HOME             CRITERIA FOR A DIAGNOSIS OF AUTISM           TREATMENTS        AUTISM/PDD  

Much has been said recently, both in the scientific literature and in the popular press, about whether or not there has been an increase in the incidence of autism. It is important to remember two things when considering the evidence for or against this claim: first, governments do not routinely collect data on autism, and second, there is no laboratory, genetic, or neurological test for autism. All diagnoses of autism rely on subjective measures (e.g. opinions or rating systems of behaviors). Different academic backgrounds or degrees of clinical or personal experience often result in children receiving different diagnoses from different professionals. 

Complicating this problem further is the explosion of information from the neurosciences over the last decade about how brains interpret sensory information, learn, and develop.  Never before have we been able to not only understand how abnormal sensory experiences affect the developing brain, learning, behavior and language.  Professional who are inexperienced or uninformed about these advances may give a diagnosis of "autism," "attention deficit" or "psychosis" to children whose behaviors or deficits are caused by an auditory or vestibular processing disorder. 

While it is true that several standardized measures exist to aid professionals in the diagnoses of autism, there is no universally accepted measure and all of the measures depend upon subjective judgments of how "abnormal" a particular behavior is considered.  To complicate matters further, these measures are based upon definitions and criteria and ideas that were proposed over 60 years ago by Kanner and Asperger, well before scientists knew much about either the developing brain or sensory processing problems.  Finally, the measures used to determine the presence or absence of autism vary between countries as well as between researchers within a single city.

Because of these difficulties, the reader should regard the following statistics with a certain level of healthy skepticism. They are only a broad and rough estimate of the incidence of autism; rates between areas will vary naturally due to differences in assessment measures, techniques, cultural attitudes, and the professional skills of the individuals who gave the diagnoses in each study.