Organic Brain Syndrome

Written by Lydia Krause | Published on July 16, 2012
Medically Reviewed by George Krucik, MD

Organic Brain Syndrome

Organic brain syndrome (OBS) is a general term for decreases in mental function that are not caused by a psychiatric disorder. Reduced mental function could include:

  • problems with memory
  • difficulties understanding language
  • changes in behavior
  • trouble performing daily activities

OBS may be caused by neurodegenerative conditions such as Alzheimer’s disease. Neurodegenerative means progressive loss of neurologic function. OBS can also be caused by brain trauma or can be a side effect of substance abuse.

The cause of OBS is not always easy to find. Doctors will examine the brain and look at a person’s symptoms to determine the cause. The cause and severity of OBS will help a doctor decide the best course of treatment.

The long-term outlook for OBS depends on its cause. Most neurodegenerative diseases have no cure, and OBS often grows worse over time. Other conditions are temporary, and patients can expect a full recovery.

Risk Factors for OBS

Your risk for OBS is at least partially dependent on your lifestyle and habits. Working in an environment with exposure to heavy metals can increase your risk of OBS. Heavy metals, such as lead and mercury, are known to cause harm to the nervous system. Regular exposure increases your risk for decreased mental function. Heavy drug dependence can also increase the odds of developing OBS.

Other risk factors for OBS include:

  • vascular disorders
  • diabetes
  • alcoholism
  • sports with a high risk of head trauma (concussions are a common cause of OBS)
  • increasing age (as age increases, so does the chance of developing a disorder such as dementia)

Symptoms of OBS

Symptoms of OBS differ by cause. Symptoms of neurodegenerative disorders typically involve confusion. OBS may make a person unable to hold a job or be independent.

Symptoms which may be caused by neurodegenerative diseases include:

  • memory loss (patients may forget family and friends; they may be continually confused as to where they are and what is happening)
  • difficulties in understanding concepts (e.g., at sunset, they may ask why the sun has gone and if it will return)
  • anxiety (people who are confused often become anxious because they do not fully understand what is happening)

Other symptoms that may present with OBS include:

  • headache (especially in those with concussion or traumatic brain injury)
  • inability to pay attention (may mean dropping out of school or losing a job)
  • short-term memory loss (there may be temporary amnesia)
  • difficulties performing routine tasks (such as driving)
  • difficulty controlling voluntary muscle movements (ataxia)
  • loss of inhibition (unable to decide which actions are safe and which are not)
  • confusion (may not understand where you are or what is happening)
  • visual disturbances (such as seeing spots)

Causes of Organic Brain Syndrome

Underlying Conditions

OBS is a general term for a problem that occurs in many disorders. The most common cause of OBS is a neurodegenerative disease. Younger people usually do not have OBS linked to a disease like dementia. They are more likely to get the syndrome from some type of trauma. Neurodegenerative diseases that can cause OBS include:

  • Alzheimer’s disease (AD)
  • dementia
  • prion disease (for example, Creutzfeldt-Jakob disease, which causes holes in the brain tissue and has no cure)

OBS is more likely to develop after injury or infection in people under 60. Nondegenerative conditions which may cause OBS include:

  • concussion
  • traumatic brain injury (TBI)
  • meningitis (infection of the tissue covering the brain)

Affected Parts of Your Brain

Symptoms of OBS depend on which part of the brain is affected. The hippocampus is the part of the brain in charge of memory. Damage to it causes memory loss. The brain stem controls motor movements. If you have brain stem damage, you may have problems walking or balancing.

Diagnosis of OBS

OBS is not caused by a psychiatric disorder. Many psychiatric disorders can falsely appear to cause OBS because their symptoms are similar. Psychiatric disorders, which resemble OBS, include:

  • schizophrenia (symptoms: mental confusion and loss of inhibition)
  • chronic depression (symptom: inability to focus)
  • psychosis (symptom: difficulty understanding what is happening)

Doctors use diagnostic imaging or mental ability tests to avoid giving the wrong treatment. These tests can separate psychiatric symptoms from those of OBS. Diagnostic tests include:

  • magnetic resonance imaging (MRI), which can look for brain damage
  • positron emission tomography (PET) scan, which can also be used to find damaged areas of the brain
  • cerebrospinal fluid markers, which can look for signs of infection, such as bacterial meningitis

Treatment of OBS

Treatment depends on the severity of injury or type of disease causing OBS. Certain conditions, such as a concussion, may only require rest and medication. Neurodegenerative diseases may require different types of therapy. Treatments for OBS include:

  • pain medications—medications such as indomethacin are often given to help with post-concussion headaches
  • brain and bed rest—during “brain rest,” you will avoid all activities (including school, watching television, sports, etc.)
  • antibiotics (to clear remaining infections in a condition such as bacterial meningitis)
  • brain surgery (in severe cases)

Treatment options to improve independence include physical therapy (to aid in walking) and occupational therapy (to help relearn daily tasks).

Long-Term Outlook for OBS

The long-term outlook for organic brain syndrome depends on the cause. Temporary causes have the best long-term outlook. Remaining on brain rest for several weeks may lead to full recovery in patients with concussions.

Patients who are diagnosed with dementia or Alzheimer’s have a poor long-term outlook. They may require long-term treatment as their mental function permanently declines.

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Show Sources

  • Galvin, J., & Sadowsky, C. (2012, May-June). Practical guidelines for the recognition and diagnosis of dementia. Journal of the American Board of Family Medicine, 25(3), 367-382. Retrieved July 26, 2012, from
  • Jansen, C., Parchi, P., Capellari, S., Ibrahim-Verbaas, C., Schuur, M., Strammiello, R. Rozemuller, A. (2012, April 30). Human prion diseases in the Netherlands (1998-2009): Clinical, Genetic and Molecular Aspects. PLoS ONE, 7(4). Retrieved July 26, 2012, from
  • Olson-Madden, J., Brenner, L., Corrigan, J., Emrick, C., & Britton, P. (2012). Substance use and mild traumatic brain injury risk reduction and prevention: A novel model for treatment. Rehabilitation Research and Practice, 2012. Retrieved July 26, 2012, from
  • Organic brain syndrome. (2012, February 16). PubMed Health. Retrieved July 2012, from
  • Qiu, C., Kivipelto, M., & Strauss, E. (2009, June). Epidemiology of Alzheimer’s disease: Occurrence determinants, and strategies toward intervention. Dialogues in Clinical Neuroscience, 11(2), 111-128. Retrieved July 2012, from

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