Association of serum brain-derived neurotrophic factor (BDNF) and tumor necrosis factor-alpha (TNF-α) with diagnosis of delirium in oncology inpatients

OBJECTIVE: To evaluate brain-derived neurotrophic factor (BDNF) and tumor necrosis factor-α (TNF-α) blood levels as disease biomarkers of delirium in oncology inpatients. METHODS: Seventeen oncology inpatients with delirium, 28 oncology inpatients without delirium, and 25 non-oncology controls (caregivers) were consecutively recruited from a Brazilian cancer center. This sample was matched by age, sex, and education level. The Confusion Assessment Method, the Mini-Mental State Examination, and the Digit Span Test were administered to ascertain delirium diagnosis. BDNF and TNF-α levels were measured by the Sandwich-ELISA method and flow cytometry, respectively. Blood samples were collected immediately after clinical evaluation. RESULTS: Oncology inpatients (with and without delirium) showed significantly lower BDNF levels compared with non-oncology controls (F = 13.830; p = 0.001). TNF-α levels did not differ between the three groups. CONCLUSION: A cross-sectional relationship of BDNF and TNF-α blood levels with delirium in oncology inpatients was not demonstrated. The association between cancer and reduced serum BDNF levels may be mediated by confounding factors.