© Congress of Neurological Surgeons 2020.BACKGROUND: Pre- and postoperative cognitive deficits have repeatedly been demonstrated in patients with glioblastoma (GBM). OBJECTIVE: To identify presurgical risk factors that facilitate the identification of GBM patients at risk for postoperative cognitive impairment. METHODS: Patients underwent neuropsychological assessment using Central Nervous System Vital Signs 1 d before (T0) and 3 mo after surgery (T3). Patients' standardized scores on 7 cognitive domains were compared to a normative sample using one-sample z tests. Reliable change indices with correction for practice effects were calculated to assess cognitive changes in individual patients over time. Logistic regression models were performed to assess presurgical sociodemographic, clinical, psychological, and cognitive risk factors for postoperative cognitive impairments. RESULTS: At T0, 208 patients were assessed, and 136 patients were retested at T3. Patients showed significantly lower performance both prior to and 3 mo after surgery on all cognitive domains compared to healthy controls. Improvements and declines over time occurred respectively in 11% to 32% and 6% to 26% of the GBM patients over the domains. The regression models showed that low preoperative cognitive performance posits a significant risk factor for postoperative cognitive impairment on all domains, and female sex was a risk factor for postoperative impairments in Visual Memory. CONCLUSION: We demonstrated preoperative cognitive risk factors that enable the identification of GBM patients who are at risk for cognitive impairment 3 mo after surgery. This information can help to inform patients and clinicians at an early stage, and emphasizes the importance of recognizing, assessing, and actively dealing with cognitive functioning in the clinical management of GBM patients.