Cause of Mysterious, Fatal Brain Disease Linked to Mad Cow Disease-Like Proteins The disease is fatal for patients after a swift neurological decline.

 -- Researchers believe they have found the cause of a mysterious and fatal brain disease that leaves patients with symptom's similar to Parkinson's disease, including rigid muscles, tremors and low blood pressure.

Called Multiple System Atrophy (MSA), the disease is rare but devastating, affecting three out of every 100,000 people over the age of 50. Researchers have now uncovered that the disease is likely caused by infectious proteins similar to the ones that cause Creutzfeld-Jakob Disease, the human form of mad cow disease.

Those with the disease generally show symptoms in their 50s and their health rapidly declines in the subsequent 5ive to 10 years, with progressive loss of motor function, according to the National Institutes of Health.

In a new study published in the Proceedings of National Academy of Sciences, researchers have found that tiny infectious proteins called prions are likely behind MSA. Prions are proteins that are folded abnormally and cause other proteins to similarly fold, which can have devastating consequences.

Researchers, led by Dr. Stanley Prusiner, director of the Institute for Neurodegenerative Diseases at University of California San Francisco, examined the brains of 14 subjects who had been diagnosed with MSA.

They then used specimens from the brains and found that they could infect mice and other healthy cells with the deadly disease. The identification of this prion, called alpha-aynuclein, is the first new prion to be discovered in 50 years, researchers said.

Mark Zabel, associate director of the Prion Research Center at Colorado State University, said while the disease is transmissible it cannot cause an epidemic.

“The main we transmit the disease [in lab animals] is to stick them in the head with the needle, that doesn’t happen to often in human life or wildlife,” he explained.

Zabel, who was not involved in the study, said the mostly likely source of infection is in the clinic or operating room.

While all subjects developed the disease spontaneously, the study authors did caution that doctors should be particularly careful when administering “deep brain stimulation” because of the potential of infecting others with MSA. The authors explain that patients with MSA are often mistaken for Parkinson's disease patients, so in theory if they are given deep brain stimulation therapy, they could put other patients at risk if the surgical tools aren’t carefully decontaminated.

Previous studies found “prions bound to stainless steel wires” tightly even after a decontamination procedure, and “retained their ability to infect mice on brain implantation, as well as in cultures of susceptible cells," according to the paper.

Dr. Valerie Sim, an associate professor in the Neurology Division at the University of Alberta, said it’s not clear from the study whether the disease is easily transmissible, and despite the disease’s outcome, people should not be afraid of contracting MSA.

“Some of the message taken from this study is fear. It’s important to avoid fear,” said Sim, who was not involved in the study. “It’s important that there’s no proof of” human-to-human transmission.

The material was directly injected into the mouse’s brain to infect them, Sim said, noting that the study may have implications about the definition of what makes a prion, since they should be considered transmissible and that more study was needed.