Impaired cognitive functioning in low-grade glioma patients: Relationship to tumour localisation, radiotherapy and the use of anticonvulsants

Objective. To determine the effects of radiotherapy and other medical interventions on cognitive functioning in patients with a low-grade glioma (LGG). Design. Cross-sectional study. Method. A total of 195 LGG patients, of whom 104 had received radiotherapy 1-22 years previously, were compared to 100 patients with a low-grade haematological malignancy and 195 healthy controls. The analysis was aimed at differentiating between the effects of the tumour (disease duration, lateralisation) and treatment effects (neurosurgery, radiotherapy, use of anticonvulsants) on cognitive function and the relative risk of cognitive disability. Results. LGG patients had lower performance levels in all cognitive domains than haematological patients and performed even worse when they were compared to healthy controls. Radiotherapy was associated with poorer cognitive functioning; however, cognitive disability was found only in patients receiving fractional doses exceeding 2 Gy. The use of anticonvulsants was strongly associated with disorders in the area of attention and planning functions. Conclusion. In this study, the tumour itself was the most damaging factor with respect to cognitive function and radiotherapy was associated with cognitive disability only if elevated fractional doses were used. Epilepsy or the use of anticonvulsants was also associated with diminished cognitive functioning.