Executive summary

This paper examines Australian population birth cohort trends in the prevalence of use, and the age of initiation of use, of six substances: alcohol, tobacco, cannabis, amphetamines, LSD, and heroin. Data were taken from the 1998 National Drug Strategy Household Survey, which was a representative sample of Australians aged 14 years and over. Nine five-year cohorts were examined in persons born between 1940 and 1984.

Results indicated that the lifetime prevalence of alcohol and tobacco use was similar among all birth cohorts, with the majority of persons reporting use of these substances. In contrast, the prevalence of illicit drug use – cannabis, amphetamines, LSD and heroin – increased significantly with successive birth cohorts. For example, while only 14% of those in the 1940-1944 birth cohort reported having used cannabis at some point in their lives, this figure was 63% among those born between 1975-1979.

Furthermore, more recent birth cohorts were significantly more likely to report using licit and illicit drugs at a younger age. Over half (56%) of those in the 1980-1984 birth cohort reported alcohol use by age 15 years, compared to 16% of those in the 1940-1944 birth cohort. Similarly, almost a third of those in the 1980-1984 birth cohort (31%) reported cannabis use by age 15 years, compared to under 4% of those born between 1940-1959.

Given the consistency of these findings with other research, and with what is known about changes in the availability of illicit drugs, it appears that more recent cohorts are more likely to use illicit drugs at some point in their lives. The consistency of the finding of reduced age of initiation among more recent birth cohorts for all drug types examined suggests that availability does not wholly explain the lower ages at which recent cohorts are using illicit drugs. These changes also reflect broader social changes and attitudes towards alcohol and other drug use.