Selective mutism (SM) is an anxiety disorder that prevents speech in certain situations. Increasingly, it is reported that a proportion of those with SM may also be autistic and that physical freezing may be an important feature of SM. Information on speech and freezing behavior in children with a diagnosis of autism only (n = 20), SM only (n = 61), both autism and SM (n = 19), or neither diagnosis (n = 131) was collected via a self-selected cross-sectional online parent survey with an embedded child survey completed by a small subsection of the children (total n = 27: autism only n = 1, SM only n = 13, both autism and SM n = 3, neither diagnosis n = 10). Throat and body freezing were reported by children with SM, whether they were also autistic or not. The most common reasons given by the children that increased their difficulty in speaking were pressure to talk, worries about how they would be perceived, and fear of making mistakes. The Selective Mutism Questionnaire (SMQ) gave the lowest median score for children with both autism and SM, with median scores increasing in the order SM only, autism only, and neither diagnosis. Children who reported more freezing tended to have lower SMQ scores.
Landrock-White et al. (Wed,) studied this question.