Many of us have witnessed family or friends who become quite confused or agitated when in the hospital. This can be disquieting, as patients may be medicated—even restrained. This confusion and agitation could be the result of delirium.

Delirium is defined as an acute confusional state with decreased attention. It is common where patients are not used to their surroundings: almost a quarter of patients admitted to Internal Medicine and up to 80 per cent of critically ill patients in the ICU experience it. Hospital environments may be a cause because of frequent room changes, invasive procedures, loud noises, poor lighting and a lack of natural light. And delirium is serious—it is associated with worse outcomes for patients who experience it. Unlike dementia, it develops rapidly. The doctor's job is first to recognize that this is delirium and not dementia, psychosis or depression.

Then the cause needs to be determined so the condition can be reversed.

Delirium can also be the result of a medical issue, such as infection, metabolic abnormality or medications. Predisposing factors include age, visual or hearing impairment, pre-existing illness (heart disease, brain disease, cancer), alcohol or drug dependence, dehydration, malnutrition, psychiatric disease and pre-existing cognitive impairment. Precipitants of delirium include metabolic causes (such as malnutrition, dehydration, anemia, hypoglycemia (low glucose in the blood), infections, medications (especially steroids, medication combinations, antihistamines), vascular (heart attack, stroke), pain, psychological stress, intoxication or withdrawal from drugs and head injury.

Better than treating is preventing delirium, and many centres have adopted policies to minimize the risk factors. Evidence indicates that promoting good sleep habits, helping the person remain calm and well-oriented and helping prevent medical problems or other complications can help prevent or reduce the severity of delirium.

Dr. Zachary Levine is an assistant professor in the faculty of medicine at McGill University Health Centre and medical correspondent for AM740 (a ZoomerMedia property).

A version of this article appeared in the May 2017 issue with the headline, "Not to be Confused with Dementia," p. 60.

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