A new study links a high-activity monoamine oxidase A (MAOA) gene with violent behavior, triggered by alcohol.

This genetic sparkplug has already been linked to violent behavior, but alcohol seems to bring out the worst in otherwise not-so-violent people.

Alcohol and a polymorphism of the monoamine oxidase A gene predict impulsive violence

“People react quite differently to acute alcohol exposure,” [Roope Tikkanen, a researcher in the department of psychiatry at Helsinki University Central Hospital and corresponding author for the study 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.”

Regarding the decline in impulsive-aggressive behavior with aging among high-activity MAOA offenders, Tikkanen hypothesized that it may be due to a correction of low central serotonin levels in the central nervous system.

Tikkanen cautioned against genetic testing for individuals who may be worried for one reason or another about their risk. “Even though whole genome scans will one day be affordable, the average person probably has very many factors that differ from the violent offenders in the study,” he said. “For instance, the average Finnish consumption is two drinks a day or 10 kg pure alcohol per year, whereas the upper 10 percent of violent offenders drink approximately one 0.75 liter bottle of liquor a day or around 100 kg pure alcohol a year.”

I think I know a few of them. They may have already reproduced, though.

No word on any genetic causes for weepy drunks, sloppy drunks, or beer goggles. I expect to hear from a representative of Mothers Against Defective DNA any day now.

The study will be published in the March issue of Alcoholism: Clinical & Experimental Research

(via Geeks are Sexy)