Abstract
Examination of the hypothalamic-pituitary-adrenal (HPA) axis via cortisol among individuals with autism spectrum disorder (ASD) has been a growing area of research interest. The following review includes investigations of cortisol conducted with cohorts of individuals with ASD across the lifespan over the past four decades. In general, studies find dysregulation when examining the diurnal rhythm as a whole in lower functioning children with ASD; however, limited evidence exists for alterations in higher functioning individuals and in specific aspects of the diurnal cycle (cortisol awakening response, daily decline, variability) relative to typically developing individuals. Studies examining the responsiveness of cortisol in ASD suggest an overall sluggishness of the HPA axis in responding to physiological or physical manipulation. Hypo-responsiveness was observed in stressors that involve social evaluative threat, however, hyper-responsiveness of the HPA axis was observed in situations involving unpleasant stimuli or relatively benign social situations. A number of important considerations when conducting studies of cortisol in ASD cohorts are discussed.