How Does Booster Work? A Mediation Analysis of the Effects of Booster Sessions in a Transdiagnostic, Selective,...

Evidence supports the efficacy of transdiagnostic interventions to prevent emotional problems in adolescents. Recently, the role of booster sessions on treatment gains over time has been suggested. However, the underlying mechanisms that explain treatment outcomes after booster dosage are unknown. This study examined possible mediation effects of booster in a sample of 100 adolescents at risk of developing emotional problems who received the selective, personalised, preventive, transdiagnostic intervention named as PROCARE+. Participants were allocated into three conditions according to the number of booster sessions received after PROCARE + was implemented: none, one (at 6 months) or two (one at 6 and another at 12 months). Mediation models were conducted to examine the role of changes in emotional regulation and resilience on several outcome measures: self-perceived and parent-rated emotional risk, emotional symptomatology and quality of life. Results showed that emotional regulation, but not resilience, significantly mediated the improvements observed after receiving the booster sessions, emerging as a key psychological mechanism. In particular, participants who received one booster session compared to those who received no booster session evidenced improvements in their levels of emotional regulation, which partially mediated the effects on emotional symptomatology and quality of life. In addition to benefits after one booster dosage, adolescents who received two booster dosage also expressed a decrease of their risk of developing emotional problems.