Even after a year of regular therapy sessions, Cambodian survivors of brutal Khmer Rouge concentration camps continued to "regard the world with suspicion and hostility," emotions that are very hard to change, according to a group of psychiatrists involved in the treatment of 300 such patients.

But the doctors report they were able to help the patients reduce their nightmares and constant thinking about their years in camps.

Twelve of the patients, who had been subjected to four years of forced labor and starvation and were forced to watch family members be executed, were compared before and after a year of therapy.

The "intrusive" symptoms, like nightmares and being easily startled, usually could be limited with supportive therapy and antidepressant drugs, report Dr. J. David Kinzie of the Oregon Health Sciences University and several colleagues in the current American Journal of Psychiatry.

But the "denial" and "avoidance" states, which include inattention, amnesia and emotional numbing, were "very resistant to change."

Kinzie saw the patients at the university's Indochinese Refugee Clinic.

"Further experience will determine if such symptom reduction is long lasting and if other, more subjective symptoms such as shame, lack of caring for others and avoidance can be treated successfully," the psychiatrists write.