Brain scans have revealed that males with a history of violent behavior have more gray matter in certain parts of the brain, while those with a substance abuse disorder have less, researchers from the University of Duisburg-Essen, Germany, revealed in Archives of General Psychiatry. Violent behavior is linked to a complex combination of social, psychological and biological factors.
The authors explain that brain studies of violent patients have provided some preliminary data. However, they stress that there is still much to learn.
They wrote:
“The interpretation of studies of the brain morphology of violent offenders is further limited by the fact that most of these men present with a substance use disorder (SUD). Thus, teasing apart alterations in brain structure associated with persistent violent behavior and those associated with SUDs presents an ongoing challenge.”
Boris Schiffer, Ph.D., and team compared four types of men:
- Violent offenders with a substance use disorder – 12
- Violent offenders without a substance use disorder – 12
- Non-violent males with a substance use disorder – 13
- Non-violent males without a substance use disorder (SUD) – 14
The first two groups came from forensic hospitals and penitentiaries while the second group were recruited through advertisements, employment agencies and psychiatric outpatient programs. All the males were aged between 23 and 54 years. Psychiatrists assessed them for mental disorders, aggressive behavior, impulsivity, and psychopathy. They all underwent an MRI brain scan at a university hospital.
The brain scans revealed that:
- Violent offenders with SUDs had more gray matter volume in the mesolimbic areas of the brain than violent offenders with no SUDs.
- Non-violent offenders had less gray matter volume in certain parts of the brain.
The mesolimbic areas of the brain are associated with antisocial behavior, psychopathology, and feelings of desire and reward.
Violent participants with more gray matter in the mesolimbic areas of the brain also had higher psychopathy and lifelong aggressiveness scores, while those with SUDs and less gray matter appeared to be linked to response inhibition.
There was less gray matter volume in parts of the brain linked to social behavior and inhibition in patients with SUDs, the researchers reported.
The authors wrote:
(more research is needed) “to link the observed structural abnormalities to specific deficits in functioning assessed by both neuropsychological tests and behavior in the real world and to the interactions of genes and environmental factors.”
Written by Christian Nordqvist