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Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in communication and social interactions, occurring with restricted patterns of behavior or interest.1 The ASD diagnosis focuses on the presentation of these behaviors and includes both identifying deficits and restrictions and determining their severity, which may range from mild to severe. Signs of ASD typically manifest within the first 2 years of life, but diagnosis may be delayed until a later age, especially with mild symptoms.

General Considerations

In 2013, the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) combined the diagnoses of autistic disorder, Asperger syndrome, and pervasive developmental disorder not otherwise specified under a single diagnosis of ASD.1

Since its introduction, there has been an increase in diagnosis of ASD, likely due to greater public awareness of the disorder and recent diagnostic changes. In 2021, the Centers for Disease Control and Prevention’s Autism and Developmental Disabilities Monitoring Network reported the prevalence of ASD in US children aged 8 years old to be around 1 in 44.2 The World Health Organization estimates global prevalence of ASD to be on average about 1 in 160 children.3 ASD is seen in all racial, ethnic, and socioeconomic levels and is seen more commonly in males compared to females (4:1).

Clinical Findings

ASD symptoms and behaviors are often first observed and noted by parents and family members. Most often, the deficits become clear by the time a child is 2 to 3 years old, and sometimes earlier. Some children with autism present with a regression in their abilities around this age. It is important for physicians to listen to parents’ observations and perceptions regarding the child’s development and to ask questions that can help identify potential delays.

Deficits in social communication and interaction may present through:

  • Poor eye contact

  • Lack of joint attention (eg, not pointing at objects of interest)

  • Abnormal prosody of speech

  • Regression of language

  • Not responding to their names

  • Preference to play by themselves

Restricted patterns of behavior and/or interest may present as follows:

  • Not playing with toys appropriately (eg, always lining toy cars up in a certain order instead of pushing them around)

  • Exhibiting an obsessive interest in a specific topic or object (eg, fascination with trains or certain cartoon characters)

  • Showing a preference for looking at letters, shapes, or other objects

Physical behaviors will frequently have stereotypies, including:

  • Hand flapping

  • Rocking

  • Looking out of the corners of the eyes

  • Other consistent repetitive movements

  • Self-injurious behaviors, such as head banging

Diagnosis and Testing

The American Psychiatric Association’s DSM-51 provides diagnostic criteria widely accepted as the standard for ASD diagnosis. Per the DSM-5, an ...

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