This paper presents some results of a cooperative American-German study of the effects of diazepam and diphenhydramine on the performance of drivers on a Daimler-Benz driving simulator. Diazepam was selected, because psychopharmaceuticals are significant drugs in traffic medicine, and because diazepam is frequently taken and has also been identified in fatally injured drivers. The antihistamine diphenhydramine was also selected, as a drug widely used in the USA. The test subjects were 60 male students, aged 22 to 26, with between 5.7 and 6.0 years of driving experience. They were verified to be in good health and not to be taking any other drugs at the time of the study. There were three groups of 20 each: (1) Group H received a high dosage of diazepam or diphenhydramine; (2) Group M received a medium dose; (3) Group L received no drug and acted as a control. The 20-minute test drive involved ten standardised driving tasks, which required either a 'normal' response or an 'emergency' response. For diazepam, no significant differences were found between the three groups tested for any of the variables considered in the ten tasks, but some specific differences were noted for some specific tasks. The results also took this form for diphenhydramine.
Abstract