Association of Severity of Autism Spectrum Disorder with Cardiac Autonomic Indices in Children

Abstract

Background & Objectives: Autism Spectrum Disorder (ASD) being a complex neuro-developmental
disorder is found to be associated with Autonomic Nervous System (ANS) dysfunction. The sympathovagal
continual dynamic excitatory- inhibitory interactions leads to Heart Rate Variability (HRV) which is
an index of cardiac autonomic regulation. Aim of the study was to evaluate cardiac autonomic regulation in
children with ASD at rest using short-term HRV analysis and to correlate it with severity of autism.
Methods: A total of 30 subjects were evaluated in the study comprising of 15 ASD children and 15 healthy
controls. A five minutes recording of resting ECG was carried out from which R-R intervals were procured
and HRV indices were analysed. Frequency domain analysis of HRV was carried out and the following
parameters were evaluated: Spectral powers in low frequency (LF) bands, High frequency (HF) bands, total
power (TP), LF/HF ratio and average heart rate (HR) were evaluated. HRV indices between the groups were
compared using Student’s t test. Severity of autism was correlated with the evaluated HRV indices using
Pearson correlation test.
Results: Cardiac sympathetic activity as assessed by low frequency power spectrum (‘p’ value 0.034) and
total power (‘p’ value 0.023) of the HRV spectrum was significantly higher in autistic children compared
to that of normal controls. However, the association between severity of ASDs and HRV indices were not
statistically significant.
Conclusion: Study concludes that here was no significant association between HRV indices and severity of
autism.