Drivers have to inform the DVLA about some medical conditions
People on anti-depressants may have impaired driving skills, a small US study suggests.
Researchers put 60 people through a driving simulation to test steering, concentration and reactions.
North Dakota University found those on high dose anti-depressant courses had poorer driving skills.
But it was not clear whether it was the pills or the actual condition that caused the impairment and researchers said a larger study was now needed.
The participants were split between those who were not on medication, those taking a low dose course and others on a high dose.
The simulation they were put through recreated a series of common driving situations, such as reacting to brake lights, stop signs and traffic signals.
The team, which is presenting its findings at the Annual Convention of the American Psychological Association, found a significant difference between those not on medication and those on high doses.
Overall, those not on medication got 69 points, those on low medication 65 and those on high 54.
The team said it could be either the pills themselves or the condition which caused the problems.
Lead researcher Dr Holly Dannewitz said: "There is obviously more work to do on this. We need a much larger study, but there certainly seems to be some sort of link.
"I think people who are depressed, especially those on anti-depressants, should be aware of this if they are driving or doing anything that relies on concentration and reaction skills."
Drivers in England and Wales are requested to inform the Driver and Vehicle Licensing Agency if they have a medical condition which could impair their driving and this does include depression.
However, driving restrictions are much more likely to be imposed on those who have a history of conditions such as epilepsy or strokes.
A spokesman for the DVLA said: "Assessments are done on a case-by-case basis. We would urge anyone who feels their driving is impaired by a medical condition to contact us."
But Alison Kerry, from the mental health charity Mind, said: "Depression can affect people in many different ways, but one of the common symptoms is experiencing difficulty concentrating.
"However, it's important to state that everyone has highs and lows in concentration and reaction times, and a period of depression doesn't mean that you're a danger on the roads."