neuro-developmental causes of autism
What actually happens in the brain of an individual with Autism?
The above image displays the rhytmic brainwave activity in the brain of an Autistic individual and in a Neuro typical (NT) individual. As you can see, in a NT individual, the rhythmic brainwave activity is fairly uniform as compared to an autistic individual.
There is an agreement in the literature that individuals with ASD have abnormalities in EEG measures. These are measures that indicate attentional states and level of alertness and relative ability to be calm and relaxed. In addition, they may be indicative of ability to learn and process new and novel information. Some findings include significantly more slow-wave theta activity, reduced biological rhythm activity, as well as less EEG wave asymmetry within and between hemispheres of the brain. These findings reflect a potential difficulty for the brain to enter a calm, relaxed state. In addition, there are reports of globally reduced biological rhythm coherence, reduced short distance coherences and increased long-distance coherences (for different eeg brainwaves), disrupted neural synchronization, reduced pre-attentional EEG response filtering as well as other indications supporting the general supposition that neural processing is different between those with autism spectrum disorder and neurotypical individuals. These findings reflect a potential fundamental difficulty in the brain of an individual with ASD to appropriately communicate information or send neural signals from one region to another, in addition to a potential inability for the brain to effectively understand novel information.
As a result of the aforementioned EEG findings in ASD, subjective symptoms of the disorder manifest and develop in order to compensate for the internal anxiety felt by the individual due to gross disruption in neural communication. These anxiety-driven responses include compensatory behaviors, such as stimming or repetitive fascination with objects or actions in order to control incoming sensory information. In addition, sensory mitigation or control behaviors, such as covering ears or eyes or trying to avoid novel places or experiences, from new sounds to new foods or clothing, is seen as ways of further reducing the information load on the brain. Through understanding the underlying brain issues via EEG, a greater appreciation of the disorder is achieved.
There is an agreement in the literature that individuals with ASD have abnormalities in EEG measures. These are measures that indicate attentional states and level of alertness and relative ability to be calm and relaxed. In addition, they may be indicative of ability to learn and process new and novel information. Some findings include significantly more slow-wave theta activity, reduced biological rhythm activity, as well as less EEG wave asymmetry within and between hemispheres of the brain. These findings reflect a potential difficulty for the brain to enter a calm, relaxed state. In addition, there are reports of globally reduced biological rhythm coherence, reduced short distance coherences and increased long-distance coherences (for different eeg brainwaves), disrupted neural synchronization, reduced pre-attentional EEG response filtering as well as other indications supporting the general supposition that neural processing is different between those with autism spectrum disorder and neurotypical individuals. These findings reflect a potential fundamental difficulty in the brain of an individual with ASD to appropriately communicate information or send neural signals from one region to another, in addition to a potential inability for the brain to effectively understand novel information.
As a result of the aforementioned EEG findings in ASD, subjective symptoms of the disorder manifest and develop in order to compensate for the internal anxiety felt by the individual due to gross disruption in neural communication. These anxiety-driven responses include compensatory behaviors, such as stimming or repetitive fascination with objects or actions in order to control incoming sensory information. In addition, sensory mitigation or control behaviors, such as covering ears or eyes or trying to avoid novel places or experiences, from new sounds to new foods or clothing, is seen as ways of further reducing the information load on the brain. Through understanding the underlying brain issues via EEG, a greater appreciation of the disorder is achieved.
When Bernard Rimland, in 1965, rejected the psychoanalytic model of autism and proposed that the disorder was purely biological, one of the responses was the movement of research in a neurodevelopmental direction (Baker, 2008). Because of many commonalities in medical conditions occurring more often among the population of individuals with autism, as opposed to the general population, a great deal of research has given the disorder a biological basis.
Autism has a high co morbidity with epilepsy (one third of individuals with autism are epileptic), medical syndromes (such as Fragile X, tuberous sclerosis, and Rett syndrome), as well as mental retardation. (Frith et al 1991).
By many leading researchers, autism is considered to be of the most genetic multifactorial neuro-developmental disorders (50% concordance rate for identical twins and less than 5% for fraternal. (Previc, 2007).
Utilizing new information, researchers and parents pushed to promote screening among children, leading to the addition of autism to the covered disabilities in the Individuals with Disabilities Education Act (Baker, 2008).
Although it is agreed that there is a multifactorial genetic component to autism spectrum disorder, no specific chromosomal region is found across all studies (Levy et al, 2005). This “mainline” community of autism research emphasizes four main points (Baker, 2008):
- The cause of autism is primarily biological and not attributed to parental behavior (rejecting the psychoanalytic causes of autism).
- Autism reflects a spectrum of disorders
- Treatment should be rehabilitative as opposed to curative.
- Early intervention is key in striving for a positive outcome
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