PHAC finds no evidence of mystery brain disease in New Brunswick, says patients still need answers

The Public Health Agency of Canada (PHAC) has concluded there is no evidence of a mysterious brain disease affecting hundreds of residents in New Brunswick. This follows similar findings from a January report and a 2025 study published in JAMA Neurology. Patients, including Sarah Nesbitt from Canaan Station, have reported symptoms such as seizures, confusion, spasms, and tremors.

Dr. Alier Marrero, who initially raised concerns in 2020, has suggested possible environmental factors like herbicides and metals as potential causes. However, PHAC's investigation, which examined 210 of the affected patients, found no evidence of an unusual neurological pattern or common health event. Dr. Marrero had previously evaluated around 400 patients, identifying signs of significant environmental exposure and rare autoimmune markers.

While PHAC emphasized that patients' symptoms are real, it recommended that health officials continue monitoring and supporting those who remain undiagnosed. The agency urged officials to consider new medical diagnoses and maintain data collection for future evidence of a common cause.