Brain-derived neurotrophic factor and neuron-specific enolase, but not S100β, levels are associated to the occurrence of delirium in intensive care unit patients

Purpose: The aim of this study was to determine the association between serum concentrations of brain-derived neurotrophic factor (BDNF), neuron-specific enolase (NSE), and S100 beta and the occurrence of delirium in critically ill patients. Material and Methods: This case-control study included 30 patients with delirium and 30 matched controls in a 16-bed general intensive care unit (ICU). Serum BDNF, NSE, and S100 concentrations were determined by enzyme-linked immunosorbent assay assays at the time of ICU admission and on the day before delirium was diagnosed. Delirium was diagnosed by confusion assessment method for the ICU. Results: At ICU admission, serum BDNF levels were significantly higher in delirious patients than in nondelirious controls (2.89 +/- 1.48 vs 1.79 +/- 0.89 ng/mL, respectively). When we compared serum S100 levels, there were no significant differences between the groups. Neuron-specific enolase values were significantly higher in the delirious patients than in the nondelirious controls (0.79 +/- 0.03 ng/mL vs 0.59 +/- 0.01 ng/mL, respectively). When patients who earlier developed delirium were separately analyzed, it was determined that serum NSE and BDNF levels at admission were significant higher only in this group. Conclusions: Our results suggest that admission serum BDNF and NSE levels are associated with the occurrence of delirium in ICU patients. (C) 2011 Elsevier Inc. All rights reserved.