DEFINITION

• Delirium is a concurrent disturbance of both consciousness and cognition resulting in changes of attention (and memory, visuospatial and/or executive dysfunction) often accompanied by changes in psychomotor behavior, perception, emotion, and sleep-wake cycle.
• Duration is variable, but onset is usually abrupt over the course of hours to days. Delirium has a fluctuating course, and symptoms range in severity. It can persist for weeks to months, and persistent delirium is typically defined as > 6 months in DSM-5-TR specifier context.
• Delirium is a clinical syndrome indicating underlying pathology. It is not a disease unto itself.
• Delirium is classified under the neurocognitive disorders (NCDs) section of the DSM-5-TR[1].