The Brazilian CARS: a standardized screening tool for autism.

Autism is not a disease. There is no blood test, neuroimaging, or electroencephalography (EEG) test for making or confirming this diagnosis. Autism is a behaviorally-defined syndrome that denotes atypical development of the immature brain and becomes manifest in late infancy, in toddlers, or young preschoolers. To the experienced clinician, classic autism is an obvious diagnosis. But experience and expertise are not measurable and therefore do not suffice when it comes to enrolling children in research studies or convincing a school district to provide expensive specialized educational services, especially to a child who has not yet celebrated his (or her) third birthday. The International Classification of Diseases (ICD-10) and the American Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) were designed to be parallel, with minor differences between them. They specify that pervasive developmental disorders (PDD – autism for short in this paper) affect three behavioral domains: 1) sociability and empathy; 2) communicative language and imagination (pretend play); and 3) cognitive and behavioral flexibility. Symptoms must be apparent by age 3 years, be significantly handicapping and not explained by some other diagnosis, although there are no exclusionary criteria for a diagnosis of PDD/autism. The DSM provides descriptors of four behaviors in each of the three domains and specifies that for a diagnosis of autistic disorder (classic or Kanner’s autism) no less than six of the descriptors must be endorsed, at least two in sociability, and at least one of each in language and play and in rigidity and perseveration. Fewer items, one of which must be sociability, or a different distribution of items yield a diagnosis of Asperger disorder if language developed at the usual age and the intelligence quotient (IQ) is at least 70, or PDD-not otherwise specified (PDD-NOS) for the remainder. We do not discuss here disintegrative disorder, for children who regress after fully normal early language and development, and Rett syndrome, a specific genetic cause of autism.