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In any case, the worry circuits quieted down after the patients completed 10 weeks of either successful drug treatment or behavior therapy involving exposure and response prevention--demonstrating that either a molecule or a learning experience can materially alter the brain. "What we now know," says the NIMH's Hyman, "is that anything--whether a drug, a war experience or a talking therapy--changes the way nerve cells talk to each other. In the brain, hardware as well as software is always changing."
In post-traumatic stress disorder, the picture of a brain reshaped by experience is even more startling. Only recently, PTSD was deemed an exclusively psychological (not biological) phenomenon. Moreover, many clinicians regarded it as something of a scam, not a real mental illness like schizophrenia. But new medical discoveries, coupled with the wide publicity given to the experiences of Vietnam War veterans in particular, have changed that.
By definition, PTSD victims have suffered a trauma that involved death or serious injury and provoked feelings of intense fear, helplessness and horror that have long outlasted the event. They are hypervigilant, often sleeping with one eye open. "One Vietnam veteran will never stand in the center of the room when he comes here because he is afraid someone will stab him in the back," says Dr. Edna Foa, a psychiatrist at the Medical College of Pennsylvania. Victims are haunted by intrusive, disturbing memories--even entire flashbacks triggered by certain cues. "If I hear a helicopter, it ruins my whole day," said a Vietnam veteran. To avoid any such reminders, PTSD victims may retreat into virtual isolation, and commonly suffer from emotional numbing, fear of intimacy, memory deficits and depression.
One intriguing clue surfaced recently when magnetic-resonance-imaging scans of brains of combat veterans with PTSD were compared with those of civilians who did not have the disorder. Scans of the veterans' brains showed that the right hippocampus, a crescent-shaped structure that plays a key role in memory, was slightly smaller than normal. This may indicate that war, rape or torture actually harms the brain as well as the spirit.
PET scans tell another tale. When eight PTSD victims, civilian and military, volunteered for an experiment at Massachusetts General Hospital in Boston, a PET scan revealed that an area of their brains--the right amygdala, a small, almond-shaped structure--was abnormally active while they were reliving traumatic memories. "The amygdala is the key to the conditioned-fear response in animal studies," explains Dr. Roger Pitman, a psychiatrist at the VA Medical Center in Manchester, New Hampshire. "This study shows us that traumatic memories are activating this 'hot learning center.' It may be that stress hormones burn these memories into the brain, and that is why you have World War II vets still suffering from flashbacks of Iwo Jima."