Comparisons were made between outpatients using various benzodiazepines and an individually age and sex matched control group regarding simulated driving (lateral position variation, brake reaction time), simple reaction time, choice reaction time and short term memory. The patients exhibited greater intra-individual speed variation in simulated driving, and impaired performance on simple reaction time and memory. No other differences were found regarding behaviour. No effects were found of a small alcohol dose (0.40 g pure alcohol/kg body weight in men and 0.36 g pure alcohol/kg body weight in women) on behaviour. BAC was just below 40 mg% at the laboratory tests and about 25 mg% at the simulator runs. Subjectively, a number of differences appeared between the two comparison groups. The patients reported higher levels of anxiety and depression, and lower wakefulness and well-being. Certain effects of alcohol appeared with regard to subjective measures; a higher degree of confusion, fatigue and depression and lower well-being. Regarding fatigue, the patients seemed to be somewhat more influenced by alcohol than the control group. Before the alcohol intake, four benzodiazepine users and two control subjects were judged, according to outward signs of drug influence, to be affected by medicines or alcohol. No relationship between dosage and performance was detected in an analysis. There was, however, a tendency for lateral position variation to increase with increased dosage. For brake reaction time, short term memory and choice reaction time, there were similar tendencies, but weaker. Reported feelings of depression and confusion increased with increasing dosage. The results do not give any clear indication that persons who use prescribed medication with benzodiazepines would constitute a significant traffic safety problem. A single dose of diazepam 5 mg had no clear effects on the control subject, regarding either behaviour or subjective measures. (A)
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