They All Got Mysterious Brain Diseases. They’re Fighting to Learn Why.

In late 2018, after an otherwise-normal Christmas holiday, Laurie Beatty started acting strange. An 81-year-old retired contractor, he grew unnaturally quiet and began poring over old accounting logs from a construction business he sold decades earlier, convinced that he had been bilked in the deal.

Over the course of several days, Beatty slipped further into unreality. He told his wife the year was 1992 and wondered aloud why his hair had turned white. Then he started having seizures. His arms began to move in uncontrollable jerks and twitches. By the end of May, he was dead.

Doctors at the Georges-L.-Dumont University Hospital Center in Moncton, the largest city in the province of New Brunswick, Canada, zeroed in on an exceedingly rare condition — Creutzfeldt-Jakob disease, caused by prions, misfolding proteins in the brain — as the most likely culprit. The doctors explained this to Beatty’s children, Tim and Jill, and said they would run additional tests to confirm the post-mortem diagnosis. Three months later, when the siblings returned to the office of their father’s neurologist, Dr. Alier Marrero, that’s what they were expecting to hear. Instead, Marrero told them that Laurie’s Creutzfeldt-Jakob test had come back negative. “We were all looking at one another,” Tim says, “because we were all very confused.” If Creutzfeldt-Jakob hadn’t killed their father, then what had? What Marrero said next was even more unsettling.

“There’s something going on,” they recall him saying. “And I don’t know what it is.”

It turned out that Laurie Beatty was just one of many local residents who had gone to Marrero’s office exhibiting similar, inexplicable symptoms of neurological decline — more than 20 in the previous four years. The first signs were often behavioral. One patient fell asleep for nearly 20 hours straight before a friend took her to the hospital; another found himself afraid to disturb the stranger who had sat down in his living room, only to realize hours later that the stranger was his wife.

But these anxieties and sleep problems quickly gave way to more acute presentations: limb pain and trouble balancing, teeth chattering and shocklike muscle spasms so violent that some patients could no longer sleep in the same bed as their spouses. Many patients developed vision problems; some experienced terrifying hallucinations. (“Like daydreaming,” Marrero says, “but a nightmare.”) As the sickness continued to manifest, muscles wasted away and cognitive decline set in. Some patients died; others plateaued in various states of distress.

In each case, Marrero struggled to determine a definitive diagnosis. The symptoms belonged to a broad spectrum of neurological disorders, but there was always something starkly atypical about the patients’ presentation. Their decline was too swift, or not swift enough; they lacked key indicators of a particular disease; or they failed to respond to known therapies, a hallmark of how neurologists diagnose conditions. Even more alarming, many of the patients were unusually young. Nearly half were middle-aged, and a few were in their 20s and 30s. At a presentation to a panel of experts at the University of British Columbia, Marrero recalled “crying out for help,” as he puts it. “What else can I do in terms of testing? What am I missing?”

The Beattys say Marrero explained that he had other patients in similar situations, but because of confidentiality laws, he couldn’t say more. “We were scared to death,” Tim told me. He and Jill wondered whether some overlooked genetic factor might put them at risk for the same fate as their father.

Because many of the symptoms resembled those of Creutzfeldt-Jacob, Marrero had been reporting each case to the Creutzfeldt-Jacob Disease Surveillance System, a federal monitoring program within the Public Health Agency of Canada, and as his referrals began to pile up, scientists at the agency had started to take notice. Six months after Marrero revealed his concerns to the Beattys, a working group of experts was convened to investigate. By then, Marrero had come to believe that his patients were suffering from a previously undescribed illness. “When you have not seen something,” he later told a reporter, “it is very likely that we have not learned to see it.”

His federal colleagues were inclined to agree. According to P.H.A.C. scientists, both the number of undiagnosable patients and, more important, their ages were “unprecedented at the national and provincial levels.” They called it the “New Brunswick neurological syndrome of unknown etiology.” In March 2021, when a memo alerting local doctors to the existence of the mysterious illness leaked to the press, the news made headlines around the world. Marrero’s patients and their families hoped that an explanation for their suffering would soon be revealed.

