What Causes Autism Spectrum Disorder?
When parents find out their child has ASD, they desperately want an answer to that question. They ask themselves, “Why did this happen?” or “What did we do wrong?”
While we don’t know what causes autism, we do know that it’s beyond parents’ control. The disorder likely starts long before parents even know something is amiss. The best advice for parents is not to focus energy on identifying the cause, but to focus on treatment. Getting started with a good, intensive behavioral program may give a child the best opportunity for optimal outcomes.
Scientific Investigations to Date
Scientists have investigated genetics, genomics, environment, gastrointestinal issues, proteins, toxins, diet, immune system, vaccines, maternal stress, paternal age, maternal age, maternal infections, societal changes, television, cell phones, microwaves—and probably a few others. Unfortunately, science has yet to identify a cause with sufficient, robust evidence that will explain ASD.
Genomics, or the study of gene sequences and interactions, present some of the most convincing evidence. While there is no evidence of hereditary factors (passed from previous generations), there is evidence of increased familial risk. That is, if there is an older sibling with ASD, a younger sibling has a higher risk of developing ASD than what we see in the general population. Still, common genetic mutations are often not found among two siblings with the disorder.
Different studies of identical and non-identical twins support both a genetic and an environmental cause of ASD. Currently, more than 400 genes are significantly associated with ASD, but none are found in every person with the disorder. Many people with ASD have no known genetic mutation. In fact, all known genetic mutations combined can only explain about 20% of all the people with ASD today. While genes matter, they are clearly not the whole story.
Focus on Early Intervention and Treatment
As with any disorder, disease, or syndrome, identifying and understanding the cause is important because it may help improve early identification and treatment. However, with a disorder like ASD, its potential causes are probably as diverse as the presentation of the disorder itself. There is so much to learn about how to best help the group of individuals who have ASD today, that at this point, research might better serve the population by first focusing on more effective treatments and then by attempting to identify causes as a secondary effort.