BEST-Foundations: a mixed methods exploration of the feasibility of a novel intervention treating internalising symptoms in children

Objective: Internalising disorders are one of the most common mental health problems in children under 12 years, yet mixed findings exist for current treatment options. This pilot involves a novel 10-session intervention, BEST-Foundations, to treat internalising symptoms in children using a family-inclusive model. Initial findings and feasibility using a mixed-methods approach are reported. Method: Twenty-two participants from eight families (n = 8 children; n = 8 mothers; n = 6 fathers) participated in an uncontrolled single treatment design. Included children (aged 3–11 years) reported clinical-level internalising symptoms on the Child Behaviour Checklist. Data were collected across four timepoints: baseline, pre-intervention, post-intervention, and 4-weeks follow-up. Results: As predicted, mothers reported large improvements in child internalising symptoms pre-post (SMD = −.83; 95% CI = 50.58–70.42) and maintained pre to follow-up (SMD = −.92; 95% CI = 50.14–69.11). Sustained improvements were also found in externalising problems and total problems. Qualitative analysis indicated families reported positive improvements in targeted areas including parent confidence and parent–child relationships. Conclusions: Findings demonstrate initial feasibility data and effect size estimates comparable to previous trials using the “BEST” framework, and larger than CBT-based interventions. Results are considered preliminary due to the small sample. Further evaluation is warranted, showing the value of family-inclusive interventions to treat child internalising problems.