No Gender Differences in Cognitive or Adaptive Functioning Abilities for Toddlers Diagnosed with DSM-5 ASD

Background: Prior studies indicate that females are less likely to have autism spectrum disorder (ASD), but when affected tend to have more severe impairment than males with ASD. Limited, if any, studies currently exist comparing functioning between male and female toddlers with a Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) ASD diagnosis.

Objectives: To compare cognitive, adaptive, and language functioning in male versus female toddlers at time of diagnosis of DSM-5 ASD.

Methods: We conducted a retrospective chart review of toddlers (18-36 months) diagnosed with DSM-5 ASD via a standardized assessment at Boston Children’s Hospital from July 2013-July 2015. Children were included if they were seen by both a developmental-behavioral pediatrician and a psychologist for developmental testing and if they met DSM-5 diagnostic criteria for ASD. The primary outcomes were standard scores from cognitive, adaptive, and language measures, specifically the Bayley Scales of Infant and Toddler Development, Third Edition, and the Vineland Adaptive Behavior Scales, Second Edition. Due to provider preference, rather than specific patient characteristics at presentation, a subset of patients (N = 99) received an additional language measure, the Receptive-Expressive Emergent Language Test, Third Edition. We conducted statistical comparison of scores between genders via independent two-sample t-tests.

Results: We abstracted data for 500 subjects; 21% were female (N = 104) and 79% were male (N = 386). There was no statistical difference in the average age at diagnosis for males versus females (26.1 versus 25.5 months, respectively; p = 0.211), the Bayley Scales of Infant and Toddler Development cognitive standard score (80.8 versus 80.0, respectively; p = 0.585) or the Vineland adaptive behavior composite standard score (75.0 versus 73.8, respectively; p = 0.283). There were no gender differences in the Bayley Scales of Infant and Toddler Development language standard score (63.8 for males versus 60.7 for females; p = 0.108), although in the subset of patients who had the Receptive-Expressive Emergent Language Test administered (N=99), males had higher receptive language scores (65.2 versus 59.5 respectively; p= 0.023) and higher expressive language scores (65 versus 59.7 respectively; p = 0.045) compared to females.

Conclusions: We found no significant gender difference in cognitive or adaptive functioning of toddlers at time of DSM-5 ASD diagnosis. This is in contrast to prior studies suggesting lower cognitive and adaptive functioning in female patients when compared to males. We did find lower receptive and expressive language scores among females in a subset of toddlers who received a separate language measure, suggesting that gender differences may exist in some developmental domains.