Consider a situation in which a prisoner is slapped across the face while wearing a hood with his hands tied behind his back. Alone, none of these abuses -- slapping, hooding, or hand-tying -- can predict whether that person will develop a long-term mental disorder. But when the techniques are grouped together, said Basoglu, their effects multiply and raise the likelihood of developing PTSD. The psychological trauma of being slapped in the face is made much worse by a blindfold and handcuffs, which prevent victims from anticipating and shielding themselves against the blow.
"We find strong correlations between clusters of events and mental health outcomes," said Basoglu.
Other combinations that predicted PTSD included putting people in stressful, helpless positions to maximize the impacts of verbal threats and stripping their clothes off to enhance the humiliation of being sprayed with cold water.
Psychologist Claudia Catani looked for traces of these long-term clinical problems in the brains of torture survivors at the rehabilitation centers of the University of Konstanz in Germany.
Using a technique that detects magnetic fields created by electrical activity in the brain, Catani compared the patterns of brain activity of non-traumatized people to those of people who had experienced torture and people had subsequently developed PTSD. She found distinct differences in the area of the brain that controls attention that suggest torture victims are more sensitive to the sight of a potential threat.
Some psychologists have argued that, when shown a picture of something horrific like a massacre or a violent act, someone with PTSD will have a stronger reaction because the part of the brain that controls attention will become overactive and fixate on the image.
But Catani found the exact opposite to be the case. The brain activity in torture victims responding to the photos shows that they actually pay less attention to a threatening photo, not that they fixate. Her explanation is that PTSD sufferers carry traumatic experiences deep in their emotional memory and consciousnesses, programming them to react more quickly and strongly to threatening scenes.
"[P]ictures with such explicit contents as war and attack scenes are immediately categorized as a threat and do not require sustained visual processing," said Catani.
Basoglu and Catani both agree that the underlying principle that makes torture so traumatic is the individual's loss of control. Comparing torture to other kinds of trauma, torture survivors tend to be just as likely to develop mental disorders as people who have survived similarly uncontrollable events like massive earthquakes or plane crashes.
"Our data on this is unpublished, but it is the first time someone has compared these groups," said Basoglu.
"If you don't do anything about the clinical condition, these long-term effects do not go away," said Catani. But the good news for people trying to rebuild their lives is that various forms of psychotherapy have been shown in clinical trials to help.
"Torture memories are among the most resilient," said Almerindo Ojeda, director of the Center for the Study of Human Rights in the Americas at the University of California, Davis. "Those neurological interconnections must be very robust."
Though the memory of trauma will always remain, said Catani, confronting that memory can help to reduce the symptoms of PTSD.
"These people can go through their entire lives focused on the traumatic experience, feeling like the trauma is timeless and spaceless," said Catani. "You have to reconnect them ... to help the people put the memory in its place in their autobiographies."