We’re still far from a cure to Alzheimer’s disease, the most common cause of dementia, but the last few years have seen several promising breakthroughs in our understanding of the illness. For example, Alzheimer’s can now be diagnosed with a routine spinal tap, while ten years ago it could only be identified post-mortem. Similarly, significant progress has been made in treatment and therapy strategies. But prevention, an aspect of Alzheimer’s research that has not seen much attention in the past, has come to the forefront in the latest trial by the National Institute of Health.
One of the first major projects of America’s mission to cure Alzheimer’s by 2025, described in the New York Times, is a large-scale test of a drug designed to prevent Alzheimer’s disease. The trial is taking place in Medellin, Colombia among a clan, or enormous extended family, where a genetic abnormality (specifically, a mutated protein on a gene of chromosome 14) predisposes people to Alzheimer’s disease. In fact, everyone with this inheritable mutation gets the disease, assuming they live long enough. And “long enough” isn’t a very long time in this case, because the mutation prompts early-onset Alzheimer’s disease, which can manifest itself as early as age 35.
One reason the study is being performed on the people of Medellin is that they are nearly certain to develop Alzheimer’s unless there is some kind of intervention. The certainty of developing a terminal illness justifies the risks associated with trying a new, relatively untested drug. The same trial on the general population would not only be less enlightening, it would be unethical.
Hundreds of people are participating in the rigorous, five year, $100 million study, and participants will receive the drug before they have any signs of Alzheimer’s. The study is, by far, the largest and most serious trial into the prevention of Alzheimer’s disease that has ever been undertaken. This will help determine, with relative certainty, whether the drug prevents Alzheimer’s in people with this genetic abnormality.
But the phrase, “with this genetic abnormality,” in the previous sentence is a significant caveat: Only a small percentage of Alzheimer’s cases are caused by a genetic mutation. The vast majority of Alzheimer’s sufferers do not have this abnormality. Still, researchers intend to gain knowledge in the study that will help them fight all Alzheimer’s cases, not just those with a genetic link.
The drug being tested is called Crenezumab, and it combats amyloid plaques within the brain, which most experts agree are the ultimate cause of Alzheimer’s. The genetic abnormality, common in in the people Medellin, causes an overabundance of these amyloid plaques. But if Crenezumab decreases (or limits the creation of) amyloid plaques in these genetically predisposed people, it may be able to do the same in people without the mutation. In fact, there are already some smaller scale trials underway to test Crenezumab on people who already have Alzheimer’s related dementia.
There is no guarantee that Crenezumab will be completely effective for the people of Medellin, let alone for preventing or treating Alzheimer’s in people without the genetic mutation on chromosome 14. But scientists are hopeful that this research, whatever the results may be, will lead to an eventual cure of Alzheimer’s disease, which is the sixth leading cause of death in the United States.
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