Changes in General and Specific Psychopathology Factors Over a Psychosocial Intervention.

OBJECTIVE

Recent research suggests that comorbidity in child and adolescent psychiatric symptoms can be summarized by a single latent dimension known as the p factor and more specific factors summarizing clusters of symptoms. This study investigated within- and between-person changes in general and specific psychopathology factors over a psychosocial intervention.

METHOD

A secondary analysis was conducted of the Systemic Therapy for At-Risk Teens study, a pragmatic randomized controlled trial that compared the effects of multisystemic therapy with those of management as usual for decreasing antisocial behavior in 684 adolescents (82% boys; 11-18 years old at baseline) over an 18-month period. The general p factor and specific antisocial, attention, anxiety, and mood factors were estimated from a symptom-level analysis of a set of narrowband symptom scales measured repeatedly during 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 bi-factor model that included a general p factor and specific anxiety, mood, antisocial, and attention factors with cross-loadings fit the data best. Although the factor structure was multidimensional, the p factor accounted for most of the variance in total scores. The p factor, anxiety, and antisocial factors predicted within-person variation in external outcomes. Furthermore, the p factor and antisocial factors showed within-person declines, whereas anxiety showed within-person increases, over time. Despite individual variation in baseline factor scores, adolescents showed similar rates of change.

CONCLUSION

The bi-factor model is useful for teasing apart general and specific therapeutic changes that 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.