What a pathologist discovered inside the brains of people with neurological disease
Pathologist Alan MacDonald found roundworms and Lyme bacteria in brains of those with neurological disease
Dr. Alan B. MacDonald was a board-certified pathologist who spent decades looking at disease under the microscope, including directly examining human brain tissue.
Beginning in the 1980s, he became deeply involved in Lyme disease research and investigated whether Borrelia, the bacteria associated with Lyme disease, could be found in tissues affected by neurological disease.
His work eventually expanded into questions surrounding Alzheimer’s disease, Parkinson’s disease, Lewy body dementia, multiple sclerosis (MS), and brain tumors.
What made his work particularly interesting was that he wasn't relying solely on blood tests.
He was looking directly at the tissue.
MacDonald passed away in 2026, but his decades of pathology research continue to raise questions about the possible relationship between infection, parasites, and neurological disease.
His Findings
MacDonald's research focused heavily on Borrelia and its possible presence in diseased brain tissue.
In autopsied brain tissue, he reported finding Borrelia associated with neurological conditions including Alzheimer’s disease and other forms of dementia.
But that's not all.
He also reported finding parasitic nematodes (roundworms) in brain tissue, including nematodes containing Borrelia bacteria.
In one line of research, his group reported finding Borrelia-a`ssociated nematodes in brain tissue from people with conditions including Alzheimer’s disease and MS.
And that's where things get particularly interesting. 👀
Parasites provide a hiding place for Lyme bacteria
MacDonald has proposed that certain parasitic nematodes may act as hosts for Borrelia bacteria. Lyme bacteria doesn't just float around on their own, his research showed that Borrelia can exist inside parasitic worms within human tissue.
That raised an important question...
Could an infection be much harder to detect when the organisms aren't where conventional testing expects to find them?
MacDonald has argued that examining blood alone may not tell the entire story when an organism has moved into tissue such as the brain. His research has therefore focused on examining actual tissue and using techniques such as fluorescent in situ hybridization (FISH) to identify Borrelia DNA.
What about brain tumors?
This is another area where MacDonald's work has generated questions. In collaboration with physician Nooshin Darvish, MacDonald examined tissue from five glioblastoma cases and reported detecting Borrelia DNA in the tumor tissue using FISH.
One more thing...
If you've ever been told:
“Your tests are normal.”
“It's just aging.”
“There's nothing else we can find.”
That doesn't necessarily mean there is nothing else worth investigating.
It may simply mean conventional medicine is still learning.
And that's exactly why research like this deserves to be discussed, carefully, critically, and with an open mind.
Imagine how many people have suffered from neurological diseases without ever having potential underlying infections or environmental triggers fully explored.
I'm not saying parasites or Lyme disease are the only possible contributors to neurological conditions. We know heavy metals, microplastics, environmental toxins and chronic stress also contribute.
But here's where I see hope: When we identify and address underlying contributors to illness, we create opportunities for healing.
And THAT is the beauty of a root-cause, holistic approach to health.
Want to learn more about parasites and detoxification?
If you're interested in learning more about parasites, parasite cleansing, and supporting your body's natural detoxification pathways, I've put together more information here:
Important: This article is for educational purposes only and is not intended to diagnose, treat, or cure Lyme disease, parasitic infections, neurological disease, cancer, or any other medical condition. Dr. MacDonald's findings represent a line of research and hypotheses that remain the subject of scientific investigation and should not be interpreted as proof that Lyme disease or parasites cause these conditions.
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