Want to be able blow the candles out on your 100th birthday cake and actually remember what you did during all of those years? Then keep your healthy HDL cholesterol high. That’s a secret shared by long-lived people who’ve never developed memory-robbing Alzheimer’s disease: They have higher-than-average HDL levels. Participants in a recent study whose HDL was above 56 (if yours is over 50, that’s great!) were 60 percent less likely to have Alzheimer’s than those with lower HDL.