Results:

A) 30 individuals were assessed in the structured diagnostic interview. Each individual's intensity of Selective Mutism would vary depending on one's environmental setting and context.

B) 97% of subjects were diagnosed with 1) Social Anxiety Disorder, 2) Avoidant Disorder of Childhood or Adolescence, or both. 30% were diagnosed with simple phobia. No other psychiatric disorders were common, and there was no evidence of a casual relationship between psychological or physical trauma with the development of Selective Mutism.

C) According to the results from the parent and teacher rating-scales, on average subjects tended to show high rated-levels of anxiety symptoms, particularly symptoms of social anxiety, and low symptoms of other psychiatric symptoms.

D) From analyzing the subjects' family history, it seemed that Anxiety and social anxiety severity correlated with mutism severity.

First-degree family history of

1. Social Phobia and
2. Selective Mutism, obtained by family history method,

was present in 70% and 37% of families, respectively.