Résumé·s
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.