New Study Links Brain Injuries to "Acquired Sociopathy"

This discovery brings into question how much free will there is in deciding to break the law.

How much of breaking legal or moral laws has to do with free will and how much with circumstances beyond our control has been fodder for philosophical debate for millennia. Mostly, this surrounded socioeconomic and political factors. The introduction of science ushered in whole other aspects.


Those with certain genetic mutations for instance, specifically the gene variant MAOA, are more likely to commit violent acts, research has shown. Others mutations are associated with mental illness, which may also contribute to violent outbursts. Now, the latest research out of Vanderbilt University finds that brain lesions can increase the risk of a person committing a crime. The findings were published in the Proceedings of the National Academy of Sciences (PNAS).

Neuroscientists have debated whether or not there’s a link between brain injuries and violent acts, beginning with the case of Charles Whitman. In 1966 the former marine sniper took a rifle and climbed an observation tower on the campus of the University of Texas, where he shot 11 passersby below dead, until he was subdued by police (he killed 16 that day total, including his wife and mother).

After his death, an autopsy revealed he had a brain tumor—but it’s been much debated whether the tumor contributed to the incident or not. Other serial killers had suffered brain injuries, either from a fall, accident, or physical abuse, including Edmund Kemper, John Wayne Gacy Jr., Jerry Brudos, Gary Heidnik, and Ed Gein. Now, research by Ryan Darby, MD, assistant professor of Neurology at Vanderbilt University Medical Center (VUMC), is reinvigorating the argument.

It shows compelling evidence that lesions in one particular brain network can increase the risk of criminal behavior, what’s technically known as acquired sociopathy. Darby had read about famous cases, including Whitman’s, which inspired the study.


Investigators have long noticed a link between brain injury and criminal behavior. However, how influential brain injuries are to such behavior has been a matter of much debate. Credit: Getty Images.

This is the first brain-mapping study linking lesions to a higher propensity of criminal acts. A lesion is abnormal brain tissue which can occur as a result of trauma, a tumor, or a stroke. What this study found is that lesions occurring not in one specific area of the brain, but in a number of different places, can contribute to the likelihood of the person committing a crime.

Darby and colleagues conducted MRI and CT scans of convicted criminals. These were murderers, rapists, thieves, con artists, and others. The first group consisted of 17 individuals, and linked criminal behavior with brain lesions. But the second, with 23 volunteers, showed lesions in different areas of the brain. Researchers compared these brain scans to enormous neuroimaging datasets of healthy, law-abiding people. They compared each group’s connectomes, or the neural networks connecting brain regions.

Darby and colleagues discovered that although lesions inhabited different brain areas, they resided within the same neural networks in those who took part in criminal activity. Volunteers with a criminal past had lesions in the moral decision-making network, which means an injury here increases the likelihood of criminal behavior.

This network is involved with morality, value-based decision-making, “theory of mind,” and criminality. Theory of mind is being able to understand someone else’s point of view. There was no lacking in the areas where empathy is created however, which is consistent with this Harvard study, which found that psychopaths and sociopaths do have empathy and can feel regret—just a little differently than most people do. 

Lesions associated with criminal behavior. These are the lesions from the initial 17 criminal patients, as compared to the brain atlas. Credit: the Proceedings of the National Academy of Sciences.

According to Darby:

We looked at networks involved in morality as well as different psychological processes that researchers have thought might be involved — empathy, cognitive control and other processes that are important for decision making. We saw that it was really morality and value-based decision making — reward and punishment decision making — that the lesions were strongly connected to.

The approach is relatively new and was used in the past to study why patients with certain psychological disorders suffered from delusions or hallucinations. In those studies, neuroscientists hunted down the brain networks the lesions resided in, causing these symptoms. But this is the first time it’s been used to try and understand criminal behavior from a neurological standpoint. Darby and colleagues caution that the fatalists haven’t won the debate on criminality, at least not from this study's results alone.

The researchers attribute only 9% of violence or crime to traumatic brain injury. While 14% is associated with frontal lobe injury. In fact, one 2014 study found that only 20% of the 249 mass murder cases that year could be attributed to a head injury.

There are other factors experts say that influence people to behave in a dangerous or immoral way. Likely, a number of genetic, biological, social, and psychological factors work in concert for such antisocial behavior to occur.

To hear more about the free will vs. destiny debate from a neurological standpoint, click here:

Ideology drives us apart. Neuroscience can bring us back together.

A guide to making difficult conversations possible—and peaceful—in an increasingly polarized nation.

Sponsored
  • How can we reach out to people on the other side of the divide? Get to know the other person as a human being before you get to know them as a set of tribal political beliefs, says Sarah Ruger. Don't launch straight into the difficult topics—connect on a more basic level first.
  • To bond, use icebreakers backed by neuroscience and psychology: Share a meal, watch some comedy, see awe-inspiring art, go on a tough hike together—sharing tribulation helps break down some of the mental barriers we have between us. Then, get down to talking, putting your humanity before your ideology.
  • The Charles Koch Foundation is committed to understanding what drives intolerance and the best ways to cure it. The foundation supports interdisciplinary research to overcome intolerance, new models for peaceful interactions, and experiments that can heal fractured communities. For more information, visit charleskochfoundation.org/courageous-collaborations.

How to split the USA into two countries: Red and Blue

Progressive America would be half as big, but twice as populated as its conservative twin.

Image: Dicken Schrader
Strange Maps
  • America's two political tribes have consolidated into 'red' and 'blue' nations, with seemingly irreconcilable differences.
  • Perhaps the best way to stop the infighting is to go for a divorce and give the two nations a country each
  • Based on the UN's partition plan for Israel/Palestine, this proposal provides territorial contiguity and sea access to both 'red' and 'blue' America
Keep reading Show less

Why a federal judge ordered White House to restore Jim Acosta's press badge

A federal judge ruled that the Trump administration likely violated the reporter's Fifth Amendment rights when it stripped his press credentials earlier this month.

WASHINGTON, DC - NOVEMBER 16: CNN chief White House correspondent Jim Acosta (R) returns to the White House with CNN Washington bureau chief Sam Feist after Federal judge Timothy J. Kelly ordered the White House to reinstate his press pass November 16, 2018 in Washington, DC. CNN has filed a lawsuit against the White House after Acosta's press pass was revoked after a dispute involving a news conference last week. (Photo by Alex Wong/Getty Images)
Politics & Current Affairs
  • Acosta will be allowed to return to the White House on Friday.
  • The judge described the ruling as narrow, and didn't rule one way or the other on violations of the First Amendment.
  • The case is still open, and the administration may choose to appeal the ruling.
Keep reading Show less