There are no medical tests for diagnosing autism. An accurate diagnosis must be based on observations of the child’s communication, behavior and developmental levels. However, because many of the behaviors associated with autism are shared by other disorders, a doctor may complete various medical tests to rule out other possible causes.
Diagnosis is difficult for a practitioner with limited training or exposure to autism, since the characteristics of the disorder vary so much. Locating a medical specialist or a diagnostician who has experience with autism is most important. 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 professionals knowledgeable about autism. Several diagnostic tools have been developed over the past few years to help professionals make an accurate autism diagnosis: CHAT (Checklist for Autism in Toddlers), CARS (Childhood Autism Rating Scale), PIA (Parent Interviews for Autism), GARS (Gilliam Autism Rating Scale) and BRIAC (Behavior Rating Instrument for Autistic and other Atypical Children).
A brief observation in a single setting cannot present a true picture of an individual’s abilities and behaviors. At first glance, the person with autism may appear to have mental retardation, a behavior disorder, or even problems with hearing. However, it is important also to distinguish autism from other conditions, since an accurate diagnosis can provide the basis for building an appropriate and effective educational and treatment program.
(Autism Society of America)