Dépression unipolaire versus dépression bipolaire : facteurs prédictifs d’une évolution bipolaire

Abstract

Bipolar and unipolar disorders share a common depressive clinical manifestation. It is important to distinguish between these two forms of depression for several reasons. First, prescribing antidepressors in monotherapy indubitably worsens the prognosis of bipolarity disorders. Second, postponing the prescription of a mood stabilizer reduces the efficacy of the treatment and multiplies the suicidal risks by two. The object of this study is to reveal the factors that distinguish between unipolar and bipolar depression. This is a retrospective study on patients' files. It includes 186 patients divided according to DSM IV criteria into two groups: patients with bipolar disorder type I or II with a recent depressive episode (123 patients) and patients with recurrent depressive disorder (63 patients). A medical record card was filled-in for every patient. It included socio-demographic data, information about the disorder, family antecedents, CGI score (global clinical impressions), physical comorbidity, substance abuse and personality disorder. In order to sort out the categorization variables, the two groups were compared using chi2 test or Fischer's test. With regard to the quantitative variables, the two groups were compared using Krostal Wallis's test or Ancova. Our study has revealed that bipolar disorder differs significantly from unipolar disorder in the following respects: bipolar disorder is prevalent among men (sex-ratio 2) while unipolar disorder is prevailing among women (sex-ratio 0.8); patients with bipolar disorder are younger than patients with unipolar disorder (38.1 +/- 5 years vs. 49.7 +/- years); the age at the onset of bipolar disorder is earlier than that of unipolar disorder (20.8 +/- 2 years vs. 38.7 +/- 5 years); family antecedents are more important in bipolar patients than in unipolar patients (51.1% vs. 33%). More importantly, bipolar disorder differs from unipolar disorder in the following aspects: The number of suicidal attempts (25.3% vs. 23.6%); the degree of substance abuse (15.4% vs. 14.5%); the level of somatic comorbidity (20.3% vs. 17.4%); the amount of anxiety manifestations (5.6% vs. 4.8%); the extent of personality disorder (30.8% vs. 23.8%); the degree of socio-professional impairment (bachelorhood and unemployment). On the other hand, we noted that unipolar patients differ from bipolar patients in terms of the frequency of hospitalizations (3.5 vs. 3.1) and the length of stays in hospitals (25.8 vs. 20.7 days) with significant differences of 0.003 and 0.0000001 respectively. Moreover, the CGI scores of unipolar patients are higher than those of bipolar patients. However, the difference is not significant. Consequently, an early distinction between bipolar and unipolar disorder is of utmost importance for the treatment of these two illnesses.