Substance use patterns among youth seeking help for mental illness: A latent class analysis

Substance use is common among youth, with emerging adulthood a high-risk period for developing both substance use disorder (SUD) and mental illness. Youth receiving mental health treatment have higher rates of substance use than their peers, providing an opportunity for early intervention for SUDs. To facilitate this, a better understanding of substance use patterns among help-seeking youth is needed.

We employed exploratory and confirmatory latent class analyses (LCA) to identify discrete classes of youth attending mental health services based on their substance use patterns, and assessed differences between groups in demographics, quality of life (QOL) and psychiatric symptoms.

Participants were treatment-seeking youth (15 - 25 years) recruited from headspace, Australia's national network of youth-focused primary mental health services, in 2 cohorts (Study 1, n = 676, female = 67.8 %; Study 2, n = 295, female = 66.3 %). Measurements included demographics, lifetime and recent substance use, mental health symptomatology and QOL.

Exploratory LCA (Study 1) revealed a four-class model of substance use: 1) current alcohol or no substance use (ALC), 2) current tobacco, alcohol, and cannabis use (TAC), 3) past polysubstance use, and 4) current polysubstance use. The current polysubstance use group reported more psychological distress than the ALC group and lower QOL than youth without polysubstance use (ALC and TAC). Confirmatory LCA (Study 2) identified four similar classes, however no differences between groups in distress or QOL were observed.

Findings identify clinically-significant substance use patterns among youth accessing mental health care, with implications for development of early interventions to address substance use in this risk-enriched population.