ABSTRACT
Delirium, a neurobehavioral syndrome, is characterized by fluctuating attention and rapid changes in cognition occurring over a short period of time. This chapter reviews the disorder, which is common in hospitalized older adults (age 65+) and is closely linked with the most prevalent diseases and complications in this population. Delirium is often the first clinical manifestation of critical illness in this age group. We provide the definition of delirium and its prevalence and discuss conceptual issues, including the major theories of its pathogenesis, the evolution of delirium over time, and risk factors. We then describe the assessment of delirium, including medical/psychological approaches and controversies. Finally, we propose means of prevention and management of delirium. A special note is also included addressing delirium in the context of the COVID-19 pandemic.
