To access the Intelligence Wechsler Scale for Children (WISC-III) as an auxiliary resource in the diagnosis of patients with suspected mental retardation.

Thirty patients were evaluated in a university psychiatric service for children and adolescents, consulted during 2008. Those patients underwent a psychiatric evaluation and, after, subsequently the WISC III scale was administered. Patients were classified, according to their intellectual coefficients, as with or without a mental retardation score, following ICD-10 criteria. The results were transferred to a SPSS (Statistical Package for Social Sciences) spreadsheet and then analyzed in its socio-demographic and clinic variables.

Of the thirty patients, 18 (60%) were children and 12 (40%) adolescents; 22 (73,33%) were male and 8 (26,67%) female. Furthermore, the sample revealed that 20 (68,97%) patients had had an axis I diagnosis. For the participants, 7 (23,3%) had an IQ below the cutoff of 70, consistent with the mental retardation diagnosis, and agreeing with the psychiatric evaluation. The other 23 (76,7%) patients had an IQ within the normal range. From those considered intellectually deficient, 5 (71,43%) had a score for mild and 2 (28,57%) for moderate mental retardation.

This study showed that clinical diagnosis of mental retardation is difficult, especially for mild cases, when the characteristics are not very clear. The error probability is increased if an instrument such as WISC III is not administered. Therefore, WISC III is an important instrument in the diagnostic process for mental retardation, in many instances changing a first clinic impression.