Purpose To identify the preoperative nonmedical predictors of functional impairment after brain tumor surgery. Methods Patients were evaluated before brain tumor surgery and after 3 months. The cognitive evaluation included MOCA for the general cognitive status, TMT for attention and executive functions, ROWL-IR and ROWL-DR for memory, and the F-A-S for verbal fluency. Anxiety, depression, social support, resilience, personality, disability, and quality of life were evaluated with the following patient-reported outcome measures (PROMs): HADS, OSS-3, RS-14, TIPI, WHODAS-12, and EORTC-QLQ C30. Functional status was measured with KPS . Regression analyses were performed to identify preoperative nonmedical predictors of functional impairment; PROMs and cognitive tests were compared with the normative values. Results A total of 149 patients were enrolled (64 glioma; 85 meningioma). Increasing age, lower education, higher disability, and lower ROWL-DR scores were predictors of functional impairment in glioma patients while higher TMT scores and disability were predictors in meningioma patients. In multiple regression, only a worse performance in TMT remains a predictor in meningioma patients. Cognitive tests were not significantly worse than normative values, while psychosocial functioning was impaired. Conclusion TMT could be used in the preoperative evaluation and as a potential predictor in the research field on outcome predictors. Psychosocial functioning should be studied further and considered in a clinical context to identify who need major support and to plan tailored interventions.