My mother was intelligent, independent, socially and physically active, didnt smoke, rarely drank, ate healthily, was slim her entire life, fitted no high risk groups, yet still succumbed to Alzheimers in her late 60s.  Every time I come across a 'new' piece of evidence that tells us something is protective against this disease, I want to scream 'but my mum did that'.  David Attenborough said 'plenty of people at 86 are in wheelchairs or have lost their marbles, it isn't virtue or eating cod liver oil, it's just luck'.  Yes, by living healthy lives, we reduce our risk of contracting a whole manner of illnesses, but it's time we accepted, some things are just bad luck.  There's alot we cannot control and we need to stop thinking it's something we did or didn't do and stop beating ourselves up.