors are free to use them for other problems.
The study, using information from a Pennsylvania prescription program, looked at 22,890 people over 65 who began taking anti-psychotics between 1994 and 2003. Taking into account age, illnesses and other factors, the researchers calculated that those on the older drugs had a 37 percent higher risk of death. The risk was highest for those on higher doses and during the first 40 days of use.
The causes of death were not disclosed. Heart problems and pneumonia accounted for most of the deaths in the studies cited by the FDA in its warning.