HALIFAX -- Two experts in brain diseases say there are many unanswered questions about a possible degenerative neurological syndrome recently disclosed by New Brunswick health officials.

University of Alberta scientists Dr. Valerie Sim and Debbie McKenzie both study prion diseases, which are caused by an abnormally folded protein in the brain. Those diseases cause the brain to waste away and the afflicted organs are often riddled with holes, Sim said.

Prion diseases include Creutzfeldt-Jakob, a rare and fatal disease in humans, as well as mad cow disease in cattle and chronic wasting disease, which affects deer, elk, moose and reindeer.

"Right now, I would say it's a good thing that they are looking in more detail," Sim said in an interview Friday. "It doesn't mean for certain that there is a progressive neurological syndrome on the loose. It just means that there is an interesting pattern, and that we need more information."

In a March 5 memo to organizations representing New Brunswick's doctors, nurses and pharmacists, deputy chief medical officer of health Dr. Cristin Muecke said her office is investigating a cluster of cases of "a progressive neurological syndrome of unknown etiology," or origin. The cases have "many similarities to Creutzfeldt-Jakob disease," she said, but testing has so far ruled out known prion diseases.

Chief Medical Officer of Health Dr. Jennifer Russell told reporters Thursday there are 43 cases under investigation stretching back to 2015, and all are concentrated in the Moncton region and the northeastern part of the province.

Both Sim and McKenzie said it's unlikely the condition is a previously unknown prion disease, though they have been known to pop up. In 1996, for example, a variant of Creutzfeldt-Jakob disease was discovered in the United Kingdom, McKenzie said in an interview Friday. Such diseases are easily identifiable in an autopsy because of the damage to the brain.

Theories put forward that the cause could be environmental, possibly some kind of toxin, make sense, McKenzie said, especially with health officials saying the cases are concentrated in specific areas.

"It would be actually stranger, in a sense, if it was spread out across all of New Brunswick or all of Atlantic Canada," she said. "Then I think we're talking about something very, very different."

She notes that tracing the origins of something like this will be challenging. First, the patient's contact with whatever triggered it was likely some time ago, and second, memory loss is one of the symptoms.

"I would suggest that people not be too concerned yet," she said. "There's a lot more information that's needed, on what the source is, or what the underlying cause of these problems are." But at the same time, she said she hopes people take care and see a doctor if they experience any of the symptoms associated with the condition.

Sim said there are still many questions to be answered before concluding the cases all result from a single condition, especially an unknown condition. The symptoms disclosed so far -- rapidly progressing dementia as well as possible muscle spasms, atrophy, hallucinations and a host of other complications -- involve a large swath of the brain and could arise for many different reasons, she said.

"Progressive, unexplained neurological syndromes do happen in all parts of the country and the world, simply because we do not know everything," Sim said. "We haven't discovered every possible thing that can happen to the brain."

This report by The Canadian Press was first published March 20, 2021.