Imaging shows structural differences in the brains of murderers
New data may hold clues into how the brains of people who commit violent crimes function differently.
Researchers recently uncovered multiple anatomical variations in the brains of convicted killers that may help explain their lack of empathy, guilt and sensitivity to consequences. MRI scans revealed that these individuals often have much smaller amygdala volumes compared to other nonviolent individuals.
To the authors’ knowledge, this research is the first to assess neural structure in pretrial murderers.
“The current structural imaging study set out to add to this very sparse literature by examining whether pretrial murderers (i.e., those awaiting trial) evidence structural abnormalities in two limbic/paralimbic regions that have been highlighted in the literature—the amygdala and orbitofrontal cortex,” corresponding author Adrian Raine, PhD, with the Departments of Criminology, Psychiatry, and Psychology, University of Pennsylvania, and colleagues explained. “It was hypothesized that murderers compared to controls would show reduced volumes of both the medial orbitofrontal cortex and amygdala.”
The team also hypothesized that psychopathy scores would have a relationship with altered volumes in the amygdala and orbitofrontal cortex as well. To that end, the group analyzed brain MRIs and psychological assessments to determine how brain structure relates to scores measuring psychopathic characteristics. Findings from a group of 37 murderers from China were compared to a group of nonviolent controls, with details such as age, gender, total intracranial volume, cognitive function, broken homes and histories of substance abuse, mental health disorders and head injuries also being considered.
Compared to the control group, homicidal offenders displayed lower amygdala and orbitofrontal cortex volumes, as expected. These findings were particularly notable in the lateral orbitofrontal cortex and the left hemisphere of the amygdala. Deformations to the left amygdala in murderers were localized to the central, lateral and basolateral nuclei. Those who planned their crimes showed more significant reductions (around 14%) in the amygdala.
The murderer group with the highest psychopathy scores also showed the greatest reductions in amygdala volume.
“Given the role of the amygdala in emotion regulation, moral decision-making and emotional decision-making— and given that poor emotion regulation, immorality and poor decision-making during fractious social encounters may act as risk factors for taking another's life—it is reasonable to anticipate some disruption to the amygdala in those perpetrating extreme violence,” the group noted.
They suggested that their findings could have important implications for forensic practice in the context of death penalty cases.
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In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.