Lifestyle Matters. Lesson 14b. Exercise

 

Be healthy. Be smart.

Exercise is not only good for the body; it is good for the brain.  The idea that exercise might benefit memory originally came from animal research revealing exercise increases learning and memory capability, presumably because exercise stimulates the birth of new nerve cells in the hippocampus, the part of the brain that is crucial for forming long-term memory. I have posted many articles on the benefits of exercise for the brain  at this blog site (type “exercise” into the search field).

It is now clear that exercise benefits memory capability in humans too, both old and young. In addition, the state of exercise is tied to memory; that is, state-dependent memory can be demonstrated with exercise. For example, in a study of humans exercising on a bicycle, word lists learned during the exercise were recalled best during another exercise episode, while words learned not riding on a bike were recalled best under that same condition. State-dependent learning has been demonstrated in other contexts too, such as with alcohol and with school-room environments.

Even when I was a kid, which was long before the whole notion of aerobic exercise, people said that being physically active could help you perform better in school. But this was mostly anecdotal, with very little research evidence. Now there is much solid evidence. Sadly, it may have come too late. Many schools have done away with or minimize physical education. Many girls think it’s not cool to sweat.

Charles Hillman and colleagues at the University of Illinois recently reported a study on the effects of exercise on cognitive function of 20 children aged 9 to 10. They administered some stimulus discrimination tests and academic tests for reading, spelling and math. On one day, students were tested following a 20-minute resting period; on another day, students walked on a treadmill before testing. The exercise consisted of 20 minutes of treadmill exercise at 60% of estimated maximum heart rate. Mental function was then tested once the heart rate returned to within 10% of pre-exercise levels. Results indicated improved performance on the tests following aerobic exercise relative to the resting session. Tests of brain responses to stimuli suggested the difference was attributable to improved attentiveness after just this one bout of exercise.

Note this is just from a single aerobic exercise experience. How can that be beneficial? The most obvious explanation is that exercise generates more blood supply to the brain, but I don't know that this has been documented. Actually, what is known is that exercise diverts blood to the muscles. The generally accepted view is that the body tightly regulates blood flow to the brain and that the brain always gets what it needs.

A more likely explanation is that single bouts of exercise relieve anxiety and stress, which are known to disrupt attentiveness and learning. Maybe the repetitive discipline of exercises like treadmill-walking help entrain the brain into a more attentive mode, akin perhaps to meditation. We need a study that compares treadmill walking with a different kind of exercise regimen (like a vigorous and competitive basketball game, for example).

As for what goes on in a typical school recess, I doubt that such activities as gossiping, text messaging, or whatever else goes on these days with kids at recess markedly interfere with learning.

There is also the possibility a continuing aerobic exercise program could produce long-lasting beneficial effects in young children. My own prejudice is that schools and parents ought to get serious about requiring aerobic exercise programs. It should not only improve the quality of school work but also help combat the epidemic of obesity and diabetes. One caveat: excessive running to achieve aerobic levels of exercise may not be advisable in children. My own experience with jogging, for example, might have been great for my heart and brain, but I now have two artificial knees and an artificial hip joint to show for it.

Here is another caveat you may have thought about: If exercise is so good for academic performance, why do varsity athletes generally make poorer grades than their classmates? Well, there are many other factors, of course. One prevailing attitude among athletes is that academics are less important to them than their sport. Athletes tend to devote their time and energy to their sport, not school work. They also have more incentive to focus on their sport. Students idolize athletic stars. But students who make all As are not considered heroes; they are often considered nerds or otherwise abnormal. What should be normal is to exercise both body and brain. 

Sources, Exercise

Hillman, C. H., Pontifex, M. B., Raine, L. B.,  Castelli,, D. M., Hall, E. E., and Kramer, A.F. (2009). The effect of acute treadmill walking on cognitive control and academic achievement preadolescent children, Neuroscience, 159 (3), 1044-1054, https://doi.org/10.1016/j.neuroscience.2009.01.057.

