Relationships between major depressive disorder and comorbid anxiety and personality disorders

The aim of the study was to examine whether comorbid anxiety disorders influence depressed patients' likelihood of meeting criteria for a personality disorder (PD) and whether comorbid anxiety disorders influence the stability of the PDs in patients with remitted depression.

The initial sample consisted of 373 outpatients who met criteria for major depressive disorder (MDD) (by Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition-Patient Edition) and who were enrolled in the 8-week acute treatment phase of a study of fluoxetine for MDD. Sixty-four subjects who responded to fluoxetine treatment in the acute phase met criteria for remission throughout a 26-week continuation phase during which they remained on fluoxetine with or without cognitive behavioral therapy. Stability of PDs was defined as meeting criteria for a PD at both beginning and end point of the continuation treatment phase.

Before fluoxetine treatment, anxious depressed patients (defined as meeting criteria for MDD as well as at least one comorbid anxiety disorder) were significantly more likely to meet criteria for any comorbid PD diagnosis compared with depressed patients without comorbid anxiety disorders. In particular, there was a significant relationship between the presence of Cluster A and C PDs and the presence of anxious depression at baseline before antidepressant treatment. After successful treatment of MDD, we found a significant relationship between anxious depression diagnosed at baseline and the stability of a Cluster C PD diagnosis.

Anxious depression may place patients at greater risk of having a PD diagnosis, especially one from Cluster A or C. Once the depression remits, patients who initially met criteria for anxious depression may be more likely to maintain a Cluster C PD diagnosis compared with patients initially diagnosed with MDD alone.