As noted above high blood pressure is strongly correlated with cognitive decline. One primary reason for that is because high blood pressure is also suggestive of and correlated with narrower less flexible, arteries, and therefore, a reduction in blood (nutrient and oxygen) flow - particularly to the brain. Here is an interesting explanation of that relationship, and how lowering your blood pressure (if on the high side) can reduce your risk for dementia.
https://www.lifeextension.com/magazine/2019/2/lower-blood-pressure-slashes-dementia-risk
How to Reduce Blood pressure safely
Here is a decent review of a variety of basic nutrients that have been shown to reduce blood pressure.
