A Japanese version of the Autism Spectrum Quotient (AQ), AQ-J was administered to 25 normally intelligent high-functioning pervasive developmental disorder (HPDD) patients (mean age, 24.2 years; 24 male, one female) and 215 controls (mean age, 30.4 years; 86 male, 129 female) randomly selected from the general population. The AQ-J had satisfactory internal consistency reliability (Cronbach's a> 0.70 in the two groups), test-retest reliability, and discriminant validity [i.e. the AQ-J score was significantly higher in the HPDD (mean, 29.6) than controls (mean, 22.2)]. At a cut-off of 26, the AQ-J had satisfactory sensitivity, specificity, and negative predictive value, but it had low positive predictive value (0.24) possibly due to the facts that the 25 mild HPDD patients scored lower and the controls scored higher on the AQ-J than British counterparts on the AQ. The AQ-J-21 (consisting of 21 items significantly associated with HPDD diagnosis) and the AQ-J-10 (consisting of 10 of the 21 items with an effect size >0.17) had higher, although not satisfactory, positive predictive values of 0.35 and 0.46 at cut-offs of 12 and 7, respectively, than the AQ-J. The AQ-J and two short forms are useful not to predict but to rule out mild HPDD, the most difficult part of HPDD to be distinguished from non-PDD conditions, in persons scoring under the cut-offs and to consider professionals' examination of HPDD in persons scoring over them, because their negative predictive values were satisfactory.

Quantitative autistic traits ascertained in a national survey of 22 529 Japanese schoolchildren.Objective: Recent epidemiologic studies worldwide have documented a rise in prevalence rates for autism spectrum disorders (ASD). Broadening of diagnostic criteria for ASD may be a major contributor to the rise in prevalence, particularly if superimposed on an underlying continuous distribution of autistic traits. This study sought to determine the nature of the population distribution of autistic traits using a quantitative trait measure in a large national population sample of children. Method: The Japanese version of the Social Responsiveness Scale (SRS) was completed by parents on a nationally representative sample of 22 529 children, age 6-15. Results: Social Responsiveness Scale scores exhibited a skewed normal distribution in the Japanese population with a single-factor structure and no significant relation to IQ within the normal intellectual range. There was no evidence of a natural 'cutoff' that would differentiate populations of categorically affected children from unaffected children. Conclusion: This study provides evidence of the continuous nature of autistic symptoms measured by the SRS, a validated quantitative trait measure. The findings reveal how paradigms for diagnosis that rest on arbitrarily imposed categorical cutoffs can result in substantial variation in prevalence estimation, especially when measurements used for case assignment are not standardized for a given population. Significant outcomes• In a large Japanese child population, behaviorally measured autistic traits are continuously distributed without any apparent deflection in the distribution plot that would signal a natural cutoff for categorical diagnoses. This is similar to the distribution pattern in US and European samples.• Autistic traits measured quantitatively by parents differ slightly by culture, suggesting the need to interpret autism spectrum disorder (ASD) severity ratings with the use of culturally calibrated norms.• Many children who do not meet the diagnosis of ASD exhibit elevations in autistic traits measured quantitatively, suggesting the need to reconsider current diagnostic systems that assume discontinuity between affected and unaffected populations. Limitations• The response rate of this nationwide survey was 29%.• There is a possibility of bias that would differentiate respondents vs. non-respondents.• High-scoring children in the sample as a whole were not confirmed using diagnostic instruments, although quantitatively measured autistic traits were extensively clinically confirmed for a separate smaller sample.

The psychosocial outcomes of individuals with high-functioning autism spectrum disorder (HFASD) appear to be diverse and are often poor relative to their intellectual or language level. To identify predictive variables that are potentially ameliorable by therapeutic intervention, this study investigated self-reported psychosocial quality of life and associated factors for adults with HFASD. All participants (n = 154) had a diagnosis of autism spectrum disorder, were over 18 years of age, lived in the community, and had used one or more support services during the survey period. The results demonstrated that psychosocial quality of life was lower than that of the general Japanese adult population. Environmental factors, such as mother's support and early diagnosis, were associated with better quality of life, and aggressive behaviors were associated with poorer quality of life, while expressive language level at preschool years, a conventional outcome predictor, did not predict quality of life. These results emphasize that quality of life measures should be included as outcome indicators in treating individuals with HFASD.

Based on the clinical records of 74 children with pervasive developmental disorders (PDD; mean age, 45.2 months; 62 boys), the utility of the Kyoto Scale of Psychological Development in cognitive assessment of young and/or mentally retarded PDD children was investigated. Because the overall developmental quotient (DQ) had the highest correlation with the IQ (Pearson's r, 0.88) and the CognitiveAdaptive DQ showed a non-significant difference in mean (65.8) from the IQ (66.4), they both seem useful as an equivalent to an IQ. The test would enable clinicians to carry out continual developmental assessments and to develop appropriate remedial programs for those children from infancy.