It is likely that Selective Mutism is a variety of anxiety disorder. In addition to refusing to speak in selective social situations, children with Selective Mutism frequently demonstrate shyness, anxiety, and fears of embarrassment and negative evaluation. Children may isolate themselves socially, withdraw from peer interactions, or cling to parents and other "safe" figures. In addition, they may demonstrate frequent temper tantrums and other negative or compulsive and controlling behaviors. Some children will engage in oppositional behaviors, especially within the home. Children with selective mutism may substitute gestures and other non-verbal forms of communication for spoken language.
According to DSM criteria, the above symptoms (including the persistent failure to speak in settings where speaking is expected) must last at least one month, and it must be clear that affected children's refusal to speak is not the direct consequence of some other disorder before the diagnosis of Selective Mutism can be made.
The course of Selective Mutism is variable across individuals. Some children will remain selectively mute over multiple years, while others will start talking after a few months. Children whose mutism remains persistent may eventually be diagnosed with one or more adult anxiety disorders.
Research suggests that that Selective Mutism is a rare condition. According to the DSM, the less than 1% of children treated by mental health professionals are diagnosed with this disorder. Between 0.03% and 0.02% of the general population of children seem to have Selective Mutism. Both boys and girls are develop the condition, but slightly more females are diagnosed than males. These prevalence data may not be entirely accurate because the general public is unfamiliar with the problem. As a result, some children with Selective Mutism may go undiagnosed and untreated.
Diagnosis of Selective Mutism
By definition, Selective Mutism is not caused by an actual language deficit or physical problem (e.g., hearing impairment) that prevents speech from occurring. Consequently, the workup to establish the diagnosis of Selective Mutism must demonstrate that such deficits/problems are not present, or at least are not the primary reason for the mutism. The diagnostic assessment for children suspected of having Selective Mutism is likely to include behavioral observations to document that the child is capable of fluent speech, as well as a hearing evaluation. In addition, a child psychologist or similar mental health clinician should interview the child and parents to assess whether there are other mental disorders or environmental factors that can account for symptoms.
In order to help ensure that no important questions are missed during the interview, the clinician may use formal structured interviews and questionnaires such as the Diagnostic Interview for Children and Adolescents, and the Child Behavior Checklist (click here to return to descriptions of these previously mentioned instruments). The range of a child's anxiety may be assessed by using the Fear Survey Schedule for Children or the Social Phobia and Anxiety Inventory (both designed to measure fears (e.g., failure, criticism, the unknown, injury, small animals, danger, death) in children).
The child's intellectual and cognitive abilities may also assessed via an IQ test designed for use with children such as WISC-IV or the WPSSI (click here to return to a description of these instruments). Both of these IQ tests require some verbal response from test subjects. Should children remain completely mute during the assessment, the clinician may switch to an alternative test of children's cognitive abilities such as the Peabody Picture Vocabulary Test, a test of vocabulary and verbal ability that does not require reading or writing ability. If all else fails, the clinician can still gain much important information by simply making careful behavioral observations of the child during various drawing and play tasks presented during the assessment.