Organic brain syndrome

Organic brain syndrome

Description, Causes and Risk Factors:

Abbreviation: OBS.

Organic brain syndrome is described as a deficiency in mental function that is due to medical disease that is not a psychiatric illness. The disorder is usually inherited; however, it can be caused from diseases or changes to the body that affects the brain. Originally, the term was created to distinguish physical (termed "organic") causes of mental impairment from psychiatric (termed "functional") disorders, but this division became increasingly difficult to make as the physical correlates of mental problems become more numerous. Thus, the term (which was never well-defined) is now almost officially obsolete in psychiatry, having been removed from DSM-IV, but still occasionally used in practice and in the literature.

Causes and Risk Factors:

1. Brain injury caused by trauma

  • Bleeding into the brain (intracerebral hemorrhage).

  • Bleeding into the space around the brain (subarachnoid hemorrhage).

  • Blood clot inside the skull causing pressure on brain (subdural hematoma).

  • Concussion.

2. Breathing conditions

  • Low oxygen in the body (hypoxia).

  • High carbon dioxide levels in the body (hypercapnia).

3. Cardiovascular disorders

  • Abnormal heart rhythm (arrhythmias).

  • Brain injury due to high blood pressure (hypertensive brain injury).

  • Dementia due to many strokes (multi-infarct dementia).

  • Heart infections (endocarditis, myocarditis).

  • Stroke.

  • Transient ischemic attack (TIA).

4. Degenerative disorders

  • Alzheimer's disease (also called senile dementia, Alzheimer's type).

  • Creutzfeldt-Jacob disease.

  • Diffuse Lewy Body disease.

  • Huntington's disease.

  • Multiple sclerosis.

  • Normal pressure hydrocephalus.

  • Parkinson's disease.

  • Pick's disease.

6. Drug and alcohol-related conditions

  • Alcohol withdrawal state.

  • Intoxication from drug or alcohol use.

  • Wernicke-Korsakoff syndrome (a long-term effect of excessive alcohol consumption or malnutrition).

  • Withdrawal from drugs (especially sedative-hypnotics and corticosteroids).

  • Infections.

  • Any sudden onset (acute) or long-term (chronic) infection.

  • Blood poisoning (septicemia).

  • Brain infection (encephalitis).

  • Meningitis (infection of the lining of the brain and spinal cord).

  • Prion infections such as mad cow disease.

  • Late-stage syphillis.

7. Other medical disorders

  • Cancer.

  • Kidney disease.

  • Liver disease.

  • Thyroid disease (high or low).

  • Vitamin deficiency (B1, B12, or folate).


Acute organic brain syndrome is (by definition) a recently appearing state of mental impairment, as a result of intoxication, drug overdose, infection, pain, and many other physical problems affecting mental status. In medical contexts, "acute" means "of recent onset." As is the case with most acute disease problems, acute organic brain syndrome is often temporary-however this is not guaranteed (a recent-onset problem may continue to be chronic or long term). A more specific medical term for the acute subset of organic brain syndromes is delirium.

Chronic organic brain syndrome is long-term. For example, some forms of chronic drug or alcohol dependence can cause organic brain syndrome due to their long-lasting or permanent toxic effects on brain function. Other common causes of chronic organic brain syndrome sometimes listed are the various types of dementia, which result from permanent brain damage due to strokes, Alzheimer's disease, or other damaging causes which are not reversible.


Someone with an OBS will typically have a rapid onset of delirium. Delirium is always due to an organic cause such as an interruption to the nervous system that is triggered by medications, medical conditions or severe trauma. Symptoms of the disorder may induce a disturbance in sleep patterns, hallucinations, anxiety and may have other medical conditions that increase the symptoms. There is a difficulty in remembering tasks and events. The person will have difficulties concentrating, be fatigued, have hypersensitivity to noise and light, experience restlessness and may have disturbing dreams.


Tests depend on the disorder, but may include:

    Blood tests.

  • Electroencephalogram (EEG).

  • Head CT scan.

  • Head MRI.


The management of OBS is typically done as an inpatient through a medical facility. The primary goal is to find the possible cause for the person to be experiencing the symptoms of the disorder. It is important that the person have the correct nutrition, fluids and rest in attempts to help them feel safe should they experience hallucinations or have difficulties in mobility. There are a variety of disorders and conditions that mimic the symptoms of the syndrome such as psychosis, depression and neurosis, therefore it is important to see a physician and have the correct testing done to determine the most appropriate treatment.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

Sources: Excerpted from various sources.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.


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