ASD (Autism Spectrum Disorder) is a condition that is mainly characterised by deficits in social and communication skills, and restricted or repetitive patterns of behaviour such as hand flapping, lining up of toys, or even showing resistance to changes. The symptoms appear very early in childhood, usually between 18 to 24 months, and can be reliably diagnosed between 2 to 3 years of age. While individuals with autism do face some form of challenges in social and communicative skills, the severity of which they are affected varies greatly with some who display excellent linguistics, and others possessing abilities that far exceed their peers in the areas of memory, music, or mathematics. As not everyone with ASD displays phenomenal abilities, a lack of language delays or the possession of exceptional abilities cannot be used as a criteria for diagnosing autism.
What are some known environmental risk factors?
Due to the rising awareness of the condition and the recent increase in the number of diagnoses, there has been a growing interest in the research on the causes and outcomes of autism. Although autism is classified as a neurodevelopmental disorder, some known causes have environmental influences from biological origins such as rubella infection during pregnancy, anti-epileptic drugs taken in pregnancy, untreated metabolic disorders such as phenylketonuria, tumour growths in organs or parts of the brain (tuberous sclerosis), and postnatal infections such as encephalitis which may result in ASD. However, reported cases of autism as an effect of medical causes is not common, and makes up only about 6-10%. Strong evidence has also shown that measles, mumps, and rubella vaccine is not an environmental risk factor for autism.
Genetics is a key factor in the development of ASD
In most people with autism, genetics play a key role. Research involving twins have shown that identical twins are 60% more likely to develop autism if one twin has the condition. The likelihood drops to about 2-6% if a non-twin sibling has autism. ASD also has a tendency to run in families although the inheritance pattern remains unknown as the interplay between multiple genes have not produced a consistent pattern that can be tracked and studied thus far. However, research has continuously uncovered these multiple genes (up to 1000) and found that the development and interactions between these genes are more likely to affect the outcome of ASD. Even with neural imaging technologies, autism is a condition that proves difficult to treat due to inconsistent brain scan patterns and cell development; some genes affect the type and number of neurons produced, while others affect cell-to-cell communication and the resulting neuronal structure of the brain. Nonetheless, the recent identification and understanding of the underlying gene linkages does help to explain the varied symptoms people with ASD display.
With the recent understanding and continuous acceptance of the condition, Autism is now recognised as a neurological disorder mainly caused by underlying gene involvement. Although the development of autism is still largely being researched at both the brain and neuronal level, studies and even testimonies of individuals have supported the use of therapies to improve the symptoms associated with ASD. Today, it is increasingly accepted to undergo therapy as a form of treatment for ASD.
Written by Marjorie.
References
ASD - Genetics Home Reference - NIH. (2020, January 7). Retrieved January 13, 2020, from https://ghr.nlm.nih.gov/condition/autism-spectrum-disorder#resources
Baird, G., Cass, H., & Slonims, V. (2003, August 30). Diagnosis of autism. Retrieved January 13, 2020, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC188387/
Szatmari, P. (2003, January 25). The causes of autism spectrum disorders. Retrieved January 13, 2020, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1125046/
Tuberous sclerosis. (2017, October 25). Retrieved January 13, 2020, from https://www.mayoclinic.org/diseases-conditions/tuberous-sclerosis/symptoms-causes/syc-20365969