To examine the difference between early-onset (< age 3) childhood disintegrative disorder (CDD) and autistic disorder with speech loss (ADSL), 8 children with early-onset CDD (mean age = 7.6 years, SD = 3.8; 6 males) were compared with 92 age and gender-ratio comparable children with ADSL (mean age = 6.8 years, SD = 4.1; 70 males) on 24 variables not directly related to the key features of CDD (regression after normal development for at least the first 2 years after birth). Compared with the ADSL group, the early-onset CDD group had a tendency to have a higher rate of a psychosocial event before speech loss (SL) (early-onset CDD, 75.0% vs ADSL, 37.0%, p = 0.057; effect size (phi) = 0.211, p < 0.05); a significantly higher rate of fearfulness during SL (62.5% vs 4.3%, p = 0.000; phi = 0.551, p < 0.05); and a tendency to have a higher rate of epilepsy (25.0% vs 3.3%, p = 0.050; phi = 0.271, p < 0.05), a tendency to have a lower rate of the Childhood Autism Rating Scale-Tokyo Version (CARS-TV) total score ≥ 30 (75.0% vs 95.7%, p = 0.072; phi = 0.236, p < 0.05), and a significantly lower rate of CARS-TV item 2 (imitation) score ≥ 2 (50.0% vs 82.6%, p = 0.049; phi = 0.221, p < 0.05) on the first visit. The two groups did not exhibit any significant difference in the other 19 variables. The findings of no significant difference in the great majority and a significant difference in the small minority of the 24 variables between the two groups support integrating CDD into regressive autism spectrum disorder and studying CDD as its prototypical form.

Aim: To test the reliability and validity of the Pervasive Developmental Disorders Assessment System (PDDAS), a Japanese semistructured interview system. Methods:The PDDAS, consisting of 91 items including 12 major items corresponding to 12 items in criterion A of DSM-IV autistic disorder criteria, 36 items on autistic symptoms and three Asperger's disorder (AS) screening items for diagnosing pervasive developmental disorders (PDD) and their subtypes and 40 items for other information including early development and past/family histories, was administered to mothers of 77 PDD children and 64 non-PDD children. Results:The PDDAS had satisfactory interrater reliability (ranges of k, r and raw agreement rate were 0.69-1.00 in 76 items, 1.00 in 11 items and 0.91-1.00 in four k un-calculable items, respectively). Thirty-three of the 36 items and all of the 12 major items scored significantly higher in the PDD than non-PDD groups to show satisfactory discriminant validity. PDDAS and consensus DSM-IV diagnoses agreed in the 77 children in PDD diagnosis and disagreed in only two children in subtype diagnoses of autistic disorder and PDD not otherwise specified. Conclusions:The PDDAS, which takes 1.5 h to administer, seems to have clinical and research utility, although further investigation is necessary.