There are many causes of autism.

Research suggests that autism spectrum disorder (ASD) develops from a combination of:

• Genetic influences and
• Environmental influences, including social determinants

These factors appear to increase the risk of autism and shape the type of autism that a child will develop. However, it’s important to keep in mind that increased risk is not the same as a cause. For example, some gene changes associated with autism can also be found in people who don’t have the disorder. Similarly, not everyone exposed to an environmental risk factor for autism will develop the disorder. In fact, most will not.

How do genetic and environmental influences give rise to autism?

Most appear to affect crucial aspects of early brain development. Many autism risk genes influence other networks of genes, increasing or decreasing their expression. Some appear to affect how brain nerve cells, or neurons, communicate with each other. Others appear to affect how entire regions of the brain communicate with each other. Research continues to explore these differences with an eye to developing interventions and supports that can improve quality of life.

Do vaccines cause autism?

Vaccines do not cause autism. It is possible that the timing of an autism diagnosis might coincide with the recommended vaccine schedule for children and adolescents. But scientists have conducted extensive research over the last two decades to determine there is no link between childhood vaccinations and autism. The results of this research is clear: Vaccines do not cause autism. Additionally, vaccination can protect children from many preventable diseases like measles.

The American Academy of Pediatrics has compiled a comprehensive list of this research.