Autism spectrum disorders have formerly been defined as a group of neurodevelopmental disorders that include “Asperger's syndrome, Rett syndrome, childhood disintegrative disorder, and pervasive developmental disorder not otherwise specified” . Asperger’s syndrome, childhood disintegrative disorder, and pervasive developmental disorder are placed under autism spectrum disorder (ASD) in the upcoming DSM-V . On the other hand, Rett syndrome has been removed from the DSM . “Deficits in social skills and communication, stereotyped and repetitive behavior, and a range of cognitive deficits” are usual symptoms within the ASD spectrum, which are typically diagnosed by 4.8 years of age . However, such symptoms have been detected as early as six months of age .
Environmental insults during pregnancy or post-pregnancy may also cause autism. In early development, the brain is more vulnerable to environmental damage . Environmental factors, including the exposure to specific toxins, can cause neuropsychological deficits closely resembling autism . Many environmental factors have been explicitly identified as causing “both autistic symptoms and an increased likelihood of a diagnosis of autism” . However, exposure to environmental agents is not the sole cause of autism. Genetic factors account for most cases. Therefore, autism is likely the result of a combination of genetic predispositions and environmental insults. The degree of severity of the phenotype may depend on the severity of the genetic predispositions and environmental insults .
Changing diagnostic criteria with the new diagnostic manual (DSM-5) may impact prevalence rates, which are currently 1 in 59 children in the United States . ASD is defined as a “neurobiological condition caused by both genetic and environment factors affecting the developing brain” . Researchers continue to discover factors associated with ASD risk, and these findings may guide the further etiological investigation, but no final causal pathway has been established . Children are first screened at the pediatric level, and then are referred to a specialist for a proper assessment and diagnosis if deemed to be at-risk for ASD . Co-morbid disorders should also be checked in children with ASD . Clinical genetic testing is recommended during the initial medical evaluation, regardless of whether there are precise biomarkers or diagnostic measures . Further medical examinations or referrals to subspecialists may be recommended .
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2. Hodges, H., Fealko, C., & Soares, N. (2020, February). Autism spectrum disorder: Definition, epidemiology, causes, and clinical evaluation. Translational pediatrics. Retrieved February 19, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7082249/
Author: Rayven Hall
Editor: Sara Giarnieri
Health scientist: Rayven Hall