OS06.7.A Underlying mechanisms of verbal fluency in glioma patients: language or executive functioning?

Abstract

Abstract Background Glioma patients often suffer from cognitive deficits, such as in language and executive functioning (EF). A sensitive test to identify these deficits is verbal fluency (VF). In VF, participants are asked to generate as many unique words within a given semantic category (category fluency - CF) or starting with a given letter (letter fluency - LF) within one minute. While both language and EF play a role in VF, the relative contribution of both domains remains unclear. We aim to retrospectively investigate performance on VF and, for the first time, on Non-Verbal Fluency (NVF), requiring to connect 5 points in different patterns within three minutes. Additionally, we aim to explore the influence of language and EF on VF performance in glioma patients. Materials and Methods 69 adults with gliomas in eloquent areas underwent a comprehensive neuropsychological test-battery at 1-2 months before surgery (T1) and 3 (T2) and 12 months (T3) after surgery. The protocol consisted of VF (CF: animals, professions, LF: D-A-T/K-O-M), language tests (Repetition (Akense Afasie Test), Token Test, Boston Naming Test) and EF tests (Five Point Test, Trail Making Test, Stroop Colour-Word Test, Wisconsin Modified Card Sorting Task). VF and NVF performance were compared 1) to healthy population using one sample t-tests/Wilcoxon rank-tests (all patients), and 2) between T1, T2, and T3 with paired sample t-tests/Wilcoxon rank-tests (31 patients). Linear regression analyses were conducted to investigate the predictive value of language and EF on VF for all patients. Results Preoperatively, patients were impaired on all VF tasks. Especially CF profession performance was more prone to deterioration after surgery at T2 and T3. In contrast, NVF was intact and even improved after surgery (T1-T3, T2-T3). NVF (p = .032, EF) was a predictor for CF animals while the Token Test (p = .023, language) was a predictor for CF professions. Both NVF (p = .032, EF) and the Token Test (p = .004, language) were predictors for LF. Conclusion First, glioma patients were preoperatively impaired in VF but were preserved in NVF, as is in line with the literature. Secondly, CF professions appeared to be particularly sensitive to detect long-term postoperative decline. Thirdly, the main result of this study is that both language and EF mechanisms appeared to be responsible for VF performance in glioma patients. These findings are useful for interpreting VF impairment in glioma patients and for therapeutic interventions, suggesting a combination of language and EF training materials.