Ten-year course of treated bipolar I disorder: The role of polarity at onset

Abstract

Introduction: Early-stage predictors of illness course are needed in bipolar disorder (BD). Differences among patients with a first depressive versus maniac/hypomanic episode have been stated, although in most studies, memory bias and time from onset to start of specialized treatment might interfere. The aim was to compare the first 10 years of illness course according to polarity at onset. Methods: 49 type I BD patients admitted for treatment for a first-time affective episode and a following 10-year attendance to the institution were included. A retrospective year by year comparison according to polarity at onset (depressive (DPO) or maniac (MPO)) was performed. Cramer's V and Cohen d were computed to determine effect size. Results: 59.2% (n = 29) started with MPO. Both groups were similar in demographic and social outcome characteristics, clinical features, and treatment variables. Patients with DPO reported more depressive episodes than MPO patients (U = 149.0 p < .001, Cohen's d = 0.87); both groups had a similar number of manic episodes. Only during the first year of follow-up, suicide attempts (SA) were more frequent in patients with DPO while the presence of a psychotic episode and psychiatric hospitalizations were more frequent in the MPO group. Conclusion: According to these findings, it can be concluded that illness onset is only indicative of depressive predominant polarity but is not related to other poor prognostic variables after the first year of illness onset, in treated BD. SA in the first year of an affective disorder could represent a marker of BD.