Study finds no evidence to support New Brunswick’s ‘mystery brain disease’

The study reviewed the cases of 25 patients and found their symptoms could be traced back to several known neurodegenerative and non-neurodegenerative conditions.

There is no evidence to support claims of a mystery brain disease in New Brunswick, says a new study that suggests the media may have played a role in feeding patients’ fears.

Published Wednesday in the journal JAMA Neurology, the study reviewed the cases of 25 patients evaluated at two hospitals in New Brunswick and Ontario and found their symptoms could be traced back to several known neurodegenerative and non-neurodegenerative conditions.

“Unfounded concerns that a potentially fatal mystery disease, possibly induced by an environmental toxin, is causing the patients’ neurological symptoms has been amplified in traditional and social media,” the study said.

Nearly 400 New Brunswick residents — mostly in the Acadian Peninsula and Moncton areas — have reported symptoms of what the province’s Health Department has called a “neurological syndrome of unknown cause.” Their symptoms included memory problems, balance issues, behavioural changes, muscle spasms and bursts of intense pain.

The Health Department under the former Progressive Conservative government in 2022 said a team of six neurologists and other health experts found no evidence that a cluster of cases existed after their investigation of 48 patients — 46 of them referred by a single neurologist. But after the list of patients reporting symptoms grew to almost 400, the Liberals, who won last year’s provincial election, promised to reopen the investigation.

Now, the JAMA study by authors affiliated with the University of Toronto, New Brunswick’s Horizon Health Network and other Canadian institutions seems to back up the initial research under the Tory government. Data for the study was collected between November 2023 and March 2025, and included initial health records and followups, as well as demographic information and autopsy reports when available.

The study says well-known conditions such as traumatic brain injury and metastatic cancer were identified in all 25 patients, who were evaluated at New Brunswick’s Horizon Health Network and Ontario’s University Health Network. As well, there is “strong evidence” against an exposure to an environmental toxin. The condition of some of the patients is “complex” and warrants a second opinion, the study said. “However, it appears few patients sought this.”

That the illness has gained a reputation as a “mystery brain disease” can be attributed to several factors such as a decreased trust in public health institutions following the COVID-19 pandemic and general misinformation, the study said.