The major genetic risk factor for Alzheimer's disease (AD), present in about two-thirds of people who develop the disease, is ApoE4, the cholesterol-carrying protein that about a quarter of us are born with. But one of the unsolved mysteries of AD is how ApoE4 causes the risk for the disease. Researchers have found a link between ApoE4 and SirT1, an "anti-aging protein" that is targeted by resveratrol, present in red wine.