Over the past few decades, a growing number of children are being diagnosed with autism. Autism is a neurodevelopmental disorder that is characterized by impairments in communication, inappropriate social behavior, and repetitive behavior. The autism spectrum (ASD) has a wide range of symptoms, with varying degrees of severity. As with many disorders, genetic and environmental factors both have a capacity to contribute. While there are many genetic factors that are responsible for autism, there are also some environmental risk factors for developing autism.
One of the proposed risk factors for autism is prenatal viral infections. Researchers have potentially found that prenatal viral infection in the mother is associated with autism development in the child. Furthermore zinc deficiency in the mother and during early development has also shown to have a strong association with autism. Zinc is a very important metal in the body as it plays a role in many different processes, such as cell division and differentiation. Deficiency in zinc during development is linked to severe brain dysfunction, including impaired learning and memory. While immune system disruption and zinc deficiency are seen as the two central factors, there are many others that have been proposed. Some other risk factors that have been associated with autism are parental age, prenatal stress, abnormal melatonin synthesis, maternal diabetes, postnatal heavy metal poisoning, and prenatal exposure to toxins including valproic acid and thalidomide.
Many of these risk factors appear prenatally, or before the child is born. This window of time is a sensitive one for brain development, as certain aspects of the brain development may be more prone to disruption by environmental factors imposed on the mother and thus the child. Although it appears that autism originates in early development, many of these risk factors need further research to strengthen their associations and provide a more direct link with autism. While there are many environmental and genetic factors that are associated with autism, researchers have yet to draw them back to a single cause. It is now clear that there are not only genetic, but environmental influences that can both lead to increased risk of developing autism. Elucidating the exact mechanism in which these environmental factors impact autism will be an important next step towards merging the genetic and environmental components.
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Autism and the Environment
