Prevalence and Factors Associated With Illicit Drug Use Among Older Australians: A Cross-Sectional Study Using a Nationally Representative Household-Based Survey (HILDA)

BACKGROUND: Illicit drug use among older adults (aged 45+ years) is increasing globally. Despite the growing impact on older adults, studies examining illicit drug use in this population remain limited. METHOD: Data were drawn from Wave 21 (2021) of the Household, Income and Labour Dynamics in Australia (HILDA) longitudinal cohort survey. The analysis included 7862 participants aged 45+ years, representing a weighted population of 8 713 896 individuals. The primary outcome was any illicit drug use in the past 12 months and was coded as a binary variable (yes/no). A series of Survey-weighted logistic regression (svy: logistic) was used to examine associations between illicit drug use and a range of explanatory variables, including individual-level, lifestyle behaviours, and social and mental health factors. RESULT: Illicit drug use prevalence among older adults was 42% (95% CI: 40-43). Illicit drug use was significantly higher among participants born in main English-speaking countries (adjusted odds ratio [aOR] = 1.47; 95% CI: 1.08-1.99), in Australia (aOR = 1.47; 95% CI: 1.16-1.87), and those living in Inner Regional areas (aOR = 1.93; 95% CI: 1.07-3.47). Participants with moderate psychological distress (K10) had 1.24 times higher odds (aOR = 1.24; 95% CI: 1.03-1.50), and those with high or very high distress had 1.57 times higher odds (aOR = 1.57; 95% CI: 1.22-2.04) of reporting illicit drug use. Lower scores on the SF-36 Mental Health scale (moderate or low mental health status) were significantly associated with increased odds of illicit drug use. Those who experienced traumatic life events were more likely to report illicit drug use (aOR = 1.22; 95% CI: 1.05-1.42). CONCLUSION: Illicit drug use among older adults is associated with smoking, high-risk alcohol use, psychological distress, and trauma exposure. These findings highlight the need for integrated interventions addressing both substance use and mental health.