Ontario Adult Autism Research and Support Network - OAARSN

What Causes Autism?

Autism involves disorders of development of brain functions. It is not a mental illness. Nor is it psychogenic, caused by anything in a child’s psychological environment. Earlier notions, that Autism was caused by emotional deprivation or emotional stress, have been discredited. The roles of nature and nurture, genes and the environment, continue to be debated. It is extremely unlikely that Autism is caused by a single factor. It is most likely that certain people are genetically predisposed to be sensitive to any of various environmental insults that actually trigger the symptoms that we call Autism. 

There are strong indications that the causes of Autism Spectrum Disorder are biological. The evidence includes the following observations.

• Autism is often accompanied by other neurological symptoms and associated with other learning difficulties.
• By adulthood, about one in three persons with Autism will have had at least two epileptic seizures.
• Most autistic children show unusual responses to sensory stimuli of any kind and have what have been called movement differences.
• Brain autopsies have shown abnormalities in the frontal lobes, limbic system, brain stem and cerebellum.
• Some 30 to 50 per cent of autistic children have abnormally high levels of serotonin, the chemical that transmits signals in nerve cells.
• The higher incidence of Autism in families points to a genetic aspect.
• There is evidence that at least one type of Autism is an immune-system dysfunction, its onset triggered by viral infections, or by antibiotics and vaccines.
• Some autistic children and adults are unable properly to digest certain foods or may have paradoxical reactions to medications.

Genetic research has identified several genes that may be mutated or damaged. And all kinds of environmental insults may be involved-from the myriad chemicals used in agriculture, forestry, industry and our homes to substances taken into our bodies as medicines or food. It is likely that Autism may be triggered in different people by varying combinations of genetic and environmental factors. This variability is reflected in the huge variety of symptoms and the differences that are so evident among people diagnosed with Autism Spectrum Disorder.

Since the late 1990s, there has been a push to promote research into the causes of Autism, with funding commitments by governments and charitable foundations. Various research centres have been set up, often as consortia of teams at several universities. Research findings are published at a quickening pace, in popular media as well as scientific journals. We recommend Spectrum News which issues frequent online research bulletins. (Spectrum | Autism Research News & Opinion (spectrumnews.org)