Cognitive functions in low-grade gliomas: disease and treatment effects

Background The role of radiotherapy and chemotherapy in the treatment of low-grade gliomas (LGG) is controversial regarding their effect on survival and the development of neurotoxicity. The few published studies examining adverse treatment effects on cognition revealed conflicting results. Objective To assess cognitive functioning in LGG patients who received conformal radiation therapy (RT), chemotherapy, or no treatment. Design 40 LGG patients participated in the study; 16 patients had RT +/- chemotherapy, and 24 patients had no treatment. All patients underwent a neuropsychological evaluation. APOE genotype was obtained in 36 patients who were classified in two groups based on the presence or absence of at least one apolipoprotein E epsilon-4 (APOE epsilon-4) allele. Results Treated LGG patients had lower scores than untreated patients on several cognitive domains; patients who completed treatment at intervals greater than 3 years and had long disease duration had significantly lower scores on the Non-Verbal Memory domain. Antiepileptic polytherapy, treatment history, and disease duration jointly contributed to low Psychomotor domain scores. 62% of treated patients showed white matter confluence on MRI, whereas only 9% of the untreated patients had such changes. Preliminary comparisons between APOE epsilon-4 carriers (n = 9) and non-carriers (n = 27) on cognitive domain scores revealed no statistically significant differences, but APOE epsilon-4 carriers had lower mean scores on the Verbal Memory domain than did non-epsilon carriers. Conclusions RT +/- chemotherapy, disease duration, and antiepileptic treatment contributed to mild cognitive difficulties in LGG patients.