Validating a Japanese Version of the Ritvo Autism and Asperger's Diagnostic Scale

Background: Diagnosing Autism and Asperger’s disorder among adults has been a concern in clinical settings.  We reported potential efficacy and limitation of a preliminary Japanese version of the Ritvo Autism and Asperger’s Diagnostic Scale (RAADS, Ritvo et al., 2007) in IMFAR 2008.  Although internal consistency of the Japanese version of the RAADS (RAADS-J) was confirmed, there were not statistically significant differences between 6 Autism Spectrum Disorders (ASD) and 49 control participants in 45 out of 80 items, including 21 items that have successfully discriminated ASD from non-ASD individuals in the previous report.  Taking these limitations into account, the Japanese translation needs to be revised, since literal translation of some social expressions, such as “I’ve got you under my skin,” might have compromised comprehensibility of the items.

Objectives: We revised the Japanese version of the RAADS, and tested the reliability and validity of the scale.

Methods: The preliminary version of the RAADS-J was revised so that people aged 18 and over can understand the meaning without confusing or difficulties, with thorough considerations on cultural perspectives of the Japanese social and colloquial expressions.  It was distributed to a hundred individuals with ASD, who participated in the public event aiming for networking of adults with ASD in which one of the authors (MT) attended as an instructor.  Fifty volunteers of students from two Universities were also recruited as control.  In addition, 60 in-patients with three different psychiatric disorders (i.e., schizophrenia, major depression, and anxiety disorders) in the hospital affiliated to Hamamatsu University School of Medicine voluntarily participated in the study.  All participants were asked for completion of the revised RAADS-J twice to check test-retest reliability as well as Autism–Spectrum Quotient Japanese version (AQ-J) to test the criterion-related validity.

Results: With the revised version of the RAADS-J, we successfully discriminate adults with ASD from non-ASD adults, as well as from adults with other psychiatric disorders.

Conclusions: Same as the original RAADS, the RAADS-J is also useful as a clinical scale to assist identification of Autism and Asperger's Disorder in adults.