The Disordered Mind: What Unusual Brains Tell Us About Ourselves

by Eric R. Kandel

The most significant risk factor found to date is the apolipoprotein E (APOE) gene. This gene codes for a protein that combines with fats (lipids) to form a class of molecules called lipoproteins. Lipoproteins package cholesterol and other fats and carry them through the bloodstream. Normal amounts of cholesterol in the blood are essential for good health, but abnormal amounts can clog the arteries and give rise to strokes and heart attacks. One allele, or variation, of this gene is APOE4. The APOE4 allele is rare in the general population, but it puts people at risk of developing late-onset Alzheimer’s disease. In fact, about half of the people with late-onset Alzheimer’s have this allele.