Washington, June 7 : A brain imaging study has suggested that men with a history of violent behaviour may have greater gray matter volume in certain brain areas, whereas men with a history of substance use disorders may have reduced gray matter volume in other brain areas.

According to background information in the article, research suggests that violent behaviour may stem from a complicated mix of biological, psychological, and social factors.

"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)," the authors wrote.

"Thus, teasing apart alterations in brain structure associated with persistent violent behaviour and those associated with SUDs presents an ongoing challenge," they said.

Boris Schiffer, Ph. D., from the University of Duisburg-Essen in Germany, and colleagues compared violent offenders, both with (12) and without SUDs (12), with non-violent men, both with (13) and without SUDs (14).

The researchers identified differences in the brains of men in the various categories.

Participants with a history of violence and had a greater volume of gray matter in certain brain areas than non-violent participants, regardless of a history of SUDs.

The increases in gray matter volume among violent offenders appeared in the mesolimbic areas of the brain, which previous research suggests are linked to feelings of desire and reward as well as antisocial behaviour and psychopathology.

Further, gray matter decreases in other areas of the brain-characterized men with SUDs regardless of a history of violence.

The larger gray matter volumes in participants with violent tendencies were associated with higher scores for psychopathy and lifelong aggressiveness, whereas the smaller volumes of gray matter in those with SUDs appeared to be related to response inhibition.

Among men with SUDs, the study found smaller gray matter volume in areas of the brain that play a part in social behaviour as well inhibition.

The study has been published online by the Archives of General Psychiatry, one of the JAMA/Archives journals. (ANI)