Hair Cortisol Concentrations in the Prediction of Early Substance Use Engagement in Youth.

Objective: Understanding factors associated with early onset of substance use is critical as using alcohol or drugs at a young age is a strong predictor of later substance dependency. Experiencing stressful life events is associated with increased risk for early substance use in youth. Hair cortisol concentration (HCC) is considered a biomarker of psychological stress experienced over longer periods of time. We examined whether HCC could predict early substance use engagement in youth followed over 5 years.

Methods: Participants were 395 young adolescents (50% female, age range 10-15 years, M_age = 12.3, SD = 1.1 at baseline). Demographic data, socioeconomic factors, and substance use habits were collected at four waves between 2015 and 2021. HCC was assayed from hair collected at a home visit between Wave 1 and Wave 2. Analytic models tested a) HCC in relation to latent class membership of substance use and b) whether HCC moderated the relation between self-reports of stress and substance use.

Results: HCC did not add to the prediction of early substance use engagement in any of the models, while self-reports of stressful life events and everyday discrimination predicted early substance use engagement in the models comparing 'Early' vs 'Late/No' substance use class membership.

Conclusion: We found no evidence of HCC to be associated with early substance use engagement in youth. Nevertheless, our results do confirm that self-reports of stressful everyday life experiences predict earlier substance use engagement, underscoring the role of psychosocial stressors as significant predictors of substance use engagement in youth.