We know that there is no single cause for autism. Research suggests that autism develops from a combination of genetic and non-genetic or environmental influences.
Autism spectrumdisorder does not have a single known cause. Given the complexity of the disorder and the fact that symptoms and severity vary, there are likely many causes.
Both genetics and the environment can play a role in the development of autism spectrum disorder (ASD). Scientists believe that both genetics and the environment are likely to be involved in ASD. There is great concern that autism rates have increased in recent decades without a full explanation as to why. Researchers have identified several genes associated with the disorder.
Imaging studies of people with ASD have found differences in the development of several regions of the brain. Studies suggest that ASD could be the result of alterations in normal brain growth very early in development. These alterations can result from defects in genes that control brain development and regulate the way brain cells communicate with each other. Autism is more common in children who are born prematurely.
Environmental factors may also play a role in gene function and development, but specific environmental causes have not yet been identified. The theory that parental practices are responsible for ASD has long been refuted. Multiple studies have shown that vaccination to prevent childhood infectious diseases does not increase the risk of autism in the population. A variety of genetic factors are likely to be the main cause of most cases of autism.
These can work on their own, or in combination with environmental factors, to lead the child's brain to develop differently and cause autistic behaviors. Most people would be surprised to learn that it is the most commonly identified cause of hereditary intellectual disability. Scientists believe that there are multiple causes of ASD that work together to change the most common ways in which people develop. One likely possibility is that many cases of autism are related to what is called “common genetic variation”.
Antibiotics, for example, are commonly used with babies in Western societies and are known to kill “good bacteria” along with the “bad” bacteria for which they were prescribed.