Organic brain syndrome (OBS) is a general term, referring to physical disorders (usually not psychiatric disorders) that cause decreased mental function.
Alternative Names
OBS; Organic mental disorder (OMS); Chronic organic brain syndrome
Causes, incidence, and risk factors
OBS is a common diagnosis in the elderly. It is not an inevitable part of aging, however. OBS is not a separate disease, 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:
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Creutzfeldt-Jacob disease -
Huntington disease -
Multiple sclerosis -
Normal pressure hydrocephalus -
Pick disease -
Senile dementia, Alzheimer type -
Parkinson's disease - Diffuse Lewy Body disease
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Cardiovascular disorders :-
Arrhythmias -- may cause some types of OBS - Cardiac infections (
endocarditis ,myocarditis , etc.) -- may sometimes cause OBS - Hypertensive (related to high blood pressure) brain injury
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Multi-infarct dementia (multiple strokes) -
Stroke -
TIA
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- Trauma-induced brain injury:
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Chronic subdural hematoma (blood clot causing pressure on brain) -
Concussion -
Intracerebral hemorrhage -
Subarachnoid hemorrhage
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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
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Septicemia (presence in the bloodstream of toxic by-products caused by infection) -
Meningitis -
Encephalitis
- Drug and alcohol related conditions
- Intoxication,
drug abuse , oralcohol use - Long-term effects of alcohol,
Wernicke-Korsakoff syndrome -
Alcohol withdrawal state - Withdrawal from drugs (especially sedative-hypnotics and corticosteroids)
- Intoxication,
- Other medical disorders
- Thyroid disease (high or low)
- Vitamin deficiency (B12 and others)
- Liver disease
- Kidney disease
- Cancer






















