Antidepressants May Add Risk to Driving
Medication appears to affect concentration and reaction times

(HealthDay News) -- Antidepressant use has been linked to driving problems, but whether this stems from the pills or from the underlying depression remains unclear.

"We already know that depression causes concentration problems," Holly J. Dannewitz, who authored a study on the issue, told HealthDay. "And now it appears [from the study] that people taking antidepressants who also have relatively higher depression scores fare significantly worse when attempting to perform a computerized simulation of driving."

Dannewitz's study included 60 volunteers who used a computerized driving simulator. About half of them were taking at least one type of antidepressant, and the others were taking no medications. People taking antidepressants were categorized as having either high or low depression.

The driving simulation included such tasks as braking, steering and scanning sightlines as the drivers dealt with simulated traffic, stop signs, speed-limit signs, traffic lights, deer crossings and bicyclists.

Highly-depressed participants who were taking antidepressants scored markedly worse on several of the driving skills than did people who were not taking antidepressants. Their difficulties seemed to be caused by poorer concentration and a reduced ability to react well to situations that divided their attention and relied on their memories, the study found.

These types of problems were not noted among participants with low depression scores who were taking antidepressants. In fact, their driving skills equaled or surpassed those of the participants who were not taking antidepressants.

"More research needs to be done, of course," Dannewitz said. "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."

People diagnosed with depression frequently are prescribed antidepressants to ease their symptoms. But experts agree that all antidepressants have side effects, some of which could interfere with driving, but that the effects vary from person to person and from drug to drug.

The most common side effects, according to the U.S. Agency for Healthcare Research and Quality, are constipation, daytime sleepiness, diarrhea, dizziness, dry mouth, headache, nausea, sexual problems, shakiness, trouble sleeping and weight gain.

Blurred vision, tremors, an increased heart rate and anxiety, which could have bearing on driving ability, also are among the side effects of some antidepressants, according to the American Academy of Family Physicians.

Many side effects go away after a person has taken the medication for several weeks, but some continue as long as an antidepressant is taken.

"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," said Dr. Bernard Carroll, scientific director at the Pacific Behavioral Research Foundation in Carmel, Calif.

But driving difficulties could very well stem from the disease that the medication is attempting to treat, Carroll told HealthDay.

"There is already a very deep literature about subtle impairments of higher cognitive function associated with clinical depression itself, apart from medications," he said.

And that applies to more than driving, Dannewitz added.

This "is not just a question for drivers," she said, "because the cognitive skills needed for driving are also needed for a lot of other skills."

On the Web

To learn more about antidepressants, visit the U.S. Food and Drug Administration.

SOURCES: HealthDay News ; Holly Dannewitz, Ph.D., psychology resident, Agassiz Associates, Grand Forks, N.D.; Bernard Carroll, Ph.D., M.D., scientific director, Pacific Behavioral Research Foundation, Carmel, Calif.; presentation, Aug. 17, 2008, American Psychological Association annual meeting, Boston; American Academy of Family Physicians (www.familydoctor.org); U.S. Agency for Healthcare Research and Quality (www.effectivehealthcare.ahrq.gov)
Author: Robert Preidt
Publication Date: Publication Date: Sept. 30, 2009
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