Sex Differences in Real-World Executive Functioning and Adaptive Behavior in Children and Young Adults with Autism Spectrum Disorder
Objectives: The present study is the largest to date examining executive function and adaptive ability in females with ASD. The aim was to utilize parent ratings of real-world executive functioning and adaptive behavior to better understand whether females present differently from males in areas of everyday functioning.
Methods: This analysis included a group of 81 females (mean age = 12.21, SD = 2.74; mean IQ = 106.88, SD = 20.15) and 162 males (mean age = 12.70, SD = 2.43; mean IQ = 106.88, SD = 18.84), ranging in age from 7-18 years, who met criteria for ASD on the Autism Diagnostic Interview-Revised (ADI-R) and/or Autism Diagnostic Observation Schedule (ADOS). Two male participants were matched to each female to within 4 years of age and 11 IQ points. Groups were equivalent on ADOS, ADOS-2, and ADHD symptom ratings for the subset of the group that had each. All participants were assessed using the Behavior Rating Inventory of Executive Function (BRIEF) and a subset of 57 females and 133 males were assessed using the Vineland Adaptive Behavior Scales-II (VABS-II). Two repeated measures ANOVAs were conducted to compare sex differences across scales on the BRIEF and VABS-II and, when appropriate, post-hoc independent t-tests were used to assess differences on specific domain scores.
Results: A mixed-model ANOVA with Sex (male, female) as the between subjects factor and BRIEF scale (8 scales) as the within subjects factor revealed a main effect of sex (F=5.035; p=.026, ηp2=.020) with females rated as exhibiting greater executive function problems. The Sex (male, female) x VABS-II Domain (3 domains) ANOVA yielded no main effect of sex, but an interaction between VABS-II domain and sex (F=5.834; p=0.003, ηp2=.030). Post-hoc t-tests revealed significantly greater impairments (i.e., lower standard scores) for females with ASD in the domain of Daily Living Skills (p=0.003).
Conclusions: Our results indicate relative weaknesses for females compared to males diagnosed with ASD on non-social executive function and daily living skills. These differences occur in the context of equivalent: clinician ratings of core autism symptomatology, parent ratings of ADHD symptoms and parent-reported social and communication adaptive skills. If these findings are confirmed, they have important implications for treatment targets in females with ASD.