Brain Injury Could Explain Sudden Criminal Behavior

FeaturedNeurosciencePsychology

·June 27, 2025

Summary: A new study has found that damage to a specific white matter pathway in the brain—the right uncinate fasciculus—may increase the likelihood of criminal or violent behavior following brain injury. Researchers analyzed scans from individuals who began committing crimes after suffering strokes, tumors, or traumatic injuries and found consistent damage to this region.

This tract connects areas involved in emotion and decision-making, and when disrupted, may impair impulse control and moral reasoning. While not all with such injuries become violent, the findings raise ethical and legal questions about culpability, intent, and the neurobiology of behavior.

Key Facts:

• Right Uncinate Fasciculus Damage: The most common brain injury among individuals who developed post-injury criminal behavior.
• Behavioral Impact: Disconnection in this area can impair emotional regulation, empathy, and moral decision-making.
• Legal Implications: Findings may influence future legal considerations around responsibility and sentencing after brain injury.

Source: University of Colorado

A new study led by researchers at the University of Colorado Anschutz Medical Campus, Brigham and Women’s Hospital and Harvard Medical School has found that damage to a specific region of the brain may contribute to criminal or violent behavior.

The study, titled “White matter disconnection in acquired criminality”, was published recently in Molecular Psychiatry.

The investigation analyzed brain scans from individuals who began committing crimes after sustaining brain injuries from strokes, tumors or traumatic brain injury. The study compared these 17 cases to brain scans from 706 individuals with other neurological symptoms such as memory loss or depression.

The investigators found that injury to the region of the right uncinate fasciculus was the most commonly affected area in the brains of those people who developed criminal behavior. The same pattern held true among individuals who committed violent crimes.

“This part of the brain, the uncinate fasciculus, is a white matter pathway that serves as a cable connecting regions that govern emotion and decision-making,” said Christopher M. Filley, MD, professor emeritus of neurology at the University of Colorado School of Medicine and one of the study’s co-authors.

“When that connection is disrupted on the right side, a person’s ability to regulate emotions and make moral choices may be severely impaired.”

“While it is widely accepted that brain injury can lead to problems with memory or motor function, the role of the brain in guiding social behaviors like criminality is more controversial,” said Isaiah Kletenik, MD, assistant professor of neurology at Harvard Medical School and lead author of the study.

“It raises complex questions about culpability and free will.”

Kletenik said during his time in behavioral neurology training at the University of Colorado School of Medicine he had the unique opportunity to evaluate patients who began committing acts of violence with the onset of brain tumors or degenerative diseases.

“These clinical cases prompted my curiosity into the brain basis of moral decision-making and led me to learn new network-based neuroimaging techniques at the Center for Brain Circuit Therapeutics at Brigham and Women’s Hospital and Harvard Medical School,” said Kletenik.

To strengthen the findings, the researchers conducted a full connectome analysis, employing a detailed map of how brain regions are interconnected. They confirmed that the right uncinate fasciculus was the neural pathway with the most consistent link to criminal behavior.

“It wasn’t just any brain damage, it was damage in the location of this pathway,” said Filley. “Our finding suggests that this specific connection may play a unique role in regulating behavior.”

The uncinate fasciculus links brain regions involved in reward-based decision-making with those that process emotions. When that link is damaged, particularly on the right side, people may have difficulty controlling impulses, anticipating consequences or feeling empathy, all of which can contribute to harmful or criminal actions.

While not everyone with this type of brain injury becomes violent the study suggests that  damage to this tract may play a role in new onset criminal behavior after injury.

“This work could have real-world implications for both medicine and the law,” said Filley. “Doctors may be able to better identify at-risk patients and offer effective early interventions. And courts might need to consider brain damage when evaluating criminal responsibility.”

Kletenik said that the findings raise important ethical questions.

“Should brain injury factor into how we judge criminal behavior? Causality in science is not defined in the same way as culpability in the eyes of the law. Still, our findings provide useful data that can help inform this discussion and contributes to our growing knowledge about how social behavior is mediated by the brain.” said Kletenik.

Experts from Vanderbilt University, University of California San Diego and Salk Institute, also collaborated on the study.

About this brain injury and criminality research news

Author: Laura Kelley
Source: University of Colorado
Contact: Laura Kelley – University of Colorado
Image: The image is credited to Neuroscience News

Original Research: Closed access.
“White matter disconnection in acquired criminality” by Christopher M. Filley et al. Molecular Psychiatry

Abstract

White matter disconnection in acquired criminality

Structural brain imaging is increasingly introduced as evidence in criminal trials.

A key imaging abnormality identified in criminal populations is alteration to the right uncinate fasciculus but it remains unclear whether these changes play a causal role in criminal behavior.

Lesion studies of acquired criminality offer the opportunity to assess the causal role of focal disruption of specific white matter connections in criminal behavior.

We studied lesion locations of focal brain damage associated with new onset criminal behavior compared to lesions associated with 21 diverse neuropsychiatric symptoms.

First, we analyzed the intersection of lesion locations with an atlas-based right uncinate fasciculus.

Second, we assessed the intersection of lesion locations with all white matter tracts from this atlas.

Third, we performed a connectome-based analysis of all possible white matter connections with each lesion location, without a priori assumptions regarding specific tracts.

We repeated all analyses limited to subjects who committed violent crimes. Lesions associated with criminality intersected the right uncinate more than lesions associated with other neuropsychiatric symptoms (p = 4.78 × 10⁻⁸).

Compared to other tracts, the right uncinate fasciculus was the tract most strongly associated with lesion-induced criminality followed by the forceps minor. An unbiased connectome-based analysis confirmed these findings.

Among subjects who committed violent crimes the right uncinate was the key tract identified. Lesions associated with criminality intersect the right uncinate fasciculus more than other lesions and more than other white matter tracts.

Damage to the right uncinate may play a causal role in criminal behavior, especially violent crime.