Anxiety Disorders in Preschool Age at Risk Children: Autism Siblings and Fragile X Syndrome

Background:  Anxiety is one of the most common co-morbid conditions presenting in individuals with autism spectrum disorder (ASD), with up to 66% meeting criteria for at least one disorder. In groups at high risk for ASD, such as infant siblings and individuals with fragile X syndrome (FXS), rates of anxiety have also been identified as elevated. In FXS, rates of anxiety disorders are reported to occur at a rate of 86% of individuals with FXS over the age of 5 meeting criteria for at least one anxiety disorder. In infant siblings without ASD, rates of anxiety are found to be greater than controls, however prevalence rates have not been reported in a preschool age sample.

Objectives:  This study aimed to examine preliminary prevalence rates of anxiety disorders in a preschool age sample of two groups at high risk for developing ASD, ASIBs and individuals with FXS, compared to a chronologically age matched control sample.

Methods:  The mothers of 58 children ages 3-6 (11 autism siblings (ASIB), 25 controls and 22 children with FXS) were administered the Preschool Age Psychiatric Assessment (PAPA) at one time point. The PAPA is a semi-structured diagnostic interview that measures symptoms consistent with DSM-IV childhood disorders and requires in-depth research training. The anxiety disorders domain was used in the analysis, which includes the following domains: Separation Anxiety Disorder, Specific Phobia, Generalized Anxiety Disorder and Social Phobia. PAPA algorithms provide a dichotomous output representing whether symptoms did or did not meet criteria for each disorder.

Results:  Anxiety disorders occurred at a rate of 18% (n=2) in the ASIB group, 36% (n=9) in the control group, and 68% (n= 15) in the FXS group. Across all groups, Specific Phobia was the most commonly endorsed disorder, with all but one participant who met who an anxiety disorder (FXS), meeting criteria for Specific Phobia. Rates of the other anxiety disorders occurred at the following rates across the ASIB, control and FXS groups respectively; Generalized Anxiety Disorder: 18%, 9%, 23%, Separation Anxiety Disorder 9%, 8%, 5% and Social Phobia 9%, 16%, 32%.

Conclusions:  This study is the first to examine rates of anxiety disorders in a preschool age sample of individuals with FXS and high risk autism infant siblings. Specific phobia had the highest prevalence across all groups, which inflated the summary level prevalence rates of anxiety disorders universally. The high rates of specific phobia may be due to its transient nature in childhood, which may represent a more developmentally appropriate fear response, rather than a stable anxiety disorder. Consistent with previous literature, rates of anxiety disorders were highest among the FXS group. In contrast with previous literature, ASIBs in the sample did not show elevated rates of anxiety compared to the control group, however interpretation is considered preliminary given the small sample size of ASIBs.