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Neurocognitive disorder

Neurocognitive disorder is a general term that describes decreased mental function due to a medical disease other than a psychiatric illness.

Neurocognitive disorders are grouped into three subcategories:

  • Delirium.
  • Mild neurocognitive disorder - some decreased mental function, but able to stay independent and do daily tasks.
  • Major neurocognitive disorder - decreased mental function and loss of ability to do daily tasks. Also called dementia.


Listed below are conditions associated with neurocognitive disorder.



  • Low oxygen in the body (hypoxia)
  • High carbon dioxide level in the body (hypercapnia)





  • Alcohol withdrawal state
  • Intoxication from drug or alcohol use
  • Medicine effect, such as corticosteroids, sedative-hypnotics, antihistamines, and antidepressants
  • Wernicke-Korsakoff syndrome, a long-term effect of deficiency of thiamine (vitamin B1)
  • Withdrawal from drugs, such as sedative-hypnotics and corticosteroids


  • 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 syphilis

Complications of cancer and cancer treatment with chemotherapy can also lead to neurocognitive disorder.

Other conditions that may mimic organic brain syndrome include:


Symptoms can differ based on the disease. In general, organic brain syndrome causes:

Exams and Tests

Tests depend on the disorder, but may include:


Treatment depends on the underlying condition. Many conditions are treated mainly with rehabilitation and supportive care to help the person with activities lost due to areas where brain function is affected.

Medicines may be needed to reduce aggressive behaviors that can occur with some of the conditions.

Outlook (Prognosis)

Some disorders are short-term and reversible. But many are long-term or get worse over time.

Possible Complications

People with neurocognitive disorder often lose the ability to interact with others or function on their own.

When to Contact a Medical Professional

Contact your health care provider if:

  • You have been diagnosed with organic brain syndrome and you are uncertain about the exact disorder.
  • You have symptoms of this condition.
  • You have been diagnosed with neurocognitive disorder and your symptoms become worse.

Alternative Names

Organic mental disorder (OMS); Organic brain syndrome



Beck BJ, Tompkins KJ. Mental disorders due to another medical condition. In: Stern TA, Fava M, Wilens TE, Rosenbaum JF, eds. Massachusetts General Hospital Comprehensive Clinical Psychiatry. 2nd ed. Philadelphia, PA: Elsevier; 2016:chap 21.

Fernandez-Robles C, Greenberg DB, Pirl WF. Psycho-oncology: Psychiatric co-morbidities and complications of cancer and cancer treatment. In: Stern TA, Fava M, Wilens TE, Rosenbaum JF, eds. Massachusetts General Hospital Comprehensive Clinical Psychiatry. 2nd ed. Philadelphia, PA: Elsevier; 2016:chap 56.

Merrick ST, Jones S, Glesby MJ. Systemic manifestations of HIV/AIDS. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 366.

Review Date 1/23/2022

Updated by: Joseph V. Campellone, MD, Department of Neurology, Cooper Medical School at Rowan University, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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