The pessimist’s mournful dirge – “It will get worse, it will get worse, it will get worse” – applies to inflation, global warming, childhood obesity, airline food, and the length and inanity of our netas’ orations. It does not apply to the common cold – that comes and goes – or, it is startling to realize, to the seven ages of man. More specifically, it does not – necessarily -- apply to the human brain.
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This is the finding that, over the last quarter of a century, has upended some dearly-cherished notions in the medical fraternity. For eons, the accepted wisdom had endorsed Plato’s dictum that, when a man grows old, he “can no more learn much than he can run much.” And it tied in with two entrenched premises: One, that humans are born with a certain number of brain cells and will never generate any more. Two, that as people grow older, there is a cascading loss of brain cells, resulting in a progressive decline in memory, problem-solving skills, concentration and other brain functions. Conclusion: after age 25 or so, it’s pretty much downhill all the way to la-la land.
Today, we know better. Beginning in the 1990s, and piggy-backing on new, sophisticated technologies, a wave of studies has caused the old venerated maxims to bite the dust. And here are some of the new truths we have learned about the human brain:
• Although people lose brain cells naturally throughout their lives, the process of brain-cell death does not necessarily accelerate with aging.
• It is also a myth that the brain cannot grow new cells into old age. It does – but at a slower rate.
• Not only does the human brain continue to create new nerve cells (called neurons) throughout its lifetime, it also continues to create new connections among neurons. And this is critical, because it is becoming increasingly clear that the aging brain is only as resilient as its circuitry.
• As always, individuals differ. Though the norm is for memory and problem-solving ability to plateau in our 20s, and then start a general decline in our 50s and 60s, the scores of some adults in their 60s on memory, problem-solving, and other cognitive tests are above the average of adults in their 20s.
These are ground-breaking findings. The current consensus among scientists is that only about 20 per cent of the variation among people in standard measures of brain function is the result of age. The rest reflects factors other than the number of candles on the birthday cake. They have more to do, scientists are realizing, with how people live their lives.
This, in turn, has led to the focus shifting, gradually but steadily, to optimizing brain health lifelong. A number of different approaches are being investigated. One looks at optimal nutrition for the brain; another looks at challenging the brain with stimulating mental activities ranging from Sudoku to chess, from crossword puzzles to learning Russian. But it is a third approach that is believed to be probably the most effective weapon in our armory – because the research shows it targets brain function at the cell level. And what might that strategy be?
Getting physical. For the last two decades, researchers have been harvesting increasing evidence of the unexpected links between mental and bodily fitness. Using cutting-edge technologies, they have discovered that exercise appears to build a brain that resists physical shrinkage and enhances cognition. (Cognition can be defined as the ability to use simple-to-complex information to meet the challenges of daily living).
These findings have come in from studies on both, mice and men (more often, women, actually). Here are some of the discoveries that have turned up:
Exercise fights brain shrinkage. One UK study on around 700 volunteers found that those who reported being the most physically active tended to retain larger brain volumes (gray and white matter) over a 3-year period than those who were mostly sedentary. In other words, they were successfully taking on the demon of brain shrinkage, which is linked with memory problems and even Alzheimer’s.
Regular exercise also seemed to protect their brains against the formation of white matter lesions, which again are linked to thinking and memory decline.
The results of the brain scans of study participants gave the researchers a clear-cut finding: the most physically inactive men showed the greatest brain atrophy.
Other studies, some of them specifically on women, have shown similar outcomes.
Exercise is a mood elevator and may combat depression. Physical activity can have potent effects on your mood. The runner’s high -- that feeling of elation that follows intense exercise -- is real. Even mice get it, research has found. It has long been credited to the “endorphin rush”, a rise in the levels of the body’s homemade opiate. But although endorphin levels do rise in the bloodstream, it is not clear how much actually gets into the brain. Instead, more recent research is pointing to a pleasurable and pain-killing chemical, an endocannabinoid - a natural brain compound similar to the active ingredient in marijuana. Levels of this chemical also increase during exercise.
Exercise is emerging as a promising way to tackle depression. A meta-analysis of studies in this area has cautiously reported that exercise – both, aerobic and resistance training – is “moderately effective” in treating depressive symptoms. Interestingly, exercise appears to be as effective as anti-depressant drugs as well as psychotherapy.
Yoga staves off stress. When anxiety levels rise, you tense up, your heart races and your attention narrows to a slit. This shift to “fight or flight” mode is automatic, but that doesn’t mean it’s wholly out of your control. Yoga teaches the deliberate command of movement and breathing, with the aim of turning on the body’s “relaxation response” Research increasingly backs this claim. For example, one study which put participants through eight weeks of daily yoga and meditation found that, along with self-reports of stress reduction, the participants’ brain scans also showed shrinkage of part of their amygdala -- a deep-brain structure involved in processing stress, fear and anxiety.
WHAT KIND OF EXERCISE WORKS BEST?
Most human studies to date on the exercise-brain connection have involved aerobic activities like brisk walking and running. But a few have looked at light-duty weight training, and these have also found cognitive benefits over a one-year period among older people. This is a particularly appealing finding for those (and there are many) who cannot get excited about going for walks or running.
Another aspect that will appeal: the workouts do not have to be intense or exhausting. In perhaps the most encouraging study, Canadian researchers worked with a large group of elderly adults over the course of two to five years. The volunteers were not spry, there were no marathon runners among them. In fact, most of them did not exercise, per se, and almost none worked out vigorously. The most active walked.
Over the study period, the group, mostly women in their 70s, completed a series of brain-function tests, as well as surveys of their activities. These activities, said the study author, generally consisted of “walking around the block, cooking, gardening, cleaning and that sort of thing.” But even so, the effects of this modest activity on the brain were remarkable. While the wholly sedentary volunteers, and there were many of these, scored significantly worse over the years on tests of cognitive function, the most active group showed little decline. About 90 per cent of those with the greatest daily energy expenditure could think and remember just about as well, year after year.
The brain-boosting results of exercise trail in faster than you might believe. Recent findings suggest that these benefits show up as early as 4 months down the road.
WHY DOES EXERCISE WORK?
Some of the mechanisms that may explain the brain-exercise connection have been identified by research. They include:
A better-fed brain. Researchers speculate that consistent exercise, particularly aerobic activities, promotes heart health, which in turn keeps nutrient-rich blood flowing to the brain to nourish its nerve cells, sprouting more connections and helping them communicate more effectively.
Other prime suspects include surges of growth hormones and expansion of the brain’s network of blood vessels.
It also appears that exercise stimulates the birth of new neurons. Until recently, few believed this could happen in adult human brains. But researchers using a technique that marks newborn cells have discovered, during autopsies, that adult human brains contained quite a few new neurons. Fresh cells were especially prevalent in the hippocampus (an area of the brain that is critical to learning and memory), indicating that the creation of new brain cells — a process called neurogenesis — was primarily occurring there.
Even more heartening, scientists have found that exercise jump-starts neurogenesis. Mice and rats that ran for a few weeks had about twice as many new neurons in their hippocampi as sedentary animals. Their brains, like their muscles, were bulking up.
And the bottomline is… Researchers believe there is enough evidence that working out keeps your brain smarter, and that this can be an ongoing process – you don’t need to wait till you’re 60 to start putting those little grey cells through the hoops.
One researcher goes so far as to say, “There is no pill that can do what exercise does.”
And who’s to say she isn’t right?
(The author is a former editor of 'Health & Nutrition' magazine, and now works as a counselling therapist)