Children with autism spectrum disorders and selective mutism.

Background: It has been suggested that autism spectrum disorder (ASD) might be a "comorbid" condition in selective mutism (SM).

Methods: In this retrospective study, we examined medical records of children with SM diagnosis (n=97) at a medical center specializing in assessment of ASD.

Results: Mean age for onset of SM symptoms was 4.5 years and mean age at SM diagnosis was 8.8 years. SM was more common among girls (boy:girl ratio=2.7:1). We found that 63% of the study group had an ASD (no gender difference). The SM group with combined ASD had later onset of symptoms, higher age at diagnosis, more often a history of speech delay, and a higher proportion of borderline IQ or intellectual disability.

Conclusions: The results highlight the risk of overlap between ASD and SM.