Memory Digest

Creutzfeldt-Jakob Disease

Creutzfeldt-Jakob disease (CJD) is a rare, fast-moving prion disease of the brain that causes rapidly worsening dementia, movement problems and, usually within a year, death.

Last reviewed: October 2026

Creutzfeldt-Jakob disease (CJD) is a rare and rapidly progressing brain disorder. It belongs to a family of illnesses called prion diseases (also known as transmissible spongiform encephalopathies). Under a microscope, affected brain tissue is riddled with tiny holes and looks like a sponge—hence "spongiform."

Most dementias, such as Alzheimer's, unfold over many years. CJD is different: it typically causes a dementia that gets worse over weeks to months. Rapid decline is one of the most important clues that a person may have CJD.

How common is it?

CJD is rare. The Alzheimer's Association estimates it occurs in about one in a million people each year worldwide, and NINDS reports roughly 350 cases a year in the United States. Sporadic CJD usually begins around age 60 to 65.

What causes it?

Prion protein is found naturally throughout the body, especially in the nervous system. In prion diseases, the protein folds into an abnormal shape. Abnormal prions then cause nearby normal prion proteins to misfold too, in a kind of domino effect. The misfolded proteins clump together and destroy brain cells.

There are three main types:

• Sporadic CJD – by far the most common, accounting for about 85% of cases. It appears for no known reason, apparently when prion protein in the brain spontaneously misfolds.
• Familial (hereditary) CJD – about 10% to 15% of cases. It is caused by changes in the prion protein gene passed down in families. Not everyone who inherits a mutation develops the disease.
• Acquired CJD – about 1% of cases. It results from exposure to infected brain or nervous system tissue, such as through certain historical medical procedures. Variant CJD (vCJD) is linked to eating beef from cattle with bovine spongiform encephalopathy ("mad cow disease"); it tends to affect younger people and often begins with psychiatric symptoms.

Is it contagious?

Not in everyday life. NINDS states that CJD cannot spread through the air, through touching, or through most other forms of casual contact. There is no evidence that caregivers, health care workers or funeral workers have a higher risk than anyone else. Families can hug, hold hands and care for their loved one without fear. Hospitals follow special sterilization rules for surgical instruments that contact brain tissue.

Chronic wasting disease, a prion disease of deer and elk in some areas, has not been shown to infect humans, according to the CDC as cited by the Alzheimer's Association.

Symptoms

Symptoms often start subtly and then accelerate quickly. They can include:

• Rapidly worsening memory loss and confusion
• Personality changes, anxiety, depression or agitation
• Problems with coordination, walking and balance
• Vision problems
• Sudden jerking movements of muscles (myoclonus)
• Trouble speaking or swallowing as the illness advances

In later stages, people lose the ability to move or speak and need full-time care.

Diagnosis

Because CJD can resemble other conditions—including treatable ones like autoimmune encephalitis, infections or severe delirium—doctors run several tests:

• MRI of the brain, which shows characteristic changes in about 90% of CJD cases (NINDS)
• Spinal fluid tests, including a newer, highly accurate test called RT-QuIC (real-time quaking-induced conversion) that detects abnormal prion activity
• EEG (brain wave test), which can show typical patterns
• Genetic testing if familial CJD is suspected

NINDS notes that the only way to confirm CJD is by examining brain tissue, usually at autopsy (brain biopsy is now rarely done). Even so, MRI and RT-QuIC have made a diagnosis during life far more reliable than in the past. See Getting a Diagnosis.

Treatment and care

There is no cure and no treatment yet proven to slow CJD. Researchers are studying approaches, including early trials that aim to lower production of prion protein. For now, care focuses on comfort:

• Medicines to ease muscle jerks, seizures, anxiety and agitation
• Help with eating, swallowing, mobility and skin care
• Palliative care and hospice, which NINDS notes are appropriate as the disease advances—see Hospice and End-of-Life Care and Late-Stage Dementia

Outlook

CJD is fatal. NINDS reports that about 70% of people die within one year of getting the disease, and the Alzheimer's Association estimates that about 90% of people with sporadic CJD die within a year of diagnosis. Some familial forms progress more slowly.

Support for families

The speed of CJD can leave families reeling, with little time to adjust. It may help to:

• Ask early about palliative care, hospice and advance care planning
• Request a social worker to help with insurance, leave from work and home care
• Consider genetic counseling if familial CJD is diagnosed
• Lean on support organizations, such as the CJD Foundation, and dementia helplines—see Helplines and Support Organizations
• Take care of yourself, too—see Caregiver Stress and Burnout

Public health departments track CJD cases, and families may be asked about brain autopsy, which helps confirm the diagnosis and supports surveillance and research.

Bottom line

CJD is a rare, rapidly progressive prion disease. A dementia that worsens over weeks or months, especially with jerking movements or coordination problems, needs urgent medical evaluation—both to look for CJD and to rule out treatable causes. If you are facing this diagnosis, talk with the medical team about comfort-focused care and support resources.

Sources

1. NINDS: Creutzfeldt-Jakob Disease
2. Alzheimer's Association: Creutzfeldt-Jakob Disease (CJD)

Not medical advice. This article is general information, not a diagnosis or treatment plan for any individual. Talk with a doctor about your situation.

Related articles

• What Is Dementia?
• Young-Onset Dementia
• Getting a Diagnosis
• Late-Stage Dementia
• Caregiver Stress and Burnout