What Is the Definition of an Organic Mental Disorder?

Find out what sets these disorders apart from other mental illnesses

A woman with dementia at a day facility for the elderly.
A woman with dementia at a day facility for the elderly. Carsten Koall/Getty Images

An organic mental disorder is a dysfunction of the brain that may be permanent or temporary. Learn more about such disorders with this review of their causes, symptoms and treatment.

What Causes Organic Mental Disorders

Organic mental disorders are disturbances that may be caused by injury or disease affecting brain tissues as well as by chemical or hormonal abnormalities. Exposure to toxic materials, neurological impairment or abnormal changes associated with aging can also cause these disorders.

Alcohol or metabolic disorders, such as liver, kidney or thyroid disease, may be factors, too. Organic mental disorders go hand in hand with organic brain syndrome.

Sometimes the term organic mental disorder is used interchangeably with the terms organic brain syndrome or chronic organic brain syndrome. OBS is simply the catchall term for reduced brain function due to illnesses that are not psychiatric in nature. Concussions, blood clots or bleeding in or around the brain may lead to organic brain syndrome. Low oxygen in the blood, high amounts of carbon dioxide in the body, strokes and heart infections can lead to organic brain syndrome as well. Degenerative disorders, including Parkinson disease and Huntington disease, may also be contributing factors.

Organic mental disorders occur as the result of developmental anomalies in the brain. There are many types of organic mental disorders. Examples of organic mental disorders include Alzheimer's disease, amnesia, dementia or delirium, which results in confused thinking.

Certain people are genetically predisposed to developing an organic mental disorder.

Sometimes medical conditions such as depression and psychosis can present in ways that resemble OBS.

Symptoms of Organic Mental Disorders

The symptoms of organic mental disorders include confusion, agitation, irritability, loss of brain function or cognitive ability or memory loss.

If you or your loved one is experiencing any of these symptoms, it's important to seek medical care as soon as possible. A serious medical condition may have caused these symptoms to surface, and early treatment is key.

Diagnosing and Treating Organic Mental Disorders

Blood tests, spinal taps or an electroencephalogram may be administered to diagnose organic brain syndrome or an organic mental disorder. Treatments for organic mental disorders vary. Medication may be prescribed or therapy recommended. Rehabilitation may help patients recover function in the parts of the brain affected by the organic mental disorder.

How People With Organic Mental Disorders Function

A person with an organic mental disorder may have difficulty concentrating for long periods of time. Students with this condition would likely qualify for special education services. Such individuals may get confused while performing tasks that seem routine to others. Collaborating and communicating with others may also prove difficult.

Complications of Organic Mental Disorders or OBS

While some organic mental disorders may only be temporary, such as amnesia, others may get worse. Disorders that don't respond to treatment may lead the patient to lose the ability to function independently or to interact with others. In short, an organic mental disorder can totally upend one's life. If your or your loved one's symptoms get worse, consult your doctor.


NIH U.S. National Library of Medicine. "Organic Brain Syndrome."

Social Security Disability Help. "Can I Work With an Organic Mental Disorder?"

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