Creutzfeldt-Jakob disease: a rapidly progressing form of dementia

CJD hit the headlines in the mid-1990s after people in the UK and Europe began contracting it as a result of eating products from cows infected with bovine spongiform encephalopathy (BSE), commonly known as ‘mad cow disease’. Almost 30 years on, we have a much better understanding of the fundamental causes of the condition.

Like more common types of dementia, CJD attacks the brain causing confusion, memory impairment, disorientation, depression, agitation, and problems with thinking skills like planning and judgement. It also affects movement, triggering involuntary jerky movements, muscle stiffness, twitches, and difficulty walking. CJD also impacts vision, resulting in abnormal perceptions, double vision and hallucinations.

These symptoms are caused by an abnormality in prion protein. Prion protein is a mysterious protein present on the surface of cells throughout the body, especially through the nervous system. In prion diseases like CJD, prion protein folds into an abnormal 3D shape, called a prion, and triggers this change in its neighbours. This misfolded shape is harmful and causes the symptoms of CJD – but scientists don’t yet understand exactly how the abnormally shaped prion proteins cause toxicity in the brain.

Fortunately, when CJD is suspected, there are some highly accurate tests. The rapid progression of symptoms suggests to clinicians that a patient has CJD. Tools that can help with diagnosis include brain scans like MRI plus procedures like lumbar punctures where a sample of spinal fluid is taken to test for certain proteins. Usually the diagnosis can be made confidently in life.

There are three main subtypes of prion disease, the main one being sporadic CJD, which affects 85% of people with the condition. This form develops randomly with no known cause and usually affects people aged 55-80. The second most common type is inherited prion disease, which causes roughly 10-15% of cases. As the name suggests, people with this form inherit one of the 50 known changes in the gene that codes for prion protein. People with inherited prion disease are usually younger than those with sporadic CJD, but often survive longer after diagnosis.

The final subtype is acquired CJD, the category which variant CJD – the form linked with BSE – falls into. Acquired CJD is contracted from exposure to prion protein from an external source, such as through eating infected produce or receiving medical procedures where human tissues are taken from cadavers (dead bodies used in medicine). Cases of acquired CJD have fallen dramatically due to greater awareness of the condition, improved animal feeding and halting the use of cadaveric medical and surgical products.

Unfortunately, there is no treatment able to slow or stop the progression of CJD, but prion protein itself is the obvious target for experimental treatment. Management includes providing accurate information, psychological support, and optimising care. Existing therapies are limited to treating symptoms (see www.nationalprionclinic.org for advice about symptom treatments).

The CJD Foundation and CJD Support Network provide emotional and practical support for people affected by any type of CJD. Meanwhile, specialist professional advice is available from the National Prion Clinic at University College London Hospitals and National CJD Research & Surveillance Unit at the University of Edinburgh. The CJD Foundation has just awarded grants of up to $100,000 to research projects aiming to find treatments for CJD, bringing fresh hope to people affected by the condition.