Altered circadian patterns of salivary cortisol in low-functioning children and adolescents with autism

Anticipation of the stressful collection procedure appears to contribute to the higher 0800 h-Day2 versus 0800 h-Day1 salivary cortisol levels in autism. This sensitization to stressors might be as, or even more, important clinically than exposure to novelty in autism. The similar group means for overnight urinary cortisol excretion indicate that basal HPA axis functioning is unaltered in low-functioning autism. The elevated salivary cortisol levels observed in autism over the 24-h period in a repeated stressful condition, flattened diurnal cortisol patterns and the apparent effect of anticipation are consistent with prior findings in high trait anxiety.