Criteria for a diagnosis of an autism spectrum disorder
As a rule, autism starts in infancy or no later than the first years of life. First concerns usually come from parents who are alarmed if their child does not use language for the purpose of communication, despite being able to recognize words (Lord et al., 2000).
Although the deficits in communicating and the social reciprocity are not always evident in early years, they are usually the first criteria for the more careful examination and assessment. Also, they become more apparent as a child grows. Therefore, the algorithms that are based on the correlation between the chronological age and operational language level were developed. Those algorithms include such criteria as verbal IQ, non-verbal IQ, patterns and levels of verbal and non-verbal communication, repetitive behaviours, etc. (Risi et al., 2006, p. 1096).
Due to the heterogeneous nature of each case of the spectrum disorders, the diagnosis is made no earlier than when a child is two years old. At that point, the assessment based on the evidence of verbal and non-verbal intelligence and communication deficits can be drafted together to the standard assessment scales, such as the Autism Diagnostic Observation Schedule and Autism Diagnostic Interview-Revised (Lord et al., 2006).
Symptoms that might complicate a diagnosis
In case of autism spectrum disorders the presence of other childhood disorders in a patient often complicates the traditional diagnostic procedure. Autism spectrum disorders may or may not be accompanied by genetic syndromes. Also, they can coexist with non-spectrum diagnoses, which include language disorder, intellectual and learning disabilities (Risi et al., 2006).
The example of the complication of a diagnosis can be a child patient with the learning disability or some of the language disorders, causing failure in verbal intelligence tests that can be misinterpreted as an autism spectrum disorder.
References
Lord, C., Cook, E. H., Leventhal, B. L., & Amaral, D. G. (2000). Autism spectrum disorders. Neuron, 28(2), 355-363.
Lord, C., Risi, S., DiLavore, P. S., Shulman, C., Thurm, A., & Pickles, A. (2006). Autism from 2 to 9 years of age. Archives of general psychiatry,63(6), 694-701.
Risi, S., Lord, C., Gotham, K., Corsello, C., Chrysler, C., Szatmari, P.,… & Pickles, A. (2006). Combining information from multiple sources in the diagnosis of autism spectrum disorders. Journal of the American Academy of Child & Adolescent Psychiatry, 45(9), 1094-1103.