Three years later, however, no satisfactory explanation has been found, and the New Brunswick syndrome remains shrouded in mystery — and controversy. At the heart of the matter is the question of whether something in the environment may be responsible, at least in part, for the onset of the patients’ illness. It’s a question that underscores not only the tangled relationship between public health and patients’ rights, but also the inherently confounding nature of neurological conditions. In the absence of answers, what began as a puzzling medical mystery has been transformed into a situation rife with suspicion: accusations of nefarious plots to silence doctors, scientists’ leaking internal documents and a growing community of patients and advocates intent on proving the government’s hand in a coverup.

“We don’t have tinfoil hats,” Tim Beatty said of the provincial government last year. “But if you are looking to breed a group of people to believe in a conspiracy theory, they have done a fantastic job.”

Neurodegenerative diseases are among the leading causes of death and disability worldwide, yet their origins largely remain mysterious. We don’t know what triggers them in some people over others or exactly how the interplay of various risk factors contributes. Genetics clearly play a role, as do aging and lifestyle considerations like smoking and heavy drinking. But genetics alone account for only a small percentage of cases of the best-known brain disorders — Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis, or A.L.S. The remaining cases appear to be a product of a complex interplay of genetic predisposition and environmental factors, including exposure to toxic substances, which a growing number of researchers believe may be responsible for triggering the onset of degeneration. The precise mechanisms behind that triggering, however, remain stubbornly elusive.

This is partly down to the newness of the science. It was only in the early 1980s that the first tangible evidence connecting a toxicant with neurodegeneration came to light. In a tragic experiment of nature, a group of drug users in California accidentally injected themselves with a bad batch of designer heroin and began suffering from symptoms closely resembling those of Parkinson’s disease. Investigators traced the batch to a back-alley chemist who had synthesized the drugs and found that he had mistakenly created a neurotoxin precursor known as MPTP as part of the concoction. As it turned out, MPTP also resembled aspects of the chemical makeup of paraquat, a common herbicide, opening the door to the notion that perhaps chronic exposure to synthetic toxins was triggering Parkinson’s in aging patients the same way that the bad batch of heroin had in the users. Since then, advancements in molecular and genetic testing have continued to reinforce the idea. Recent studies have linked brain disorders with chronic exposure to cyanobacterial blooms, pesticides, air pollution and numerous other toxicants. Some researchers have gone so far as to describe Parkinson’s disease in particular as “man-made.”

Despite the growing consensus, the link remains diabolically difficult to prove. After all, it’s not ethical to feed people toxic substances and then watch them get sick. Scientists are largely constrained to studying a given toxin’s structure and effects in a lab setting, or trying to connect the dots between disease clusters on the ground and the presence of that toxin in the environment. Even then, the surrounding variables are so complex and numerous that proving a definitive connection is nearly impossible. Complicating the issue further is the fact that many symptoms of neurological diseases overlap, making a definitive diagnosis hard to pin down even under ideal circumstances.

In New Brunswick, the evidence for a shared environmental contaminant was strong. The patients were grouped in two primary locations: the Moncton area and the Acadian Peninsula, a francophone region home to picturesque fishing villages and blueberry farms along New Brunswick’s northeast coast. Investigators wondered whether a common source of food or water might explain the geographic clustering. There were also a number of households with multiple patients who were not genetically linked: husbands and wives, stepfathers and stepdaughters, a nursing student and her ward. These “close contact” cases were difficult to explain outside of a common exposure.

The hard part was figuring out what that exposure might be. During weekly meetings in the spring of 2021, Marrero and his colleagues consulted experts in zoonotic disease, water science and pathology in an effort to whittle down a long list of hazardous environmental agents to a select few worth targeting in their research. The goal was a full-scale epidemiological study — “boots on the ground,” as one senior scientist put it — including interviews, diagnostic tests and environmental and tissue sampling. Many of the scientists saw the situation as a rare opportunity: If this potential cluster of patients really was being caused by a toxic substance, it would offer a rare chance to study the toxin-brain relationship in real time.

