Cognitive deficits in long-term survivors of childhood brain tumors: Identification of predictive factors

BACKGROUND: To describe cognitive function and to evaluate the association between potentially predictive factors and cognitive outcome in an unselected population of survivors of childhood brain tumors. PROCEDURE: We studied a consecutive sample of 133 patients (76 had received radiotherapy (RT)) who had a brain tumor diagnosed before the age of 15 years and were treated during the period January 1970 through February 1997 in the Eastern part of Denmark. Biologic effective dose of irradiation (BED) was assessed in 71 patients. One hundred twenty-seven patients were able to cooperate to WISC-R and WAIS-R. Multiple regression models were constructed to evaluate relationships between possible risk factors and cognitive outcome. RESULTS AND CONCLUSIONS: The mean intelligence (IQ) scores were substantially lower than the expected means of the general population. Younger age at diagnosis, tumor site in cerebral hemisphere, hydrocephalus treated with shunt, and treatment with RT were found to be significant predictors of lower cognitive functions. RT was the most important risk factor for impaired intellectual outcome. The mean observed full scale IQ was 97.1 (SD = 14.3) for the non-irradiated patients and 78.8 (SD = 14.3) for the irradiated patients (adjusted P < 0.001). Verbal IQ, but not performance and full scale IQ, had a significant negative correlation to BED to the tumor site (P < 0.05). These results can be used to identify subgroups of children who are at increased risk for cognitive deficits allowing early and goal-directed intervention.