These variations cannot be regarded as static: there was greater drug involvement among younger than older adults in all countries, suggesting that drug use has and may continue to change over historical time. Interestingly, there was also evidence to suggest that male-female differences in risk of initiating drug use may be changing in more recent birth cohorts. This change was a consistent finding across countries, suggesting that a general shift may be occurring with respect to the traditional sex differences so often documented with drug use.
