Currently the causes of Autism are all theoretical in nature. It is appears that many causes come together to ‘flip on the switch’ for Autism. There is no ‘one cause’ for Autism.
(Some of the) Theories for Autism causes:
Genetics: One of the latest studies coming out has found that Autism may begin before birth, which lends to the theory that Autism is in part caused by the genetics of the child. The study found patches of disorganized neurons in the brains of Autistic children and these patches were found throughout the patients’ brains. (1)
The pollution that infants and pregnant women are exposed to has been tied to Autism as well. Studies into the realm of environmental pollution and its connection to Autism are also being done. These studies include ones looking at the prevalence of Autism in children who were exposed to: Air pollution (in utero and during 1st year of life) (2), Freeways, and Phthalates (most often in flooring) (3)
This is a controversial theory that was first put forward by Dr Andrew Wakefield and has yet to be accepted by the medical world at large. Autistic enterocolitis is said to include bowel disorders including chronic inflammation, constipation, diarrhea and pain. This inflammation has been tied to a theory known as the Gut and Psychology Syndrome which postulates that issues in the gut lead to issues in the brain. (4)
studies are currently being done regarding how DNA methylation influences susceptibility to Autism. There is a controversial study correlating use of prenatal vitamins including folic acid with an increased risk for Autism. (5)
As fathers age there is a higher percentage of mutations present in the genes they pass on to their children, thus increasing the chances that their children will develop Autism etc. “A 36-year-old will pass on twice as many mutations to his child as a man of 20, and a 70-year-old eight times as many.” (6)