Genetics

Drunken Recklessness May Be Genetic

A "relatively common" genetic mutation may trigger poor impulse control, especially when drinking.

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Had too much to drink and acted impulsively recently? Blame your genes! At least if you're Finnish, anyway… Research from Finnish scientists shows a "relatively common" genetic mutation in the Finnish population may prompt carriers toward more impulsive or reckless behavior when they consume alcohol. 

According to the study, published November 17 in the journal Translational Psychiatry, more than 100,000 Finns (2.2. percent of the population) carry this serotonin 2B receptor gene mutation. Identified in 2010, it's broadly associated with poor impulse control, a trait the researchers define as "a learned protective mechanism against overt reactions to negative emotions, and also [one that has] has a genetic foundation." 

In the new study, researchers looked at drunken impulse control among 14 carriers of the serotonin 2B receptor mutation and 156 non-carriers, using personality questionnaires, aggression screenings, alcoholism screening tests, and reports of lifetime drinking history. Analyses showed the presence of the mutation "predicted impulsive and aggressive behaviors particularly" when carriers had consumed alcohol. 

The [serotonin 2B receptor mutation] carriers demonstrated aggressive out-bursts, got into fights and behaved in an impulsive manner under the influence of alcohol. They were also arrested for driving while under the influence of alcohol more often than the controls. The HTR2B Q20* carriers were not alcoholics per se, as measured by average alcohol consumption, and were not diagnosed as alcoholics, but they had a tendency to lose behavioral control while under the influence of alcohol.

"The impact of one gene on complex phenomena is typically minor," said lead researcher and University of Helsinki psychiatry professor Roope Tikkanen. "But it is possible to identify the impact of such a genetic mutation in the Finnish population, as our historical isolation has led to a relatively homogenous gene pool." 

In their paper, Tikkanen and team—which includes scientists from the Finnish National Institute for Health and Welfare, the University of Eastern Finland, New York University School of Medicine, and the U.S. National Institute on Alcohol Abuse and Alcoholism's neurogenetics laboratory—note that the function of the serotonin 2B receptor gene is "poorly understood, especially in humans." But a pattern is starting to emerge. In addition to impulsivity, their research detected "high prevalence of mood disorder symptoms and emotional dysregulation" among carriers. And although their sample population was small, this finding is backed up by (limited) previous research on the mutation. 

"Apart from overt behavior, we observed an effect … on temperament, as a persistent tendency to react to stimuli in a certain way," they added. "Though not fully consistent, a pattern matching that of a passive-dependent personality emerged. Personality features such as relatively low interest in novelty and exploratory activities, anxiety, fear of uncertainty, attachment or dependence and low persistence were characteristic" of carriers. The mutation may also have a role in insulin and glucose metabolism, though this is speculative, they say.

At any rate, researchers caution that "the small sample size… increases the possibility of spurious results." Sampling was also "compromised by the fact that it was not originally designed for this particular study" and, perhaps more egregiously, the fact that half of the mutation group was comprised of female relatives of violent offenders. The study authors say they "tried to rule out all these … potentially biasing factors by adjusting the regression analysis with a categorical variable separating" the relatives with the gene from the non-relatives with the gene.