The differential diagnosis of APD (or its "horizontal" boundaries) includes mainly other psychiatric disorders. While there may be theoretical distinctions between APD and related diagnoses, these differences can be very difficult to untangle in practice, especially if one takes a developmental perspective of the patient. The Table lists some features that may distinguish other traits and disorders from APD.
The main theoretical distinction between APD and both schizoid personality disorder and an autistic spectrum disorder is the notion that persons with APD very much want social contactbut are afraid to seek it out, while those with schizoid personality disorder or an autistic spectrum disorder are less intrinsically interested in social contact. However, many individuals with an autistic spectrum disorder do seek out human contact but struggle with how to achieve it. It is thus advisable to obtain a good developmental history if both of these disorders are being considered as alternatives to APD.
Developmentally, it is also possible that over time a person with APD who initially craves social contact will begin to settle into a pattern in which this contact is no longer sought. Another point of divergence between APD and an autistic disorder relates to social cues. Children with an autistic spectrum disorder tend to ignore these cues, while those with APD are hypersensitive to them.
Perhaps the greatest diagnostic dilemma pertains to the boundaries between APD and the general subtype of social anxiety disorder (GSAD). The diagnostic criteria overlap considerably. Attempts to find distinguishing characteristics in the epidemiology, physiology, and response to treatment have yielded little in the way of qualitative differences.15 Indeed, there may be more differentiation between the specific and generalized form of GSAD than between generalized GSAD and APD, despite their existence on different axes.
Researchers have similarly been interested in the "vertical" boundaries between APD and established personality or temperamental traits, such as shyness. There certainly appears to be significant overlap between certain disorders, such as APD, and specific personality dimensions. Nevertheless, the increasingly popular hypothesis that APD simply represents the extreme end of a normally distributed trait such as shyness appears to be overly simplistic.
Studies of the relationship between shyness and generalized social phobia show that many people with very high levels of shyness do not meet criteria for GSAD.16 This lack of continuity has stimulated researchers to begin looking for other features that could moderate the relationship between shyness and psychiatric disorders. These include other personality or temperament traits (such as emotion regulation) or specific cognitive factors that may exacerbate shyness into full-fledged APD.
Assessment for APD is part of a general psychiatric evaluation; the condition should be suspected in patients in whom social avoidance, fear of embarrassment, and intimacy difficulties are uncovered. Instruments to aid in the diagnosis of APD and other personality disorders continue to be refined, although their use in routine practice remains limited.17
As with most personality disorders, most patients who meet criteria for APD will meet criteria for other Axis I and Axis II conditions. Notable among these are Axis I anxiety and affective disorders, other cluster C disorders, and substance abuse.
Treatment of APD involves psychotherapy and/or medication. Unfortunately, treatment studies rarely focus primarily on APD and instead analyze patients with APD as a subset of those with GSAD or other personality disorders.18 Given this limitation, multiple types of psychotherapy have been shown to be effective in adult APD, including cognitive- behavioral, psychodynamic, and supportive-expressive therapy.19-21
No medications have been specifically approved for the management of APD. However, research has documented improvement in patients who meet criteria for both APD and social anxiety disorder when treated with selected serotonin reuptake inhibitors and benzodiazepines.22,23 Current recommendations include consideration of pharmacotherapy in APD, regardless of whether a patient meets criteria for a comorbid Axis I disorder,24,25 although additional research in this area is sorely needed. Given the risk of substance use in APD, physicians should be cautious in prescribing benzodiazepines.
Regardless of treatment modality, however, one of the keys to treatment success (as with other anxiety conditions) is exposure. Patients who simply take a medication or who speak with a therapist are not likely to report symptom relief before they take the risk of confronting their feared situations.
Greater success can be anticipated if the therapist supports patients and encourages them to confront their fears. This can take the shape of a specific homework assignment within a cognitive- behavioral format or therapist support of the patient's willingness to risk intimacy and no longer be the "perfect patient" within a psychodynamically oriented framework.
The bottom line
APD is a relatively common condition that is associated with significant impairment in multiple domains. The boundaries of the disorder—both horizontally with other psychiatric diagnoses and vertically with personality dimensions such as shyness—continue to be blurry and not well established. In particular, there seems to be little to qualitatively distinguish APD from the generalized type of social anxiety disorder.
Research into the course of APD demonstrates the disorder's origin in early temperamental traits. Increasing data exist to suggest that during adulthood APD may be more changeable over time than originally thought. These data suggest that positive responses can occur with psychotherapy and/or medications.
Avoidant personality disorder:
Comparative features of other psychiatric diagnoses
|Trait or disorder||Category||Distinguishing features|
|Shyness||Personality trait||Less severity of features and lack of marked distress or impairment|
|Generalized social anxiety disorder||Axis I disorder||Almost none|
|Autistic spectrum disorders||Axis I disorder||Restricted interests; developmental delays; may be less interested in social contact; under-reading of social cues rather than over-reading|
|Schizoid personality disorders||Axis II disorder||Lack of interest in social encounters; less worthlessness and feelings of inadequacy|
Dr Rettew is assistant professor of psychiatry and pediatrics at the University of Vermont College of Medicine in Burlington.
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