Autism and the ANS

A writeup I did for my college Biological Psychology Course

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Hari Srinivasan

Psych 22: Biological Psychology

Autism and the ANS

Abstract

Autism as a spectrum disorder is still not fully understood as it comes in many variants which indicate varied underlying psychological basis. This paper discusses the role of the nervous system in Autism, specifically the Autonomic Nervous System. While research is underway in the path towards its biological underpinnings, a much better understanding is required before it can translate into meaningful treatments in order to improve the quality of life for the affected ASD population.  

        Autism and the Nervous System

Autism Spectrum Disorder (ASD) is a lifelong neurological disorder with its onset commonly in early childhood. The DSM-V classification of ASD is largely based on observable external behaviors such as  deficits in social-emotional skills, repetitive behaviors, and communication skills. However the condition also seems to be accompanied by a whole host of co-morbid conditions such as ADHD, mood disorders, sleep disorders, intellectual disability, obsessive compulsive behaviors, and sensory dysregulation. Epigenetics could also play a role wherein the environment affects gene expression. A mix and match of varying degrees of severity in these parameters result in huge numbers of people that fit this spectrum disorder. One in every 110 children is being diagnosed with ASD in the US today . The severity ranges from individuals who are non -verbal and/or with many challenging behaviors to those who are barely distinguishable from their peers.

         

There has been an increasing focus on the role the nervous system plays in the physiological underpinnings of autism. For instance, my personal experience as a person in the ASD spectrum points to the inability of the ASD individual’s nervous system to handle environmental input as the probable cause behind the atypical “stim” (ie: self  stimulatory) mannerisms. An example is walking into a crowded room and hearing every conversation in the room at the same volume, and being unable to filter out the ones the individual needs to focus on.  The ASD individual may resort to atypical behaviors like flicking fingers in front of his eyes, generating their own verbal sounds or even banging their hands on their heads, all in an attempt to drown out the environmental visual and auditory cacophony. Social and communication skills are part of a typical person’s toolbox in coping with stressful situations; deficits in these areas often prevent an easy resolution for the ASD individual, heightening the problem. So sensory stimulation can result in hyper-arousal, hypo arousal or sensory seeking behaviors in ASD individuals.  

My personal observation and experience as an individual on the ASD spectrum has also been that of an unclear sense of body-schema  which could well be the cause of the constant movement exhibited by many on the spectrum.  It is almost as though the brain has to continually ascertain the position of the parts of the rest of the body in space and time.  The continual movement of the body (a movement disorder) could be an adaptive effort to keep this connection between brain and body alive. Without the movement, it would be like a brain that was lost as it did not feel attached to the body. A sense of panic could well set in when waking up in the dark at night and feeling body-less, thereby affecting sleep patterns and mood. According to the Subiaul et al (2007), “ It is well known that individuals with autism have poor body schemas and suffer from impairments in motor functioning, and planning.”  Ergo, ASD individuals exhibit atypical Autonomic Nervous System activity,

         

The Autonomic Nervous System (ANS) is part of the Peripheral Nervous System.  The ANS regulates our internal organs thus involving a lot of actions that are involuntary in nature. The ANS has 3 parts  - the Sympathetic Nervous System, the Parasympathetic Nervous System and the Enteric Nervous System.  The Sympathetic, “controls functions that accompany arousal and expenditure of energy,” while the parasympathetic, “controls functions that occur during relaxed state,” (Carlson, 2013). Many studies have backed observations about atypical ANS activity in Autism, such as the study by  Schaaf et al. (2015) which found that  ASD participants exhibited,  “a different pattern of parasympathetic activity”.  Changes in heart rate (specifically RSA or Respiratory Sinus Arrythma) in response to sensory stimuli is an oft-used measure of Parasympathetic activity in studies due to its non-invasive nature while variants of EGC’s are needed for measuring sympathetic activity (Schaaf et al., 2015).  Schaaf et al. also point to other studies that show atypical arousal levels in sympathetic system in ASD individuals. Interestingly the sympathetic activity  decreased in some studies and increased in other studies,  leading researchers to conclude that  ASD individuals would, “engage in self-stimulatory  or active sensory seeking behaviors to either dampen or increase sympathetic levels in order to calm or arouse themselves,” respectively (Schaaf et al, 2015).  Even as scientists and researchers agree more and more on ANS dysregulation in the ASD population,  “the exact nature  of the ANS dysregulation is [still] not clear,”.

         

Such self stimulatory mannerisms and movement issues, being almost involuntary in nature, pose one of the biggest challenges for an ASD individual and their families as they are considered socially inappropriate and make societal inclusion and acceptance all that much harder for the ASD individual especially as an adult.  It is clear that further insight into understanding the biological underpinnings of the ANS dysregulation in Autism is necessary before it can translate into meaningful and targeted treatments for the ASD population.  For instance, the neurotransmitters,  acetylcholine and norepinephrine play a major role in the ANS; the manipulation of which via pharmaceuticals could potentially play a future role in treatment and thereby improving the quality of life for ASD individuals. In the meantime, many in the Autism population continue to muddle through their overwhelming sensory environment hampered by a dysregulated Autonomic Nervous System.