The increased demand for assessment and treatment of Autism Spectrum Disorders in adults has caused long delays in mental health services. There is currently no diagnostic tool available to assess the urgency of the autistic symptoms, preventing a prioritization in the waiting lists. Promising new instruments are the 80-item Ritvo Autism Asperger Diagnostic Scale-Revised, (RAADS-R)(Ritvo et al., 2010) and abridged forms of the 50-item Autism Spectrum Quotient (AQ-10 and AQ-28).

To determine the ability of the RAADS-R and the abridged versions of the AQ to predict a clinical diagnosis of ASD in an adult outpatient population.

RAADS-R and abridged AQ versions will be completed by 250 normally intelligent adults, sequentially recruited from new referrals for ASD assessment in six outpatient settings in the Netherlands. Assessing clinicians are blind to the RAADS-R and AQ scores. At the end of the study, the clinical diagnosis (ASD or no ASD) will be related to the RAADS-R and AQ-scores collected prior to the assessments

At present 198 adults have been included in the study, as well as 50 normal controls. The average age is 39 years (SD 13.2), and 80% is male. In March 2014 we will be able to present preliminary data on the predictive values of the RAADS-R, the AQ-10 and the AQ-28.

Ritvo, R. A., et al. (2010). The Ritvo Autism Asperger Diagnostic Scale-Revised (RAADS-R): A Scale to Assist the Diagnosis of Autism Spectrum Disorder in Adults: An International Validation Study. J. Autism Dev. Disord.