Initially, government support for the study was robust. At a briefing in April 2021, Dr. Theresa Tam, the country’s chief public-health officer, advised the working group to engage the widest expert network possible and ensured that the investigation wouldn’t be tied up in bureaucracy. The Canadian Institutes of Health Research offered the province $5 million to help fund a two-year clinical investigation.

But then something changed. A month later, on the afternoon of May 6, 2021, an email from the provincial health department began to circulate saying that all currently scheduled meetings would be “paused” until provincial researchers “had the time to delve more deeply into existing data.” Meetings that had been planned months in advance were wiped from the calendar. Field experts and neurologists were left waiting on Zoom links that never came. “There was a stop, suddenly, abruptly, with no apparent explanation,” says Marrero, who called the decision “unusual by any standards.”

Things grew even murkier 10 days later, when Marrero says he got a call on his cellphone from Dr. Hanan Smadi, the province’s acting lead epidemiologist, telling him to stop reporting potential new cases to the provincial authorities. Marrero was appalled. The number of patients in the cluster — at the time 48, eight dead — was continuing to rise. According to Marrero, when he asked where the request was coming from, Smadi told him, “It comes from higher up.” The province also sent a note to the federal authorities asking them to take a “step back from public communications” because of “heightened sensitivities in New Brunswick,” a request that one senior scientist told a reporter from a Canadian magazine was tantamount to being “muzzled.” (Public Health New Brunswick says that Smadi never reached out to Marrero and told him to stop reporting cases. The agency declined to make its employees, including Smadi, available for comment.)

Provincial officials would later claim that their reason for pausing the federal working group’s involvement was largely jurisdictional — because the patients in the cluster were from New Brunswick, it was the province’s responsibility to lead an investigation — and a few weeks later, Dorothy Shephard, New Brunswick’s health minister at the time, announced a province-run surveillance study to examine potential dietary and geographic links between cluster members, as well as an oversight committee that included six neurologists to independently investigate the unknown illness. The new committee would, as the announcement put it, “provide expert second opinions” and “rule out other potential causes.” Unaware at the time that the federal scientists had been sidelined, patients and their advocates celebrated the news.

Internal emails from that period, however, call the province’s rationale into question: They appear to show New Brunswick officials strategizing to keep the investigation from spreading to the federal level. In one example, Smadi notes that two cluster patients who had moved out of the province should not be interviewed specifically because their inclusion would make the effort multijurisdictional.

Suspicions also quickly surfaced about the objectives of the study Shephard had promised. A few days after the announcement, Kat Lanteigne, a New Brunswick native and a founder of BloodWatch, a nonprofit that promotes a safe public blood system in Canada, received a cryptic text on her cellphone from an anonymous source claiming that the province was not taking its investigation seriously.

Lanteigne began asking around among sources in both the provincial and federal governments and was disturbed by what she learned. Rather than implementing the “boots on the ground” approach recommended by the federal scientists, it appeared that New Brunswick officials had decided instead to relitigate the working group’s original findings — namely, whether a cluster of patients existed at all. They apparently were not even trying to investigate the possibility of a toxicant: “Not one single environmental sample had left the province,” Lanteigne says. “Not water, not food.” If the oversight committee concluded that the patients weren’t linked by a common condition, then there was little point in a strapped public-health department trying to find one. “I think they’ve pulled the plug from the wall and nobody knows,” Lanteigne remembers thinking.

