Selective mutism is a childhood anxiety disorder where a child cannot speak in almost all social situations despite being able to. Selective mutism usually begins in children under five years of age, though it may only become noticeable when a child begins school.
Most children with selective mutism are believed to have an inherited predisposition to anxiety. Some may have sensory integration dysfunction (trouble processing some sensory information) which causes anxiety making them "shut down" and unable to speak.
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