Deadly Variant of Dementia Surfaces in US

A new form of Creutzfeldt-Jakob disease (CJD has surfaced in the US. Ten have died so far died from this fast-advancing form of fatal dementia called PSPr, New Scientist reports.

Creutzfeldt-Jakob disease (CJD) is a very rare and incurable degenerative neurological disorder that is ultimately fatal. The disease was first described by German neurologists, Hans Gerhard Creutzfeldt and Alfons Maria Jakob in the first half of the last century.

It is rare and only occurs in about one out of every one million people. It usually affects people aged 45–75, most commonly appearing in people between the ages of 60–65. The exception to this is the more recently-recognised 'variant' CJD (vCJD), which occurs in younger people.

The first symptom of CJD is rapidly progressive dementia, leading to memory loss, personality changes and hallucinations. This is accompanied by physical problems such as speech impairment, jerky movements (myoclonus), balance and coordination dysfunction (ataxia), changes in gait, rigid posture, and seizures. The duration of the disease varies greatly, but sporadic (non-inherited) CJD can be fatal within months or even weeks, doctors say.

No one yet knows how the disease originates, or under what conditions it might spread. Nor is it clear how many people have the condition.

The new cases were referred to CJD surveillance units in the US because they were a suspiciously fast-advancing form of dementia with additional symptoms such as the loss of the ability to speak and move, even though traditional tests that normally help diagnose CJD proved negative.

Post-mortems on those who died revealed the familiar "spongy" brain tissue, covered with tiny holes.

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This damage is thought to be caused by the accumulation of prions, misfolded versions of a brain protein called PrP that can convert normal PrP molecules into their own misshapen form.

Some features of the new disease are different, however. All known disease-causing prions resist degradation by proteases - enzymes which digest the normal form of PrP. But prions from patients with the new disease are broken down by the enzymes.

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Some very rare forms of CJD run in families and are caused by mutations in the gene for PrP. "I believe the disease has been around for many years, unnoticed," says Pierluigi Gambetti, director of the US National Prion Disease Pathology Surveillance Center at Case Western Reserve University in Cleveland, Ohio.

Most forms of CJD develop spontaneously, for unknown reasons, but can be spread if someone is exposed to brain material from people with CJD, for instance, by neurosurgery using inadequately sterilised instruments.

One variant of CJD has been linked to the consumption of contaminated meat from cattle with mad cow disease. If the new condition is similarly caused by something in the victims' diet, or another environmental cause, new measures might be needed to protect public health.

Gambetti is now conducting experiments in mice to see how the disease is transmitted. He suspects that there is no cause for alarm. "I believe the disease occurs naturally, and is not due to environmental causes," he says.

Dr Mark Head, from the UK's National CJD Surveillance Unit, in Edinburgh, said the finding had prompted scientists to start reviewing cases of sporadic CJD in Britain to see if there were any of the newly discovered version.

He said: "What is interesting about this is that it may mean there are other genes out there waiting to be found which are associated with prion disease, and looking at these patients in the US could help find them."



Source-Medindia
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