Selective Mutism

Selective mutism (SM) is a disorder of childhood of unknown cause. It is characterized by a lack of speech in many social settings and is often first noticed when a child begins school. Adolf Kussmaul first identified SM in publication in 1877, as aphasis voluntaria. In 1934, Moritz Tramer renamed it Elective Mutism. The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-Text Revision (DSM-IV-TR) (2000) identifies six major characteristics that must be satisfied for a diagnosis:

• 1.
  There is a persistent lack of speech in many social settings such as school.
• 2.
  The individual is able to produce clear and spontaneous speech in some settings and with some individuals, most often at home.
• 3.
  The lack of speech interferes with education or social communication.
• 4.
  The lack of speech must last beyond the first month of school.
• 5.
  The lack of speech is not caused by lack of knowledge of the language.
• 6.
  The lack of speech is not caused by the effects of another disorder (e.g., pervasive developmental disorder, autism, communicative disorder, schizophrenia, or psychosis).

SM is a rare disorder. Prevalence studies provide widely ranging estimates from 0.06% to 0.89%. The frequency of SM is higher for girls than boys, with a ratio of 1.6:1.

SM was originally thought to be primarily related to oppositional defiant behavior in a child, leading to a refusal to speak in an effort to control other individuals in his or her environment. Another initial theory was [Page 490]that the onset of SM was induced by a trauma such as physical or sexual abuse. These theories have not received support. Research into the etiological factors and familial characteristics since 1995 has supported the theory that SM behaviors are anxiety related and stimulated when the individual is in a social situation requiring speech. In this model, the child is unable to speak initially because of anxiety. Later, the individual continues not speaking in an attempt to control his or her anxiety level. Over time, the individual makes fewer efforts to speak; thus, the pattern of SM behavior develops. Research also supports the association between SM in children and familial factors of anxiety disorders, social phobias, and parents who themselves were reluctant speakers.

The interpretation of children with SM behaviors as being oppositional is still prevalent. Demanding speech from a child can exacerbate the disorder. Longterm negative effects on educational performance and occupational outcomes are assumed but as yet unsubstantiated. Other associated features may include shyness, behavioral inhibition, and enuresis.

Interventions from different theoretical models have been developed and include psychodynamic therapy, family systems therapy, cognitive–behavioral interventions, applied behavioral analysis, and biological approaches. Investigation into the effectiveness of these treatment methods supports the conclusion that behavioral and cognitive–behavioral interventions (e.g., fading, shaping, extinction, and positive reinforcement) are more effective than no treatment. Evidence of the effectiveness of the other treatment methods (e.g., psychodynamic therapy and family systems therapy) has not been substantiated. Medication such as selective serotonin reuptake inhibitors (SSRIs) has demonstrated some success in reducing anxiety sufficiently to establish speaking behaviors in children and is best used in conjunction with other therapeutic methods such as behavioral and cognitive–behavioral therapy.

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