Brain Lesions May Explain Criminal Behavior

Author: Megan Brooks

Exerpted from Medscape

Brain lesions temporally associated with criminal behavior map to a common functional brain network involved in aspects of moral decision making, a finding that may help explain why certain brain lesions may predispose individuals to criminal behavior, new research suggests.

"Prior case reports have noted that lesions can cause a previously normal person to be prone to criminal behavior. However, lesions in several different locations are able to cause this same behavior. We used a new technique and a map of the human brain's connectivity to show that all of these lesions were connected to the same brain network involved in morality," lead author Richard Darby, MD, from Vanderbilt University Medical Center in Nashville, Tennessee, told Medscape Medical News.

The study was published online December 18 in the Proceedings of the National Academy of Sciences.

Criminality-Associated Connectivity Pattern

The investigators systematically mapped brain lesions in 17 patients from the literature whose lesions were temporally associated with criminal behavior. They all exhibited criminal behavior after, but not before, the lesions occurred. The causes of the brain lesions included stroke, trauma, and tumors.

The lesions were located in spatially diverse brain regions. All of the regions were functionally connected to the network involved in morality, value-based decision making, and theory of mind, but not cognitive control or empathy.

The lesions involved in the "criminality-associated connectivity pattern" differed from lesions causing four other neuropsychiatric syndromes, the researchers report in their article.

The researchers replicated their results in a separate cohort of 23 cases in which a temporal relationship between brain lesions and criminal behavior was implied but not definitive.

"Our results suggest that lesions in criminals occur in different brain locations but localize to a unique resting state network, providing insight into the neurobiology of criminal behavior," they write.

It is important to note, say the researchers, that not all individuals with brain lesions within this network commit crimes. Genetic, environmental, and social factors are also likely to be important.

"We don't yet know the predictive value of this approach," Dr Fox said in a news release. "For example, if a brain lesion falls outside our network, does that mean it has nothing to do with criminal behavior? Similarly, we don't know the percentage of patients with lesions within our network who will commit crimes."

"Our study adds to the understanding of how the brain regulates moral behavior. Future studies are needed to see if our findings align with other diseases that may predispose patients to criminal behavior, such as frontotemporal dementia," Dr Darby told Medscape Medical News.

"Criminal responsibility is complex and ultimately determined by the legal system, not science. Usually, diminished responsibility requires that a patient have an impairment in their mental state that prevents them from understanding that their behavior was wrong or from conforming their behavior to the law," he added. "Whether the patient has a brain lesion or another reason for this impairment doesn't necessarily matter, although the presence of a lesion can give an explanation for why someone's behavior would change in this way."

Brain Imaging for New Criminals?

Commenting on the findings for Medscape Medical News, Virginia A. De Sanctis, PhD, chief of neuropsychology at Lenox Hill Hospital in New York City, said this is "an interesting article and topic."

"The notion that frontal lobe abnormalities or dysfunctional frontal systems are involved in abhorrent/criminal/pathological behavior is nothing new. It echoes back to a time when surgical interventions...that targeted the frontal lobes rose to popularity in the mid-20th century. The popularity of these surgical procedures preceded the invention of brain imaging (CT, MRI) in the 70s. Many of these procedures were probably effective because they were disrupting an abnormal network stemming from an undetected lesion," said Dr De Sanctis, who is also affiliated with Northwell Health Neuroscience Institute in New York.

This new study "highlights the importance of the lesion 'network' over the specific location of the lesion. The most hopeful aspect of the study results is the implication that treatment of lesions could prevent further criminal acts. 'Rehabilitation' of criminals could include surgical intervention for those with resectable lesions," Dr De Sanctis said.

"Should all individuals who develop criminal behavior undergo brain imaging? Perhaps," she said.

The study was supported by funding from the Sidney R. Baer, Jr, Foundation, the National Institutes of Health, the Dystonia Foundation, the Nancy Lurie Marks Foundation, the Alzheimer's Association, and the BrightFocus Foundation. The authors and Dr De Sanctis have disclosed no relevant financial relationships.

Proc Natl Acad Sci. Published online December 18, 2017.

Full text: Medscape