Sex Differences in Social Information Processing in ASD

Background: Autism Spectrum disorders (ASDs) differentially affect males and females at a rate of 4:1. This disparity has led to an underrepresentation of females in the ASD literature and a consequently limited understanding of differences in social function across the sexes. Face perception is a well-studied facet of social behavior that is affected in ASD. Individuals with ASD are noted to exhibit both behavioral and neural anomalies in face processing, which has been theorized to reflect a lack of specialization from reduced motivation to attend to people throughout development. Investigations of face perception represent a promising target for understanding differences in social functioning between genders.

Objectives: This analysis aimed to investigate sex differences in the historically understudied population of females with ASD. Specifically, we used electrophysiological brain recordings to examine the neural correlates of face perception, which have been linked to social functioning in ASD.  Differential results at early stages of face perception were expected to relate to differential expression of social disability across sexes.

Methods: 10 females and 10 males with ASD matched on age (mean = 11.6) and Full Scale IQ (mean = 101) participated in the study. Event related potentials were recorded with a 256 electrode Geodesic Sensor Net while participants viewed human faces, inverted human faces, and houses.  Peak amplitude and latency were extracted for an ERP component reflecting structural face encoding (N170) from electrodes over lateral posterior scalp.

Results: Males with ASD displayed a characteristic pattern of shorter N170 latency to upright faces relative to inverted faces (p = .001) and houses (p < .05). In females, however, N170 latency did not differentiate conditions, with equivalent latencies for faces relative to inverted faces and houses (ps > .1). Significant differences were not detected for N170 amplitude.  

Conclusions: Results reveal distinct patterns of brain response to social information in females versus males with ASD. A tightly controlled and sex-balanced sample indicated that females showed relatively reduced sensitivity at an ERP marker of the early stages of face processing. Compared to males, females differentiated neither social from non-social information (faces versus house) nor social information in prototypic versus atypical configurations (faces versus inverted faces). These findings suggest distinct neural phenotypes for males and females with ASD, with females exhibiting more significant impairment in basic social perception. These results offer clarification of heterogeneous results in prior studies with mixed samples and hold promise for development of sex-specific screening measures for early detection of atypical social development.