CHAPTER 16
Selective Mutism
Selective mutism affects children and generally resolves well before ado-
lescence. Children with selective mutism are able to understand what
other people say, but restrict their own speech to a small group of very
familiar people in specific circumstances. Typically, the child talks freely to
parents and siblings at home, but does not speak to classmates or teachers
at school. Much more rarely, the child speaks at school but not at home.
Mutism usually develops at about 3–5 years of age. However, it does not
usually lead to specialist referral while the child is at playgroup; referral is
more often made after the start of formal schooling. Many clinicians only
make the diagnosis if the period of mutism exceeds six months, though
DSM-IV and ICD-10 only stipulate a period of one month (not counting
the first month at school).
Epidemiology
Refusal to speak at school is relatively common during the first few
months after school entry, affecting almost 1% of children in one study
(with higher rates among the children of immigrants). These problems
are nearly all short-lived. By the age of 6 or 7, the reported rates range
from 3–18 per 10,000 (roughly a tenth as common as autistic spectrum
disorders). Whereas boys are more prone than girls to developmental
language disorders, selective mutism is probably more common in girls.
There is no clear association with socio-economic status, family size, or
birth order.
Associated features
1 Other psychiatric problems. Increased rates of anxiety, depression, enure-
sis, encopresis, hyperactivity and tics have all been described. Recent
studies have particularly emphasised the high rate of social anxiety, with
Child and Adolescent Psychiatry, Third Edition. Robert Goodman and Stephen Scott.
©c2012 Robert Goodman and Stephen Scott. Published 2012 by John Wiley & Sons, Ltd.
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