Gender Differences in Parent-Reported and Clinician-Rated Autism Symptoms

Background:  Females are diagnosed with autism spectrum disorder (ASD) at significantly lower rates than males, with particularly discrepant rates among those without intellectual disability (Kirkovski, Enticott, & Fitzgerald, 2013). Prior research has found indications of differences in core ASD symptoms, including peer relationships, play, communication, and restricted/repetitive behaviors and interests (Kirkovski et al., 2013). Some have questioned whether high-functioning females may actually be under-diagnosed with ASD, due to differences in symptom presentation (Halladay et al., 2015). However, specific symptom profiles and patterns of impairment differ significantly across studies and by the particular measure used.

Objectives:  The aim of the present study was to investigate differences in core symptoms of ASD by gender on gold standard measures using both clinician observation and parent report.

Methods:   Participants included 129 children (n=43 females, n=86 males) with a confirmed ASD diagnosis, ages 4-14 years, with IQ>70 recruited from research and specialty clinic samples. Female participants were double-matched (i.e., two males to every one female) on IQ within 10 points. There were no significant differences in age (t= -.42, ns) or full-scale IQ (t=.25, ns) by gender. All participants were assessed using Module 3 of the Autism Diagnostic Observation Schedule (ADOS; Lord, Rutter, DiLavore, & Risi, 2002) or its recent revision the ADOS-2 (Lord et al., 2012), the Autism Diagnostic Interview-Revised (ADI-R; Rutter, Le Couteur, & Lord, 2003), and the Social Responsiveness Scale (SRS; Constantino & Gruber, 2004) or its recent revision, the SRS-2 (Constantino & Gruber, 2012).

Results: Chi-square analyses were used to examine differences on individual items on the ADOS. Overall, males and females performed similarly on ADOS items. However, females received significantly more severe scores for “Compulsions/Rituals” (χ²=8.29, p<.02), and males performed worse on “Offers Information” at the trend level (χ²=5.08, p<.07). Gender differences in parent-reported ASD symptoms were compared on subscales and total scores of the SRS and the ADI-R using t-tests (Table 1). Parents reported statistically significant differences on the SRS in Social Cognition (t= -1.99, p<.05), Social Communication (t= -2.71, p<.008), and Restricted/Repetitive Behavior (t= -2.67, p<.009) and approaching significant differences in Social Awareness (t= -1.87, p<.07), with females rated as more impaired than males on all subscales. In contrast, ADI-R scores showed males as more impaired in Social Interaction (t=1.98, p<.05) and Communication (t=2.25, p<.02).

Conclusions:  Parent report measures showed greater impairment in current functioning for females, while greater impairment was reported for males during the crucial historical period for diagnosis (preschool years). This pattern of findings suggests that females with high-functioning ASD are at risk for delays in diagnosis and consequently are more impaired than their male peers during school-age years, perhaps due to related delays in access to services. Importantly, males and females performed similarly on clinician observation, with no significant differences on ADOS algorithm items, suggesting those who meet criteria for a diagnosis present similarly to expert clinicians during middle childhood and early adolescence. This may indicate a need for sex-normed early screening measures to increase access to early diagnosis for females with high-functioning ASD.