RESUMO
The present study has two main aims: (1) To assess whether childhood trauma helps to differentiate Major Depressive Disorder (MDD) from Bipolar Disorder (BD) in a cross-sectional design; and (2) Describe the rate of conversion from MDD to BD, as well as the clinical and demographic predictors of conversion from MDD to BD in a prospective cohort design. We conducted a prospective cohort study in two phases, in the city of Pelotas, RS, Brazil. In the first phase, 565 subjects diagnosed with MDD, and 127 with BD according to the Mini International Neuropsychiatric Interview were included. In the second phase, only individuals with MDD were reevaluated for potential conversion to BD. The rate of conversion from MDD to BD in 3 years was 12.4%. Predictors of conversion from MDD to BD included lower educational level, use of illicit substances, younger age of the first depressive episode, and family history of BD. Childhood trauma was not a significant risk factor for conversion to BD in our prospective study. Our findings can contribute to the prevention and identification of conversion from MDD to BD, as well as to the establishment of more targeted therapeutic interventions, improving the prognosis of these individuals.