Currently 1 in 88 children will be diagnosed with autism.  Boys are four times more likely to be diagnosed than girls.  Do you know the signs?  Learn more.

Autism Research


Autism spectrum disorder (ASD) and autism are both general terms for a group of complex disorders of brain development. These disorders are characterized, in varying degrees, by difficulties in social interaction, verbal and nonverbal communication and repetitive behaviors. They include autistic disorder, Rett syndrome, childhood disintegrative disorder, pervasive developmental disorder-not otherwise specified (PDD-NOS) and Asperger Syndrome. ASD can be associated with intellectual disability, difficulties in motor coordination and attention and physical health issues such as sleep and gastrointestinal disturbances. Some persons with ASD excel in visual skills, music, math and art.

Autism appears to have its roots in very early brain development. However, the most obvious signs of autism and symptoms of autism tend to emerge between 2 and 3 years of age. 

How Common Is Autism?
Autism statistics from the U.S. Centers for Disease Control and Prevention (CDC) identify around 1 in 88 American children as on the autism spectrum -- more than a 600 percent increase in prevalence over the past two decades. Careful research shows that this increase is only partly explained by improved diagnosis and awareness. Studies also show that autism is three to four times more common among boys than girls.  An estimated 1 out of 70 boys is diagnosed with autism in the United States.

More children will be diagnosed with autism this year than with childhood cancer, juvenile diabetes or pediatric AIDS combined. ASD affects an estimated 3 million individuals in the U.S. and tens of millions worldwide. Moreover, government autism statistics suggest that prevalence rates have increased 10 to 17 percent annually in recent years. There is no established explanation for this continuing increase, although improved diagnosis and environmental influences are two reasons often considered.

What Causes Autism?
Not long ago, the answer to this question would have been "we have no idea."  Research is now delivering the answers.  First and foremost, we now know that there is no one cause of autism just as there is no one type of autism.  Over the last five years, scientists have identified a number of rare gene changes, or mutations, associated with autism.  A small number of these are sufficient to cause autism by themselves.  Most cases of autism, however, appear to be caused by a combination of autism risk genes and environmental factors influencing early brain development.

In the presence of a genetic predisposition to autism, a number of nongenetic, or "environmental," stresses appear to further increase a child's risk. The clearest evidence of these autism risk factors involves events before and during birth. They include advanced parental age at time of conception (both mom and dad), maternal illness during pregnancy and certain difficulties during birth, particularly those involving periods of oxygen deprivation to the baby's brain. It is important to keep in mind that these factors, by themselves, do not cause autism. Rather, in combination with genetic risk factors, they appear to modestly increase risk.

A small but growing body of research suggests that autism risk is less among children whose mothers took prenatal vitamins (containing folic acid) in the months before and after conception.

Increasingly, researchers are looking at the role of the immune system in autism.


What Does It Mean to Be "On the Spectrum"?
Each individual with autism is unique. Many of those on the autism spectrum have exceptional abilities in visual skills, music and academic skills. About 40 percent have average to above average intellectual abilities. Indeed, many persons on the spectrum take deserved pride in their distinctive abilities and "atypical" ways of viewing the world. Others with autism have significant disability and are unable to live independently. About 25 percent of individuals with ASD are nonverbal but can learn to communicate using other means.