Overview

Creutzfeldt-Jakob Disease (CJD) or subacute spongiform encephalopathy is a rare neurocognitive/neurodegenerative disorder that leads to Alzheimer-like symptoms, both characterised by memory loss and ultimately, death. CJD is characterised by prion proteins in the brain. The condition was first described by German neurologist Hans Gerhard Creutzfeldt in 1920 and Alfons Maria Jakob shortly thereafter giving the disease its name.¹

CJD is a rare condition, with the Centre for Disease Control estimating an annual incidence of about 1 case per million people in the United States, and it is most common in ages 55-65, with risk increasing with age.¹

Types of CJD

According to cause, CJD may be divided into 4 types:

Sporadic CJD (sCJD) – It is the most common subtype of CJD – and occurs in almost 8 out of 10 cases. The specific cause of sporadic CJD is still unknown. This type of CJD progresses very rapidly with median survival at only around 4 months, and it typically affects middle to older-aged adults.^{2, 3}

Variant CJD (vCJD) – Variant CJD is believed to be caused by eating meat from cattle which suffer from bovine encephalopathy, or “mad cow” disease – a similar prion protein causes vCJD. There have also been reports of vCJD occurring after blood transfusion, albeit very rare (5 cases reported in the UK).³ Variant CJD affects younger age groups, and progresses more slowly than sCJD.²

Iatrogenic CJD (iCJD) - Iatrogenic CJD occurs when infection is spread from someone already suffering from CJD, through surgery or medical treatment. In the past, human growth hormones from deceased individuals infected with CJD have been known to spread CJD. CJD may also be spread through improper sterilisation of surgical instruments used in brain surgery.³

Genetic or familial CJD (gCJD) – The second most common cause of CJD, genetic CJD is associated with the mutation of the human PrP gene (PRNP). The pattern of inheritance is autosomal dominant – any parent carrying the mutation may transmit it to their offspring. Genetic CJD usually affects a younger age group than sCJD, and illness duration is longer than sCJD.^{2, 4}

Pathogenesis

CJD is caused by abnormal infectious proteins known as prions, which form as a result of misfolding of their normal amino acid structure. Prion build-up in the brain may also cause normal proteins to fold abnormally, causing cell death and the release of additional prion proteins. After the release of excessive prions, brain cells die, and these prions are deposited in the form of plaque. This loss and damage to brain cells lead to a loss in mental and physical function, and ultimately, death.³

Signs and symptoms

Following are some signs and symptoms of CJD.^{5, 6}

Early symptoms:

• Lack of coordination
• Impaired balance
• Impaired thought, memory
• Mood swings, anxiety, depression
• Insomnia
• Vision changes
• Confusion
• Irritability and impatience

Progressive symptoms:

• Wasting of arms and legs
• Restricted movement
• Pneumonia and other infections
• Blindness
• Trouble speaking
• Sudden, jerky movements

Diagnosis

The gold standard for CJD diagnosis is a brain biopsy after the death of the patient. However, clinical professionals can diagnose patients through the following methods: ⁶

• Medical history
• Neurological examination for muscle spasming, twitching, coordination, vision
• Electroencephalogram (EEG)
• Magnetic resonance imaging (MRI)
• Spinal fluid test

Prevention

There is no technique to prevent sporadic and genetic CJD. Iatrogenic CJD may be prevented by measures such as the destruction of surgical equipment used on individuals suffering from CJD, using single-use needles and similar equipment, and the use of synthetic human growth hormone. To prevent variant CJD, the CDC recommends animals such as deer and elk be tested before their meat is consumed in areas known to have animals infected with chronic wasting disease.⁶

Management

Unfortunately, no treatment exists for Creutzfeldt-Jakob disease. Management is mainly focused on palliative care: alleviation of symptoms and making the person feel as comfortable as possible. ^{3, 6}

Conclusion

Creutzfeldt-Jakob disease is a rare neurodegenerative condition caused by prion deposition in the brain, leading to progressive loss of a person’s mental and physical capabilities. It may occur due to genetic causes, consumption of prion-infected meat, iatrogenic, or, in most cases, simply idiopathic. Middle to older age groups are at higher risk for the condition, and management of the condition is palliative – the person is made to feel comfortable with the treatment of specific symptoms.