Objectives: Three patients presenting with a first episode of psychosis each had a past history of social phobia. We sought to explore the literature on the co-occurrence of these disorders and investigate three hypotheses to explain this: (1) the chance co-occurrence of two illnesses with distinct aetiologies; (2) two clinical presentations reflecting different points on the same spectrum of illness; and (3) two distinct disorders representing different end points resulting from the same aetiology.

Method: A literature review of Embase, PubMed and Psych Lit was performed.

Results: We found no reports on social phobia preexisting an episode of psychosis, and prevalence studies indicate that their chance co-occurrence is extremely unlikely. Psychological explanations for co-occurrence include attributional theories, and theories related to cognitive biases and loss of self-esteem.

Conclusion: There is a phenomenological overlap between social phobia and paranoia but the two concepts should and can be distinguished. Epidemiological studies indicate that their chance occurrence as two unrelated disorders is unlikely. Most people with one of these disorders do not develop the other and hypothesis (2) is also unlikely. There is increasing speculation that anxiety, and in particular social phobic symptoms have a central role in the development of psychotic symptoms. The greatest evidence was found to support hypothesis (3).

However, it seems more likely that social phobia and psychosis, rather than representing manifestations of the same illness, instead are implicated in a complex interaction where symptoms which characterise social phobia and psychosis, have the capacity to affect, alter and possibly provoke each other. The recognition and treatment of co-occurring anxiety disorders, especially social phobia with psychosis, may have an important impact on prognosis and quality of life.