Alzheimer's & cognitive aging
Debbie frames Alzheimer's prevention as something that has to start one to two decades before symptoms, because the damage begins long before memory problems appear. Across her posts, the common endpoint is neuroinflammation, fed by circadian disruption, oxidative stress, and pathogens or molecules that reach the brain. Newer research leads her to see the blood-brain barrier as the common thread tying together amyloid, tau, APOE4, pathogens, and inflammation, with amyloid and tau possibly acting as part of the brain's immune defense. She also keeps connecting the brain to the gut and mouth, where microbes and their metabolites can reach the brain and drive disease.
How it connects
In APOE4 carriers especially, astrocytes build up excess fibronectin around brain blood vessels, making the blood-brain barrier leaky, letting in fibrinogen and pathogens, and slowing amyloid clearance.
Fibronectin, the Blood-Brain Barrier, and Alzheimer'sAmyloid-beta and tau may be part of the brain's innate immune defense against microbes such as herpes simplex 1, rather than just toxic accidents.
Herpes, Gut Bacteria, and the BrainIn mice fed a high-fat diet, gut bacteria reached the brain by traveling up the vagus nerve, even with an intact blood-brain barrier.
Herpes, Gut Bacteria, and the BrainThe gut-microbe metabolite imidazole propionate is associated with Alzheimer's biomarkers in people, and in mice it increased blood-brain barrier permeability and tau phosphorylation, which a GSK-3β inhibitor reversed.
Imidazole Propionate (ImP) and DementiaOral bacteria like P. gingivalis can enter the bloodstream through bleeding gums and have been found in Alzheimer's brains, which connects oral health to a leaky blood-brain barrier.
Alzheimer's Prevention StrategiesIn mice, the protective glycocalyx lining the blood-brain barrier thins with age, much like the gut mucosal barrier thins in the autodigestion research.
Blood-Brain Barrier: Key to Longevity and SuperAgersInterventions, strongest evidence first
Everyday steps
- Sleep in a completely dark room, turn off screens a couple of hours before bed, and get morning sunlight to support circadian rhythm and melatonin.Alzheimer's Prevention Strategies
- Cut junk foods made with omega-6-rich oils such as corn and soybean oil, which are linked to higher fibronectin levels.Fibronectin, the Blood-Brain Barrier, and Alzheimer's
- Practice good oral hygiene, try a water flosser if regular floss makes your gums bleed, and skip antiseptic mouthwash.Alzheimer's Prevention Strategies
- Eat plasmalogen-rich seafood such as mussels, clams, oysters, squid, scallops, salmon, and shrimp.Alzheimer's Prevention Strategies
- Eat more fiber-rich fruits and vegetables, which are associated with lower levels of the gut metabolite imidazole propionate.Imidazole Propionate (ImP) and Dementia