Background: Social phobia symptoms have been reported to be common among patients with essential tremor, but characteristics of this comorbidity have not been systematically described.
Method: Cases with essential tremor (N = 94) and controls without essential tremor (N = 85), ascertained from movement disorder clinic and community samples, were evaluated for social phobia symptoms (using the social phobia module of the Structured Clinical Interview for DSM-IV Axis I Disorders and the Liebowitz Social Anxiety Scale), characteristics of tremor, and associated disability (via videotaped examination, performance test, and disability questionnaire).
Results: Lifetime combined prevalence of primary social phobia and clinically significant social phobia symptoms occurring secondary to essential tremor was 32.7% (16/49) among essential tremor patients in the clinic sample. Essential tremor cases with secondary social phobia symptoms reported a markedly later age at onset of clinically significant social phobia symptoms than essential tremor cases with primary social phobia (51.0 vs. 8.8 years). Cases with secondary social phobia also reported greater fear and avoidance of eating, drinking, and writing in public than essential tremor cases with primary social phobia and control subjects with social phobia. Essential tremor cases with secondary social phobia symptoms also demonstrated more severe tremor and tremor-related disability than essential tremor cases with primary social phobia and essential tremor cases without social phobia. Among all essential tremor cases, severity of social phobia symptoms and tremor independently contributed to disability.
Conclusion: Social phobia appears to occur in a substantial minority of essential tremor patients, and severity of social phobia symptoms is associated with disability, independent of tremor severity. Persons with social phobia symptoms secondary to essential tremor evidence clinical characteristics that differ from those of persons with primary social phobia. Further research is needed to determine the efficacy of treatment of social phobia in essential tremor patients with significant social phobia symptoms.