Miles, Christopher, and Hardman, Elinoir. (2010). State-dependent memory produced by aerobic exercise. Ergonomics. 41(1), doi.org/10.1080/001401398187297

 

 

Two New Discoveries to Explain Why Exercise Is Good for You

Have you noticed that so many elderly people seem frail, walk slowly, and seem to lack energy? If this applies to you, noticing it is unavoidable. These problems are preventable. For 25 years, I jogged at least a mile and a half three times a week. This was crucial for helping me stop smoking. I don’t know why, except that I could not smoke and jog at the same time. Also, the 15-30 minute recovery time reminded me just how bad the smoking had been for my health.

Why did I quit jogging? The jogging messed up my joints. So, I took up swimming, but since I sink like a lead mannequin, that is just too much work. So now, I joined a gym, where I use the elliptical, treadmill, and muscle-building machines. This environment helps because I have companions in my discomfort, and occasionally I get the satisfaction of comparing myself to the few “90-pound weaklings” that show up.

We have known for many years that exercise is good for you, especially as you get older. Known benefits of exercise include:

• Relieve stress and promote a sense of well being. (Well, at least after the soreness wears off).
• Improve heart and cardiovascular function. (If the damage is already done, don’t expect huge improvements).
• Lose weight. (Pushing away from the table is the best exercise for this effect).
• Strengthens bones. (Reduces loss of bone density in old age. But high-impact exercise may damage joints).
• Lower blood sugar and help insulin work better.
• Help quit smoking. (Ever try to smoke while jogging? Ha!).
• Improve mood and resist depression. (Ever heard of “runner’s high? It comes from release of endogenous opiates).
• Releases proteins and other chemicals that improve the structure and function of your brain. (Memory ability improves too).
• Improve your sleep. (I mean, besides making you really tired. To reduce interference from soreness, take acetaminophen before bed time).\
• Reduce your risk of some cancers, including colon, breast, uterine, and lung cancer.

What was not as well known until recently was the effect of exercise on the immune system. Recent research indicates that exercise in older age can prevent the immune system from declining and protect people against infections. A recent study followed 125 long-distance cyclists, and found that some of those in their 80s had the immune systems of 20-year olds. Maybe this is a reason exercise can help prevent cancer.

The key indicator was the level of T-cells in the blood. T cells, named after the thymus where they first appear, are a type of white blood cell that makes antibodies. As people age, the thymus gland, located in the neck, shrinks and T-cell activity resides mostly in bone marrow. The study of cyclists revealed that they were producing the same level of T-cells as 20-year olds, whereas a comparison group of inactive older adults were producing very few. Thus, it would seem that, though not tested in this study,   physically active seniors would also respond better to vaccines than sedentary people.

The other new discovery is the importance of exercise on brain white matter integrity. White matter electrically insulates nerve fibers, which has two effects: 1) speeds communication in neural networks and 2) reduces “cross talk” among adjacent fibers. The study compared people averaging 65 who were mentally normal and those who had mild cognitive impairment, which is a risk factor for later development of Alzheimer’s Disease. In both groups, investigators measured cardiovascular function with a standard measure of heart and respiratory fitness, the VO2 Max test. They also used brain scans to measure white matter integrity. Levels of physical activity were positively associated with white matter (WM) integrity and cognitive performance in normal adults and even in patients with mild cognitive impairment.

Given all this, how much more reason do you need to get off the couch and start moving? Besides, at the end of a good workout, it feels so good to quit.

*****

"Memory Medic's latest book is for seniors: "Improve Your Memory for a Healthy Brain. Memory Is the Canary in Your Brain's Coal Mine," available in inexpensive e-book format at https://www.smashwords.com/books/view/496252.  See also his recent books, "Memory Power 101" (Skyhorse), and "Mental Biology. The New Science of How the Brain and Mind Relate" (Prometheus).

