Understanding silence in adolescence and young adulthood: a mixed methods systematic review on selective mutism.

The aim of this study was to identify the characteristics of adolescents and young adults with selective mutism (SM) and their specific (treatment) needs, as well as those of their environment. We conducted a mixed methods systematic review of scientific databases APA PsycINFO and MEDLINE until February 2025. Descriptive studies were included if they incorporated information on individuals between 10-24 years old with a current diagnosis of SM. Two independent reviewers extracted data using combined deductive and inductive coding, with categories finalized by consensus. Data were synthesized using a convergent segregated approach. A total of 749 records were identified, of which 40 studies (n = 54 participants) met inclusion criteria. Methodological quality varied, with 27.5% studies rated as high quality, 65% as moderate, and 7.5% as low. Key findings showed that SM manifests differently in adolescents and young adults compared to children, and therefore requires a different approach to treatment. The reviewed literature shows that adolescents and young adults with SM have a later onset, longer diagnostic delays, and a prolonged history of negative reinforcement of symptoms from accommodations by others. Consequently, SM tends to be more therapy-resistant, requiring greater patience and diligence from therapists.