A new study suggests that taking prescription antidepressants while still highly depressed could impair driving ability. Study author Holly J. Dannewitz says, “We already know that depression causes concentration problems. And, now, it appears that people taking antidepressants who also have relatively higher depression scores fare significantly worse when attempting to perform a computerized simulation of driving.” Dannewitz conducted her research while she was in graduate school at the University of North Dakota in Grand Forks. She is currently a psychology resident there in a private practice. Dannewitz and colleagues were scheduled to present their findings this weekend at the American Psychological Association annual meeting, in Boston.
The research team asked 60 people to “drive” a computerized version of a car in a program that mimicked real-world conditions. About half the participants were taking at least one type of antidepressant; the other half was generally taking no medication, except for oral contraceptives in some cases. Those on antidepressants were screened for current levels of depression and were then listed as either experiencing low or high depression at the time they underwent the test. Participants were asked to perform common driving tasks such as braking, steering, and scanning sightlines in response to an unfolding video of car traffic, stop and speed limit signs, traffic lights, deer crossings, bicyclists, and even the appearance of helicopters.
Those participants who were taking antidepressants and were highly depressed registered markedly worse scores on some driving skills than those not taking antidepressants, which appeared tied to poorer concentration and a weakened ability to react well in situations that divided attention and required memory skills. This result did not occur in those who were taking antidepressants and had low depression scores. That group actually was able to execute their driving tasks with a precision equal to that of those not taking antidepressants.
According to Dannewitz, “More research needs to be done, of course.” Dannewitz plans to study patients diagnosed with clinical depression but not on antidepressants to determine if the depression or medications cause the concentration problems. “And I wouldn’t want to instill fear in drivers. But I think that perhaps individuals who are taking these medications should just be aware of the fact that they may cause concentration problems and impair reaction time,” she said. “This issue is not just a question for drivers, because the cognitive skills needed for driving are also needed for a lot of other skills,” Dannewitz added
Dr. Bernard Carroll, scientific director of the Pacific Behavioral Research Foundation based in Carmel, California, also agreed that it’s too early to draw conclusions from the study, but was not surprised by the results. “There is already a very deep literature about subtle impairments of higher cognitive function associated with clinical depression itself, apart from medications,” he noted. “I would add that, in any case, medication package inserts routinely warn patients about a whole host of issues when starting a course of psychotropic drugs, including warning against the handling of machinery, driving, or engaging in any occupation in which you can be injured. So, to that extent, this concern isn’t new,” he noted.