The cortisol awakening response (CAR) in male children with autism spectrum disorder.

Our ability to adapt to change is fundamental. The cortisol awakening response (CAR) is a sharp rise in cortisol 30min after waking to help prepare an individual for ensuing stress. Children with autism spectrum disorder (ASD) often have difficulty adapting to change. Exploration of the CAR is warranted; yet, the few studies investigating it are inconclusive. The CAR was investigated in 94 pre-pubertal male children 8-to-12years of age with ASD (46) and typical development (TD, 48). Salivary samples were collected over three diurnal cycles involving two morning samples: M1: Immediately upon Waking and M2: 30-min Post Waking (M2-M1=CAR). The magnitude of the CAR was measured by independent two sample t-tests, variability was measured using Levene's Test, the sequence of the CAR was analyzed by a linear mixed-effects model and proportion of children exhibiting a CAR by chi-square test of independence. There were no significant differences on the CAR between the groups based on magnitude (t(92)=-0.14, p=0.89, d=0.04), variability (F(45,47)=1.11, p=0.72, η(2)=0.11) or the sequence over three days (F(2,88)=0.26, p=0.77, η(2)=0.01). No significant differences were shown in the proportion of children exhibiting a CAR across the groups based on child (χ(2)(1)=0.02, p=0.89) or adult criterion (χ(2)(1)=1.82, p=0.18). Despite group differences in the regulation and responsivity of cortisol, the CAR is indistinguishable between children with and without ASD. Inconsistencies across studies may be due to age, criterion used, and diagnostic distinctions.