Naturally, the idea that trauma could cause a brain to shrink could be completely wrong, the sort of chicken-and-egg mess that often trips up scientists just when they think they’ve found a clue. Put a bunch of soldiers through some unspeakable hell of combat and typically only a subset of them, 15 to 30 percent, get PTSD. Maybe we have the story backward. Maybe the person with a small hippocampus who goes into a trauma is the one vulnerable to PTSD. Maybe that person processes information differently, forms memories differently, and is more at risk for flashbacks. Pitman and his colleagues have reported that soldiers who wind up with PTSD were likely to have had a higher-than-average rate of what are called “soft” neurological signs—not out-and-out neurological diseases but some minor red flags such as delayed developmental landmarks or a higher than average rate of learning disorders.

Some researchers are trying to figure out whether a small hippocampus predisposes someone to PTSD. Pitman, Arieh Shalev, and their colleagues are doing a prospective study, examining MRIs of people who have just undergone a trauma and following up with later scans. The neuroscientists will examine the before-and-after images to see whether a small hippocampus really does precede and predict who will get PTSD, or if hippocampal volume decreases in the later picture.

Meanwhile, Thomas Freeman, a psychiatrist at the North Little Rock Veterans Administration Medical Center, is taking another approach to untangling the question of cause and effect. If the hippocampus shrinks after the trauma, especially if it does so as a function of the ongoing post-trauma period, the extent of atrophy should be more dramatic in survivors of older disasters than of recent ones. Freeman and his colleagues are comparing brain scans of PTSD victims from the Gulf War, Vietnam, Korea, and so on.


So we’ve got scientists disagreeing, experiments to be done, grants to be written. What does all this mean? Let’s start with what it doesn’t mean. At present, there isn’t a shred of evidence to link everyday stress—traffic jams, money worries, crummy bosses, unhappy relationships—to neurons keeling over dead. Those stressors are not good for things like blood pressure and may result in hippocampal neurons not functioning at their best, but the neurons almost certainly remain intact.

Remembering the crash of TWA flight 800.

The National Institute of Mental Health defines post-traumatic stress disorder as “an extremely debilitating condition that can occur after exposure to a terrifying event or ordeal, in which grave physical harm occurred or was threatened.”

At least 4 percent of adults in the United States (5.7 million people) suffer from PTSD every year. One million Vietnam veterans have developed the disorder, as have nearly one in three people who have spent time in war zones.

Triggers include military combat, violent personal assault (rape, torture, physical or sexual abuse), accidents (car wrecks, plane crashes), natural disasters (floods, hurricanes, earthquakes). Families of victims can also develop PTSD.

PTSD sufferers may experience flashbacks in which they feel they are reliving the ordeal. They may have trouble falling asleep or stay awake because of nightmares, night after night. They may feel emotionally numb and cut off from the people closest to them. They may have terrifying intruding thoughts or memories. They may turn to drugs or alcohol to keep their thoughts and feelings at bay. They may become depressed, anxious, or irritable, snapping or lashing out at people around them. And they may suffer from extreme feelings of guilt, as if they should or could have prevented the disaster.

Anyone who goes through a severe ordeal risks developing the disorder, but the threat is greatest for people with previous traumatic experiences—particularly those who were sexually, physically, or emotionally abused as children.

PTSD patients are often given antianxiety or antidepressant drugs, such as nefazodone and trazodone, to treat symptoms of depression, anxiety, and sleeplessness. Behavioral and cognitive-behavioral therapy can also be useful. For example, a therapist may teach a patient to head off panic attacks by taking slow, deep breaths. The therapist may gradually expose the patient to images or sensations that remind him of the trauma (battle photos, loud noises), then help him deal with the fears that come up.

Another caveat: The business about the branches that connect neurons in the hippocampus shriveling up from stress and later recovering has provided an irresistible metaphor to some folks who believe in “recovered memory.” The term describes a controversial scenario in which victims of horrendous traumas utterly repress all memory of the experience, only to recover it years or decades later. Lives have been destroyed over this incendiary issue—either those of the trauma victims (in one interpretation), left to wait decades for justice because of the workings of memory, or, in the counterview, those of the victims of false accusations, consumed in this season’s witch-hunt. Civil war has nearly broken out among neuropsychologists over this issue, so let me tread lightly here—I will simply say that I have seen no scientific evidence for how such recovered memories might work, no supposed cases of it documented to be legitimate in a way that should satisfy a rigorous scientist, and plenty of scientific explanations for why various claims have not been legitimate.

Although the recent hippocampal research has little to say about everyday stress and recovered memory, it does have some valuable practical lessons for us. If a small hippocampus is indeed a risk factor for PTSD, neuroanatomy should be taken into account when we decide whom to ship off to battle, the same way we’d consider the presence of a heart murmur. And if the atrophy is a consequence of the trauma or the post-trauma period, scientists have their usual marching orders: figure out how the process works so we can learn how to prevent it.

But these findings should mean something larger as well. For most of us, all the alarming lectures in the world about how we are endangering our environment don’t have the power of that first, iconic picture from the moon of Earth—tiny, vastly alone, fragile. Reading about the Nazis can’t take our breath away like a visit to the U.S. Holocaust Memorial Museum, with its room filled beyond number with the shoes of the murdered. We need concrete images when trying to grasp the ungraspable. And thus a thousand people writing a thousand words each about the consequences of human violence may not have the impact of a single picture, like a brain scan. Look what they did to my brain. Look what they did to me.