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Changes in Behavior


A change in how a person acts is called altered behavior. A change may include:

  • Confusion.
  • Disorientation to time and place.
  • Unusually aggressive or combative behavior.
  • Lethargy, unexplained sleepiness, or the inability to arouse a person from sleep.

Altered behavior can be caused by conditions or substances that may affect the brain, such as:

  • Prescription and nonprescription medicine.
  • Drug and alcohol abuse or withdrawal.
  • Electrolyte imbalances.
  • Exposure to toxins, such as carbon monoxide, arsenic, or lead.
  • Lack of oxygen to the brain.
  • Head injury.
  • Seizure.
  • Abnormally high blood sugar (hyperglycemia) or abnormally low blood sugar (hypoglycemia).
  • Infection, especially in older adults.
  • Mental health problems, such as anxiety disorders, depression, or psychosis.
  • Blockages in the blood vessels in the brain, such as in a stroke .
  • Bleeding in the brain from a head injury or stroke.
  • Destruction of brain tissue by a tumor.
  • Pressure on brain tissue by a tumor or swelling.

Changes in behavior may be sudden, such as those caused by a stroke or head injury. Or they may be gradual, such as those caused by a tumor or swelling in the brain.


By Healthwise Staff
Primary Medical Reviewer William H. Blahd, Jr., MD, FACEP - Emergency Medicine
Specialist Medical Reviewer H. Michael O'Connor, MD - Emergency Medicine
Last Revised September 1, 2011

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