alt Hacker News> A lack of oral hygiene and gum disease is associated with nerodegeneration.
It's important to remember that association/correlation is not causality. People who brush their teeth reliably are probably more likely to exercise and do other healthy behaviors, too (avoid smoking, ...).
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It's also very possible to practice great oral hygiene and have bad gum disease. Gum disease seems to be carried by a potentially strong genetic risk factor.
As nice as this statistical thinking alone is, it can also slow things down.
There's a reason why this finding is valuable. It suggests a mechanistic hypothesis that bacteria are entering the bloodstream, heart, and passing the blood-brain barrier.
This is a very valuable line of investigation that can lead to a smoking gun for one class of casual mechanisms and potentially to preventative care or treatment.
If we blindly follow just the statistics, we'd never get any real science done.
Correlation does not imply causation. But when it gives you something to investigate, don't sit on it.
That's been studied and the evidence suggests that there is some causation. Bacteria that cause your gum disease can get into the bloodstream and reach the brain, where they release enzymes that cause inflammation and can damage cells.
In particular this can seriously impair microglial cells which is something you really don't want to have happen if you value maintaining a well functioning brain.