Females with Autism Spectrum Disorder: An Analysis of the Simons Simplex Collection

Background:

The existing literature has long reported that females with autism spectrum disorders (ASD) may be more cognitively impaired than males with ASD (Lord, Schopler, & Revicki, 1982; Tsai, Stewart, & August, 1981). More recent work on children with ASD has revealed sex differences in specific cognitive and behavioral domains (Carter, 2007) and has suggested that this variation may be moderated by VIQ (Skuse et al., 2009). Work that has taken NVIQ into account has identified specific dimorphic patterns in comorbid and autism-specific symptoms such that females demonstrate fewer restricted and repetitive behavior (RRBs) but more communication deficits and greater anxiety and depressive symptoms than males (Hartley & Sikora, 2009: Lord et al., 1982). Further work is needed to better understand sex differences in ASD.

Objectives:

This study will examine the female autism phenotype with a specific focus on the moderating role of IQ.

Methods:

The sample for the current study was drawn from the Simons Simplex Collection and consists of1632 males and 255 females with ASD. Children, ages 48 to 216 months, completed a battery of cognitive and diagnostic measures that included the Autism Diagnostic Observation Schedule (ADOS) and parents completed the Autism Diagnostic Interview-Revised (ADI-R), the Vineland Adaptive Behavior Scales-2^nd Edition (Vineland-II), and other measures of functioning such as the Aberrant Behavior Checklist (ABC).

Results:

Preliminary results support previous findings: females with ASD obtained a significantly lower mean FSIQ than males. In addition, scores on adaptive behavior were significantly lower for females.  Additional analyses will examine differences in social and communication impairments and other behavioral symptoms while taking into account level of functioning.

Conclusions:

This sample contains one of the largest groups of females with ASD ever studied.  Thus, the results from this study will greatly add to our existing knowledge of ASD sex differences and the female phenotype.