Sex Differences in Real-World Executive Functioning and Adaptive Behavior in Children and Young Adults with Autism Spectrum Disorder

Friday, May 13, 2016: 10:55 AM
Room 308 (Baltimore Convention Center)
E. I. White1, A. B. Ratto2, A. C. Armour3, K. Register-Brown4, H. S. Popal1, G. Wallace5, A. Martin1 and L. Kenworthy6, (1)NIMH, Bethesda, MD, (2)Children's National Medical Center, Silver Spring, MD, (3)Children's National Medical Center, Arlington, VA, (4)University of Maryland, Gaithersburg, MD, (5)The George Washington University, Washington, DC, (6)Children's Research Institute, Children's National Medical Center, Rockville, MD
Background:   Females with Autism Spectrum Disorder (ASD) are diagnosed less frequently (Rivet & Matson, 2011) and later (Begeer et. al., 2012), on average, than males. Questions surround whether these differences could be due to a distinctive profile of behavioral deficits for females with ASD as compared to males. 

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.