Unexpected Criminality: When The Cause Is In The Anatomy Of The Brain

A new study has shown that damage to a specific part of the brain, called the right uncinate fasciculus, may be linked to the emergence of criminal behavior after injuries such as strokes or trauma. This region connects areas that control emotions and moral decisions. When it is affected, a person may have more difficulty controlling impulses or evaluating the consequences of their actions, which can contribute to violent or antisocial behavior.

In recent years, human brain imaging has been increasingly used as evidence in court, especially in criminal trials. This is due to the growing understanding that certain brain injuries can directly affect a person's behavior.

A new study led by researchers from the University of Colorado, Harvard Medical School, and other American institutions makes an important contribution to this debate: it suggests that damage to a specific region of the brain may be linked to the development of criminal behavior, especially violent behavior.

Scientists analyzed brain scans of 17 people who began committing crimes only after suffering brain injuries caused by events such as strokes, tumors, or head trauma. These injuries were compared with those of hundreds of other patients who presented with various neurological symptoms (such as memory loss, depression, or anxiety) but had no history of criminal behavior.

The major finding was that in cases where criminal behavior emerged after the injury, one region of the brain was frequently damaged: the right uncinate fasciculus.

The uncinate fasciculus is a strip of white matter in the brain that functions like a kind of "electrical wire," connecting two very important areas: one involved in rational decision-making and the other linked to emotions. In other words, it helps the brain balance reason and emotion, and therefore plays a central role in our ability to make moral decisions, control impulses, and feel empathy.

When this "wire" is damaged, particularly on the right side of the brain, the functioning of this connection can be impaired. This can make it more difficult for a person to predict the consequences of their actions, control aggressive impulses, or understand how their actions affect others.

To confirm this link, the researchers used an advanced analysis approach called connectome analysis, which maps the connections between different brain regions. This allowed them to more precisely understand which white matter pathways were affected in each case.

The right uncinate fasciculus was the pathway most strongly associated with criminal behavior, especially in cases of violence. A second tract called the forceps minor, which also connects important areas of the mind, appeared less relevant.

It's important to note that not all people with injuries to this area become criminals or violent. However, data show that when criminal behavior emerges after a brain injury, this region tends to be involved. This points to the possibility that specific brain damage, rather than brain damage in general, may cause or facilitate profound changes in social and moral behavior.

Example of a connectome-based analysis.

The researchers themselves acknowledge that these findings raise complex questions. Dr. Isaiah Kletenik, of Harvard Medical School and lead author of the study, commented that the work contributes to the difficult discussion of culpability and free will.

If the brain is damaged and this influences a person's behavior, to what extent can they be considered fully responsible for their actions?

Furthermore, the authors emphasize that this information could be useful for both medicine and law. Doctors could identify at-risk patients and offer more targeted monitoring or interventions. The judicial system could eventually consider these factors when evaluating cases in which brain injury is demonstrably linked to the crime committed.

In summary, the study reveals that lesions in the right uncinate fasciculus of the brain may be linked to the emergence of criminal behavior, especially violent behavior, after a brain injury. This helps expand our understanding of how the brain influences human behavior and why, in certain cases, the root of violent actions may lie in specific physical injuries, not just conscious choices.

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White matter disconnection in acquired criminality

Isaiah Kletenik, Christopher M. Filley, Alexander L. Cohen, William Drew, Patricia S. Churchland, R. Ryan Darby, and Michael D. Fox 

Molecular Psychiatry (2025)

https://doi.org/10.1038/s41380-025-03076-z

Abstract: 

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.