Men with ADHD are less likely to be involved in road traffic accidents if they take the correct medication for their condition, a new study indicates.

ADHD (attention deficit hyperactivity disorder) is a behavioural disorder, the main symptoms of which include inattention, impulsivity and hyperactivity. Those affected show poor concentration, are often unable to complete tasks, day dream a lot, are distracted easily, act without thinking and can suffer temper tantrums.

Hyperactive symptoms can include restlessness and not being able to remain seated, such as during meals. In adults, this can manifest itself through excessive talking and feelings of being overwhelmed.

Previous research suggests that many adults with the disorder are left undiagnosed or untreated. However this latest study indicates that failing to treat the condition in adult men could be costing lives on roads.

Swedish researchers looked at 17,000 people with ADHD over a four-year period. They analysed the risk of road accidents for those diagnosed with the condition. They also analysed how ADHD medication influenced this risk.

Similar to previous studies, the researchers found that people with ADHD have a 45% increased risk of being involved in a serious road traffic accident, compared to people without ADHD.

However, the study also found that up to 50% of road accidents involving men with ADHD could be avoided if they were taking medication for the condition.

"Even though many people with ADHD are doing well, our results indicate that the disorder may have very serious consequences. Our study also demonstrates in several different ways that the risk of transport accidents in adult men with ADHD decreases markedly if their condition is treated with medication," the team from the Karolinska Institutet said.

The study compared men with ADHD who were on medication to men with ADHD who were not on medication. However, it also compared the men to themselves, i.e. it looked at periods when they were on medication and when they were not.

From this, the researchers were able to ascertain that medication played an important role. They found that during times of ADHD medication, men were 58% less likely to be involved in a road accident compared to when they were not on medication.

The researchers believe that the results may be due to the effect ADHD medication has on problems such as distractibility and impulsiveness.

"Despite having shown that medication for ADHD very likely reduces men's risk of transport accidents, we could not establish a similar reduction in women's accident risk. We need further data to be able to comment about the effect on women with statistical certainty," they noted.

Details of these findings are published in the journal, JAMA Psychiatry.