WISC-III profiles of subjects with high-functioning pervasive developmental disorders who visited child and adolescent psychiatry clinics at a university hospital

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THE THIRD EDITION of the Wechsler Intelligence Scale for Children (WISC-III) is commonly used clinically, especially for the diagnosis of pervasive developmental disorders (PDD). However, the usefulness of WISC-III for this purpose remains controversial.1 We examined WISC results in cases of high-functioning PDD (HFPDD).

The subjects were 27 consecutive individuals (male/female = 16/11) who visited the Psych-Developmental Clinic at Sapporo Medical University Hospital and met the following inclusion criteria: (i) they were primary/junior high school students; (ii) they underwent the Japanese version of WISC-III; (iii) they were diagnosed with PDD based on DSM-IV-TR; and (iv) their full-scale IQ (FSIQ) was 85 or higher. Four had autistic disorder, nine had Asperger's disorder, and the remainder had PDD–not otherwise specified (PDD–NOS). Most visited our clinic complaining of school refusal/absenteeism. Comparisons were made by gender. Informed written consent was obtained.

Mean FSIQ score was 106.3 ± 10.7 (verbal IQ 107.6 ± 15.7/performance IQ 103.3 ± 13.2) for boys (11.6 ± 2.8y) and 106.7 ± 5.6 (verbal IQ 110.5 ± 7.9/ performance IQ 101.5 ± 6.9) for girls (12.0 ± 2.4y). By subtest, boys scored higher for Information (M/F = 11.1 ± 3.0/10.6 ± 2.2), Arithmetic (11.4 ± 3.4/10.5 ± 2.4), Digit Span (10.7 ± 3.5/9.2 ± 3.5), Block Design (12.3 ± 3.0/10.9 ± 2.3), Object Assembly (10.1 ± 3.5/9.9 ± 2.7), and Symbol Search (11.6 ± 2.7/10.3 ± 2.6), while girls scored higher for Similarities (10.7 ± 3.6/12.1 ± 2.1), Vocabulary (11.1 ± 3.5/11.5 ± 2.4), Comprehension (10.8 ± 3.3/12.0 ± 3.0), Picture Completion (9.4 ± 2.7/9.6 ± 2.2), Coding (10.6 ± 4.0/12.0 ± 3.6), and Mazes (9.4 ± 3.8/11.3 ± 2.9). Only on Picture Arrangement was a significant difference observed (10.2 ± 2.6/8.0 ± 2.4; P = 0.036, t-test).

Recent studies report that PDD is increasing and that almost half of the cases are the NOS subtype.2 Correspondingly, HFPDD remains underdiagnosed until the development of secondary psychological problems that attract medical attention.

Among WISC-III subtests in HFPDD, previous studies demonstrated that boys scored higher on Block Design while girls scored higher on Coding and Symbol Search.3 We found a significant difference for Picture Arrangement only. This task entails arranging pictures to tell a story, and could reflect social competence.4 Our clinic has a relatively high number of patients with school refusal/absenteeism. Our sample included a higher proportion of girls than is representative of PDD overall. These findings might be due to isolation from female groups that characteristically form at school in adolescence, and impairment of social interaction, one of the triads of PDD, would contribute to such a situation.

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