Borderline and avoidant personality disorder co-occur so frequently that in some samples over 40% of individuals with borderline personality (BPD) also meet criteria for avoidant personality disorder (APD).
What is Avoidant Personality Disorder?
APD is one of 11 personality disorders recognized in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). APD is one of the "Cluster C" or anxious/fearful personality disorders.
The DSM-IV defines avoidant personality disorder as "a pervasive pattern of social inhibition, feelings of inadequacy, and hypersensitivity to negative evaluation..." In addition, an individual must have four or more additional signs or symptoms, including avoidance of social interactions due to fears of criticism, preoccupation with rejection, inhibition in unfamiliar social situations, and low self-worth.
People with APD might be described as being extremely shy, socially anxious, self-conscious, and self-critical. This pattern of behavior rises to the level of a clinical disorder when it significantly interferes with relationships, occupation, or other important domains in life.
How Often do Borderline and Avoidant Personality Co-Occur?
The research findings about the co-occurrence of borderline and avoidant personality vary depending on the characteristics of the study sample. In a treatment sample (i.e., a sample of individuals with BPD who were in treatment), 43 percent of patients with BPD also met the diagnostic criteria for APD. In another study that used a community sample, about 14 percent of people who met BPD criteria in their lifetime also met criteria for APD in their lifetime.
Why do APD and BPD Occur Together So Frequently?
We don't know why so many people with BPD also meet criteria for APD, but experts have speculated about two main causes for this comorbidity. First, BPD and APD share a key symptom: both are associated with intense fear of criticism and rejection. It may be that having this trait increases an individual's chances of meeting criteria for both disorders.
In addition, it may be that people with BPD have such intense emotional pain in their relationships that a subset may withdraw from relationships altogether in order to reduce this pain.
Treatment for Avoidant Personality and BPD
There are currently no published clinical trials that have examined treatments for co-occurring APD and BPD. However, cognitive behavioral therapy (CBT) appears to be efficacious for the treatment of APD (and a variation of CBT, called dialectical behavior therapy (DBT) is the BPD treatment with the strongest research support).
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