November 17, 2015

Does violence lurk in psychopaths' brains?

People with a particular set of biological and social factors could have a predisposition to kill

It was the summer of 1966 when 25-year-old Charles Whitman murdered his wife and mother, stabbing them both in their homes. The following day, he packed an assortment of firearms into a foot locker, drove to the University of Texas at Austin's campus, and took the elevator to the top of the Main Building's tower. Upon reaching the observation deck, one by one, he began to shoot at passersby down below.

Whitman, left, killed a total of 16 people and wounded 32 more before being shot dead by police. The incident sent shockwaves through the nation and seemed particularly chilling because Whitman had no hallmarks of being a psychopath. He came from a good family, was the youngest boy to achieve the rank of Eagle Scout at the time, and later became a clean-cut Marine.

What could have caused this young man to go from model citizen to ruthless mass murderer? A likely explanation was found in his autopsy, which revealed a tumor pressing against his amygdala – an area of the brain associated with intense emotions like aggression and fear.

“It's a fascinating case study not only because of the amygdala involvement, but also because he really came from a good home. Poverty, bad home environment, and the other environmental suspects were not a cause of his violence,” said Adrian Raine, a professor in the Departments of Criminology, Psychiatry, and Psychology at the University of Pennsylvania and author of the book The Anatomy of Violence: The Biological Roots of Crime.

While such social influences on violence have been identified for decades, Raine studies the biological basis behind criminal behavior. As controversial a view as this may be – particularly to victims or families of victims – his research explores the idea that perhaps society should view criminals not as inherently evil, but as patients suffering from a clinical disorder.

In an eerie letter written the day before the mass shooting, Whitman described seeing a psychiatrist for a single session to talk about his “overwhelming violent impulses.” But afterwards he writes, “... since then I have been fighting my mental turmoil alone, and seemingly to no avail.” He also describes having terrible headaches for the last three months, and himself requests the autopsy to be performed after his death “to see if there is any visible physical disorder.”

Not all criminals will have a growing tumor, but physical deformities or impaired functioning in certain parts of the brain have been associated with violence or psychopathic behavior.

In a recent study, researchers found that males with lower amygdala volume exhibited higher levels of aggression and are at elevated risk for committing future violent crime. (iStock)

In one of his recent studies, published by the journal Biological Psychiatry in 2014, Raine and his colleagues found that males with lower amygdala volume exhibited higher levels of aggression and psychopathic features, and are at elevated risk for committing future violent crime. They used structural magnetic resonance imaging (MRI) to measure the volume of this critical brain area from when the subjects were young boys (7.5 years old) until the age of 29. Those subjects who had smaller amygdala were more prone to violence from childhood onwards.

“We need to replicate and extend these findings, but the question is, what if we bring on board biological factors alongside social factors to predict who among us would be violent?” he said. “So far we aren't using biological factors, but biology is 50 percent of violence, so we're ignoring half the picture.”

A physically deformed amygdala could explain why some psychopaths lack the remorse and guilt that comes alongside committing crimes for normal individuals. When the brains of control subjects are scanned while contemplating moral dilemmas, the amygdala will light up. But in Raine's 2009 study on psychopaths, functional MRI scans showed reduced amygdala activity, hinting that dysfunction in this area of the brain may be responsible for such callous, unemotional behavior.

“We know these psychopaths do terrible things, and we punish them very harshly, but are they really responsible for having an amygdala three sizes too small?” questions Raine. “Emotion is the engine that drives moral behavior. If we lack that feeling for what's moral, it's no surprise that we will act in an immoral fashion.”

Another brain area that has been implicated in criminal behavior is the prefrontal cortex, which is involved with impulse control and emotional regulation. Using positron emission tomography (PET) imaging, his laboratory scanned 41 murders and 41 normal controls and showed that the former group had poorer functioning in this particular region of the brain. The study was published by the journal Biological Psychiatry in 1997.

“We all get angry at times, but what stops us from lashing out? It's having our frontal cortex say, 'Calm down.' In a way, it's a little bit like the guardian angel of behavior,” he said. “But if it's asleep, then the devil can come out, and people can get killed.”

But just because these relationships exist between violence and biology does not mean that everyone with poor frontal lobe functioning will become a murderer. Think of the brain as one factor among many, including social influences like a poor childhood, poverty, or abuse. But for someone with a number of these switches flipped in the right direction – as in, biological plus social factors – he or she could be a walking time-bomb with a predisposition to kill.