Autism Spectrum Disorder

On this page

The National Institute of Mental Health (NIMH), a component of the National Institutes of Health (NIH), is a leading federal funder of research on ASD

What is autism spectrum disorder? 

Autism spectrum disorder (ASD) refers to a group of complex neurodevelopment disorders caused by differences in the brain that affect communication and behavior. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5)—a guide created by the American Psychiatric Association used to diagnose health conditions involving changes in emotion, thinking, or behavior (or a combination of these)—people with ASD can experience: 

  • Challenges or differences in communication and interaction with other people
  • Restricted interests and repetitive behaviors
  • Symptoms that may impact the person's ability to function in school, work, and other areas of life 

ASD can be diagnosed at any age but symptoms generally appear in early childhood (often within the first two years of life). Doctors diagnose ASD by looking at a person's behavior and development. The American Academy of Pediatrics recommends that all children get screened for developmental delays and behaviors often associated with ASD at their 18- and 24-month exams.  

The term “spectrum” refers to the wide range of symptoms, skills, and levels of ability in functioning that can occur in people with ASD. ASD affects every person differently; some may have only a few symptoms and signs while others have many. Some children and adults with ASD are fully able to perform all activities of daily living and may have gifted learning and cognitive abilities while others require substantial support to perform basic activities. A diagnosis of ASD includes Asperger syndrome, autistic disorder, childhood disintegrative disorder, and pervasive developmental disorder not otherwise specified that were once diagnosed as separate disorders.  

In addition to differences or challenges with behavior and difficulty communicating and interacting with others, early signs of ASD may include, but are not limited to: 

  • Avoiding direct eye contact
  • Delayed speech and language skills
  • Challenges with nonverbal cues such as gestures or body language
  • Showing limited interest in other children or caretakers
  • Experiencing stress when routines change 

Scientists believe that both genetics and environment likely play a role in ASD. ASD occurs in every racial and ethnic group, and across all socioeconomic levels. Males are significantly more likely to develop ASD than females.  

People with ASD also have an increased risk of having epilepsy. Children whose language skills regress early in life—before age 3—appear to have a risk of developing epilepsy or seizure-like brain activity. About 20 to 30 percent of children with ASD develop epilepsy by the time they reach adulthood.  

Currently, there is no cure for ASD. Symptoms of ASD can last through a person's lifetime, and some may improve with age, treatment, and services. Therapies and educational/behavioral interventions are designed to remedy specific symptoms and can substantially improve those symptoms. While currently approved medications cannot cure ASD or even treat its main symptoms, there are some that can help with related symptoms such as anxiety, depression, and obsessive-compulsive disorder. Medications are available to treat seizures, severe behavioral problems, and impulsivity and hyperactivity. 

Learn About Clinical Trials
Clinical trials are studies that allow us to learn more about disorders and improve care. They can help connect patients with new and upcoming treatment options.

How can I or my loved one help improve care for people with autism spectrum disorder?

Consider participating in a clinical trial so clinicians and scientists can learn more about ASD and related conditions. Clinical trials are studies that use human volunteers to look for new or better ways to diagnose, treat, or cure diseases and conditions. 

All types of volunteers are needed—people with ASD, at-risk individuals, and healthy volunteers—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with ASD at

Order publications from the NINDS Catalog
The NINDS Publication Catalog offers printed materials on neurological disorders for patients, health professionals, and the general public. All materials are free of charge, and a downloadable PDF version is also available for most publications.