Etiology of Autism Spectrum Disorder

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Karina Dolgilevica 07.01.2013 Word count: 1 637

5) There are many questions about the etiology (cause) of

Autism Spectrum Disorder. Please pick

one

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(neurological, cognitive, or social) and discuss the research that

explores ASD.

(1500words +/- 10%)

The investigation of the causes of Autism Spectrum Disorders (ASDs) has been surrounded by myth and controversy throughout history, mainly because of difficulties of diagnosis and a lack of feasible evidence. With technological progress, however, a large body of scientific evidence has emerged during the past few decades. The fields of neuroscience and neurogenetics have contributed enormously to our understanding of ASDs, but the underlying cause of this complex neurodevelopmental disorder is yet to be discovered.

Autism Spectrum Disorder comprises a range of conditions that vary in their individual characteristics and severity, but the main symptoms found in people diagnosed with ASD are a lack of empathy, the inability to interpret and understand other peoples’ emotions and feelings, and impaired verbal and non-verbal communication and social interaction, often accompanied by repetitive behaviours (Kanner, 1943; Geschwind, 2007; The National Autistic Society, 2012). This essay is going to look at recent research evidence from studies of the basis of ASD, focusing mainly on the recent genetic and neurobiological research within the field of neurology.

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offspring of multiplex have a higher risk of developing ASDs. Current research concludes that more than twenty different genes could be giving rise to ASD, for example those genes responsible for grammar and language (Fisher, 1998). Furthermore, environmental factors, such as the development in the womb, a range of individual differences in the anatomy of the brain and genotype of the individuals diagnosed with ASD, must to be considered and highlighted when studying the origin of ASD. Researchers apply various methods in their studies to prove the genetic basis of these conditions, but the attempt at isolating gene(s) causing specific ASD symptoms and linking then together have so far proved to be very complex and relatively unsuccessful.

Statistics show that a vast majority of individuals diagnosed with ASD are male, with a ratio of four males to one female. It has been widely found that an autistic brain contains higher levels of testosterone hormone than a normal human brain, (Baron-Cohen, 2005; Hu, 2011; Green, 1997), which has encouraged researchers to look at the neurodevelopment of an autistic brain in more detail and to try to illuminate the question of the sex bias in autism.

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Neuroimaging studies demonstrate the difference between workings of a normal human brain and that of an individual diagnosed with ASD, by examining the neuroanatomy of an atypically developing human brain and nervous system. From the evidence of various magnetic resonance imaging (MRI) studies many developmental disorders, such as autism, indeed show structural and functional differences in the biology and chemistry of the brain (Green, 1997; Komuro & Rakic, 1998). The activation of numerous brain regions (in particular temporal, parietal and occipital regions as well as temporal lobes and amygdala, involved in language and social cognition) appear to differ from case to case due to

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affecting the structural and functional development of the brain, behaviour, and cognition in people with ASD.

A timesaving method of diagnosis of ASD has been recently devised by the Institute of Psychiatry in London (Laurance, 2010). This involves an MRI scan and special software (involving facial recognition and handwriting techniques) that allows a distinction to be made between the normal brain and an autistic brain. The procedure only takes about fifteen minutes. The software is programmed to respond to certain patterns of autistic brains. This expeditious method is still in development, but could allow the screening to be used for common diagnostic purposes in the future, especially with children, which would probably allow earlier diagnosis of ASDs and encourage people to come forward. The research team has tested 20 adult male subjects with ASD against 20 normal subjects during the programming stage of the software. One of the other advantages of such technology is that it is more equipped to pick up on subtle and intricate neuroanatomical details. Further research would be necessary to ensure that this method is sufficiently accurate and reliable. This non-invasive and efficient diagnostic test would potentially contribute to our knowledge of the autistic brain and perhaps help classify the diagnosed individuals, but it is not very likely to serve as a means to identifying causes of ASD. Being able to match the studied subjects better would decrease the heterogeneity of the ASDs and allow the decrease of some of the inconsistencies gathered from various MRI studies.

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