Mood Instability in Youth at High Risk for Bipolar Disorder.

OBJECTIVE: Mood instability is associated with the onset of bipolar disorder (BD) in youth with a family history of the illness. In a clinical trial with youth at high risk for BD, we examined the association between mood instability and symptomatic, psychosocial, and familial functioning over an average of 2 years. METHOD: Youth (aged 9-17 years) with major depressive disorder or other specified BD, current mood symptoms, and a family history of BD were rated by parents on a mood instability scale. Participants were randomly assigned to 4 months of family-focused therapy or enhanced care psychoeducation, both with medication management as needed. Independent evaluators rated youth every 4-6 months for up to 4 years on symptom severity and psychosocial functioning, whereas parents rated mood instability of the youth and levels of family conflict. RESULTS: High-risk youth (N = 114; mean age 13.3 ± 2.6 years; 72 female) were followed for an average of 104.3 ± 65.8 weeks (range, 0-255 weeks) after randomization. Youth with other specified BD (vs major depressive disorder), younger age, earlier symptom onset, more severe mood symptoms, lower psychosocial functioning, and more familial conflict over time had higher mood instability ratings throughout the study period. Mood instability mediated the association between baseline diagnosis and mother/offspring conflict at follow-up (Z = 2.88, p = .004, αß = 0.19, 95% CI = 0.06-0.32). Psychosocial interventions did not moderate these associations. CONCLUSION: A questionnaire measure of mood instability tracked closely with symptomatic, psychosocial, and family functioning in youth at high risk for BD. Interventions that are successful in reducing mood instability may enhance long-term outcomes among high-risk youth. CLINICAL TRIAL REGISTRATION INFORMATION: Early Intervention for Youth at Risk for Bipolar Disorder; https://clinicaltrials.gov/; NCT01483391.