#BrainScience #Brain #Aging
Ten years ago, right after, I delivered a speech on innovation to the top tier of executives at a Fortune 100 company, one of the executives sought me out with a compliment. “Gee, Eric you haven’t lost a step at all.”
The executive, in his forties, had known me for a couple decades, and what he really meant was that, in my late fifties, I hadn’t slowed down mentally nearly as much as he expected I would.
Now in my late sixties, every other week or so, I experience this sort of attitude from people of all ages with comments like “Wow, you’re still doing that?!” or, more subtly and insidiously, having my opinion discounted because of my age. For example, I have “aged off’ a few technology advisory boards on which I served.
So, yeah, I’m not happy about age bias, but is age bias grounded in reality? Do we lose a step, or two, or three as the decades accumulate?
Reality vs. myths of brain aging
Let’s address that question by starting with some of the latest neuroscience on brain aging, and there is some good news.
Whereas brain scientists used to think we lost about 1% of our brain cells every year after our late 20’s, it turns out these estimates were based on methodological errors (e.g. failing to account for brain shrinkage as opposed to neuron loss, over inclusion of dementia patients in samples, etc.) and current estimates are that healthy brains lose only about 4% of neurons by the time they get to their 70’s and 80’s.
Also, the conventional wisdom that we don’t replace dead neurons with new ones as we age has also proven incorrect; for example the hippocampus (important to forming memories) of even elderly people grow new neurons from scratch all the time.
Finally, the brain retains its plasticity well into old age, growing, like an exercised muscle, with mental and physical exercise. For instance, older subjects taught to juggle showed increases in volume of motor cerebral cortex (coincidentally, this physical exercise also increased cognitive function).
So that’s the good news.
The other side of the story is that, on average the speed of cognition, including reaction time, does slow down in healthy brains as they age, and as we get older we generally have a harder time “inhibiting” (tuning out distractions while we concentrate). So on average, we don’t get “dumber” as we age, but numerous replicated studies reveal we do take longer to be as smart as we always were and we have a harder time concentrating.
Questioning even the “hard facts” on cognitive slowing
Although the research demonstrating cognitive slowing and age related deficits is quite solid, I question the true cause of such declines, and whether they are completely inevitable.
Take tuning out distractions as a case in point. A study by Dr. Arthur Shimamura and colleagues at UC Berkeley, that compared the ability of young adults and senior professors, to tune out distractions showed that senior professors, but not age-matched non-professors, were just as good at tuning out distractions as young adults. But a control group in the study, made up of seniors who were not professors performed worse on tuning out distractions than either senior professors or young adults. The authors interpreted these findings to mean that senior professors kept their brains young by staying much more mentally active than elderly non-professors.
Many other studies suggest that staying both mentally and physically active can stave off cognitive decline, but I suspect there may be an additional, more subtle reason why some people experience cognitive decline as they age.
And that reason is expectation bias, also known as the Pygmalion effect” or Rosenthal effect. Back in the 1960’s, Dr. Robert Rosenthal of UC Riverside showed that when teachers were told that random groups of students had high or low IQ’s respectively, students given fictitiously high IQ at the beginning of the school year actually scored higher on real IQ tests at the end of the year than students with fictitiously low IQ’s. In other words, teacher expectations created a self-fulfilling reality: we can be as smart or dumb--as people think we are.
Expectation has other powerful effects, such as the placebo effect (inert drugs work shockingly often when we’re told they will work) and the nocebo effect (negative side effects of inert drugs crop up when patients are told to expect these side effects).
So, taking research on expectation into account, and having aged myself, and witnessed the effects of aging on those around me, here’s what I suspect contributes to some of the cognitive decline shown in tests of elderly subjects,..self-fulfilling prophecy.
It’s hard to imagine that, given the power of the Rosenthal/Pygmalion, placebo and nocebo effects, that all of the stereotypes we’ve heard our whole lives about how people inevitably slow mentally with age, haven’t created the self-fulfilling prophecy of cognitive decline as we age. These effects can arise both from external expectations of others, as with the Rosenthal/Pygmalion effect, and with internal expectations, as with placebo and nocebo effects.
The sad reality is that both types of expectations, those of others and of ourselves, can negatively affect our physical brains, producing the very results we expect. If others don’t give us mentally challenging problems to solve, or we don’t mentally and physically challenge ourselves because we think we’re over the hill, then abundant research suggests that our brain volumes—especially cerebral cortex and hippocampus—will actually shrink, fostering real cognitive slowing.
But any vicious circle, such as the low-expectation-low mental activity-low brain sustenance–low expectation feedback loop, can be quickly transformed into a virtuous circle: high expectation—active mental engagement—healthy brain—high performance-high expectation.
Here are some factoids that re-calibrate expectations about mental ability in old age
James Michener published 14 top selling novels after the age of 70.
Stephen King, Dean Koontz and John LeCarre (all over 70) continue to bang out bestsellers.
Sophocles wrote Oedipus in Colonus at 89.
Composer Sir Edward Elgar created a musical masterpiece at 62, Richard Strauss at 82.
Picasso was painting masterpieces well into his 80’s.
All of these creative minds apparently didn’t get the memo—and didn’t buy into the expectation-- that our minds dull as we age.
Playwright George Bernard Shaw (who incidentally won an academy award for a movie script while publishing numerous plays in his 80’s) summed up the situation best when he said
“We don’t stop playing because we grow old
We grow old because we stop playing”
By Eric Haseltine, Ph.D.
References
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.886.71&rep=rep1&type=pdf
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4938247/
https://www.health.harvard.edu/mind-and-mood/can-you-grow-new-brain-cells
https://global.wustl.edu/breaking-misconceptions-successful-cognitive-aging/
https://www.frontiersin.org/articles/10.3389/fnagi.2015.00027/full
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