Doctor of Philosophy (PhD)


Department of Psychology

Document Type



The higher prevalence of autism spectrum disorder (ASD) among males compared to females is well documented but poorly understood. The ASD sex ratio may provide valuable insight into the underlying neurobiological mechanisms of the disorder. A review of studies examining the prevalence in ASD published in the last 5 years was conducted, revealing a mean male/female (M/F) ratio of 4. Literature examining the ASD sex ratio in relation to risk factors and associated features of ASD was also summarized. The study aimed to examine the ASD sex ratio and its association to various risk factors among an early intervention sample. Participants (n= 12,598) were children aged 17-37 months enrolled in EarlySteps, the State of Louisiana’s early intervention program. The Baby and Infant Screen for Children with aUtism Traits- Part 1 (BISCUIT- Part 1) and Battelle Developmental Inventory, Second Edition (BDI-2) were administered to parents/caregivers as part of the EarlySteps assessment protocol. An overall ASD prevalence rate of 12.12% was found using DSM-5criteria, along with an overall M/F ratio of 3.15. Significant differences in the M/F ratio were found: between cases with and without cognitive impairment; between cases with and without advanced maternal age; across birth weight categories; and between cases with and without seizure disorder. Advanced maternal age was found to significantly increase the risk of ASD for females but not males. These findings are discussed in relation to previous research as well as theories pertaining to the male predominance in ASD.



Committee Chair

Matson, Johnny