When parents or support providers become concerned that their child is not following a typical developmental course, they turn to experts, including psychologists, educators and medical professionals, for a diagnosis.

At first glance, some people with autism may appear to have an intellectual disability, sensory processing issues, or problems with hearing or vision. To complicate matters further, these conditions can co-occur with autism. However, it is important to distinguish autism from other conditions, as an accurate and early autism diagnosis can provide the basis for an appropriate educational and treatment program.

Other medical conditions or syndromes, such as sensory processing disorder, can present symptoms that are confusingly similar to autism’s. This is known as differential diagnosis.

There are many differences between a medical diagnosis and an educational determination, or school evaluation, of a disability. A medical diagnosis is made by a physician based on an assessment of symptoms and diagnostic tests. A medical diagnosis of autism spectrum disorder, for instance, is most frequently made by a physician according to the Diagnostic and Statistical Manual (DSM-5, released 2013) of the American Psychological Association. This manual guides physicians in diagnosing autism spectrum disorder according to a specific number of symptoms.

A brief observation in a single setting cannot present a true picture of someone’s abilities and behaviors. The person’s developmental history and input from parents, caregivers and/or teachers are important components of an accurate diagnosis.

An educational determination is made by a multidisciplinary evaluation team of various school professionals. The evaluation results are reviewed by a team of qualified professionals and the parents to determine whether a student qualifies for special education and related services under the Individuals with Disabilities Education Act (IDEA) (Hawkins, 2009).