What Causes Autism?
At this time, the exact cause of autism remains uncertain, but research suggests that any one of several factors may be involved in its onset: genetic factors, possible environmental influences; certain types of infections; problems before, during, or after birth. Some studies suggest the possibility of a disruption of very early brain development, before birth.
There is extensive past and ongoing research intending to delineate the causes of autism.
Increased frequency of occurrence of autism within families supports a probable genetic contribution to the disorder; however, it is very unlikely that any one single genetic defect will explain all cases of autism. Observations that the identical twins of an individual with autism has only about a 60% chance of also having autism, lead to the conclusion that genetics alone do not explain the condition. Ongoing research is seeking to find out if a genetic predisposition to autism may be triggered to develop into autism by the occurrence of certain environmental, infectious, immunological, and other conditions or events.
At this time, there is no evidence that specific toxins in the environment, immunization practices, dietary differences, or immunologic differences cause autism. It is quite likely that some combination of genetic, neuropathologic, and environmental agents will explain the etiology of autism, and that the etiology may vary from one individual to another.
Since the definition of autism is a behavioral definition, meaning that it is solely defined through a certain constellation of behaviors, and not through biological tests, it is quite likely that different types of conditions could result in similar behavioral manifestations among individuals. For instance, in some specific disease entities, such as Fragile X syndrome, untreated phenylkotonuria, and other specific genetic disorders, affected individuals have the behavioral characteristics of autism.
At one time, autism was thought to be caused by faulty parenting (“refrigerator mothers”) and it is now clear that this is not a cause of autism. The theory of faulty parenting as causative of autism has not disappeared entirely however, and still crops up in “failure to bond” theories and “attachment disorder” theories about the genesis of autism. Most researchers reject this type of explanation as misguided and harmful.