*****

Sources:

Ding, Kan, et al. (2018).Cardiorespiratory fitness and white matter neuronal fiber integrity in mild cognitive impairment. Journal of Alzheimer's Disease, 61(2), 729-739.

Duggai, Niharika A. et al. (2018). Major features of immune senescence, including reduced thymic output, are ameliorated by high levels of physical activity in adulthood. Aging Cell. 8 March. 

https://doi.org/10.1111/acel.12750.

https://medlineplus.gov/benefitsofexercise.html

Aerobic Exercise Makes You Smarter

On several occasions, I have written about the anti-aging beneficial effects of exercise. New studies, confirm earlier findings of exercise benefit. Now, a new study shows that exercise reduces levels of the major inflammatory chemical, interleukin-6, and an associated enhancement of neural activity in the brain circuitry used to encode information and form memories.

In response to earlier studies by others showing that exercise improves mental function, a team from mostly German universities studied the effects of exercise on 32 subjects aged 52 to 71 years old. They were particularly interested in memory because prior studies by others made it clear that age usually impairs memories of names and faces, situations and events, which are categorized as episodic memory. Tests of recall of episodic memory show marked age decrements in many subjects, even if they are given reminder cues.

Other researchers had shown that exercise, particularly aerobic exercise, reduces decline of episodic memory. This group of researchers wanted to explore why this benefit occurs. They examined two possibilities for the benefit of exercise:

1. Reduction of inflammatory chemicals (interleukin-6), which is known to occur with aerobic exercise in younger people, and

2. Strengthened connection among neurons that encode and form episodic memories (in the hippocampus, thalamus, and medial prefrontal cortex).

In the experiment on day one, subjects completed a survey that revealed each person's level of physical activity over the past week and gave a blood sample for measuring the baseline level of interleukin-6. Each subject then took several standardized tests of episodic memory. Then each subject had their brains scanned with fMRI while they were asked to memorize a series of faces and their association with a profession (pilot, electrician, bus driver, etc.). After the scan, they were tested for recall. The purpose of the scan was to assess functional connectivity, that is, how strongly the activation correlated in the brain areas that participate in encoding and memory formation.

The exercise survey allowed subjects to be grouped on the basis of aerobic and non-aerobic exercise during the prior week. The aerobic group remembered more items on the episodic memory task. The aerobic group also revealed stronger functional connectivity among several areas in the memory network. Additionally, there was a correlation with levels of the inflammatory chemical: subjects showing strong functional connectivity had the lowest levels of interleukin-6.

Limitations of the study include a failure to distinguish the intensity of exercise. For example, one can jog three hours a week at high speed or rather leisurely. Also, actual fitness of each subject was not measured, just a log of their exercise activities during the prior week. Another factor is that only one inflammatory chemical was studied. Interleukin-6 is one of a large family of such chemicals known as cytokines, and there are other inflammatory chemicals as well. Moreover, the significance of interleukin was not evaluated. When brain is damaged (by stress, metabolic production of free radicals, or whatever), interleukin-6 is released as a defense mechanism.

Nonetheless, a strong correlation, consistent with prior studies, was demonstrated between aerobic exercise, inflammation, and mental function. The authors did not speculate on why these effects occurred. I will.

Two contributing factors are obvious. One obvious factor is that aerobic exercise improves cardiovascular function and likely improves blood flow through the brain. The other obvious factor is that aerobic exercise releases the "feel-good" endorphins. Endorphins alleviate stress. Stress, more specifically the cortisol released during stress, shrinks the synaptic connections between neurons, which of course can be expected to diminish functional connectivity and information processing efficiency. Stress increases the level of inflammatory chemicals like interleukin-6. The low level of interleukin-6 in the aerobic group indicates that these brains were somewhat protected from the ravages of stress and free radicals.

Bottom line: aerobic exercise is good for older people. In addition to the well-known cardiovascular benefits, aerobic exercise makes people more sharp mentally. How one gets the needed aerobic exercise probably doesn't matter, as long as the exercise is sufficiently intense and sustained. Jogging, bike riding, swimming, and fast-moving sports should all prove beneficial.

