Comorbidity of personality disorders in unipolar aand bipolar depressive disorder

The distinction between bipolar and unipolar illness provides a basis for the evaluation and understanding of the genetic, pharmacological, clinical and biological differences in affective disorders. Depression and comorbid personality disorders relate to one another in three distinct ways: 1) personality disorders may induce the development of depression and render an individual vulnerable to depression; 2) depression may induce personality disorder or foster its development; 3) there may be a correlation between personality disorders and depression, which could be considered as depressive personality disorder. The effect of commorbid personality disorders on treatment for depression, as well as the effect that treatment for depression has on personality disorders is important. The aim of this study is to investigate the comorbidity of personality disorders and the possible differences in patients with bipolar and unipolar illness.

Method: In total, we accessed fifty eight (58) patients with affective disorder who were admitted in a psychiatric department (C Psychiatric ward, Psychiatric Hospital of Thessaloniki). Patients were assessed into two diagnostic categories according to DSM-IV criteria. Twenty nine of them (29) had bipolar depression (55.17% females, 44.83% males) and twenty nine (29) who had unipolar depression (55.17% females, 44.83% males). We applied a structured interview for personality disorders, axis II, according to DSM III-R (SCID II). The interview was applied following depression remission. The Hamilton-D scale was used to assess depression levels. Personality disorders were assessed and compared against both groups of patients. X2 test was used for statistical analysis.

Results and conclusions: An increased prevalence of personality disorders in patients with both bipolar illness (23 out of 29) and unipolar illness (29 out of 29) was found. 68.96% of unipolar patients and 41.38 of bipolar patients showed three or more coexisting personality disorders (PDs), meaning that disorders overlap extensively on Axis II.

No statistically significant correlation was found between personality disorders and age or education of patients.

Among patients with unipolar depression, the most prevalent axis II diagnoses were borderline PD (62.07%) obsessive, compulsive PD (62.07%) and self-defeating PD (62.07%), whereas among patients with bipolar illness the most prevalent axis II diagnoses were histrionic PD (60.87%), self-defeating PD (43,48%) and borderline PD (34.78%). An increased percentage of personality disorders such as obsessive, compulsive PD (81.25%), self-defeating PD (68.75%), self-defeating PD (68.75%), avoidant PD (50%) and borderline PD (68.75%) were found in the females who were hospitalized for unipolar depression.

A statistical significant prevalence between Schizoid, borderline, dependent and obsessive, compulsive PD in patients with unipolar depression was found, whereas in bipolar depression, histrionic PD had a statistical significant prevalence. We could assume that a perfectionist and steer super ego could make people feel that they fail. Intrapsychic situations that emergee could cause a major depressive episode.

As mentioned above, in the group of bipolar patients a high percentage of histrionic, self-defeating and borderline PD is observed. We could hypothesize that a personality disorder with dependent needs and insecure such as the histrionic and borderline PD could be related with bipolarity. In order to confirm this, a larger group of bipolar patients should be examined.

The overall level of comorbidity and frequencies of multiple Axis II disorder diagnoses in the present study are likely to be affected by the fact that patients were admitted in a psychiatric hospital and were considered to be severe cases. Another limitation is that patients in both groups might have not reached same levels of recovery and this could have affected PDs’ evaluation in both groups.

Key words: Comorbidity, personality disorder, unipolar depression, bipolar depression.