Official investigation into New Brunswick’s mysterious brain disorder finds no new condition

“The oversight committee has unanimously agreed that these 48 people should never have been identified as having a neurological syndrome of unknown cause, and that based on the evidence reviewed, no such syndrome exists," said Jennifer Russell, chief medical officer of health for the Canadian province. "Public Health concurs with these findings. But I stress again, this does not mean that these people aren’t seriously ill. It means they are ill with a known neurological condition.”

The report’s authors say the 48 cases in what was thought to be a cluster were randomly allocated to pairs of neurologists who reviewed them and presented their findings to an oversight committee of six New Brunswick neurologists and other officials. The committee said none of the cases met the full criteria of the case definition.

But that finding, coming at the end of an investigation marred by accusations of opacity from the start and allegations that Canada’s top scientists and experts from around the world had been abruptly shut out of the process, appeared unlikely to assuage alarm in the province and more likely to deepen mistrust.

A mysterious, devastating brain disorder is afflicting dozens in one Canadian province

What doctors thought could be a new disorder was first identified by Alier Marrero, a Moncton-based neurologist, in 2015. Over the next several years, he was visited by patients who he said presented with a baffling and incapacitating range of symptoms common to Creutzfeldt-Jakob disease, a rare and fatal brain disorder.

They suffered from atypical anxiety, depression, sleep disorders and brain atrophy. They had blurred visions and memory problems, unexplained weight loss and terrifying hallucinations that made them afraid to go to sleep. Some had muscle jerks so severe that they couldn’t be controlled with strong medication. One symptom, particularly devastating for loved ones, was Capgras delusion, a belief that family members have been replaced by impostors.

Marrero ran a battery of tests, looking for autoimmune disorders, metabolic deficits, cancer and genetic disorders. There were no answers.

The 48 patients — all but two were identified by Marrero — in the supposed cluster ranged in age from 18 to 85 and lived primarily in Moncton and New Brunswick’s Acadian peninsula. There have been 10 deaths.

The cluster was detected by the federal public health agency’s Creutzfledt-Jakob disease surveillance system, which monitors for CJD and other prion diseases. They occur when misfolded proteins build up and cause normal proteins in the brains to misfold.

Tests for CJD came back negative. Brain autopsies for several of the dead — the gold standard for confirming a diagnosis — displayed no hint of a known prion disorder.

Federal public health officials in 2020 identified the cases as a cluster meriting further investigation. Doctors began to think that they were dealing with something new, including a novel prion disorder or a syndrome caused by an environmental toxin.

The committee said that a confirmed case must involve rapidly progressing dementia, at least four clinical features with most manifesting within the first 18 to 36 months of the illness, one or more supporting investigations and insufficient evidence for another diagnosis. None of the cases met the threshold.

In October, the provincial public health agency reported that a survey that was distributed to patients in the cluster did not identify specific behaviors, environmental exposures or foods that could be risk factors.

Scientists interviewed by The Washington Post last year said that it could take years to conduct an investigation into the disorder. They said the pandemic had slowed the work of interviewing patients and their family members and conducting environmental samples.

Concerns about opacity have plagued the investigation.

The federal CJD surveillance system brought the province into its investigation in December 2020, and a draft case definition was compiled the next month. But the public wasn’t made aware of a possible cluster until March 2021 — and only because the Canadian Broadcasting Corp. had obtained a leaked memo.

Meanwhile, local and international media reported that federal scientists had been shut out of the investigation and that the questionnaire that was distributed to residents was insufficient. A whistleblower told The Guardian that there were far more suspected cases than were being publicly acknowledged.

Marrero stood by his theory.

“I believe that there is an unknown disease for which I see more and more cases and more and more young people who must have a diagnosis and who deserve to have a thorough research by teams, experts in the field, nationally and even internationally,” he told Radio-Canada last month.