Cognitive Functioning of Low-Grade Glioma Patients with and Without Adjuvant Treatment Before and One Year After Tumor Resection

Background/Objectives: For low-grade glioma (LGG) patients, adjuvant treatment (AT) with radiotherapy and chemotherapy may adversely impact cognition. However, existing evidence is limited by methodological heterogeneity and shortcomings. This study explored the cognitive functioning of LGG patients who underwent resection with both radiotherapy and chemotherapy (AT+) or without AT (AT−), from before resection to one year after resection. Methods: We included patients with World Health Organization 2021 grade 2 isocitrate dehydrogenase-mutated glioma who underwent resection between 2011 and 2024. All patients completed a neuropsychological screening battery one week before (T0) and twelve months after resection (T12), measuring reaction time, attention span, information processing speed, working memory, inhibition, cognitive flexibility, and verbal fluency. We compared cognitive performance between AT+ and AT− patients at T0 and T12, as well as trajectories of cognitive functioning, at the group and individual level. Results: We included 60 LGG patients (M age = 38.8 years; 63.3% male). Compared to AT− patients (n = 35), AT+ patients (n = 25) were significantly older, more frequently had tumors that crossed the midline, and reported more depressive symptoms. At T0, no significant cognitive performance differences existed between AT+ and AT− patients, despite lower observed performance in the AT+ group. At T12, AT+ patients performed significantly worse than AT− patients on mean information processing speed, due to an improvement over time in the AT− group. Conclusions: Patients allocated to AT may show limited cognitive recovery of information processing speed up to 12 months after surgery, without pronounced effects on other cognitive functions. These findings can guide future studies into treatment-related cognitive decline of LGG patients.