Objectives: As only a few studies so far systematically reported on bipolar patients subtyped according to first-episode polarity, we took the opportunity of having at disposal a large sample of bipolar I patients to specify the characteristics of patients included in these subtypes, with a special focus on temperament and triggering events.
Methods: A total of 1089 consecutive DSM-IV bipolar I manic inpatients were subtyped in manic onset (MO), depressive onset (DO) and mixed onset (MXO), and assessed for demographic, illness course, clinical, psychometric, comorbidity and temperament characteristics.
Results: The main characteristics of MO patients were a hyperthymic temperamental predisposition, a first episode triggered by substance abuse and an illness course with pure, severe and psychotic mania. In comparison, DO patients had more depressive temperaments, a first episode triggered by stress and alcohol, an illness course with more episodes, cyclicity, suicide attempts, anxious comorbidity and residual symptoms. Although sharing characteristics with either MO or DO, MXO patients had more mixed episodes and cyclothymic temperament.
Limitations: The following are the limitations of this study: retrospective design, bias toward preferential enrolment of MO patients, and lack of information on the number and polarity of lifetime episodes.
Conclusions: Findings from this study tend to confirm most of the differences previously evidenced among patients subtyped according to first-episode polarity. Differences found in temperamental predisposition and illness onset triggering events are worth noting and may help target early preventive interventions as well as orientate the search for specific genetic risk factors.
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