Cross-Lagged Panel Models of Symptom Patterns in Transdiagnostic Treatment for Children and Adolescents with Comorbidities.

OBJECTIVE: Youth mental health disorders are commonly categorized as internalizing (e.g. depression, anxiety) or externalizing (e.g. disruptive misconduct), yet many youths meet diagnostic criteria for both. The purpose of this study was to assess the directionality of change of internalizing and externalizing symptoms among youths with comorbid presentations who received the Modular Approach to Treatment of Children with Anxiety, Depression, Trauma, or Conduct Problems (MATCH). METHOD: We investigated trajectories of symptom patterns during treatment for youths with comorbidity/elevations in both internalizing and externalizing broadband scales of the Child Behavior Checklist (CBCL) and/or Youth Self Report (YSR) at baseline. We used data from youths and caregivers (N = 273, Mage = 10.1 years old, 56.8% cisgender boys, 60.1% white) reporting clinically elevated internalizing and externalizing symptoms at baseline in three randomized trials of the transdiagnostic MATCH. Cross‑lagged panel models were conducted to assess patterns of symptoms across four timepoints. RESULTS: No significant directional pattern was found for youth-reported symptoms, but caregiver-reported symptoms showed a significant directional relationship such that when externalizing symptoms improved, internalizing symptoms subsequently improved. This finding was robust across sexes and treatment priority groups - i.e. regardless of whether treatment initially focused on internalizing or externalizing symptoms. CONCLUSION: The findings highlight the potential importance of reducing externalizing symptoms in youths receiving transdiagnostic treatment for comorbid presentations.