Report on health brain aging summit; pathology explains only 40% of cognitive decline

Earlier in April, the National Institute on Aging (NIA) held a summit on healthy brain aging, focusing on cognitive reserve and resilience.  “The idea is that cognitive reserve helps the brain preserve cognition in the face of ongoing pathology, and if scientists better understand the processes involved, maybe they can boost reserve.”  One thing holding researchers back is that there isn’t a good definition of “cognitive reserve.”  One researcher proposed that “reserve modulates the effect of injury on cognition, such that for a given degree of pathology, people with more reserve show less cognitive decline.”  Similarly, there is no definition for “resilience” or “compensation.”

Alzforum has an interesting report on the NIA conference.  The report is a good reminder that pathology in the brain is not the whole story.  According to one research at Rush, neuropathology explained “only 40 percent of the cognitive decline.”

Here are some excerpts:

“Scientists generally accept that education and intellectual enrichment contribute to cognitive reserve, and that people with a lot of it live dementia-free longer. Beyond that, the concept remains something of a black box.”

“What can researchers glean from studying people, notably the lucky few who make it into their 80s and 90s with crystal-clear memories? Some of these spry minds have advanced pathology in their brains, while others harbor genetic risk factors for cognitive decline.  Data from the 90-plus study…suggest that at very old ages, the amount of amyloid in the brain has little bearing on how fast people decline cognitively in the years before death. In fact, the eight highest performers on memory tests who have come to autopsy had a wide range of pathology, ranging from little to full-blown plaques and tangles. This adds to evidence that a low pathology burden doesn’t explain better memory in older people, [the UC Irvine researcher] concluded. In support of that idea, Patricia Boyle, Rush University Medical Center, Chicago, analyzed 1,200 autopsied brains from the Rush Memory and Aging Project and found brain pathology explained only 40 percent of cognitive decline. That leaves 60 percent of total impairment unexplained, she said.”

“One possibility comes from the lab of Emily Rogalski, Northwestern University, Chicago. Her data suggest that atrophy, or the lack thereof, may play a role in resilience to age-related memory loss. She reported in the April 4 JAMA that the cortices in a cohort of 24 superagers—people over 80 with episodic memory scores typical of middle age—shrank at half the rate of the average 80-year-old.”

“Scientists led by Adam Gazzaley, University of California, San Francisco, have been creating games to improve cognition. How can they tell if those games have lasting benefits over time that generalize to daily activities? … He described efforts to construct double-blind trials using ‘placebo’ games. These games are designed to seem beneficial to participants, without actually exercising the cognitive domains being tested.”

The full Alzforum blog post can be found here:

www.alzforum.org/news/conference-coverage/nih-summit-examines-what-makes-healthy-aging-brain

Robin