Chronic organic brain syndrome

Chronic organic brain syndrome


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


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:

Other conditions that may be related to organic brain syndrome include: depression, neuroses, and psychoses of various types, which may occur at the same time as the OBS.


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

Exams and Tests

Testing and physical examination vary, depending on the specific disorder. Head CT scan, head MRI, EEG, and blood tests, to evaluate for medical conditions, are done frequently.


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.

Outlook (Prognosis)

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

Possible Complications

Loss of ability to interact with others or function independently is common.

When to Contact a Medical Professional

Call your health care provider if:

  • Organic brain syndrome has been diagnosed and you are uncertain of the actual, specific diagnosis
  • You have symptoms which suggest this problem
  • You have been diagnosed with OBS and symptoms become worse
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