What is Autism Spectrum Disorder? Symptoms, Causes, Treatment

DSM-5 autism spectrum disorder definition. Trusted, detailed information on autism spectrum disorder, including symptoms, causes, treatments.

Autism spectrum disorder (ASD) takes on a new meaning in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). The American Psychiatric Association (APA), responsible for developing the new DSM, believes that the changes in diagnostic criteria provide a more accurate and useful way of diagnosing people with autism-related disorders.

Under the old DSM-IV, people could receive one of four separate diagnoses:

  1. autism
  2. Asperger's disorder
  3. childhood disintegrative disorder
  4. pervasive developmental disorder not otherwise specified (PDD-NOS)

According to research, clinicians did not consistently apply these diagnoses in their clinics and treatment programs. The DSM-5 removes these four disorders as separate conditions and places them all under the autism spectrum disorder umbrella.

Even though the four pervasive developmental disorders now appear on the autism spectrum, anyone previously diagnosed with one of them should continue to meet ASD criteria in the DSM-5. (Read about Children with Autism Spectrum Disorder – Learning, Behavior Issues)

What Is Autism Spectrum Disorder?

The term autism spectrum disorder refers to a range of disorders classified as pervasive developmental disorders (PDD) in the DSM-5. The autism spectrum disorder definition was revised to reflect important advances in research since the DSM-IV criteria were published in 1994. Autism represents the core of the autism spectrum disorders. Autism is characterized by "persistent deficits in social communication and social interaction across multiple contexts", according to the Autism Speaks website. Individuals with autism show impairment in the following:

  • Impairment in social and emotional reciprocity that ranges from abnormal social approaches and failure to participate in typical give-and-take conversations to diminished sharing of interests and emotions as well as failure to respond to social cues and interactions.
  • Impairment in use and understanding of nonverbal communications used in social interactions, such as inability to make eye contact and abnormalities in body language. These children also have difficulty understanding the use of physical gestures and often have a complete lack of facial expression.
  • Impairment in developing and maintaining social relationships

Individuals with autism also exhibit restrictive, repetitive patterns of behavior, interests and activities, including:

  • Repetitive motions or repetitive use of objects or speech
  • Inflexible insistence on sameness in routines, exhibit ritualized behavior patterns or nonverbal behavior
  • Restricted, narrow and fixated interests
  • Extreme sensitivity or insensitivity to sensory input from the environment, such as temperature, sounds, and textures

These represent a broad overview of autism spectrum disorder symptoms. The symptoms can range from mild to very severe on the autism spectrum. The severity dictates the type of interventions and treatments the clinician advises.

Asperger's syndrome disorder is closely related to typical autism when it comes to symptoms and probably causes. People with this type of autism, formerly called Asperger's syndrome, don't have a significant delay in language development as they do with more severe forms of autism.

Those with the condition formerly known as childhood disintegrative disorder seem to develop normally and show age-appropriate verbal and non-verbal communication skills as well as appropriate motor, social, and self-care skills. But somewhere between the ages of 2 and 10 years, people with this type of autism lose these skills almost completely in at least two developmental areas.

Children with the form of autism previously called PDD-NOS have severe and pervasive impairment in reciprocal social interaction or verbal and nonverbal communication skills and show other stereotypical behaviors associated with autism, but do not meet criteria for a specific pervasive developmental disorder.

Causes of Autism Spectrum Disorder

Experts don't have a clear understanding about the causes of autism spectrum disorder, but scientists believe that genetics and environment play a significant role. Research studies have identified a number of genes associated with ASD and have found differences in brain structure of people with the disorder. Some studies suggest that individuals with ASD have insufficient levels of the neurotransmitter, serotonin, in the brain. These abnormalities may occur due to disruption of normal brain development during a critical time of fetal development. While these findings are interesting, scientists have a long way to go before they pinpoint exact causes of ASD.

How Is Autism Spectrum Disorder Treated?

While there's no cure for autism spectrum disorder, there are treatments for ASD and interventions available that can alleviate certain symptoms and lead to significant improvement. The clinician will develop a treatment and intervention plan based on the child's individual needs and the severity of the ASD. Treatments and interventions may include:

  • Education and behavior interventions
  • Medications (i.e. to treat anxiety, depression, OCD, and other autism-related symptoms)
  • Other therapeutic interventions

On the Autism Spectrum

Understanding the levels of severity and criteria associated with disorders on the autism spectrum can be daunting. Most individuals who received a diagnosis of one of the pervasive developmental disorders from a clinician using DSM-IV criteria will retain their diagnosis of ASD and still be eligible for interventions and other resources.

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next: Autism Spectrum Disorder Signs, Symptoms, Diagnosis
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Last Updated: 08 August 2016
Reviewed by Harry Croft, MD

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