Understanding Autism -- the Basics
What Causes Autism?
Because autism runs in families, most researchers think that certain combinations of genes may predispose a child to autism. But there are risk factors that increase the chance of having a child with autism.
Advanced age of the mother or the father increases the chance of an autistic child.
When a pregnant woman is exposed to certain drugs or chemicals, her child is more likely to be autistic. These risk factors include the use of alcohol, maternal metabolic conditions such as diabetes and obesity, and the use of antiseizure drugs during pregnancy. In some cases, autism has been linked to untreated phenylketonuria (called PKU, an inborn metabolic disorder caused by the absence of an enzyme) and rubella (German measles).
Although sometimes cited as a cause of autism, there is no evidence that vaccinations cause autism.
Exactly why autism happens isn't clear. Research suggests that it may arise from abnormalities in parts of the brain that interpret sensory input and process language.
Researchers have no evidence that a child's psychological environment -- such as how caregivers treat the child -- causes autism.