Mechanisms of personality-targeted intervention effects on adolescent alcohol misuse, internalising and externalising symptoms

Abstract

Objective: This study aims to explore the mechanisms of personality-targeted intervention effects on problematic drinking, internalising and externalising symptoms. Method: As part of a cluster-randomised trial, 1210 high-risk students (mean age 13.7 years) in 19 London high schools (42.6% white, 54% male) were identified using the Substance Use Risk Profile Scale. Intervention school participants were invited to participate in personality-matched interventions by trained school staff. MacKinnon’s products of coefficients method was used to compare three complementary mechanism hypotheses, namely, whether early changes in i) alcohol use, ii) internalising and externalising symptoms or iii) personality during the 6 months post-intervention accounted for intervention effects over 2 years. Results: Early intervention effects on drinking behaviours during the 6 months postintervention partially accounted for longer term intervention effects on the onset of binge drinking (95% CI -.349 to -.062) and drinking problems (95% CI -.206 to -.016) over 2 years. Intervention effects on anxiety symptoms and conduct problems were partially mediated by early reductions in depressive symptoms (95% CI -.013 to -.001; 95% CI - .047 to -.001), and intervention effects on internalising symptoms were also partially mediated by reductions in anxiety sensitivity (95% CI -.003 to 0). Conclusions: 2 year intervention effects on problematic drinking were largely accounted for by early changes in drinking behaviours, and were not mediated by changes in mental health symptoms or personality risk factors. Early improvements in mood and anxiety sensitivity partially mediated longer term reductions in mental health problems.