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Personality disorders: Co-occurring psychiatric disorders

Common co-occurring psychiatric disorders

Patients with personality disorders often have co-occurring psychiatric diagnoses. Considerable research shows that co-occurring disorders are extremely frequent in borderline personality disorder (BPD). Zanarini et al. (1998) found the following lifetime psychiatric comorbidity in people with BPD:

  • mood disorders: 96 per cent (9 per cent with bipolar disorder)
  • anxiety disorders: 88 per cent
  • posttraumatic stress disorders: 55 per cent
  • eating disorders: 53 per cent
  • substance use disorders: 64 per cent

Given this high comorbidity, the challenge in working with these patients is not only to identify and optimally manage the personality disorder but also to not overlook comorbid psychiatric diagnoses. Primary care providers may find these diagnoses easier to deal with than the personality disorder. Patients with co-occurring diagnoses need treatment plans that address both conditions.

Challenges in making the co-occurring diagnosis

Clinicians often overlook psychiatric disorders that co-occur with a personality disorder. The typically chaotic presentation of patients with personality disorders and clinicians' reactions to them make it difficult to assess other psychiatric disorders.

Overlooking these diagnoses diminishes the capacity to use the appropriate pharmacotherapy and psychotherapy to help alleviate the co-occurring psychiatric disorder.

Clinician reactions

Sometimes patients with personality disorders elicit frustration in the clinician that contributes to overlooking a careful review of the longitudinal history and clarifying the comorbid psychiatric diagnosis. Again, this diminishes treatment options. Frustration may arise, for example, if a patient is very difficult and disruptive in the waiting room, threatens self-harm and has a history of being emotionally reactive, responding to slights with self-harm and impulsive behaviours.

Treatment prospects

Research shows that patients with borderline personality disorder (BPD) can improve with treatment. Zanarini et al. (2004) found that on six-year follow-up, over half of patients no longer met BPD diagnostic criteria. Patients who no longer met BPD diagnostic criteria also had a substantial decline in traits of the comorbid disorder, whereas patients who still met BPD diagnostic criteria did not have a reduction of comorbid diagnoses.

There is controversy over whether these findings indicate that treating the personality disorder decreases the rates of co-occurring psychiatric disorders or vice versa. The practical point for primary care providers is that all patients with personality disorders should be screened for comorbid psychiatric disorders. These diagnoses should be treated robustly. This study and others with similar positive outcome findings are very encouraging. With proper diagnosis, treatment and time, most patients will "outgrow" their BPD condition.


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