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, and both genotypes have been linked to aggression and violence. A Finnish study has found that drinking and high-activity MAOA can predict the risk of impulsive violence, while aging may decrease this risk.
Results will be published in the March issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.
“Alcoholism, alcohol consumption and violence are clearly related,” said Roope Tikkanen, a researcher in the department of psychiatry at Helsinki University Central Hospital and corresponding author for the study. He noted that crime statistics show that most impulsive homicides occur among adolescent and middle-aged groups rather than among the elderly, and habitually violent-impulsive offenders are often expected to “grow out of their difficulties” with increasing age. “Surprisingly little accurate information, however, is available on this aging-impulsive aggression issue,” he said.
Tikkanen 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.” On the other hand, he added, 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 continued. “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.”
Tikkanen and his co-authors suggest 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.
“In some countries, prison sentences may be very long - even a lifetime or more - and the reason for the sentence may be an accumulation of minor convictions committed in a drunken state,” said Tikkanen. “In such cases, it could perhaps benefit all parties to decrease the length of the sentence. Our results suggest that the risk for new violent crimes decreases by 150 percent when high-activity MAOA individuals become 20 years older. Perhaps we could increase the efficacy of addiction rehabilitation by focusing resources particularly on younger heavy-drinking high-activity MAOA individuals.”
— — — — — — — — — -
Article adapted by Medical News Today from original press release.
— — — — — — — — — -
Alcoholism: Clinical & Experimental Research (ACER) is the official journal of the Research Society on Alcoholism and the International Society for Biomedical Research on Alcoholism. Co-authors of the ACER paper, “Effects of MAOA-genotype, Alcohol Consumption, and Ageing on Violent Behavior,” were: Richard L. Sjöberg of the Laboratory of Neurogenetics at the National Institute on Alcohol Abuse and Alcoholism, the Center for Clinical Research at Uppsala University in Västerås, Sweden, and the Department of Neurosurgery at University Hospital in Umeå, Sweden; Francesca Ducci of King’s College in London; Davie Goldman of the Laboratory of Neurogenetics at the National Institute on Alcohol Abuse and Alcoholism; Matti Holi and Matti Virkkunen of the Department of Psychiatry in the Institute of Clinical Medicine at the University of Helsinki; and Jari Tiihonen of the Department of Forensic Psychiatry and Clinical Physiology at the University of Kuopio, Finland. The study was funded by the National Institute on Alcohol Abuse and Alcoholism, and the Olle Engkvist Byggmästare foundation.
Source: Roope Tikkanen, M.D.
University of Helsinki
Alcoholism: Clinical & Experimental Research
Similar Posts:
- Drinkers With The Alcohol Dehydrogenase 1C*1 Gene Are At Greater Risk Of Colorectal Cancer
- The Language Of Intoxication: The Term ‘Drunk’ Doesn’t Really Cut It Any More
- White Matter, The Brain’s Connective Network Damaged By Prenatal Alcohol Exposure
- Alcohol And Licensing Policy Could Be Changing The Habits Of Young Drinkers
- Risk Takers, Drug Abusers Driven By Decreased Ability To Process Dopamine
Chronic drinking is a risk factor for colorectal cancer, possibly through the effects of acetaldehyde, which is created by the alcohol dehydrogenase (ADH) enzyme. This study investigated if a polymorphism of the ADH1C gene that is found in Caucasians may effect acetaldehyde concentrations. Findings confirm ADH1C*1 as a genetic risk marker for colorectal tumors among people who drink more than 30
The language that drinkers typically use to describe alcohol’s effects on them are quite different from the language used by alcohol researchers, no doubt limiting researchers’ understanding of self-reported alcohol use. New findings show that researchers could do well to tap into a wide spectrum of terms used by drinkers to describe their levels of intoxication; also, these tend to differ by gen
One part of the prenatal brain that may be particularly sensitive to alcohol’s effects is white matter, nerve fibers through which information is exchanged between different areas of the central nervous system. A recent study has demonstrated that alcohol consumption during pregnancy can alter the microstructural integrity of developing fetal cerebral white matter in the frontal and occipital lob
In a new report published online in the January issue of Addiction, researchers question whether current licensing policies have contributed to a rise in the phenomenon of “pre-drinking” amongst young people. “Pre-drinking” or “pre-gaming” involves planned heavy drinking, usually at someone’s home, before going to a social event, typically a bar or nightclub. As defined by young people themselves
For risk-takers and impulsive people, New Year’s resolutions often include being more careful, spending more frugally and cutting back on dangerous behavior, such as drug use. But new research from Vanderbilt finds that these individuals – labeled as novelty seekers by psychologists – face an uphill battle in keeping their New Year’s resolutions due to the way their brains process dopamine. The res