Gene linked to impulsive behaviour while drunk

A common mutation in a serotonin receptor gene has been linked to impulsive and aggressive behaviours, particularly under the influence of alcohol.

The mutation, which affects the gene HTR2B, is found in 2.2 percent of the Finnish population, where the study was carried out.

'The results indicate that persons with this mutation are more impulsive by nature even when sober, and they are more likely to struggle with self-control or mood disorders,' said the study's first author, Dr Roope Tikkanen, a psychiatrist at the University of Helsinki.

The study, which was published in the journal Translational Psychiatry, included 14 people with the mutation and 156 controls. The participants completed questionnaires to assess their personality traits, aggressive and impulsive behaviours and alcohol consumption. They completed the questionnaires while sober and also after drinking alcohol.

Participants with the mutation reported more outbursts of aggression and displayed more impulsive traits, particularly in the context of a small amount of alcohol. Impulsive behaviours included spending sprees, impulsive sex and driving under the influence of alcohol.

The gene HTR2B codes for a receptor present throughout the brain. While the receptor's precise function is unclear, it has been linked to serotonin signalling. Serotonin has an established association with mental disorders and is targeted by major classes of psychiatric drugs. The mutation is present in 2.2 percent of the Finnish population, meaning that more than 100,000 Finns are carriers, but the mutation has not been found is those without Finnish ancestry.

The mutation was originally identified by a study in 2010, which analysed DNA from a group of Finns, a significant proportion of whom were violent offenders affected by alcoholism and personality disorders.

However, many participants were drawn from relatives of offenders in the original 2010 study, so some of the findings may be a product of a shared environment or other genes. Dr Tikkanen acknowledged that a larger study is required to establish a whether there is a real association between the mutation and behaviour.

He hopes that it might be possible in the future to use genetic screening to identify individuals at increased risk of offending and to tailor interventions – such as cognitive behavioural therapy – to increase self-control among individuals with the mutation. He also suggests that drugs affecting serotonin signalling may also be more effective in individuals with the mutation.

'Having this biologic mutation suggests that these persons could benefit more from medication than people without the mutation,' Dr Tikkanen told the Telegraph. 'However, there are only a couple of approved medicines available which have a partial affinity for this receptor. This gives an opportunity develop new, more receptor-specific medicines.'