Why didn't she get Alzheimer's? The answer could hold a key to fighting the disease

A new study examines the case of a woman with a genetic mutation that often causes memory and thinking problems for people starting in their 40s, but she experienced no cognitive decline until she reached her 70s.

A new study examines the case of a woman with a genetic mutation that often causes memory and thinking problems for people starting in their 40s, but she experienced no cognitive decline until she reached her 70s. Another genetic mutation appears to have protected her from dementia, even though her brain has developed a major neurological feature of Alzheimer's disease, researchers report. According to the researchers, the extremely rare mutation appears to fend the disease off by minimizing the binding of a specific sugar compound to an important gene—a finding that indicates treatments could eventually be developed to give others such a protective mechanism. The woman, who is now in her late 70s, lives in Medellin, Colombia, which is the epicenter of the world's largest family to experience Alzheimer's. The extended family of about 6,000 members has been affected by dementia for centuries. Research conducted by Francisco Lopera, a Colombian neurologist, revealed years ago that the family's Alzheimer's was caused by a mutation in the Presenilin 1 gene. This type of hereditary early-onset dementia accounts for just a small proportion of the Alzheimer's patients worldwide; but it is important because, unlike most forms of the disease, it has been traced to a specific cause and a consistent pattern. Researchers investigated further when they discovered this woman with the Presenilin 1 mutation who had not yet even developed mild cognitive impairment, though her brain had high levels of amyloid protein plaques. "We have a single person who is resilient to Alzheimer's disease when she should be at high risk," said Eric Reiman, MD, executive director of the Banner Alzheimer's Institute in Phoenix and a leader of the research team. The new findings are published in Nature Medicine.