You've probably noticed how the quietest of simpletons turn violent and boisterous after a few pegs of their favorite booze. Finnish researchers attribute this post-booze behavior to an over-active gene which triggers aggression.
Finnish researchers have found that drinking and MAOA gene can help predict impulsive violent behavior in men.
The monoamine oxidase A (MAOA) gene is an outer membrane mitochondrial enzyme that breaks down monoamines such as serotonin, noradrenalin and dopamine.
A common polymorphism in MAOA results in high- or low-activity MAOA that has been linked to aggression and violence.
The researchers have found that drinking and high-activity MAOA can predict the risk of impulsive violence, while aging may decrease this risk.
Roope Tikkanen, a researcher in the department of psychiatry at Helsinki University Central Hospital and corresponding author for the study and his colleagues decided to look at the MAOA gene, alcohol consumption and aging as predictors for recidivism in impulsive violent behavior among a sample of 174 Finnish alcoholic male offenders originally recruited between 1990 and 1998.
Each offender was given a psychiatric assessment; in addition, their alcohol consumption was measured, their violent behavior was assessed, and they were genotyped for polymorphisms of MAOA.
"Increased alcohol consumption and aging seem to predict violence," said Tikkanen, "although these risk factors 'work' in opposite directions, and only concern individuals who have been given by nature a high-activity variant of MAOA."
He said additional research has suggested that individuals with low-activity MAOA seem to be at risk for criminality and violence after exposure to severe childhood maltreatment.
"People react quite differently to acute alcohol exposure," Tikkanen said.
"Most individuals become relaxed and talkative, while some - particularly persons who are introverted while sober - become expansively extroverted and aggressive.
"A dramatic change from a normally introverted personality to extroverted aggressiveness and uncontrolled behaviors under the influence of alcohol was formerly called 'pathological intoxication' in Finland," he added.
Tikkanen suggests that high-activity MAOA offenders may be helped to control their violent behaviors by coaching to maintain alcohol abstinence, and possibly by psychopharmacological treatment to increase central serotonin levels.
The study will be published in Alcoholism: Clinical and Experimental Research and are currently available at Early View.