Introduction: We extend prior reports about the risk of dependence on specific drugs by providing developmental-specific risk estimates for progression from first use to meeting criteria for DSM-III-R dependence upon cannabis, cocaine, or alcohol, as well as male-female differences.
Methods: The data are from the National Comorbidity Survey, with a national probability sample of persons 15-44 years old in the United States, which included many respondents who used cannabis, cocaine and alcohol on at least one occasion (n=3558, 1337, and 6149, for cannabis, cocaine, and alcohol, respectively). Survival analysis procedures provided cumulative risk estimates of progression from first use to dependence upon each drug.
Results: The estimated risk of cannabis dependence among male cannabis users was 1% in the first year after first use, and reached a peak at 4% per year 2 years later, before declining. In contrast, the estimated risk of cannabis dependence among female cannabis users remained at 1% per year for 3 years, without the peak. For both male and female cocaine users, the estimated risk for developing cocaine dependence was 5 to 6% within the first year after first use. Thereafter, the estimated risk declined from the peak value, with a somewhat faster decline for females in the next 3 years after first use. For alcohol, the estimated risk period extended for many years after the first drink, with female drinkers becoming alcohol dependent at a rate of about 1% per year; with somewhat higher risk for male drinkers. For both male and female drinkers, the period of risk for developing alcohol dependence extended for a span of more than 20 years since first use; for cannabis and cocaine, the estimated period of risk was much shorter.
Comment: There are male-female differences in the risk of becoming cannabis dependent during the first several years after initiation of cannabis use, less pronounced male-female differences for alcohol, and relatively smaller male-female differences for cocaine. These results should interest scientists whose focus is upon the origins of male-female differences in the occurrence of drug dependence.