A new study of 17,000 Swedish residents with ADHD found a startlingly lower serious accident rate when male drivers were on their medication versus when they were not. The study found there was no such connection for female drivers. A UCLA researcher who studies attention-deficit/hyperactivity disorder noted Friday that the findings, while important, can’t yet definitively connect whether the medications prevented the accidents.
Researchers in Sweden found that having ADHD made men 47% and women 41% more likely to be in a serious vehicle crash, according to their report published in January in the journal JAMA Psychiatry. The research team tracked 17,408 drivers with ADHD for four years, using a trove of data available via government registries. The team then analyzed those involved in serious vehicle crashes and whether they were on ADHD medicine, they said in the JAMA report.
“Attention-deficit/hyperactivity disorder is associated with an increased risk of serious transport accidents, and this risk seems to be possibly reduced by ADHD medication, at least among male patients,” the researchers concluded “This should lead to increased awareness among clinicians and patients of the association between serious transport accidents and ADHD medication.”
One of the study authors, Zheng Chang, told Reuters that he believes the findings are “the tip of the iceberg,” given that only accidents serious enough to require hospitalization or death made the government data registry.
More follow-up study was suggested, but the researchers urged healthcare providers to educate patients with ADHD to take extra care and consider medication options. Attention-deficit advocacy groups agreed.
“This study confirms the importance of treatment and medication for adults with ADHD as well as teens,” Ruth Hughes, CEO of Children and Adults With Attention-Deficit/Hyperactivity Disorder (CHADD), a national non-profit advocacy group supporting patients and families, told webmd.com
“The core symptoms of ADHD include problems with sustained attention and impulsivity, which can have an adverse effect on driving safely,” Hughes, who was not involved in the new study, was further quoted. “All drivers with ADHD need to responsibly manage their treatment to reduce driving risks.”
The JAMA report, authored by five PhDs, said findings “suggested that 41% to 49% of the accidents in male patients with ADHD could have been avoided if they had been receiving treatment during the entire follow-up.”
The patients ranged from 18 to 46 years old. The study at Karolinska Institutet was not funded by the pharmaceutical industry.
“Even though many people with ADHD are doing well, our results indicate that the disorder may have very serious consequences,” said Henrik Larsson, associate professor at the Department of Medical Epidemiology and Biostatistics. 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 researchers were able to canvas an impressively large number because Sweden has socialized medicine and thus a large government database available to scientists. Dr. Stephen S. Lee, associate professor at UCLA’s Department of Psychiatry, teamed with Kathryn Humphreys, a doctoral candidate in UCLA’s Department of Psychology, to study children with ADHD and ADHD medicines. Specifically, the pair analyzed 15 long-term studies that followed 2,500 children with ADHD.
In 2011, the pair’s research found that children with ADHD are two to three times more likely to become substance abusers than are youth without the condition.
The pair conducted what was billed as the most comprehensive study of children with ADHD and future substance abusers. Humpreys wrote: “We found no association between the use of medication such as Ritalin and future abuse of alcohol, nicotine, marijuana and cocaine.”
The UCLA research will follow the youthful study subjects. Lee said that juvenile research subjects pose challenges in the scientific attempt to control for key factors. The Swedish researchers, one of whom Lee called a friend, have moved the ball forward on what we know about ADHD. But Sweden is a fairly racially homogenous country, he added, and it will be interesting to see whether the findings hold true in other countries.
“It’s a really well-done study, but to me it’s one piece of evidence addressing this important question, but it’s not the only evidence,” said Lee. “This is a really important finding. Now let’s see how well the finding stands up to replication and extension.”