Driving is dangerous. 1.35 million people die from road accidents every year, according to the World Health Organization . Young people who just obtained their driving license, and especially young men, are at the highest risk for accidents. They are often seeking sensation, are more likely to take risks, and are more prone to take impulsive or thoughtless decisions while driving. To target this specific group, Estonian researchers have developed a training program for driving schools to make people aware of their impulsive tendencies.
Genetic predictors of traffic accidents
Interestingly, this Estonian research group that is led by professor Jaanus Harro specializes in genetics. Next to studying rats, Harro wanted to also investigate impulsive and aggressive behavior in humans. To measure this objectively outside of a laboratory setting they used data on traffic offences and accidents. Harro and his group found that a particular variation in the gene called 5-HTTLPR was associated with the number of speeding offences and traffic accidents . People who have the short version of this variant are less likely to be caught for speeding or be involved in accidents, compared to those with the long variant.
The gene 5-HTTLPR is an important player in the serotonin system in the brain. Serotonin is a messenger molecule with many functions, one of them being the regulation of mood, impulsivity and aggression. Some people are more prone to act without thinking, or without considering the consequences, and this can partly be explained by genetics.
Reducing impulsive driving behavior
So should only people with the short version of 5-HTTLPR be allowed to drive? No, Harro and his team came up with something better: a program to reduce impulsive behavior on the road. They gave this to students who were learning to drive. In the training, students discussed their own impulsive tendencies, and ways to overcome these tendencies. There was also a control group that did not receive this extra lesson. Four years after obtaining their licenses, the group that received the training had been less involved in traffic violations and accidents than the control group. What’s more, those individuals with the long variant of 5-HTTLPR – so the ones who are more likely to be impulsive, based on this gene – benefited from the training the most.
For the driving schools the main implication of this experiment is that it is very beneficial to incorporate awareness training about impulsivity into driving lessons. Already eight driving schools in Estonia are providing the program to their students. The genetic findings however are mainly of interest to the researchers, who are hoping to gain a better understanding of impulsive and aggressive behavior. In addition to the serotonin-gene, they have found that genetic variations in the noradrenaline and dopamine system are also linked to traffic offenses and speeding, and to the effectiveness of the training [3, 4]. And just recently, they found that the neuropeptide orexin is linked to both aggression and to the prevalence of drunk driving and traffic accidents .
In addition to genes, other factors such as age, intelligence, and stressful life events influence the risk of offences and accidents as well, but we still know very little about how this works. That is why Harro and his team are now investigating the interactions between genes and environment. This research is part of the horizon2020 projects CoCA and Eat2beNICE. Ultimately, through a better understanding of our biology they hope to improve the way that people behave on the road, thereby reducing the number of accidents.
Meanwhile, Jaanus Harro travels to ministries and other governmental organizations in Estonia and Finland, to convince them to implement the training program on a national level, and to provide funds for further research. And in case you wonder about Harro’s own driving habits: although he acknowledges that he is quite impulsive, he assures us that he has learned to keep this under control while driving.
Jaanus Harro was recently interviewed by Science Business about this topic. Parts of this blogpost ar based on this interview. You can read the article here: https://sciencebusiness.net/keeping-drivers-impulses-check
 https://www.who.int/news-room/fact-sheets/detail/road-traffic-injuries (accessed 3 January 2020).
 Eensoo, Paaver, Vaht, Loit & Harro (2018). Risky driving and the persistent effect of a randomized intervention focusing on impulsivity: The role of the serotonin transporter promoter polymorphism. Accident Analysis and Prevention, 113, 19-24. https://www.ncbi.nlm.nih.gov/pubmed/29407665
 Paaver, Eenso, Kaasik, Vaht, Mäestu & Harro (2013). Preventing risky driving: A novel and efficient brief intervention focusing on acknowledgement of personal risk factors. Accident Analysis and Prevention, 50, 430-437. https://www.ncbi.nlm.nih.gov/pubmed/22694918
 Luht, Tokko, Eensoo, Vaht & Harro (2019). Efficacy of intervention at traffic schools reducing impulsive action, and association with candidate gene variants. Acta Neuropsychiatrica, 31, 159 – 166. https://www.ncbi.nlm.nih.gov/pubmed/31182183
 Harro, Laas, Eensoo, Kurrikoff, Sakala, Vaht, Parik, Maëstu & Veidebaum (2019). Orexin/hypocretin receptor gene (HCRTR1) variation is associated with aggressive behaviour. Neuropharmacology, 156. https://www.ncbi.nlm.nih.gov/pubmed/30742846