In the search for more effective treatments for Alzheimer’s disease, a new clinical trial will test whether a prevention drug has any effect on patients who are genetically predisposed to develop the disease, but who don’t yet exhibit symptoms. In the study, scientists are focusing on members of a large, extended family in Medellín, Colombia, some of whom have a specific genetic mutation that is linked to early-onset dementia. The trial will be “the first to focus on people who are cognitively normal but at very high risk for Alzheimer’s disease,” said Dr. Francis S. Collins, director of the National Institutes of Health (NIH), in a May 15 interview with the New York Times.

Members of the Colombian family who have the genetic mutation begin showing cognitive impairment around age 45 and develop full dementia by age 51. Three hundred family members, some as young as age 30, will participate in the initial trial.

The five-year study is a collaboration between the NIH, the nonprofit Banner Alzheimer’s Institute, Genentech (maker of the drug crenezumab, which will be used in the trial), and the University of Antioquia in Medellín. The trial will help to test the amyloid theory of Alzheimer’s, which holds that the disease is caused by a steady buildup of the beta amyloid protein. Some results of the trial—specifically those that address whether the drug can delay memory decline—may be available in as little as two years, according to study leader Ken Kosik, codirector of the Neuroscience Research Institute at University of California, Santa Barbara.

Although only a small percentage of people with Alzheimer’s have the genetic early-onset form, researchers expect the trial to yield information that will help millions people who are affected more common forms of the disease. “It offers a tremendous opportunity for us to answer a large number of questions, while at the same time offering these people some significant clinical help that otherwise they never would have had,” said Dr. Steven T. DeKosky, an Alzheimer’s researcher from the University of Virginia School of Medicine, in the New York Times article.

To learn more about this and other ongoing studies of Alzheimer’s disease, visit the NIH’s National Institute on Aging Web site.