Three categories of drugs, and specific commonly used drug subcategories are examined in this paper: depressants (benzodiazepines, methadone), stimulants (cocaine), and hallucinogens (cannabis). Descriptive, epidemiological studies on the incidence of drugs in driving populations show that cannabis or benzodiazepines are the most common drugs detected in most industrialised countries. The large number of experimental studies on the impact of various drugs on psychomotor performance show that the effects of the three categories of drugs and specific drugs with each category vary considerably. Some psychoactive drugs within these three categories have the potential to alter the skills required for driving. Analytic epidemiological studies, where comparison groups are utilised, provide the best information on the role of drugs in traffic crashes. The most rigorous epidemiological studies have been conducted on benzodiazepines and traffic crashes. Generally, benzodiazepine users are up to 6 times more likely to be in crashes than non-users, depending on the study; however; the effects can be mitigated by altering the mode and type of prescriptions. In terms of the other types of drugs, the research is less rigorous and has not clearly shown they are associated with increased rates of traffic crashes. (Author/publisher)
Abstract