Report on mystery brain disease delayed while feds check the data

By Brian Owens, The Courier

A report on cases of undiagnosed neurological illnesses in New Brunswick has been delayed until the end of the year, after the provincial government asked the Public Health Agency of Canada (PHAC) to review the data.

The report, which is examining potential environmental toxins that may be contributing to the cluster of illnesses, was originally expected to be published at the end of this summer. But patient representatives asked that federal scientists review the data first, so it is now expected to be published at the end of December.

“The chief medical officer of health and his staff have done significant and important work to date on the analysis and incorporation of the Public Health Agency of Canada’s feedback, and we look forward to having that information shared with the public,” said Health Minister John Dornan in a press release. “At the same time, we have asked the Public Health Agency of Canada to review all the data so we can draw on every available expertise to better understand these complex cases.”

The existence of a potential “mystery brain disease” in the province was first suggested in 2019 when a neurologist in Moncton identified several patients with unexplained neurodegenerative symptoms.

Since then more than 200 possible cases have been identified.

An investigation by Public Health New Brunswick, published in 2022, concluded that there was “no evidence of a cluster of a neurological syndrome of unknown cause”.

An independent study, published in May 2025, also concluded that there was no new disease, and that patients were suffering from well-known conditions, including common neurodegenerative diseases such as Alzheimer’s or Parkinson’s disease, traumatic brain injury, and cancer. 

The absence of a new, previously unknown disease does not, however, mean that nothing is wrong. The current provincial investigation is looking into whether there might be a common environmental cause behind the cluster of unexplained symptoms but is not intended to determine whether there is a cluster of any particular disease, or its characteristics.

“From the start of our investigation, we have been clear about our objective to develop a robust understanding of what the data is telling us, which will help us determine what next steps are needed to support affected patients and their families,” said Yves Léger, New Brunswick’s chief medical officer of health, in a press release. “The work has been underway for several months, and we’ve received valuable feedback from our partners throughout the process. Taking the time to reflect that input in the final report is essential to ensuring the findings are as thorough as possible.”