Drug Abuse and Dependence

3258 randomly selected adult household residents of Edmonton were interviewed by trained lay interviewers using the Diagnostic Interview Schedule (DIS). The lifetime prevalence of drug abuse/dependence was 6.996, with a male:female ratio of 3:1. The most commonly used drug was cannabis followed by amphetamines, opiates, barbiturates, hallucinogens and cocaine. 80.370 of those with drug abuse/dependence also had a lifetime diagnosis of another psychiatric disorder. In those with a comorbid diagnosis, the mean age of onset for the other psychiatric disorder was generally found to be younger than for the onset of drug abuse/dependence. Different comorbid disorders were found to significantly affect patterns of drug use.