Behavior - unusual or strange

• Alternative Names

  Acting strangely

• Considerations

  Unusual or strange behavior may include:

  • Loss of memory that continues over time or gets worse
  • Loss of the ability to concentrate and perform other mental tasks
• Common Causes

  There are many causes of unusual or strange behavior, including medical and psychiatric illnesses. Two of the more common causes are:

  • Delirium -- Sudden or quick onset of reduced consciousness, awareness, perception, or thought that may be a symptom of a medical illness such as brain or mental dysfunction
  • Dementia -- Chronic, worsening loss of cognitive function that occurs with brain disorders

  Possible causes of strange behavior in older people include:

  • Alcohol in excess
  • Alzheimer's disease
  • Chronic exposure to cold (hypothermia)
  • Dehydration
  • Electrolyte abnormality
  • Emotional problems (depression or feeling useless)
  • Head injury (subdural hematoma)
  • Heart attack, pulmonary embolism, stroke
  • Infection (including pneumonia, gastroenteritis, urinary tract infection)
  • Malnutrition (particularly vitamin B12 and thiamine deficiency)
  • Medications
  • Thyroid disorders (either underactive or overactive)
  • Unfamiliar surroundings

  Possible causes in people of all ages include:

  • Anxiety, emotional problems
  • Diseases affecting the nervous system (neurological diseases)
  • Illicit drug use (such as amphetamines and cocaine)
  • Environmental hazards
  • Low or high thyroid function
  • Non-neurological diseases, especially those with fever (for example, pneumonia)
  • Side effects of antidepressants, such as Prozac
  • Side effects of medication for attention deficit disorder, such as Ritalin
• Home Care

  A doctor should check any unusual behaviors or personality changes. Treatments are based on the following causes of delirium:

  • Brain tumor, head injury, stroke, infection, fever, or pneumonia -- seek immediate medical attention
  • Anxiety and emotional problems -- support, talk therapy, and medications
  • Malnutrition -- medical exam, followed by proper diet and vitamin supplements
  • Medication -- ask the doctor about adjusting the dosage, changing medications, or stopping them
  • Excess alcohol -- stop drinking (abstinence)
  • Illicit drug use -- stop taking the drug and seek a doctor's advice for withdrawal symptoms
  • Emotional problems -- psychological counseling
  • Hypothermia -- warmth (rewarming should be carefully monitored)
  • Surgery -- this is usually temporary, but avoid long-term use of sedatives and painkillers
  • Alzheimer's disease -- medications, sympathetic care, occupational therapy, family support
  • Huntington's chorea -- supportive care
  • Environmental causes -- change the environment or change environments
  • Low thyroid function -- see your health care provider about thyroid hormone replacement treatment
• Call your health care provider if

  Contact your regular health care provider or a doctor who treats disorders of the nervous system (neurologist) if:

  • The unusual or strange behavior is severe, long-term, unexplained, or is affecting your life
  • You have dementia or delirium
• What to expect at your health care provider's office

  The health care provider will perform a physical examination and will take a medical history. The physical examination will probably include a detailed evaluation of the nervous system (neurological evaluation).

  Medical history questions may include:

  • What unusual behaviors are present?
  • How much is the lifestyle affected?
  • Can the person eat, dress, and perform other everyday activities?
  • When did the unusual behavior begin?
  • Is it getting worse, better, or staying about the same?
  • How fast is the behavior changing?
  • What other symptoms are present?

  The following tests may be performed:

  • Blood tests
  • CT scan of the head
  • Mental status test
  • Other neurological tests

Review Date: 2/13/2008

Reviewed By: Luc Jasmin, MD, PhD, Departments of Anatomy & Neurological Surgery, University of California, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.