August 2, 2011 -- Risperidone, antipsychotic medication normally prescribed to treat symptoms of schizophrenia and bipolar disorder, may not be effective in treating symptoms of chronic post-traumatic stress disorder, according to a study published Tuesday in the Journal of the American Medical Association.
Risperidone is commonly prescribed as an add-on treatment for veterans with the more severe forms of PTSD who do not respond to antidepressants.
"There are many in the VA that are exposed to multiple traumatic situations," said Dr. John Krystal, director of the clinical neuroscience division for the Veterans Affairs National Center for PTSD and lead author of the study.
Eighty-nine percent of veterans diagnosed with PTSD who are treated with medication are given antidepressants, the only type of medication that's FDA-approved to treat the disorder. But for many, anti-depressants aren't enough.
"It's fallen to the art of psychiatry not the science to treat those that don't respond to medications," said Krystal.
In Krystal's study, 267 patients from 23 Veteran Administration medical centers nationwide were randomized to either receive risperidone or a placebo along with additional therapies the patients received through the centers.
Common symptoms of PTSD include nightmares, hypervigilance, anxiety, depression and unwanted flashbacks. The study found risperidone was not more effective overall in reducing any of those symptoms compared with the placebo group.
In fact, PTSD symptoms in both groups improved over six months, regardless of whether risperidone was added to their treatment equation.
"There's a tendency to believe that all of the changes happen because of one medication," said Krystal. "But sometimes it doesn't."
Still, the study is not enough to discount risperidone as an effective treatment for other forms of PTSD, said Krystal.
While the study suggested that antipsychotics did not work for some patients who did not respond to antidepressants, it did not clarify what subset of patients could potentially benefit from the treatment.
The study was limited to patients who had combat-related PTSD, and most of the patients studied were men.
Risperidone is an effective method to treat symptoms of psychosis, such as paranoia. Many of the patients studied did not suffer from psychosis.
The data, however, is useful for doctors and a certain group of patients to discuss the continued benefit, if any, of being on risperidone, said Krystal.
"If it's treating psychosis, a case could be made," said Krystal. "But the overall avoidance and numbing symptoms of PTSD, it's not helpful."