Diagnosing autism spectrum disorders in adults: exploring the utility of the ADOS-2 and the ADI-R

Diagnosing autism spectrum disorders (ASD) in adults, particularly those with good cognitive abilities, may represent a challenge for professionals. Clinical diagnoses need to be supported by the use of standardized tools, which have been under-studied in the adult population. The present dissertation aimed to examine the utility of the Autism Diagnostic Observation Schedule-2 (ADOS-2) and the Autism Diagnostic Interview-Revised (ADI-R) - currently considered the “gold standard” instruments - in adults with average or above-average IQ. First, literature published from 1980 to 2016 was systematically reviewed, showing an impressive growth of the use of standardized tools. Second, data regarding the assessment of 140 adults referred to the Laboratorio Autismo of the University of Pavia for diagnosis of ASD were reported. Results showed that accuracy of ADOS-2 in adults is good, while suggested that ADI-R might not be reliable in adults without intellectual disability. Female gender was a negative predictor of agreement between ADOS-2 and clinical diagnosis in the ASD sample. IQ seemed to negatively predict the agreement between ADI-R and DSM-5, while in people with more stereotypes ADI-R better agreed with clinical diagnosis. Finally, some of the most paradigmatic and fascinating cases have been reported in the last chapter. In conclusion, training and experience of professionals remain of primary importance while assessing adults who could potentially belong to the autism spectrum. Women and individuals with higher IQ, in particular, seem to present more camouflaging strategies and less pronounced symptoms. Future research should focus on the improvement of diagnostic tools in order to allow a correct identification of ASD in adults, with the promotion of positive outcomes.