What is autism?

ASD and autism are 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 inflexible, repetitive behaviors.

With the May 2013 publication of the fifth edition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM-5), all autism disorders were merged into one umbrella diagnosis of ASD. Before the DSM-5, they were recognized as distinct subtypes, including:

You may also hear the terms “classic autism” or "Kanner's autism" (named after the first psychiatrist to describe autism) used to describe the most severe form of autism.

The DSM is the main diagnostic reference used by mental health professionals and insurance providers in the United States. Under the current DSM-5, the diagnosis of autism requires that:

  • At least six developmental and behavioral characteristics are observed.
  • Problems are present before the age of 3.
  • There is no evidence of certain other conditions that are similar.

Diagnostic criteria

The first two diagnostic criteria for ASD are:

1. Persistent deficits in social communication and interaction across multiple settings, including difficulty (either in the past or in the present) in these three areas:

  • Social-emotional reciprocity
  • Nonverbal communicative behaviors used for social interaction
  • Developing, maintaining and understanding relationships

2. Restricted and repetitive patterns of behavior, interests or activities. A person must show at least two types, including:

  • Stereotyped or repetitive motor movements
  • Insistence on sameness or inflexible adherence to routines
  • Highly restricted, fixated interests
  • Hyper- or hyporeactivity to sensory input or unusual interest in sensory aspects of the environment

Symptoms can be currently present or reported in past history but should have been present early in life.

In addition to the diagnosis, each person evaluated is described in terms of:

If your child is diagnosed with autism, experts recommend they have genetic testing. Some genes linked with autism also carry risks for other health conditions. Knowing these genetic links can help your child’s health care team screen for health problems and treat them quickly.

Social communication disorder (SCD)

The DSM-5 has an additional category called social communication disorder (SCD). This allows for a diagnosis of difficulties in social communication without the presence of repetitive behavior. SCD is a new diagnosis, and much more research and information are needed about this condition. There are currently few guidelines for the treatment of SCD. Until guidelines become available, treatments that target social communication, including many autism-specific interventions, should be provided to people with SCD.

Severity levels of autism

Autism affects everyone differently, and the extent to which it may create challenges in daily life is also different for each person. The DSM-5 also includes new guidelines that break down the diagnosis into three levels based on the amount of support the person might need. A health care provider will look at many factors to choose a severity level. The level is based on communication skills and types of restrictive, repetitive behaviors.

Level One: Requiring Support

For example, a person who uses full sentences but has trouble with a back-and-forth conversation.

Level Two: Requiring Substantial Support

For example, a person who uses short sentences, talks only about a narrow set of their interests, and whose body language or nonverbal communication is not typical.

Level Three: Requiring Very Substantial Support

For example, a person with few or no words who rarely starts a conversation, only engages to meet a need, and/or who uses very unusual approaches to interact with other people.