Alas no, brain aneurysms don't have to have any outward symptoms at all until they strike, and then you're dead within minutes.

You can spot some issues before they kill you if you have a brain scan, but as you've got no symptoms, why would you be having a brain MRI once a month?

So, alas, it's a silent, deadly killer. One day you just drop dead for seemingly no reason.

RIP Grant, you were fuckin rad.

Depends. If he had an AVM (arteriovenous malformation) then that could perhaps have been treated. But finding one without before having an aneurysm is really hard. So you would need time travel + a way to convince everyone that he had an AVM and they needed to find out where it was. If he had one.

If there is, we don't know enough about the brain and how it works to find out, let alone implement it