Daniel Levitin on the Myth of the Ageing Brain
Challenging widely held assumptions about the diminishing abilities of an ageing brain, in The Changing Mind, leading neuroscientist Daniel Levitin argues that we should view getting older as a beneficial experience rather than a form of cognitive entropy. In this exclusive essay, Levitin outlines the myths surrounding the geriatric mind.
One of the key messages in The Changing Mind is that there are many advantages to getting older. It’s easy to become preoccupied with the possible downsides – that you'll experience aches and pains, some of your friends might die, your brain might deteriorate into dementia. In fact, neuroscience research has shown that ageing can bring with it increased happiness, meaning, and engagement with others.
There are a number of myths about ageing that persist in our societal narrative, but they are not supported by science. Here are three examples. Many more are detailed in the book, as well as decades of research distilled into actionable tips for ageing well.
Age-related memory loss is the subject of many jokes. But could it be that some aspects of memory actually improve? Memory is not just one thing, it’s several biologically and cognitively distinct systems. Older adults may slow down and not be able to retrieve memories or solve problems as quickly as younger adults, but they can be superior in a range of problem-solving skills, particularly those that involve experience and accumulated knowledge.
The technical term for accumulated knowledge is "Crystallized intelligence." It is knowledge you have already acquired, regardless of how easy or difficult it was for you to obtain it. It includes things such as your vocabulary, your general knowledge (how many people live in London?), your skills, and any mathematical rules or formulas you might have learned. Crystallized intelligence increases throughout the lifespan, because our concrete knowledge base increases with age as we learn and experience new things. Of course this isn't true in cases of amnesia and Alzheimer's, when our memories aren't functioning well, but both are much rarer than people think they are. Most of us can sail through our 80s or 90s with minimal memory disturbance, provided we stay mentally active and in good overall health.
Related to intelligence is the question of how we acquire information in the first place. What humans excel at, compared to other animals, is making associations: taking information, both old and new, and seeing how it interacts with other information. Whenever we encounter new information, our brains place it in a contextual frame and then seek to associate it with other things we’ve experienced. The brain is a giant pattern detector, applying statistical analysis to make decisions. Our brains add to that the ability to form analogies, something that (as far as we know) is uniquely human. Analogies, or analogical reasoning, have led to some of the biggest discoveries in science, from the Big Bang origins of our universe to immunotherapy for cancer.
The way neuroscientists see memory is that it’s a puzzle with many missing pieces. Only some things we experience get stored in memory. Our brains fill in the missing information with creative guesses, based on experience and pattern matching. This is because one of the evolutionary functions of memory is to abstract out regularities from the world, to generalise. That generalisation allows us to use objects like toilets and pens—you can use a new toilet, or a new pen, without training because functionally, it’s the same as all the others you’ve used.
Back in the 1960s, scientists wanted to provide evidence of this. They presented computer-generated patterns of dots that they had made by starting with a parent, or prototype, and then shifted some of the dots one millimetre or so in a random direction. This created patterns that all shared a family resemblance with the original—very much like the variation in faces that we see in parents and their children. Here is an example of the one they began with (the prototype, upper left) and some of the variations (at the ends of the arrows). The one on the upper right is an unrelated pattern, used as a control in their experiment.
You’ll notice a resemblance across the four related squares—all have a similar triangular pattern of three dots in the lower left. All have a diagonal of three dots running down the centre roughly from the upper left to the lower right. In the experiment, people were shown version after version of squares with dot patterns in them, each of them different. The participants weren’t told how these dot patterns had been constructed. Here’s the clever part: the researchers showed people the descendants (like the ones on the bottom row) but not the parents (like the one on the upper left), along with things they had never seen (like the one on the upper right).
A week later the same people came back in and saw a bunch of dot patterns, some old and some new, and had to indicate which they’d seen before. Although the participants didn’t know this, some of the “new” patterns were actually the parents, the prototypes used to generate the other dot patterns. If people are storing the exact details of the figures—if their memories are like video recordings—this task would be easy. On the other hand, if what we store in memory is an abstract, generalised version of objects, people ought to recall seeing the parent even if they hadn’t—it constitutes an abstract generalisation of the children that were created from it. That’s exactly what they found.
Our brain adapts in a continuous fashion using powerful pattern-recognition systems like this. As we age, the ratio of how much our brains rely on the input signal versus our perceptual inferencing shifts with every decade after 40. Our magnificent pattern-matching brains do more and more filling in, not just because our senses require them to, but because they’ve had so many more experiences than young brains that it is simply more efficient to make inferences than to try to decode every little perceptual detail.
Making associations underpins learning. To assimilate new information, we need to associate it with what we’ve seen before. Life experience gives us more associations to make, more patterns to recognise. So, as we age, our brains become better and better at this kind of pattern matching and abstraction, and it accounts for one of the most widespread traits that oldsters have: wisdom.
From a neurocognitive standpoint, wisdom is the ability to see patterns where others don’t see them, to extract generalised common points from prior experience and use those to make predictions about what is likely to happen next. Oldsters aren’t as fast, perhaps, at mental calculations and retrieving names, but they are much better and faster at seeing the big picture. And that comes down to decades of generalisation and abstraction.
The wisdom that we find in older adults—the most experienced members of our population—follows from these four specific things: associations, experience, pattern recognition, and the use of analogies. Wisdom results from the accumulated set of things we’ve seen and experienced, our ability to detect patterns in those experiences, and our ability to predict future outcomes based on them. (And what is intelligence if not that?) Naturally, the more you’ve experienced, the more wisdom you are able to tap into. In addition, certain changes in the ageing brain facilitate these kinds of comparisons.
Young upstarts may be faster at playing video games and quicker to adapt to new technologies, but in the realm of wisdom they can’t hold a candle to old-timers who have been witness to so many things that seem to cycle around again and again. Wisdom enables you to handle some problems more quickly and effectively than the raw firepower of youth. A young, strong person might be able carry a heavy load up a hill without breaking a sweat. An older person will think to put it on a trolley or trailer.
Putting It All Together
We need to educate ourselves and our families about these advantages of aging. As individuals, as community members, as a society, it is in all of our best interests to help construct a culture that embraces the gifts of the elderly, weaving cross-generational interactions into the fabric of everyday experience. By learning from the science of the brain we can create a transformative understanding of the aging process, its human story, and in the process create a richer quality of life. This is the new truth about aging.
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