Lanteigne reached out to Steve Ellis, who started a Facebook group for patients and family members after his own father, Roger, was referred to Marrero, and told him what she had learned. “Do you want to fight back?” she asked. Before long, Ellis amassed a cohort of patients and family members who shared deep misgivings about the province’s methods. For one, the investigation was happening almost entirely in secret. Not only was Marrero kept at a distance, ostensibly so that he wouldn’t bias the work of the oversight-committee neurologists, but so were the patients. “We had no idea what was going on,” says Stacie Quigley Cormier, whose daughter Gabrielle Cormier was the youngest confirmed case in the cluster. “There was just crickets on all ends.” The patients had invested so much hope in the possibility of an answer that the silence became maddening. Gabrielle, then 20 years old and struggling to walk without the help of a cane, asked to be checked into a hospital for psychiatric support while her family waited to hear from the public-health officials in charge.

In October 2021, news arrived that further complicated the case. Dr. Gerard Jansen, the neuropathologist in charge of autopsies for the eight cluster patients, had published a shocking conclusion: All eight patients died not from a mysterious illness but from known diseases, including cancer, Lewy body dementia and Alzheimer’s disease. Tim Beatty was driving to work when he heard on the radio that the autopsy results had been made public. “I can literally point on the road where I was,” he says, “because I almost drove off.”

As it turned out, Jansen had stopped believing in the cluster months before the autopsies leaked. In an email to colleagues that May, he offered what’s known in the world of public health as a “null hypothesis,” the premise that there is no relationship between findings until overwhelming evidence proves otherwise. Jansen hadn’t seen any signs of a uniform pathology in the brains of patients during the autopsies and was wary of the various theories put forward by the working group. “The available evidence,” he wrote, “actually suggests directly that this cluster does not exist.”

When I asked Marrero about the autopsy results, he told me he was taken aback by the authority with which Jansen presented them. “Causality is not for the pathologist to establish,” he said. Marrero didn’t doubt that Jansen had found evidence of numerous diseases, but that didn’t exclude the possibility that those diseases might have been triggered by something in the environment. “People exposed to heavy metals sometimes develop Parkinsonism, sometimes develop cancer, sometimes develop severe neuropathy,” he explained. “But it’s still exposure to heavy metals.”

In the context of a cluster of atypical cases that had stumped some of the most experienced scientists in Canada, Marrero believed that Jansen had not only overstepped his bounds but had failed to address the situation’s most critical questions: “Why so many young? Why so many in one area? Why so many in one family?” Many of Marrero’s colleagues in the working group agreed. In a leaked email from last year, one of them referred to Jansen’s findings as a “‘loophole’ through which the politicians have eagerly leaped to conclude nothing coherent is going on.”

For patients and their advocates, the release of Jansen’s findings was a turning point. “That’s when we said, ‘Gloves are off,’” Jill Beatty told me. Ellis’s Facebook group became a clearinghouse for ideas about how to counter the official narrative. There was talk of the patients crowdfunding environmental testing themselves and of inviting Erin Brockovich to do an outside investigation. Ellis began appearing on podcasts and TV demanding that the federal experts be invited back to New Brunswick. Lanteigne and others filed so many freedom-of-information requests that Marrero says provincial officials contacted him wondering whether he had hired a private investigator.

But the patients’ efforts left them no closer to answering the questions fueling the controversy. Why had the province declined the help of the federal experts? And considering the ambiguity of the science, why weren’t they also testing for toxic substances? In lieu of satisfactory responses from officials, theories of all kinds began to circulate, from bureaucratic incompetence to conspiracies blaming the influence of malevolent corporate interests. Marrero’s position was perhaps the most popular. “I think that what created the scare was the word ‘environment,’” he told me last summer. He believes that in the spring of 2021, as a tangible plan for testing New Brunswick’s air, soil and water began to materialize, the province got cold feet. Forestry, tourism and seafood are among the region’s most prominent — and profitable — industries, all of which rely on a healthy environment to thrive. If testing revealed that New Brunswick’s environment was compromised, it could spell disaster for the provincial economy.

