Katrina survivors sort through mix of emotions.(Clinical Rounds)

Forget everything you learned about treating survivors of the Sept. 11, 2001, terrorist attacks, and the Oklahoma City bombing. The fallout from Hurricane Katrina will be unique in that the mental health challenges facing survivors will be impossible to predict, according to disaster psychiatry experts.

"In terms of natural domestic disasters, we've never seen anything quite like Katrina," said Barry A. Hong, Ph.D., of Washington University, St. Louis.

To this point, most domestic disasters, including Sept. 11, were confined to a discrete geographical area. In addition, Katrina's devastating blows came in stages. "In some sense, you almost have a cascade of disasters--the hurricane was one, the flooding was [another], and the relief efforts were [yet another] disaster," he said.

Another factor that makes Katrina different from other disasters is the displacement it created, said Craig Katz, M.D., co-founder of Disaster Psychiatry Outreach (DPO), in New York.

"We know that one of the best ways to help people recover emotionally from disaster is being reunited with friends and family," he said. "Here, people are being sent wherever, some with family and some without. That is an enormous setup for whatever initial psychological reactions occur naturally, which could coalesce into a longer-term problem that's more entrenched."

The locations to which evacuees are sent also can affect their psychiatric well-being, said Anthony Ng, M.D., chair of the American Psychiatric Association's Committee on the Psychiatric Dimensions of Disaster. "If people have family in the area, those folks are able to get resettled a bit," he said. But a lot of folks ended up far from Louisiana or Mississippi, and they may have acculturation stress, he added.

When faced with such an enormous disaster, physician help at the beginning involves just making sure people are functioning reasonably well, Dr. Katz said. They can "make sure someone's sleeping, eating, and not lapsing into depression and anxiety. That's an ...