Hair and Nail Cortisol as Biomarkers of Adolescent Stress: The Mental Health in the Moment Biosampling Protocol

Background Previous studies have suggested associations between stress and mental health in adolescence; however, studies are needed to illuminate the developmental relations between cortisol and mental health in longitudinal data. This study combines hair and fingernail cortisol with ecological momentary assessment (EMA) and survey data to offer a new way of examining developmental relations between cumulative stress and mental health throughout adolescent development. The objective is to assess the relations between stress biomarkers and mental health outcomes and trajectories throughout adolescent development. Methods Participants will include approximately n = 500 adolescents from the Mental Health in the Moment (MHIM) project and attending school in Scotland in years S1-S5 (aged 11–16 years) at intake. Cortisol, cortisone and gonadal hormones will be measured via either hair or fingernail samples. Samples will be collected alongside a biosampling survey at a minimum of three time-points during the 5-year data collection period. As part of the MHIM project, participants will complete a survey on demographics, mental health, and lifestyle-factors, as well as daily surveys via EMA, which will be linked to the stress biomarker data. Analysis Data will be analysed with methods such as linear regression, latent growth curve models, random intercept cross-lagged panel models, and dynamic structural equation modelling to illuminate the predictors, outcomes, and developmental trajectories of stress biomarkers over adolescence, as well as their relations with mental health. Discussion Measuring stress biomarkers across the course of adolescence has the potential to provide developmental insights into cumulative stress and its links to mental health during this critical developmental period. Insights can inform intervention and mitigation strategies throughout adolescence. However, stress biomarker measurement carries a number of challenges, including potential difficulties with acceptability. Working closely with a young person’s advisory group and offering multiple participation options (hair and fingernails) is anticipated to help mitigate these challenges.