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Wednesday, November 19, 1997 Published at 21:40 GMT


Scientists discover a new prion link to mental illnesses
image: [ Prion diseases cause large vacuoles in the brain ]
Prion diseases cause large vacuoles in the brain

Scientists have found new evidence to suggest that prions, the warped proteins in the brain that cause "mad cow" disease and its human equivalent Creutzfeldt-Jakob disease, may also cause other mental diseases which resemble schizophrenia in humans.

A Brazilian university research team, whose findings are published in the scientific journal Nature, have yet to fully prove their theory, but they say there is cause for concern.

Prion protein is found in the brains of all humans and higher animals. It is only when it is abnormal that it is harmful. Abnormal prion protein has the extraordinary ability to transform normal prion protein into the abnormal form.

Warped prions can enter the brain either due to an inherited genetic defect, or because the animal or person involved has consumed meat containing it.

Many scientists believe that this is the way how BSE, or mad cow disease, moved from cattle to humans who fell ill with CJD.

When abnormal prions enter the brain, they start a chain reaction. More and more prion protein in the brain becomes abnormal, causing worsening symptoms of staggering and mental derangement.

Now Professor Ricardo Brentani, who is Director of the Ludwig Institute for Cancer Research in Sao Paulo in Brazil, with colleagues in two Brazilian universities has put forward evidence that abnormal prion protein can cause another kind of mental disease. The symptoms include auditory hallucinations, illusions of persecution, and depression, but not the loss of control of movement and the dementia found in CJD.

The scientists examined a family of six. Five members of the family displayed symptoms of schizophrenia, and all were found to have a defect in the gene for the brain chemical prion protein. The sixth family member was both healthy and did not show the genetic defect.

The Brazilian team emphasize that evidence from one family is not enough to prove that an inherited abnormality in prion protein can cause mental illness similar to schizophrenia.

But Ricardo Brentani says that there is now a strong case for psychiatrists around the world to take a look at the genes for prion protein in samples of their patients. He hopes the findings will be negative.

He thinks it would be bad news, if a link would be found: Humankind would have to come to terms with a new class of progressive and incurable mental diseases.

It is considered very unlikely that BSE spread to humans could be causing psychiatric symptoms that have not yet been linked to it. But the possibility may now require investigation.

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Internet Links

Information on Prions

The UK Creutzfeldt-Jakob Disease Surveillance Unit

Information on BSE

Ludwig Institute for Cancer Research

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