Stranger Fear and Early Risk for Social Anxiety in Preschoolers with Fragile X Syndrome Contrasted to Autism Spectrum Disorder.

Only boys were studied, so results may not apply to girls with fragile X syndrome or autism. The idiopathic autism group was very small (12 boys initially), so findings for that group are tentative. The study was cross-sectional, so it cannot show that stranger fear later develops into social anxiety. Children were not matched on age or developmental level, and age differed between sites for some groups. Six children were removed from analyses because coding times were extreme, and 101 of 107 remained. Parent report and observed stranger fear did not line up consistently, so neither measure alone captures anxiety clearly. ASD symptoms were categorized using the CARS, which does not account for developmental level, although agreement with the ADOS-2 was high in a small subset.

Do not conclude that stranger fear is a proven early marker of later social anxiety in fragile X syndrome or autism. This was a cross-sectional observation of preschool boys, the idiopathic autism group was very small, and no child was followed over time.