Friday, November 25, 2016

Where Alzheimer's is the norm

Could a village in Colombia, devastated by Alzheimer’s like no other community, generation after generation, provide clues toward developing a cure for the disease? Dr. Pierre N. Tariot, the director of the Phoenix-based Banner Alzheimer’s Institute, is among researchers who believe so. Speaking at the annual Matthew & Marcia Simons Symposium on Alzheimer’s Disease on Nov. 9 in Newton, Massachusetts, Tariot displayed a pedigree chart reflecting the misery of the town of Yarumal. “Roughly every other person was laid low with Alzheimer’s,” Tariot said. “You can see it in every generation,” dating from the 1640s. Historians have long understood that diseases brought from Europe, such as smallpox, were ruinous for native populations. But the Spaniard who founded Yarumal did not bring a sickness that killed people quickly. Far from it. Because of a genetic mutation carried by the founder, the village’s plight over the centuries has been far-reaching. And that has made it important to Alzheimer’s researchers.
As the New York Times reported back in 2010, people in Yarumal show symptoms of Alzheimer’s as early as their early thirties. The typical resident with the disease has severe symptoms by age 47. One man, a reporter noted, “babbles incoherently, shreds his socks and diapers, and squirms so vigorously he is sometimes tied to a chair.” Another man was in denial about his condition, and when he was sent to the market to buy two basic staples—bread and milk—he was able to remember only one of the two items.
Could any good come out of this suffering? Not for the villagers who are dying in agonizing and humiliating ways. But there may be hope for their children and their descendants. Rowan Hooper, writing in the journal New Scientist about a year ago, noted the work of Kenneth Kosik and his colleagues at the University of California at Santa Barbara. Hooper cited a process called “identity-by-descent analysis.” Because Kosik’s team had information on the genome sequence around the Yarumal mutation, they were able to apply the approach to the town, to get a better sense of how people in the study were related. “It’s hard to explain why all these people would share a large chunk of DNA, if there hadn’t been a common founder,” Hooper wrote.
The scientists appear to concur that the village’s founder, a conquistador who founded Yarumal around 375 years ago, brought the fateful gene with him. The strangeness of the disease is captured by a detail in One Hundred Years of Solitude by the late Colombian novelist Gabriel García Márquez. As Hooper noted, residents call the disease La Bobera (foolishness), the kind of term that characterizes the real-life town of Yarumal. In an article in the British newspaper The Telegraph, Michael Jacobs reflected on the eerie similarities between the forgetfulness of García Márquez’s characters and the real-life people suffering in Yarumal.
What is the likelihood of this previously obscure village being the place where crucial insights are learned about Alzheimer’s, including slowing the disease’s pace? Dr. Tariot told his audience in Newton that the key to stopping Alzheimer’s is to prevent it well before symptoms surface. Yarumal’s unique genetic pool could shed light on an approach that could lead to a cure.
That, of course, would not directly help those of us who already have been diagnosed with the disease. But that is beside the point. It’s our children’s generation who have the promise of a future when Alzheimer’s will have become a manageable disease. And, of course, the Yarumal residents would, over time, begin to escape from the plague that has shortened the lives of their ancestors for centuries.

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