Important new research: brains continue to make new neurons into the 9th decade of life. People with lots of amyloid in their brains but NOT having Alzheimer's continue to make lots of new neurons, but people with Alzheimer's make less than half as many.

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One 78-year-old brain from a person who didn’t have Alzheimer’s had about 23,000 new neurons per cubic millimeter of hippocampus, while a brain of the same age but from someone who died with Alzheimer’s disease had 10,000.

That might solve a longstanding Alzheimer’s mystery: that some elderly people who died with brains full of amyloid showed no signs of dementia. That suggests some sort of resilience or compensatory mechanism: Inflammation, which more and more scientists believe causes Alzheimer’s, kills neurons, but high rates of neurogenesis supply replacements.

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https://www.statnews.com/2019/03/25/old-brain...lzheimers/