Brief Report: Reduced Heart Rate Variability in Children with Autism Spectrum Disorder.

The sample was small, with 21 children with ASD and 21 typically developing children, so the findings may not represent the wider autism population. The ASD group was matched to controls on age and had no group mean IQ difference, and children with ASD-related medical conditions were excluded, so it may not reflect the full range of cognitive and medical profiles seen in ASD. Medication use and comorbidity were not controlled in the analyses, although 10 participants in the ASD group were taking psychotropic medication and overall HRV did not differ between those on and off medication. There was no final resting block, so recovery HRV may reflect task habituation rather than return to baseline. The primary HRV measure did not incorporate respiration, although the analyses were repeated with a respiration-based measure and results were unchanged unless noted. The authors describe the reduced HRV finding as preliminary evidence.

All authors report no conflict of interest. No funding source is stated in the supplied text.

Do not conclude that reduced HRV explains social communication difficulties in autism or that autonomic testing should guide therapy. The ASD group had lower overall HRV, but HRV did not differ in reactivity or recovery and was not associated with social communication or restricted and repetitive behavior scores.