Our project cannot answer the question as to whether NfL concentrations at admission is simply a marker of vulnerability to delirium and worse clinical outcomes, whether the higher concentrations of NfL is solely related to the severity of the disease that got the patients admitted to the ICU in the first place, or whether delirium/deep sedation itself can cause permanent neuronal damage and worse clinical outcomes. The gene discussed is NEFL; the disease is delirium.