In one of Hamster's posts she talked about her grandmother who didn't drink, etc. and may have been healthier with some "vices".
My grandmother lived until 90. She was an alcoholic who drank until she was about 80. She also had depression, but refused to take her meds most of the time.
With all of this, my grandmother had a keen mind and never forgot anything up until the day she died. As a matter of fact, we believe she willed herself to die because she decided it was time. When she went into a nursing home there really wasn't anything wrong with her except that her birthday was coming up, and she had decided that 90 was old enough.
I have no scientific proof, but always suspected that the alcohol pickled her mind, keeping her sharp all of those years. On the other hand, I dutifully take my meds, try to avoid alcohol except for the occasional binge, and my short-term memory is awful! Go figure.
Bluemountains