Changes in General and Specific Psychopathology Factors Over a Psychosocial Intervention

Abstract Objective Recent research suggests that comorbidity among child and adolescent psychiatric symptoms can be explained by a single general psychopathology (‘p’) factor, as well as more specific factors summarizing clusters of symptoms. We investigated within- and between-person changes in the general and specific psychopathology factors over a psychosocial intervention. Method We ran a secondary analysis of the Systemic Therapy for At-Risk Teens study, a pragmatic randomized controlled trial that compared the effects of multisystemic therapy to management-as-usual for reducing antisocial behavior in 684 adolescents (82% male; 11-18 at baseline) over an 18-month period. The general p factor, as well as specific antisocial, attention, anxiety, and mood factors, were estimated from a symptom-level analysis of a set of narrow-band symptom scales measured repeatedly over the study. General and specific psychopathology factors were assessed for reliability, validity, and within- and between-person change using a parallel process multilevel growth model. Results A revised bifactor model that included a general p factor and specific anxiety, mood, antisocial, and attention factors with cross-loadings fit the data best. While the factor structure was multidimensional, p accounted for most of the variance in total scores. The p, anxiety, and antisocial factors predicted within-person variation in external outcomes. p and antisocial factors showed within-person reductions, while anxiety showed within-person increases over time. Despite individual variation in baseline factor scores, adolescents showed similar rates of change. Conclusion The bifactor model is useful for teasing apart general and specific therapeutic changes which are conflated in standard analyses of symptom scores. Clinical trial registration information : START (Systemic Therapy for At Risk Teens): A National Randomised Controlled Trial to Evaluate Multisystemic Therapy in the UK Context. http://www.isrctn.com; ISRCTN77132214