Is Antisocial Behaviour Hardwired in Some People?

Lisa Franchi December 19, 2014

New research found that teenagers carrying common variants of three genes are more likely to show significantly different levels of antisocial behaviour, depending on whether the individual grows up in an abusive or caring environment.

Every single high school student aged 17 to 18 years old in Västmanland, a Swedish county, was invited to participate in the study, and 1,337 agreed to do so. They anonymously completed questionnaires reporting on delinquency, family conflict, experiences of sexual abuse, and the quality of their relationship with their parents. They also provided a sample of saliva from which the researchers extracted DNA.

The Monoamine oxidase A (MAOA) gene is a key enzyme in the catabolism of brain neurotransmitters, monoamines, especially serotonin. Catabolism is the breaking down of complex materials and the releasing of energy within an organism. "About 25% of Caucasian men carry the less active variant of MAOA. Among them, those who experience physical abuse in childhood are more likely than those who are not abused to display serious antisocial behaviour from childhood through adulthood," Hodgins explained. "Among females it is the high activity variant of the MAOA gene that interacts with adversity in childhood to increase the likelihood of antisocial behaviour."

"We found that the three genetic variants interacted with each other and with family conflict and sexual abuse to increase the likelihood of delinquency, and with a positive parent-child relationship to decrease the risk of delinquency," Hodgins explained. "Among carriers of the low activity variants of all three genes, those exposed to family conflict or sexual abuse or both reported high levels of delinquency while those who reported a positive and warm relationship with their parents reported little or no delinquency." Thus, the same genetic variants were associated with high and low levels of delinquency depending on exposure to negative or positive environments.

The new study was published in the International Journal of Neuropsychopharmacology.

Source of this article:

http://medicalxpress.com/news/2014-12-genetically-predisposed-antisocial-behavior.html#ajTabs