RESUMO
BACKGROUND: This study, for the first time, compared illness and antidepressant response characteristics of young subjects with major depression (MDD) at low (LRMDD) or high-risk (HRMDD) for developing bipolar disorder with characteristics of young bipolar (BPD) subjects and healthy controls (HC). METHODS: One hundred and six young (15-30â¯yr), medication-free subjects MDD subjects (HRMDD, Nâ¯=â¯51; LRMDD, Nâ¯=â¯55) were compared with 32 BPD (Type I: 14; Type II: 18) as well as 49 HC subjects. Baseline illness characteristics and frequency of comorbid conditions were examined using Analysis of Variance and Cochran-Armitage trend test. Additionally, in MDD subjects, the effect of open-label antidepressant treatment for up to 24 months with periodic assessments was compared between HRMDD and LRMDD groups for treatment response, remission and (hypo)mania switch while controlling for attrition. RESULTS: Significant gradation from LRMDD to HRMDD to BPD groups was found for increasing occurrence of alcohol dependence (pâ¯=â¯0.006), comorbid PTSD (pâ¯=â¯0.006), borderline personality traits (pâ¯=â¯0.001), and occurrence of melancholic features (pâ¯<â¯0.005). Antidepressant treatment response was similar between the two groups except that for the 12-month period HRMDD showed a trend for a lower response. Switch to (hypo)mania was infrequent in both groups though the HRMDD showed a higher occurrence of spikes in (hypo)mania symptoms (>25% increase in YMRS scores)(pâ¯=â¯0.04). CONCLUSION: Findings of the study indicate that a substantial proportion of young MDD subjects share BPD illness characteristics. These HRMDD subjects, if treated with antidepressants, need to be monitored for development of BPD. TRIAL REGISTRATION: NCT01811147.