The epidemiology of mental and substance use disorders in Australia 2020-22: Prevalence, socio-demographic correlates, severity, impairment and changes over time.

Objective: Mental and substance use disorders are the leading causes of disability worldwide. Contemporary estimates of prevalence, severity and impairment are essential for service planning. This study provides estimates of prevalence, severity, impairment and demographic correlates of mental and substance use disorders in 2020-22 and changes in prevalence since 2007.

Methods: Data were from the two Australian National Surveys of Mental Health and Wellbeing conducted in 2020-22 (N = 15,893) and 2007 (N = 8841). Descriptive statistics report prevalence of lifetime and 12-month mental and substance use disorder by sex and age, proportion of people with each mental disorder by levels of severity (mild, moderate and severe) and mean days out of role by mental disorder class (mood, anxiety, substance use). Logistic regression analyses examined demographic correlates of mental disorder class and assessed changes over time.

Results: The lifetime prevalence of any mental or substance use disorder in 2020-22 was 40.2%. The 12-month prevalence was 20.2% (mood disorder - 7.4%, anxiety disorder - 15.7% and substance use disorder - 3.1%). Mood disorders were associated with significant impairment. The prevalence of mental disorders has changed over time, with mood and anxiety disorders increasing and substance use disorders decreasing. These changes were most evident among young adults.

Conclusion: Mental disorders are common in Australia. Impairment associated with mental disorders remains significant. Particular focus should be paid to young adults aged 16-24 years who have shown the largest increases in anxiety and mood disorder prevalence over the past 13 years.