TL;DR Shingles vaccines reduces chances of dementia by 20%. Yet, most countries health systems only look at the upfront cost of ~$300 and don’t recommend for all who could benefit.
In a separate article the other factors are quoted with similar impact (listed in order of max potential magnitude) - anti depression treatment - education increases - hearing improvement - obesity reduction - low alcohol The earlier you start the better.
Injecting people with a shingles vaccine is far easier than the others you listed, which is why it stands out.