While Marrero’s theory was pure speculation, a number of experts involved in the working group also came to believe that political forces had eclipsed scientific ones. Citing concerns over how their statements might affect their access to public funding, these experts declined to speak on the record, but one sentiment appeared ubiquitous among the group: By limiting their investigation at the outset, provincial officials had squandered a rare opportunity for advancing the kind of broad scientific inquiry that a full-scale study offered. “We have an unbelievably capable set of tools to look at biological and epidemiological and environmental characteristics,” one senior scientist explained to a reporter from The Walrus, a Canadian magazine, shortly after the working group was sidelined. “It’s amazing, the potential that is not being tapped.”

Marrero felt as if he was in a bind. As the neurologist of record, he was still needed to provide consent forms to the oversight committee, and he encouraged patients to comply with the province’s inquiry. But he maintained his belief that the illness was triggered by something environmental — which he believes made him a target. In a letter to Dr. Jennifer Russell, the province’s chief medical officer of health, he complained that his efforts were “being sidelined with attempts to dismiss my concerns and my pleas and create hurdles.” During appointments, he started quieting patients with a finger before checking the hallway to see if someone from the hospital brass was listening in.

Over time, his nerves began to fray. During our conversation, he told me gravely about an incident a few years ago when he was followed by a man in a blue car as he drove from his home to a television interview in an industrial section of Moncton. At the studio building, he asked the show’s producer to come down; when she appeared, the other car sped away. “I could have an ‘accident,’” he said, “and no one’s going to know.”

On Feb. 24, 2022, Russell announced that the oversight committee had finished its work. The survey, she said, ‘‘could find no common exposure in the group.’’ It was the same conclusion that Jansen, the neuropathologist, reached after his autopsies. In short, the syndrome didn’t exist.

In their final report, provincial health officials explained what they believed had gone wrong. They argued that the case definition for the illness was overly broad, to the point that it overlapped with other conditions. Because of that, no human-tissue testing was needed. They also singled out Marrero for not seeking second opinions before referring patients to the cluster, an assertion he rejects. He notes that in 2021, the working group had offered second opinions in a number of cases, going so far as to remove a few from the cluster. Marrero says he also spent countless hours discussing the situation with Dr. Neil Cashman, one of Canada’s foremost neurologists, and Cashman later agreed to go to New Brunswick to meet with patients face to face before the province’s inward turn scuppered the plan.

In recently leaked emails, Marrero’s federal colleagues also appeared to reject the province’s findings. “It seems that the best interests of those affected have not been at the forefront of the actions taken,” wrote Dr. Samuel Weiss, a neuroscientist working for the federal agency that offered the $5 million to fund the investigation. “How this has and continues to be the case — is part of a larger mystery around the intentions of the Government’s focus on politics, power and process — over the humanity of care.” Dr. Michael Coulthart, head of the federal surveillance system for Creutzfeldt-Jakob disease, was even more direct. “My scientific opinion is that there is something real going on in NB that absolutely cannot be explained by the bias or agenda of an individual neurologist,” he wrote in an email to colleagues. He, too, felt that the decline in Marrero’s patients was most likely caused by an environmental trigger. “I believe the truth will assert itself in time,” he concluded.

For the patients, the government’s report was a devastating blow. Before its release, they began receiving letters from provincial health officials detailing different diagnoses for their physicians to consider. Gabrielle Cormier was told she might be schizophrenic. Ellis was told that his father might have progressive supranuclear palsy. The committee hadn’t seen either patient in person; it based its second opinions on medical charts alone, a particularly challenging assignment considering the nuance involved in diagnosing neurological conditions. As it turned out, those two specific conditions had been ruled out by specialists before either Cormier or Ellis had been referred to Marrero. In fact, in Ellis’s case, it had been ruled out by one of the neurologists on the oversight committee itself.

Other cluster members were provided with possible diagnoses of cancer, alcohol-induced brain damage, H.I.V. and a broad range of dementias, all of which were dismissed by testing years earlier. The patients were now being told to return to the same doctors who had been so perplexed by their symptoms that they referred them to Marrero. The circular logic of it was particularly insulting because there was no other recourse. The final report had been issued. The case was closed. “It just felt like the ultimate betrayal,” Ellis said. “My father has paid taxes his entire life in New Brunswick, is languishing in a care home, and no one federally or provincially is doing anything anymore to help him.”

