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For those who carry a mutation in a gene called presenilin 1, a dementia diagnosis is typically guaranteed.
In a normal brain, presenilin 1 makes a protein that aids in chopping up the long, stick amyloid precursor protein. Then, the smaller bits are washed out of the brain with no problem.
However, when presenilin 1 is mutated, like in around 1,000 members of one Colombian family, there’s a kink in the chopping process which creates an abundance of amyloid which ultimately plaques between brain cells.
All of these family members have or will develop full-blown dementia by age 50. Except for one woman who evaded her seemingly inevitable diagnosis.
The woman who escaped Alzheimer’s
The details of the Colombian woman’s case were reported in the journal Nature Medicine. The Harvard researchers omitted the woman’s name and precise age for privacy purposes.
Her entire family’s participation in consistent Alzheimer’s research has been invaluable to researchers. Moreover, the disease is simply accepted as a part of this family’s lives. “If I have the disease, I know that my family, my brother and my sister, will take care of me. And if I don’t, I will take care of them,” one of the family members told immunologist and aging expert Richard J. Hodes, director of the National Institute on Aging in Bethesda, Md.
So, researchers were surprised when one member of the Colombian family stayed sharped all the way into her 70s. They arranged for her to travel to Boston in 2016, along with a research assistant and some of her family members.
When she arrived in Boston, Yakeel T. Quiroz, a neuroimaging researcher, used brain scans to measure her amyloid levels and other markers of brain health. What Quiroz found was a brain full of amyloid buildup — “pretty much the highest that we have seen in anybody we have scanned so far,” Quiroz told ScienceNews.
So how did she escape dementia?
The brain-protecting gene
Genetic analyses of the woman’s brain revealed that, along with her presenilin 1 mutation, she also had what’s called the Christchurch mutation. The latter mutation was, for years, protecting her brain from early-onset Alzheimer’s.
The Christchurch mutation’s role as a shielding mechanism came as a huge surprise to the researchers. And though they need to do more work to confirm and understand how the Christchurch mutation protected her brain, scientists can now say that amyloid buildup itself is not necessarily a precursor of early dementia.
Though amyloid pileup in the brain is typically indicative of oncoming full-blown Alzheimer’s, this woman has told a different story — one that provides significant hope for the future of dementia research.
