Every now and then, someone with a medical problem needs a CT scan or MRI of the brain. With luck, the test rules out a threatening disease, and in the resultant relief, the doctor shows the patient the scan. If it's his or her first one, the patient will probably get the willies. Unlike pictures of other organs, which inspire a bemused response ("Hey, lookie here, that's my liver"), brain scans provoke awe. That's your brain in there, with its convoluted surface and all those mysterious subsections. Rookie med students feel the same disquiet in anatomy class when they first hold a cadaver's brain in their hands. The same uneasiness makes neurosurgeons joke, "There go the piano lessons," when they cut into gray matter. The brain, after all, is the Seat of the Soul, the Big Enchilada of Consciousness, the organ of Me-ness. From this mass of tissue resembling marinated tofu emanates a person.
By the time a child’s body stops growing, the brain has long since settled into its adult size. Which is why it’s mighty interesting when the size of some part of the brain changes dramatically in an adult. Check out the brain of a chronic alcoholic and you’ll often find a particular region badly disintegrated; autopsy someone who was exposed to lots of organic toxins and you’ll see damage in another brain area. And a third brain region has attracted a lot of attention recently because it may atrophy in response to a certain type of serious stress.
Take a green 18-year-old, stick him in a uniform, ship him off to a war, and expose him to something truly horrific even by the standards of human violence—say, a battle in which he’s the only soldier in his entire unit to survive. Some rare, inexplicable supermen may come out of such an experience unfazed or even strengthened, having found life’s meaning during that moment when the world melted around them. But the average guy comes out a lot worse. He may suffer from nightmares for a while. He may feel estranged from loved ones who can’t understand what he’s been through. And that’s if he’s lucky. Some survivors are apparently damaged for decades.
During the First World War the phenomenon was called shell shock; it produced men who even as octogenarians would shake and leap for cover when a door slammed. Something similar was called battle fatigue in World War II. And in modern psychiatric parlance, the long-lasting residue of horror is called post-traumatic stress disorder. It’s not just restricted to combat trauma, either. Gang rape, childhood sexual abuse, the carnage of yet another choirboy next door going postal with an automatic weapon, imprisonment in Auschwitz—all are experiences that have produced the broken person labeled with the acronym PTSD.
According to the American Psychiatric Association, patients with PTSD suffer from flashbacks, nightmares and other sleep problems, emotional numbness or outbursts, loss of pleasure, an inappropriate startle reflex, and problems with memory and concentration. Those last two symptoms have prompted recent brain-imaging studies.
