Social Communication and Cognitive Profiles: How Do Males and Females Compare?

Background:  The predominance of autism spectrum disorder (ASD) diagnoses among males, with average estimates suggesting a 4:1 ratio (Baird et al., 2006), is one of the most consistent features of the disorder. Previous research examining gender differences in clinical profiles of core social communication symptomatology among individuals with ASD has presented discrepant findings with females having superior, equivalent, or poor social communication skills compared to males (for reviews see Kirkovski et al, 2013, Van Wijngaarden-Cremers et al., 2014). Past research has suggested differences in profiles of cognitive strengths and weaknesses (Ankenman et al., 2014), which may impact the presentation of social and communication symptoms in ASD (Black et al., 2009). 

Objectives:  The purpose of this study was to examine gender differences in social communication symptoms, profiles of verbal and nonverbal intelligence and adaptive behavior in a community-based clinic sample of individuals referred for an ASD evaluation. This study attempted to overcome past methodological limitations by using a large sample of females including young children (5 years, 0 months) through adulthood (56 years, 4 months).

Methods:  Evaluations were conducted across statewide outpatient clinics operated by the University of North Carolina TEACCH Autism Program between January 2001 and March 2013. A total of 679 participants (males=566, females=113) who provided consent for their clinical data to be used for research purposes were selected for analysis. These participants were administered a diagnostic battery including an ADOS-G, a CARS, and an IQ measure and received a DSM-IV clinical diagnosis of Autistic Disorder, Asperger’s Syndrome, or PDD-NOS. Approximately 24% of the sample had an IQ score below 70. 

Results:  Females scored slightly lower on the ADOS-G total algorithm (12.85 vs. 13.58 for males) but this difference was not significant, t(677) = -1.59, p = .11. However, when specific modules were examined, gender differences on the ADOS-G were found on some modules. Specifically, no significant differences were found on modules 1 or 4, but females obtained lower scores on module 2 social, t(96) = -2.26, p = 0.3, and total, t(98) = -2.08, p = 0.4, domains and on all domains of module 3, Wilks’ λ = .978, F (3, 378) = 2.9, p =. 04, η_p² = .022. No gender differences in Full Scale IQ was found, both genders had average IQ scores of 86. Across both genders, the cognitive profile of Verbal IQ=Nonverbal IQ was most frequently observed (52%). No significant differences in Verbal-Nonverbal IQ discrepancies were noted across gender.  However, for females, a higher Verbal than Nonverbal IQ was associated with lower ADOS ratings. This difference was not found for males. 

Conclusions:  Overall, these results suggest that females, particularly those receiving ADOS modules 2 and 3, have fewer autism symptoms than males. This may point to periods in development, particularly in childhood and early adolescence, when ASD social communication symptoms may present in different or more subtle ways in females. This is particularly true for girls with higher verbal than nonverbal IQ. More research is needed on the subtle expression of ASD in girls.