The province has maintained that its investigation was scientifically sound and that the Public Health Agency of Canada supported the results, but implicit in its version of events was a sobering concession. According to provincial officials, the patients were suffering not from an unknown illness but from incurable diseases that are known all too well. And they were doing so at rates, especially among young people, that were shockingly high.

Last year, I met Marrero at a hotel in Moncton overlooking the Trans-Canada Highway. He was dressed in a finely tailored gray suit and introduced himself warmly. As we rode the elevator to my room, however, it became clear that his dark suspicions had yet to abate. Before our meeting, he refused to speak with me over his work phone and was hesitant to talk in the hotel conference room. He hadn’t spoken to the press in nearly 18 months. “If I was thinking strictly in terms of me as an individual and as a physician, it’s better I don’t talk,” he explained. His lawyer had advised against it. Marrero, however, felt dutybound. “I have to provide answers to people who are sick,” he said. “And to do everything I can do for them.”

Marrero told me that since the province concluded its investigation, things had gotten worse. The number of undiagnosable patients currently under his care has risen to more than 430, 111 of whom are under age 45. Thirty-nine have died. By Marrero’s accounting, New Brunswick is now the center of one of the most prolific young-onset dementia clusters in the world. “Nobody who was involved in this can pretend they didn’t know,” he said.

There had been clinical developments as well. In December 2022, Marrero found a toxicology lab in Quebec that was willing to test patients for four different types of pesticides, including glyphosate, a herbicide that is regularly used as part of the forestry industry in New Brunswick. He had noticed a pattern of new referrals peaking in the late summer and early fall, when pesticide use is at its highest, and wondered if there could be a connection. When the lab accepted a sample from one patient, Marrero quickly sent over a hundred more. The results were astonishing. Ninety percent of Marrero’s patients came back with elevated amounts of glyphosate in their blood, in one case as high as 15,000 times the test’s lowest detectable concentration.

On their own, the results mean little. Without a control group, it’s impossible to understand the results in context. Perhaps everyone in New Brunswick has elevated levels of glyphosate because of spraying in the province. The findings do, however, align with an increased push throughout Canada and the world to recognize the risks that chemicals like glyphosate pose to human health. Part of the reason Marrero was able to get the tests done in Quebec was that in 2021 the province officially recognized the link between glyphosate and an increased risk for Parkinson’s disease. Recent studies have shown that glyphosate crosses the blood-brain barrier and that chronic exposure can lead to neurological inflammation that can trigger Alzheimer’s disease. “I am not concluding that this is the cause of what is happening,” Marrero said. “But it is something that is telling me that something is wrong with the environment they live in.”

Marrero’s conviction notwithstanding, the fact remains that the situation in New Brunswick has raised far more questions than answers. Was the epidemiological study blocked by political or corporate interests, as Marrero told me he suspected? Or was he an overzealous physician who had rushed to stamp his name on a novel disease, as the province’s report implied? And of course the answer to the most fundamental question of all — what exactly is making New Brunswickers ill? — remains elusive.

What does seem clear, however, is that the collision of politics and science unfolding there is unlikely to remain exclusive to the province. As the evidence linking neurological disorders and environmental factors continues to grow, the way in which diseases manifest in the human body will undoubtedly be altered as well. It’s not difficult to imagine the next puzzling disease cluster right around the corner.

It’s a concern that keeps Marrero up at night. “This is a collective effort that is needed,” he said. “Not only for the people here in New Brunswick, but because whatever is causing this might be happening elsewhere.” He has already received referrals from a half-dozen other Canadian provinces. When I asked how he thought the situation would play out over the long term, he was uncertain. “I don’t pretend to have the answer,” he said. “I think science should be the answer.”

Brendan George Ko is a visual storyteller based in Toronto and Maui who works in photography, video, installation, text and sound. He recently had a solo exhibition at the Patel Brown gallery in Toronto.