Medical Dictionary Search Engines

Please be patient! It may take up to ONE minute to load all the Engines.
Problems? Please contact our support.


Search For


Specialty Search




Other encyclopedia topics: A-Ag Ah-Ap Aq-Az B-Bk Bl-Bz C-Cg Ch-Co Cp-Cz D-Di Dj-Dz E-Ep Eq-Ez F G H-Hf Hg-Hz I-In Io-Iz J K L-Ln Lo-Lz M-Mf Mg-Mz N O P-Pl Pm-Pz Q R S-Sh Si-Sp Sq-Sz T-Tn To-Tz U V W X Y Z 0-9   

Organic brain syndrome

Alternative names

OBS; Organic mental disorder; Chronic organic brain syndrome


Organic brain syndrome is a general term which refers to physical disorders that cause a decrease in mental function, usually not including psychiatric disorders.

Causes, incidence, and risk factors

OBS is a common "diagnosis" of the elderly. It is not an inevitable part of aging, however. OBS is not a separate disease entity, but is a general term used to categorize physical conditions that can cause mental changes .

Disorders associated with OBS include, but are not limited to:
  • Degenerative disorders:
    • Creutzfeldt-Jacob disease
    • Huntington disease
    • Multiple sclerosis
    • Normal pressure hydrocephalus
    • Pick's disease
    • Senile dementia/Alzheimer's type
  • Cardiovascular disorders :
    • Arrhythmias -- may cause some types of OBS
    • Cardiac infections ( endocarditis , myocarditis , etc.) -- may sometimes cause OBS
    • Hypertensive brain injury
    • Multi-infarct dementia (multiple strokes)
    • Stroke
    • TIA
  • Trauma-induced brain injury:
    • Chronic subdural hematoma (blood clot causing pressure on brain)
    • Concussion
    • Intracerebral hemorrhage
    • Subarachnoid hemorrhage
  • Dementia due to metabolic causes
  • Respiratory conditions -- may cause or aggravate OBS
    • Hypoxia (decreased oxygen in the body)
    • Hypercapnia (increased carbon dioxide levels in the body)
  • Infections
    • Any acute or chronic infection
    • Septicemia (presence in the bloodstream of toxic by-products caused by infection)
    • Meningitis
    • Encephalitis
  • Drug and alcohol related conditions
    • Intoxication, drug abuse , or alcohol use
    • Long-term effects of alcohol, Wernicke-Korsakoff syndrome
    • Alcohol withdrawal state
    • Withdrawal from drugs (especially sedative-hypnotics and corticosteroids)
  • Parkinson's disease
Other conditions that may be related to organic brain syndrome include: depression , neuroses, and psychoses of various types, which may occur simultaneously with the OBS.


Symptoms vary with the specific disease. In general, organic brain syndromes cause varying extents of confusion , delirium (severe, short-term losses of brain function), agitation , and dementia (long-term, often progressive, losses of brain function).

Signs and tests

Testing and physical examination vary depending on the specific disorder.


Treatment varies with the specific disorder. Many of the disorders have nonspecific treatments -- primarily supportive care to assist the person in areas where brain function is lost.

Medications may be needed to reduce aggressive behaviors typical of some of the conditions in this category.

Expectations (prognosis)

See the specific disorder. Some disorders are acute and treatable, but many are chronic or progressive.


Loss of ability to interact or function independently is common.

Calling your health care provider

Call your health care provider if "organic brain syndrome" has been diagnosed and you are uncertain of the actual, specific diagnosis; if you have symptoms which suggest this problem; or if you have been diagnosed with it and symptoms become worse.

Update Date: 7/28/2002

Elaine T. Kiriakopoulos, M.D., MSc, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard University, Boston, MA. Review provided by VeriMed Healthcare Network.

©2009 [Privacy Policy] [Disclaimer]
Last updated: Tue, 06 Jan 2009 00:20:03 GMT