Superagers with amazing memories have Alzheimer’s brain plaques

 作者:钟离器档     |      日期:2018-01-22 04:49:36
Peter Dazeley/Getty By Jessica Hamzelou in San Diego Having an agile mind in your 90s might sound like wishful thinking, but some people manage to retain youthful memories until their dying days. Now post mortems have revealed that these “superagers” manage to do this even when their brains have the hallmarks of Alzheimer’s diseases. Superagers have the memory and cognition of the average person almost half their age, and manage to avoid Alzheimer’s symptoms. Aras Rezvanian at Northwestern University in Chicago, Illinois, and his colleagues have been looking at brain samples donated by such people to try to understand what their secret might be. The group looked at eight brains, all from people who had lived into their 90s, and had memory and cognition scores of the average 50-year-old until their final days. Specifically, the team studied two brain regions – the hippocampus, which is involved in memory, and the prefrontal cortex, which is key for cognition. They found that the brain samples of the superagers had plaques and tangles in them to varying degrees. These are sticky clumps and twisted fibres of protein that seem to be linked to the death of neurons, and are usually found in the brains of people with Alzheimer’s disease after they die. Of the eight superager samples, two had such a high density and distribution of these proteins that they resembled the most severe cases of Alzheimer’s. When the team counted the neurons in the brain samples, they found that they had many more neurons than samples from people who had died with Alzheimer’s. This is surprising, as it is thought that plaques are toxic and lead to the loss of neurons during Alzheimer’s disease. “The oldest old with superior memory can display the full range of Alzheimer’s pathology,” says Rezvanian, who presented his findings at the Society for Neuroscience annual meeting on Monday. “It points to some unknown factors that protect some elderly from the plaques and tangles of Alzheimer’s,” he says. Perhaps superagers just had more neurons to begin with, says Changiz Geula, who led the study. “They may actually be losing cognition and neurons, but start at high levels,” he says. The findings support growing evidence that plaques and tangles might not be a direct cause of Alzheimer’s, says Cheasequah Blevins at University of Texas at Austin. “A lot of money was spent on getting rid of plaques, but it didn’t help – it actually made the patients quite sick,” she says. The next step is figuring out what the protective factor might be, she says. Read more: Superagers with amazing memories have shrink-resistant brains; Drug that stops brain plaques may show if they cause Alzheimer’s More on these topics: