Effects of long-term administration of buspirone and diazepam on driver steering control

The effects of buspirone, diazepam, and placebo on tracking control were investigated over a nine-day period, using three groups of subjects, each with eight females and eight males. Subjects were tested using an interactive, computer-based driving simulator on days one, eight, and nine of the treatment period. On day nine, subjects received alcohol with their drug treatment. Measures of steering control were derived from car-driver transfer functions. Tracking performance was also measured. Diazepam was found to adversely affect steering control measures in comparison with placebo. This was true both after doses on the first as well as the eighth day of treatment. Thus, there was no evidence of behavioral tolerance to diazepam. In contrast, buspirone was not found to have any adverse effects on steering control; in fact, some evidence of improved tracking control was found. When alcohol was added to each treatment on the ninth day, differences between the drug treatment groups were less pronounced but in the same direction as on the first and eighth days.