Adults with attention-deficit/hyperactivity disorder (ADHD) who stay on their medication may be safer when they get behind the wheel than those who don't, a new study suggests.
Researchers found a link between a person's use of prescribed ADHD medications and a reduced risk for motor vehicle accidents: U.S. men with ADHD were 38 percent less likely to be involved in a car crash during the months when they received medication for the condition, compared with the months when these same men were not receiving medication.
For U.S. women with ADHD, the rates of motor vehicle crashes were 42 percent lower during the months when the women had received their ADHD medications than during the months when these same women went without treatment, according to the findings. The research was published today (May 10) in the journal JAMA Psychiatry. [10 Ways to Keep Your Mind Sharp]
The researchers concluded that people with ADHD are more likely to have motor vehicle crashes than people who do not have the condition, but that taking medication may help to reduce this risk, said lead study author Zheng Chang, a postdoctoral researcher in medical epidemiology and biostatistics at the Karolinska Institutet in Stockholm.
This is the first study to examine the association between the use of ADHD medication and motor vehicle crashes in the U.S., Chang told Live Science.
Previous studies have suggested that people with ADHD are more likely to be involved in motor vehicle crashes, because many of the symptoms of the disorder, such as inattention and impulsivity, may interfere with the ability to drive safely. However, researchers also thought that the use of ADHD medication could have a protective effect, reducing unsafe driving behaviors and resulting in fewer crashes and injuries.
In one study done in Sweden and published in 2014 in JAMA Psychiatry, researchers found that the use of ADHD medication in men was tied to a lower risk of traffic crashes, but it was unclear whether women's use of ADHD medications had a similar effect.
ADHD medications and car accidents
In the new study, the researchers tracked more than 2 million American adults who had been diagnosed with ADHD between 2005 and 2014. The data came from a health insurance claims database that contained patient information from more than 100 health insurers, including inpatient and outpatient hospital visits as well as prescriptions filled.
To determine whether individuals with ADHD had been involved in car crashes, the researchers looked at visits to hospital emergency rooms resulting from motor vehicle accidents.
The findings showed that ADHD medications were associated with a reduced risk of motor vehicle accidents in both men and women, Chang said. In a separate analysis, the researchers estimated that up to 22 percent of the car crashes could have been avoided if the patients had received ADHD medications at some point during the entire study period, he noted.
Chang said he suspects the findings may actually underestimate the effect of ADHD medication on car accidents. That's because the study did not include crashes in which people did not seek out medical services, Chang said.
"Many (possibly most) vehicular collisions do not result in an emergency room visit," two other researchers wrote in an editorial accompanying the study that appeared in the same issue of JAMA Psychiatry. In addition, the data did not include car crashes that involved a person dying at the scene, the editorial noted.
In all, the new study probably underreports the benefits of appropriate ADHD medication and its effects on driving safety, suggestedthe editorial authors, Dr. Vishal Madaan, a child psychiatrist, and Daniel J. Cox, a professor of psychiatry and neurobiology, both at the University of Virginia School of Medicine in Charlottesville.
Both of the editorial authors acknowledged receiving research support from pharmaceutical companies. [10 Facts Every Parent Should Know About Their Teen's Brain]
Madaan and Cox suggested that another limitation of the study is the way the researchers defined a patient's "use" of the ADHD medication; this was based only on whether he or she had filled the prescription during a given month. This "may have little bearing on whether the medication was active in the driver's body at the time of the driving mishap," the editorial said.
It is not uncommon for people with ADHD to forget to take their prescribed medications or for the medication to have worn off at the time of the crash, especially if the accident occurred later in the evening, the editorial said.
But overall, the editorial concluded that the study findings confirm and extend the existing evidence for the influence of ADHD medications on accidents. The results "have impressive implications for [the] judicious use of ADHD medication," the editorial said.
Originally published on Live Science.