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By: Muzamil Arif, Sumiya Banoo

Organic brain syndrome, also known as organic brain disease, organic brain disorder, organic mental syndrome, or organic mental disorder, refers to any syndrome or disorder of mental function whose cause is assumed to be known as organic (physiologic) rather than purely of the mind. An organic mental disorder is a previously used term to describe a dysfunction of the brain that was meant to exclude psychiatric disorders. It is currently under the category of neurocognitive disorders and describes reduced brain function due to illnesses that are not psychiatric in nature.  Sometimes the term organic mental disorder is used interchangeably with the terms organic brain syndrome (OBS), chronic organic brain syndrome or neurocognitive disorder, this latter term is the one used more commonly now.

It can be divided into two major subgroups: Acute (delirium or acute confusional state) and Chronic (dementia). A third entity, encephalopathy (amnestic), denotes a grey zone between delirium and dementia. The Diagnostic and Statistical Manual of Mental Disorders has broken up the diagnoses that once fell under the diagnostic category organicmental disorder into three categories: delirium, dementia, and amnestic.


Delirium or Acute organic brain syndrome is 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, although this does not guarantee that it will not recur or progress to become chronic, that is, long-term. A more specific medical term for the acute subset of organic brain syndromes is delirium. Thinking, remembering, sleeping, and paying attention can become difficult during alcohol withdrawal, after surgery, or with dementia.


Dementia or 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 irreversible. Amnestic pertains to amnesia and is the impairment in ability to learn or recall new information, or recall previously learned information. Although similar, it is not coupled with dementia or delirium.


Amnestic conditions denote a gray zone between delirium and dementia; its early course may fluctuate, but it is often persistent and progressive. Damage to brain functioning could be due not only to organic (physical) injury (a severe blow to the head, stroke, chemical and toxic exposures, organic brain disease, substance use, etc.) and also to non-organic means such as severe deprivation, abuse, neglect, and severe psychological trauma.

Associated conditions

Disorders that are related to injury or damage to the brain and contribute to OBS include, but are not limited to Alcoholism, Alzheimer’s disease, Attention deficit /hyperactivity disorder, Autism, Concussion, Encephalitis, Epilepsy, Fetal alcohol syndrome, Hypoxia, Parkinson’s disease, Intoxication/overdose caused by substance use disorders including alcohol use disorder, Non-medical use of sedative hypnotics, Intracranial hemorrhage/traumaKorsakoff syndrome, Mastocytosis, Meningitis, Psychoorganic syndrome, Stroke/transient ischemic attack (TIA), Withdrawal from drugs, especially sedative hypnotics, e.g. alcohol or benzodiazepines. Other conditions that may be related to organic brain syndrome include: clinical depression, neuroses, and psychoses, which may occur simultaneously with the OBS.


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, or vitamin deficiencies, may be factors too. Concussions, blood clots, or bleeding in or around the brain from trauma may lead to organic brain syndrome. Low oxygen in the blood, high amounts of carbon dioxide in the body, strokes, brain infections, and heart infections can lead to an organic mental disorder as well. Degenerative disorders like Parkinson’s disease, Alzheimer’s disease, Huntington disease, and multiple sclerosis may also be contributing factors.


A person with an organic mental disorder may have difficulty concentrating for a long period of time. Others may get confused while performing tasks that seem routine to others. Managing relationships and collaborating and communicating with colleagues, friends, or family may also prove difficult. Primary Symptoms like Confusion, Agitation, Irritability, A change in behaviour, impaired brain function, cognitive ability, or memory.

Diagnosis and Treatment

Blood tests, spinal taps, or an electroencephalogram may be administered to diagnose organic brain syndrome or an organic mental disorder. Imaging of the brain, like a CT scan or MRI, is also useful, depending on a doctor’s suspicion.

Treatments for organic mental disorders vary on what the underlying cause of the disorder is. Medication may be prescribed or rehabilitation therapy may help patients recover function in the parts of the brain affected by the organic mental disorder. Treatments can include, but are not limited to, rehabilitation therapy such as physical or occupational, pharmacological modification of the neurotransmitter function, or medication. The affected parts of the brain can recover some function with the help of different types of therapy. Online therapy can be just as intense and helpful as rehabilitation therapy, in person, and can help those affected regain function in daily life.

The writers are Graduate students

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