IQ as a predictor of clinician‐rated mental health problems in children and adolescents

Abstract

Previous studies indicate that low IQ is a substantial risk factor for developing mental health problems. Based on these results, we hypothesized that IQ may predict some of the variance in clinician-rated severity of children's mental health problems measured with the Children's Global Assessment Scale (CGAS) and Health of the Nation Outcome Scales for Children and Adolescents (HoNOSCA). The other aims of this study were to examine if there was any difference in the predictive ability of the different IQ scores of the Wechsler Intelligence Scale for Children, Third edition (WISC-III) and to examine if parent-rated measure of child mental health problems could predict the scores on CGAS and HoNOSCA after controlling for IQ, age, and gender. In this study, 132 patients at three outpatient clinics in North Norway were assessed with the parent version of the Strength and Difficulties Questionnaire (SDQ), HoNOSCA, CGAS, and with the WISC-III. Hierarchical regression analyses were conducted with HoNOSCA and CGAS as dependent variables. Demographics, WISC-III IQ scores, and SDQ were entered as independent variables. The model with HoNOSCA as the dependent variable predicted 25% of the total variance. The WISC-III full-scale IQ predicted an additional 6% of the variance. The analyses with CGAS as the dependent variable gave no significant results. When a patient has a high HoNOSCA score, an intelligence test in addition to an evaluation of symptoms on mental health should be considered. Future research ought to examine whether HoNOSCA's ability to detect change might be affected by patients IQ.