Delirium and confusional states are among the most common mental disorders encountered in patients with medical illness, particularly among those who are older. They are associated with many complex underlying medical conditions and can be hard to recognize. Systematic studies and clinical trials are difficult to perform in patients with cognitive impairment.
Definition and Terminology: The American Psychiatric Association’s Diagnostic and Statistical Manual, 5th edition (DSM-V) lists five key features that characterize delirium:
1) Disturbance in attention (reduced ability to direct, focus, sustain, and shift attention) and awareness.
2) The disturbance develops over a short period of time (usually hours to days), represents a change from baseline, and tends to fluctuate during the course of the day.
3) An additional disturbance in cognition (memory deficit, disorientation, language, visuospatial ability, or perception)
4) The disturbances are not better explained by another preexisting, evolving or established neurocognitive disorder, and do not occur in the context of a severely reduced level of arousal, such as coma
5) There is evidence from the history, physical examination, or laboratory findings that the disturbance is caused by a medical condition, substance intoxication or withdrawal, or medication side effect.
Additional features that may accompany delirium and confusion include the following:
● Psychomotor behavioral disturbances such as hypoactivity, hyperactivity with increased sympathetic activity, and impairment in sleep duration and architecture.
● Variable emotional disturbances, including fear, depression, euphoria, or perplexity.