Comparison of Physiological and Biochemical Autonomic Indices in Children with and without Autism Spectrum Disorders

Abstract

Background and objectives: Autism Spectrum Disorder (ASD) is a complex neuro-developmental disorder and it has been suggested that symptoms of ASD are associated with neural networks that regulate the Autonomic Nervous System (ANS). However, the nature of autonomic atypicalities in ASDs remain largely unknown. Measures like Heart Rate Variability (HRV) and urinary Vanillylmandelic Acid (VMA) estimation are sensitive and non-invasive physiological and biochemical indicators of autonomic nervous activity. This study aimed to compare the physiological and biochemical autonomic indices in children with and without ASD. Materials and Methods: In this case-control study, 40 children with autism and 40 Typically Developing (TD) children were recruited. Measures of physiological autonomic index were assessed by the analysis of short term HRV, and the urinary levels of VMA estimation was used as a biochemical autonomic index. Results: Cardiac sympathetic activity assessed by Low Frequency (nu) of HRV was significantly higher in the ASD group in comparison with the TD group (p = 0.006). On the contrary, both the High Frequency (abs) and (nu) of HRV were found to be significantly lower in autistic children (p = 0.034 and p = 0.000) than controls. Autistic children also exhibited a significantly higher level (p = 0.049) of VMA concentration compared to TD children. Conclusion: The study concludes that children with ASD exhibit lower cardio-vagal activity as measured by HRV and increased sympathetic activity as assessed by urinary VMA compared to that of TD children. The core autistic symptoms exhibited by children with ASD could be due to the differences in baseline arousal or stress which might be associated with autonomic dysfunction. Further studies are needed to examine the association of this autonomic dysregulation with ASD symptoms and comorbidities.

Alterations in the autonomic nerve activities of prenatal autism model mice treated with valproic acid at different developmental stages

“…The STV and HF (ln) of male Sal, male VPA, and female Sal mice were significantly increased from 4 to 8 weeks of age, whereas these of female VPA mice remained unchanged, suggesting the strong suppression of parasympathetic nervous development in female VPA mice. Several reports revealed that the assessment of the sympathetic and parasympathetic activity using HRV in children with ASD yielded inconsistent results [25][26][27]48 . As ASD is a heterogeneous disease 1 , it can be inferred that such diversity occurred because of the characteristics of the population and the environmental factors that were involved in the studies.…”

Autism risk in neonatal intensive care unit patients associated with novel heart rate patterns

“…Maturation of autonomic responses occurs throughout gestation ( 35 ) ( 36 ) and in the neonatal period ( 37 ) ( 38 ), with a shift from more sympathetic to more parasympathetic drive. Autonomic imbalance occurs in a variety of pathologic conditions and has been reported in children with ASD ( 16 ) ( 18 ) ( 20 ) ( 21 ) ( 22 ) ( 23 ) ( 25 ). Some studies have reported a slightly higher HR in children with ASD compared to typically developing children, especially during certain activities or phases of sleep ( 23 ).…”

“…Children with ASD have been reported to have differences in HR patterns compared to neurotypical individuals, including higher HR ( 16 ) ( 17 ). The mechanism of these findings is not well understood, but there is some evidence of overactive sympathetic tone ( 18 ) ( 19 ) ( 20 ) and decreased parasympathetic or vagal tone ( 21 ) ( 22 ) ( 23 ) ( 24 ) ( 25 ). These HR differences have particularly been noted during sleep and in response to social and non-social stimuli ( 26 ).…”

Determining bioenergy field of autistic and normal healthy children: an electrophotonic imaging study

“…31 The healthy children showed physiological flexibility which may be helpful for acute stress adaptation in healthy children and impaired in autism children. 32 The poor adaptation is associated with dysregulation of the autonomic activity, particularly sympathetic and parasympathetic outflow that outflows via brainstem and sacral spinal region. In the present study, sacrum showed high level of energy in children with autism compared to normal healthy.…”