If diagnosed with Alzheimers I'll be dead within 24 hours
That's the only way of defeating this hideous disease. You need to die early, even if you die two years early it's still better than dying two weeks too late, as two weeks too late probably means 10-20 years too late.
If there is such a thing as an 'evil' disease, this is it. It slowly destroys you and wrecks the lives of those closest to you (for a few years at any rate), and you probably have no idea it's happening. It's like slow demonic possession, destroys you from the inside out and turns you into someone that everyone around you wishes was dead, but you have no idea.