Changes over time in prevalence rates of past-year cannabis use by men and women with a psychotic disorder.

Abstract

Background: General population data show cannabis use by younger people is declining but increasing in older adults. Overall, the gap between men and women appears to be narrowing. Little has been documented about sex and age differences in patterns of cannabis use over time by people with a psychotic disorder. We examined rates of past-year cannabis use by sex and age to determine whether use by this population has changed over time. Methods: Data on cannabis use from Australian National Psychosis Surveys (1997, 2010) were analysed by sex and age and compared to National Drug Strategy Household Surveys (1998, 2010). Results: Prevalence of past-year cannabis use by people with psychotic illness dropped significantly from 38.2% to 33.7%. Both sexes showed a decline in use. The steeper decline in use by men aged 18-29 years (70.2% to 47.8%) contributed to a narrowing of the sex gap. Conversely, use by men aged 55-64 increased from 4.8% to 18.8%. General population data showed a similar pattern of change across sex and age groups. Conclusions: Despite declining rates of past-year cannabis use in people with a psychotic illness, rates remain more than double that of the general population. Traditionally, men were more likely to use cannabis than women, but convergence in rates in younger people shows this is changing. Furthermore, cannabis use is not restricted to young people. Increasing use of cannabis by older men will place additional demands on drug and alcohol services.