There are no medical tests for diagnosing autism. An accurate diagnosis must be based on observation of the individual’s communication, behavior, and developmental levels. However, because many of the behaviors associated with autism are shared by other disorders, various medical tests may be ordered to rule out or identify other possible causes of the symptoms being exhibited.

Since the characteristics of the disorder vary so much, ideally a child should be evaluated by a multidisciplinary team which may include a neurologist, psychologist, developmental pediatrician, speech/language therapist, learning consultant, or other professional knowledgeable about autism. Diagnosis is difficult for a practitioner with limited training or exposure to autism. Sometimes, well-meaning professionals have misdiagnosed autism. Difficulties in the recognition and acknowledgment of autism often lead to a lack of services to meet the complex needs of individuals with autism.

A brief observation in a single setting cannot present a true picture of an individual’s abilities and behaviors. Parental (and other caregivers’) input and developmental history are very important components of making an accurate diagnosis. At first glance, some persons with autism may appear to have mental retardation, a behavior disorder, problems with hearing, or even odd and eccentric behavior. To complicate matters further, these conditions can co-occur with autism. However, it is important to distinguish autism from other conditions, since an accurate diagnosis and early identification can provided that basis for building an appropriate and effective educational and treatment program. Sometimes professionals who are not knowledgeable about the needs and opportunities for early intervention in autism do not offer an autism diagnosis even if it is appropriate. The hesitation may be due to a misguided wish to spare the family. Unfortunately, this too can lead to failure to obtain appropriate services for the child.