The Food and Drug Administration warned doctors Monday that prescribing a certain group of psychiatric drugs to seniors suffering from dementia can increase their risk of death.

Antipsychotic drugs are approved to treat schizophrenia and bipolar disease, but doctors frequently prescribe them to treat elderly patients with dementia.

FDA's announcement was an update to a 2005 action, when regulators added warnings about increased heart attacks and pneumonia to drugs called atypical antipsychotics. The medicines include blockbusters like Eli Lilly & Co.'s Zyprexa and Johnson & Johnson's Risperdal.

FDA said Monday those same risks apply to 11 older drugs known as typical antipsychotics, including Pfizer's Navane and Endo Pharmaceutical's Moban. The drugs were developed in the 1950s and have largely been replaced by the newer medications, which are believed to have fewer side effects, such as tremors.

Under FDA's orders, both drug types will now carry boxed warnings--the most serious a drug can carry--describing their risks to dementia patients.

Analysts did not expect the announcement to negatively impact drug company earnings because the original antipsychotics are available as low-cost generics.

Federal officials have repeatedly urged doctors not to medicate seniors unnecessarily. Despite such warnings, health professionals continue to prescribe psychiatric drugs "off-label," or for uses that have not been approved by FDA. About 20 percent of seniors in nursing homes who receive antipsychotics have not been diagnosed with psychiatric problems, according to data released by Medicare earlier this year.

While FDA regulates the approval and marketing of drugs, doctors are free to use their judgment when prescribing drugs.

The agency based its decision on two studies of a combined 65,000 seniors which showed those taking antipsychotics were more likely to die than those not on the drugs. Agency officials said it's not clear why antipsychotics hasten death. Scientists also could not determine from the data whether one group carries greater dangers than the other.

"We've struggled with this decision but we ultimately decided the data are strong enough to expand this label to drugs in both classes," said Thomas Laughren, director of FDA's psychiatric drug division.

The agency stressed there is "no approved drug for the treatment of dementia-related psychosis," and recommended doctors consider other treatment options.

"A lot of the things can be done to help change one's environment so elderly patients can be more oriented and engaged," said Dr. Eric Hollander, a professor at the Mt. Sinai School of Medicine.

Many of the behavioral problems seen in seniors can be improved with simple, daily routines that patients can follow, Hollander said.