Definitions

Delirium: a syndrome of acute confusion characterized by fluctuations in awareness, cognition, and attention, that fulfills the diagnostic criteria (e.g., DSM-5 or “Confusion assessment method” criteria)

• A pathobiological process in the brain that:

  • Is diffuse (i.e., without an associated structural lesion)

  • Develops rapidly (i.e., within hours to days, but < 4 weeks)

  • Can manifest as delirium, stupor, or coma

• Can be further specified according to the suspected underlying mechanism, e.g., acute toxic-metabolic encephalopathy