The diagnosis of AS is complicated by the lack of a standardized diagnostic screen or schedule. In fact, because there are several screening instruments in current use, each with different criteria, the same child could receive different diagnoses, depending on the screening tool the doctor uses.
To further complicate the issue, some doctors believe that AS is not a separate and distinct disorder. Instead, they call it high-functioning autism (HFA), and view it as being on the mild end of the ASD spectrum with symptoms that differ — only in degree — from classic autism. Some clinicians use the two diagnoses, AS or HFA, interchangeably. This makes gathering data about the incidence of AS difficult, since some children will be diagnosed with HFA instead of AS, and vice versa.
Most doctors rely on the presence of a core group of behaviors to alert them to the possibility of a diagnosis of AS. These are:
abnormal eye contact
the failure to turn when called by name
the failure to use gestures to point or show
a lack of interactive play
a lack of interest in peers
Some of these behaviors may be apparent in the first few months of a child’s life, or they may appear later. Problems in at least one of the areas of communication and socialization or repetitive, restricted behavior must be present before the age of 3.
The diagnosis of AS is a two-stage process. The first stage begins with developmental screening during a “well-child” check-up with a family doctor or pediatrician. The second stage is a comprehensive team evaluation to either rule in or rule out AS. This team generally includes a psychologist, neurologist, psychiatrist, speech therapist, and additional professionals who have expertise in diagnosing children with AS.
The comprehensive evaluation includes neurologic and genetic assessment, with in-depth cognitive and language testing to establish IQ and evaluate psychomotor function, verbal and non-verbal strengths and weaknesses, style of learning, and independent living skills. An assessment of communication strengths and weaknesses includes evaluating non-verbal forms of communication (gaze and gestures); the use of non-literal language (metaphor, irony, absurdities, and humor); patterns of inflection, stress and volume modulation; pragmatics (turn-taking and sensitivity to verbal cues); and the content, clarity, and coherence of conversation. The physician will look at the testing results and combine them with the child’s developmental history and current symptoms to make a diagnosis.