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Delirium (PDQ®)

Patient Version
Last Modified: 12/12/2013

Diagnosing Delirium



Possible signs of delirium include sudden personality changes, problems thinking, and unusual anxiety or depression.

When the following symptoms occur suddenly, they may be signs of delirium:

  • Agitation.
  • Not cooperating.
  • Changes in personality or behavior.
  • Problems thinking.
  • Problems paying attention.
  • Unusual anxiety or depression.

The symptoms of delirium are a lot like symptoms of depression and dementia.

Early symptoms of delirium are like symptoms of depression and dementia. Delirium that causes the patient to be inactive may appear to be depression. Delirium and dementia both cause problems with memory, thinking, and judgment. Dementia may be caused by a number of medical conditions, including Alzheimer disease. Differences in the symptoms of delirium and dementia include the following:

  • Patients with delirium often show changes in how alert or aware they are. Patients who have dementia usually stay alert and aware until the dementia becomes very advanced.
  • Delirium occurs suddenly (within hours or days). Dementia appears gradually (over months to years) and gets worse over time.

Older patients with cancer may have both dementia and delirium. This can make it hard for the doctor to diagnose the problem. If treatment for delirium is given and the symptoms continue, then the diagnosis is more likely dementia. Checking the patient's health and symptoms over time can help diagnose delirium and dementia.

Physical exams and other laboratory tests are used to diagnose the causes of delirium.

Doctors will try to find the causes of delirium.

  • Physical exam and history : An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient's health habits, past illnesses including depression, and treatments will also be taken. A physical exam can help rule out a physical condition that may be causing symptoms.

  • Laboratory tests : Medical procedures that test samples of tissue, blood, urine, or other substances in the body. These tests help to diagnose disease, plan and check treatment, or monitor the disease over time.