It's a curious but well-established fact that certain people whose brains look like they have Alzheimer's disease upon autopsy didn't actually have clinical symptoms to speak of during life.
Researchers have tried to account for this disconnect for some time: the fact that one's amount of brain "gunk" -the plaques and tangles that accumulate and clog the lines of communication between brain cells-
doesn't match one's cognitive function so closely. In fact, a full third of people with significant plaques don't have symptoms of dementia.
This phenomenon has given rise to the 'cognitive reserve' hypothesis, which suggests that some brains are better able to deal with breakdowns in machinery: Maybe they're able to better withstand their own breakdown.
It's ironic, but possible. And of course, difficult to prove.
But now a new study in Neurology has added some fuel to the theory, finding that one's cognitive
activity throughout life- not just in adulthood, but also in childhood- is an important predictor of cognitive function, and one's risk of dementia.
In the study, the team asked 294 people above the age of 55 how often they engaged in mental activities over the course of their lives, from childhood through the present. They also gave them cognitive tests to assess their brain function throughout the average six years of follow- up, along with neurologic tests. After the participants died, all of their brains were autopsied, for evidence of tangles, plaques, Lewy bodies, and infarcts or lesions.
What they found was cognitive decline was about 15% slower for the mentally active than for people who were less so. Interestingly, bot mental activity in one's later years and in the childhood years seemed to offer some protection against cognitive decline, suggesting that what we do as kids can contribute to whatever it is that fortifies the brain against aging and Alzheimer's.
Also interesting was the fact that the greater part of the variability in cognitive decline was not dependent on the well-established markers. There's still that great divide between what "should" be and what is . As study author Robert Wilson tells me, "That is the big question. In this study, makers of the leading causes of late life dementia accounted for one third of the variability in rates of cognitive decline, leaving two thirds unexplained".
Thought a bit mysterious, the "unexplained" two-thirds are also encouraging, since they suggest that what we do throughout our lives can greatly effect our cognitive function at the end of our lives, giving us a sort of power over the situation. "Better understanding of the factors contributing to this residual variability in cognitive aging not explained by dementia-related pathology and the neurobiological bases of the associations, " Wilson adds," could suggest novel strategies for delaying the onset of late life cognitive dysfunction".
In other words, like we've heard so many times before, use it or lose it. And as Wilson tells HealthDay, "Find a hobby that is sustainable:quilting, photography, acting in the theater, even learning Morse code. Physical
activity is also important." So is the issue of taking care of one's mental health, since perceived stress and depression have also been linked to risk for Alzheimer's disease. As always, the brain is no simple organ, and seems to need a good balance of variables. Focusing single-pointedly on one are apparently won't cut it.
The original article; http://neurology.org/content/early/2013/07/03/WNL.0b013e31829c5e8a
After a year of struggle with SAS and stat courses, I found that it's much easier for me to understand the
result part of the original article.
In a mixed-effects model (meaning it is the repeated regression model since the study collected the data from the same participants overtime) adjusted for age at death, sex, education, gross and microscopic infarction, neocortical Lewy bodies, amyloid burden, and tangle density (those are Independent variables in the regression model), more frequent late-life cognitive activity (estimate = 0.028, standard error [SE] = 0.008, p < 0.001) and early-life cognitive activity (estimate = 0.034, SE = 0.013, p = 0.008) were each associated with slower cognitive decline(frequent cognitive activities both late and early life were significantly associated with slower cognitive decline). The 2 measures together accounted for 14% of the residual variability in cognitive decline not related to neuropathologic burden(standardized beta estimated of the measures accounted for 14% of the residual variability). The early-life–activity association was attributable to cognitive activity in childhood (estimate = 0.027, SE = 0.012, p = 0.026) and middle age (estimate = 0.029, SE = 0.013, p = 0.025) but not young adulthood (estimate = −0.020, SE = 0.014, p = 0.163).
The definition of "young adulthood' was not clear in the abstract, but if what it means is "high schoolers or 20's", then it would be great news for me since I spent in vain my late teenage through 20's: no cognitive and physical exercise.
0 件のコメント:
コメントを投稿