As we know all too well, bad things happen when deadly weapons get into the hands of angry or deranged people. So if we're going to minimize the chances of another shooting rampage like the one on Monday at the Washington Navy Yard, we have to address two problems simultaneously: too much firepower too easily available to those who shouldn't have it; and too many disturbed people on the streets who are hell-bent on killing.
We already know how to cut down on the first one -- enforce the laws already on the books, close background check loopholes, ban assault weapons. We just haven't yet found the political will to do it.
The human element is another matter.
Our mental health/legal system makes it extremely difficult to involuntarily commit people who are falling apart unless they are judged to be an imminent threat to themselves or others, and even then they may be released much too soon. But many rampage killers don't have a serious mental illness, let alone a diagnosis, and are not in the system to begin with.
A recent analysis of 298 mass murderers found only 22 percent were "flat-out psychotic," in the words of Dr. Michael Stone, the Columbia University clinical professor of psychiatry who studied the matter. Of the remaining 78 percent, Dr. Stone told The New York Times, a few were deeply depressed while many others were angry, jealous or looking to punish their bosses. In those cases, even a perfect mental health system would not have caught them.
The D.C. shooter, Aaron Alexis, did have serious mental problems and was even in treatment for them. Nevertheless, he became a walking IED, ready to detonate under pressure.
Alexis was a four-year veteran of the Naval Reserves who had a pattern of misconduct. His father said he had post-traumatic stress disorder. He also had several violent encounters in civilian life and was hearing voices. Yet he had a gun and a security clearance --granted by the same private contractor that had cleared Edward Snowden -- that allowed him entry into the Navy Yard. So, major gaps there, too.
No system will ever be perfect, and our treatment of people with serious mental illness is far from that anyway. Is there something else we're missing that could minimize these incidents?
A recent interview with a brain researcher made me wonder if the latest advances in the field could help predict and prevent violent behavior. So I called some experts to ask. They said no. At least, not yet.
"Research is moving us to greater understanding of normal functioning of the human brain and how it is altered in psychiatric conditions," said David Lewis, chairman of the department of psychiatry at the University of Pittsburgh Medical School, "but we're not at the point where it can be used to predict behavior or make a diagnosis on an individual level."
There are some things that can be identified in the human brain in laboratory experiments. For example, scientists at Carnegie Mellon University are learning to "read" the electrical activity in the brain that indicates what a subject is thinking or feeling by use of functional magnetic resonance imaging, or fMRI, combined with analysis of big data. But that's a long way from predicting malevolent acts.
"Every thought is in the brain in some sense," said Marcel Just, a psychology professor at Carnegie Mellon and director of its Center for Cognitive Brain Imaging. "Does that include thoughts of homicide? I don't think it can currently be detected.
"I bet if you did an MRI [on Alexis while he was alive], nothing would pop out at you. If you did one of him and 10 controls you might find some difference, but we can't incarcerate on that basis."
Nor should we. If thought equaled action, half the population would be behind bars.
Other research has found that traumatic stress can physically change the brain by shrinking the hippocampus, which plays a major role in inhibition and memory. People with PTSD have been found to have a smaller hippocampus, although those who suffer most from the effects may have had a smaller one to begin with. In any case, PTSD is not, in itself, a predictor of violence.
Dr. Lewis, who is also a professor of translational neuroscience, said scans have shown how the brains of people diagnosed with schizophrenia differ from the brain of those with no history of mental illness, but the technique won't tell much on an individual basis. For example, schizophrenics tend to have a smaller amount of gray matter in the cerebral cortex, he said, but that's in comparison to what they would have had otherwise. The actual amount of gray matter could still be well within the normal range.
As imaging improves and researchers learn more abut the relationship between brain structure and function and psychiatric disorders, Dr. Lewis said, the technology could help identify people who are at risk for psychiatric disorder.
"The goal would be to intervene in a way that prevents the progression of the illness. The science is advancing rapidly, and we're closer to that goal than ever," he said, but still nowhere near being able to use brain scans to prevent criminal acts.
So it's back to the fixes that are actually possible -- more effective gun curbs, better mental health treatment and saner legal procedures. At the rate we're going, however, there will be a lot more bodies on the way.
Sally Kalson is a columnist for the Post-Gazette (email@example.com, 412-263-1610).