Does Alzheimer’s Start in the Gut? Part 1
A new study shows that gut microbes may lead to Alzheimer's disease.
“With something like cancer, there is a feeling that you can fight it in some way or control your response to it, but with dementia there is the fear of losing control of your mind and your life.” —Kevin Whately
A recent study from a group of researchers at University College Cork (UCC), in Ireland, has found that symptoms of Alzheimer’s can be transferred by gut microbes. This has major ramifications for the prevention and treatment of this horrible malady.
Alzheimer’s is an intractable disease that afflicts one in nine people over the age of 65. It leads to a progressive decline in cognitive function, memory, and behavior. There are no cures, even after decades of research. It is characterized by the accumulation of amyloid beta, a protein that builds up between nerve cells in the brain and is a common target of drug treatments.
However, some people with amyloid beta do not show symptoms of dementia, and some people with dementia do not have amyloid beta in their brains. Thus, amyloid beta is a less than perfect marker of the disease. In fact, there is some evidence that amyloid beta is part of the brain’s defense against inflammation, and therefore is more like the fireman at the fire than the arsonist.
The hundreds of drugs created to treat amyloid beta have not made much of a dent in the rates of Alzheimer’s and many researchers believe it is time to reevaluate the amyloid theory altogether. That is why this new study is so important: It posits a new way of looking at the disease and potentially offers a hopeful way to prevent or even treat Alzheimer’s.
What they found
The study, by Yvonne Nolan, Stefanie Grabrucker, Sandrine Thuret, Annamaria Cattaneo, John Cryan, and colleagues, transferred fecal matter from people with Alzheimer’s to rats, and found that doing so impaired nerve growth in the rat hippocampus, a part of the brain responsible for memory, cognition, and mood. The more severe the donor’s disease, the greater the cognitive loss in the rats. As they put it, “Our findings reveal for the first time that Alzheimer’s symptoms can be transferred to a healthy young organism via the gut microbiota, confirming a causal role of gut microbiota in Alzheimer’s disease.”
Alzheimer’s research has long suffered from low expectations and failure, so this is a heartening breakthrough. Importantly, it demonstrates causality, and cross-species causality to boot. The study used rats, so it awaits clinical confirmation. What works in rats often fails in humans, so caution is warranted.
Still, it’s a powerful finding. Revealing a possible microbial root of the disease is especially cheering because we can control our gut microbiota.
Next week, we’ll look at how you can start to dementia-proof your gut microbiota to minimize your odds of getting Alzheimer's. Don’t forget to subscribe so you don’t miss it!
References
Grabrucker, Stefanie, Moira Marizzoni, Edina Silajdžić, Nicola Lopizzo, Elisa Mombelli, Sarah Nicolas, Sebastian Dohm-Hansen, et al. “Microbiota from Alzheimer’s Patients Induce Deficits in Cognition and Hippocampal Neurogenesis.” Brain, October 18, 2023, awad303.
Connell, Emily, Gwenaelle Le Gall, Matthew G. Pontifex, Saber Sami, John F. Cryan, Gerard Clarke, Michael Müller, and David Vauzour. “Microbial-Derived Metabolites as a Risk Factor of Age-Related Cognitive Decline and Dementia.” Molecular Neurodegeneration 17, no. 1 (June 17, 2022): 43.
Du Preez, Andrea, Sophie Lefèvre-Arbogast, Vikki Houghton, Chiara de Lucia, Dorrain Y. Low, Catherine Helmer, Catherine Féart, et al. “The Serum Metabolome Mediates the Concert of Diet, Exercise, and Neurogenesis, Determining the Risk for Cognitive Decline and Dementia.” Alzheimer’s & Dementia 18, no. 4 (2022): 654–75.
That's the new theory, but we are still pumping millions of dollars into the amyloid hypothesis. My money is on a microbial cause, but only time will tell!
Amyloid plaques on the brain possibly more from fighting inflammation than Alzheimers itself. "...therefore is more like the fireman at the fire than the arsonist."