Chicago ? People with a gene variation that blocks a cholesterol-transport protein in the body have a lower risk of developing Alzheimer’s disease, a study found.

Those that had this variation in both copies of the gene, which inhibits the cholesterol ester transfer protein, were about 70 percent less likely to develop Alzheimer’s disease during the study than those without the variation, research in Wednesday’s Journal of the American Medical Association showed.

More than 30 million people worldwide have Alzheimer’s disease, according to the London-based advocacy group Alzheimer’s Disease International. There is no cure yet for the disease, which attacks the brain and causes memory loss. Medicines called CETP inhibitors that mimic the effect of the gene variation in the study are under development by Merck and Roche Holding for cholesterol and may prove to work in fighting Alzheimer’s, said study author Richard Lipton.