The impact of brief depressive episodes on the outcome of bipolar disorder and major depressive disorder: a 1-year prospective study

Background: Brief depressive episodes (BDEs) cause psychosocial impairment and increased risk of suicide, worsening the outcome and long-term course of affective disorders. The aim of this naturalistic observational study was to assess the frequency of BDEs and very brief depressive episodes (VBDEs) and their impact on clinical outcome in a sample of patients with major depressive disorder (MDD) and bipolar disorder (BD).

Method: Seventy patients with a diagnosis of MDD or BD were followed up and monthly visited for a period of 12 months, assessing the eventual occurrence of BDEs and/or VBDEs. Clinical and demographic variables of the total sample and of the groups divided according to the presence of BDEs or VBDEs were collected and compared by one-way ANOVAs. Hamilton Depression Rating Scale 21 items (HDRS), Young Mania Rating Scale (YMRS), Clinical Global Impression (severity of illness) (CGIs) and the Short Form Health Survey (SF-36-item 1) were administered at baseline and logistic regression was performed to evaluate whether baseline scores were predictive of the onset of BDEs or VBDEs.

Results: BDEs (88.6% of the total sample), VBDEs (44.3% of the total sample) and BDEs+VBDEs (40.0% of the total sample) were found to occur frequently across the sample. BDE patients showed more death thoughts during major depressive episodes (χ(2) = 4.14, df = 1, p = 0.04, Phi = 0.24) compared to patients without BDEs. Indeed VBDE patients showed a higher rate of hospitalization (χ(2) = 5.71, df = 1, p = 0.031, phi = 0.29), a more frequent prescription of a combined treatment (χ(2) = 13.07, df = 7, p = 0.03, phi = 0.43) and higher scores at SF-36 item 1 (F = 6.65, p = 0.01) compared to patients without VBDEs. Finally, higher SF-36 item 1 scores were found to be predictive of VBDEs (odds ratio = 2.81, p = 0.03).

Discussion: Major depressives, either unipolar or bipolar, with BDEs or VBDEs showed a worse outcome, represented by a more severe psychopathology and higher rates of hospitalization. VBDEs were predicted by a negative subjective general health perception. Studies with larger samples and longer follow-up are warranted to confirm the results of the present study.