Post-traumatic stress disorder (PTSD) is the most common mental-health problem among veterans returning from Iraq and Afghanistan, but officials say it's not clear if the therapies used to treat them are working.

Reuters reported Oct. 18 that the Institute of Medicine issued a report saying that only "exposure therapies" -- a long, slow process of confronting patient fears -- have been shown effective.

"At this time, we can make no judgment about the effectiveness of most psychotherapies or about any medications in helping patients with PTSD," said panel chairman Alfred Berg of the University of Washington. "These therapies may or may not be effective -- we just don't know in the absence of good data. Our findings underscore the urgent need for high-quality studies that can assist clinicians in providing the best possible care to veterans and others who suffer from this serious disorder."

About 12.6 percent of Iraq War vets suffer PTSD, as do 6.3 percent of those who serve in Afghanistan. Many patients with PTSD also have related alcohol and other drug problems.