Clinical subtypes of delirium in the elderly.

Psychomotor disturbance is common in delirium, with some patients being restless and hyperactive and others lethargic and hypoalert. Although patients with hyperactive delirium may be recognised more readily, hypoactive and mixed forms of delirium are more common on general hospital wards. Recent evidence suggests that hyperactive delirium has a better prognosis than other subtypes. It remains uncertain whether this reflects fundamental differences in the pathophysiology of different subtypes.