Cholesterol metabolism remains a focus in the work of Nir Barzilai on the genetics of the long-lived. "A gene variant linked to living a very long life - to 90 and beyond - also serves to help very old people think clearly and retain their memories ... Known as CETP VV, [this] protein affects the size of 'good' HDL and 'bad' LDL cholesterol, which are packaged into lipoprotein particles. Centenarians were three times likelier to possess CETP VV compared with a control group representative of the general population and also had significantly larger HDL and LDL lipoproteins than people in the control group. Researchers believe that larger cholesterol particles are less likely to lodge themselves in blood vessels. So people with the CETP VV gene (and the larger cholesterol particles they produce) run a lower risk of heart attacks and strokes, which may explain their unusual longevity. ... CETP VV also protects the cognitive integrity of the brain - either through the same vascular 'anti-clogging' benefit that prevents heart attacks and strokes or through an independent protective mechanism that remains to be found."