Selective mutism

Essential (Required) Features:

• Consistent selectivity in speaking, such that a child demonstrates adequate language competence in specific social situations, typically at home, but consistently fails to speak in others, typically at school.
• The duration of the disturbance is at least 1 month, not limited to the first month of school.
• The disturbance is not due to a lack of knowledge of, or comfort with, the spoken language demanded in the social situation.
• The symptoms are not better accounted for by another mental disorder (e.g., a Neurodevelopmental Disorder such as Autism Spectrum Disorder or Developmental Language Disorder).
• Selectivity of speech is sufficiently severe so as to interfere with educational achievement or with social communication or is associated with significant impairment in other important areas of functioning.

Additional Clinical Features:

• Symptoms of Selective Mutism may interfere with direct assessment of expressive language. However, many affected children cooperate with receptive language testing if communication is restricted to carrying out commands or pointing to pictures, which can provide valuable information about a child’s general language levels. Furthermore, reports from informants who know the child well (e.g., parent or caregiver) may be necessary to establish that the child can speak in certain social situations.
• Selective Mutism is often regarded as a variant of Social Anxiety Disorder because affected individuals experience significant anxiety in social situations and when able to express themselves indicate that they fear negative evaluation, in particular of their speech. However, unlike Social Anxiety Disorder, children with Selective Mutism are more likely to display these difficulties at an earlier age of onset (in most cases before the age of 5 years but may only become apparent when starting school), be more likely to have associated subtle language impairments, and exhibit oppositional behaviour in response to being asked to speak in feared situations.
• Co-occurrence with other Anxiety or Fear-Related Disorders (particularly Social Anxiety Disorder, Separation Anxiety Disorder, and Specific Phobias) is very common among individuals with Selective Mutism.
• Selective Mutism is associated with severe impairment in academic and social functioning that can manifest as inability to complete expected school work, not getting personal needs met, inability to initiate or reciprocate social interactions with peers, or becoming the target of bullying.
• Social anxiety, withdrawal, and avoidance in Selective Mutism may be related to temperamental factors such as behavioural inhibition and negative affectivity.

Boundary with Normality (Threshold):

• Transient reluctance to speak at the time of first starting school is a common occurrence. Selective Mutism should only be diagnosed if symptoms persist beyond the first month of schooling. Immigrant children who are unfamiliar with or uncomfortable in the official language of their new host country may, for a discrete period of time, refuse to speak to strangers in their new environment. This may also occur with children from linguistic minorities. Selective Mutism should not be diagnosed in such cases.

Course Features:

• Although the onset of Selective Mutism typically occurs during early childhood (i.e., prior to age 5), significant impairment of functioning may not manifest until entry into school when children experience increased demands to speak publicly (e.g., reading aloud) and engage socially.
• A majority of children with Selective Mutism will present with symptoms of another Anxiety or Fear-Related Disorder, particularly, Social Anxiety Disorder.
• Children with Selective Mutism may also display signs of oppositionality, particularly in situations requiring speech. A co-occurring diagnosis of Oppositional Defiant Disorder should not be assigned if refusal to speak can be entirely accounted for by features of Selective Mutism.
• The course of Selective Mutism varies among individuals. Although the average duration of the disorder is 8 years, after which symptoms begin to dissipate or remit completely, some individuals may experience a persistence of symptoms or manifestation of another disorder, primarily Social Anxiety Disorder.
• Even after the core symptoms of Selective Mutism resolve, individuals often continue to experience difficulties related to social communication and anxiety.
• Prognosis is worse when there is a family history of Selective Mutism.

Culture-Related Features:

• People in cultures with a high level of shame-based emotions may avoid speaking about particular topics or in situations that would evoke shame for themselves or others. When this is culturally normative, it should not be considered to be reflective of Selective Mutism.

Boundaries with Other Disorders and Conditions (Differential Diagnosis):

• Boundary with Developmental Speech and Language Disorders: Selective Mutism is differentiated from the range of Developmental Speech and Language Disorders (i.e., Language Disorders or Speech Fluency Disorder) that involve impairments in expressive language across all social situations. Although some children with Selective Mutism exhibit expressive language difficulties or phonological problems, these are often subtle and functioning is usually found to be in the normal range. Selective Mutism may occur in the presence of Developmental Speech and Language Disorders and both can be diagnosed if warranted.
• Boundary with Autism Spectrum Disorder and Disorders of Intellectual Development: Some individuals affected by Autism Spectrum Disorder or Disorders of Intellectual Development exhibit impairments in language and social communication. However, unlike in Selective Mutism, when language and communication impairments are present in Autism Spectrum Disorder and Disorders of Intellectual Development, they are notable across environments and social situations.
• Boundary with Schizophrenia or Other Primary Psychotic Disorders: Individuals with Schizophrenia or Other Primary Psychotic Disorders may exhibit disruptions in speech and social communication as a function of symptoms of disordered thought. Unlike individuals with Selective Mutism, those with disrupted communication in the context of psychotic disorders display similar disruptions to speech across all social situations.
• Boundary with Social Anxiety Disorder: Selective Mutism is characterized by a failure to speak in specific situations whereas in Social Anxiety Disorder fear and anxiety result in avoidance of multiple social contexts.