The most common introduction to heroin and its use was through a friend (Table 2). However women were more likely than men to be introduced to heroin by a partner, boyfriend or spouse, whereas men were more likely than women to be introduced to heroin by a friend. There were no sex differences in age of initiation to drug or alcohol use, or in onset of heroin dependence. On average, females sought treatment for heroin dependence at a younger age than males (Table 1). Onset of cannabis use and first alcohol intoxication occurred, on average, at about the same age (~14 years, Table 1).
