This is the same as all health research. We don't do controlled studies for ethical reasons, so we end up with lots of confounds. There are lots of clever ways

This is the same as all health research. We don't do controlled studies for ethical reasons, so we end up with lots of confounds. There are lots of clever ways to eliminate those confounds, and current research is considered sufficient to find a correlation between high blood pressure and heart disease, heart failure, stroke, kidney damage, vision loss, memory loss, and cognitive decline. There could be confounds not yet considered yet, but after reading a lot of research myself, I believe this is causative. HOWEVER, we should put this in context. Apologies in advanced for switching to cholesterol for this example. For example, from memory, total cholesterol above 7mmol/L increases the risk of heart attack by around 20%. Your average typical annual risk of having a heart attack is 0.23%, so high cholesterol increases this to 0.28%. That's still low in nominal terms. Smoking, on the other hand, can increase risk of hart attack by as much as 700%. This raises one's annual risk to 1.61%. Still low in nominal terms, but much higher than high cholesterol. Now consider the many other factors we control, like diet, pollution, exercise, stress, and alcohol and other drugs. These mediate the nominal risk further still. My current position is to lead a healthy lifestyle while individually combating the clearly bad lifestyle choices like smoking. I don't smoke anymore because it's so obviously hazardous that the benefits are not worth it. I might consider taking statins in the future if the side effects are few.