In two studies, delirium in stroke was examined [25, 92] but these studies did not identify differences in cortisol [92] or TNF- α, IL- 1β, IL-18, Brain-derived neurotrophic factor (BDNF) and Neuron specific enolase (NSE) [25] between patients who developed delirium after stroke compared to those who did not develop delirium. The gene discussed is BDNF; the disease is delirium.