Readers of this column will be interested in "Memory Medic's" e-book, Improve Your Memory for a Healthy Brain. Memory Is the Canary in Your Brain's Coal Mine (available in all formats from Smashwords.com). The book, devoted exclusively to memory issues in seniors, includes review of many of the ideas in these columns over the last five years.

Sources:

Thielen, Jan-Willem et al. (2016. Aerobic activity in the healthy elderly is associated with larger plasticity in memory related brain structures and lower system inflammation. Frontiers in Aging Neuroscience. 26 December. doi.: 10.3389/fnagi.2016.00319

Erta, M., Quintana, A., and Hidalgo, J. (2012) Interleukin-6, a Major Cytokine in the Central Nervous System. Int. J. Biol. Sci. 8(9):1254-1266. doi:10.7150/ijbs.4679. Available from http://www.ijbs.com/v08p1254.htm

Aging Shrinks the Brain

In most people, their brains get smaller as they age. It is not so much that neurons die but that their terminals and synaptic junctions shrivel. A known cause is the over-secretion of cortisol by stress, but perhaps there are also other age-related causes.

However, shrinkage with age is not inevitable. Certain people are "super-agers," defined as adults over 80 with memory at least as good as normal middle-aged adults. A usually reliable index for decline in memory ability is the degree of brain shrinkage, specifically cortical volume. Brain-scan studies show that super-agers have thicker layers of cortex than do others of the same age. Thus, their cortex has not shrunk as much as average elderly or they had more to start with. It is possible that something about the lifestyle of super-agers protected them from brain atrophy. It is not convenient to know how much cortical volume the elderly had in their youth. But the second option has been tested in a study that compared the rate of cortical aging in 36 adults averaging 83 years of age. The investigators recruited super-agers and normal elderly and tested them in an initial visit and again 18 months later. Before and after cognitive and memory tests and brain scans provided a basis for tracking the rate of aging.

Super-agers scored higher on cognitive and memory tests than the average group at both the beginning and end of the study period. This suggests that they may have been endowed with more mental capability when they were young. But it also indicates that super-agers are more resistant to age-induced mental decline. The two groups did not differ in any other neuropsychological measures, education, or estimated IQ.

A clear correlation occurred between the two groups and cortical volume. The average memory group had over twice as much cortical shrinkage over the 18 months as did the super-agers. Some in the average group lost as much as 3.4% of cortical volume per year. If that continued over the next 10 years, they would suffer a devastating loss of over 30% in cortical volume.

Unfortunately, the study did not examine the lifestyles in the two groups. The super-agers may have just had good genes or may have been more mentally active over their lifetime and had healthier diets, more exercise, and less stress than those in the average group. Notably, some shrinkage did occur in the super-agers, on average at a rate of 1.06% per year. They still scored as well as the average 50-year old on various cognitive and memory tests. It is possible that some shrinkage is a good thing, reflecting perhaps a pruning of neural circuitry as the brain learns and develops more efficiency. Pruning is a conspicuous phenomenon in the brains of the fetus and infants as maturation progresses. Obviously too much pruning can leave neural circuitry with insufficient resources.

These results also emphasize that age discrimination is not defensible. Each elderly person's mental competence has to be judged on its own merits, not on a negative stereotype of the elderly.

Sources:

Rogaalski,E. J. et al. (2013) Youthful memory capacity in old brains. J. Cognitive Neuroscience. 25(1), 29-36.

Cook, Amanda H. et al. (2017). Rates of cortical atrophy in adults 80 years and older with superior vs. average episodic memory. JAMA. 317(13), 1373-1375.

Is Your Brain Older Than You Are?

"You are as old as you think you are," the saying goes. Well, not quite. You, that is the inner you in your brain, is as old as your brain is. But your brain age may or may not correlate with chronological age.

The other day at my gym workout, I again saw a young black guy, built like Captain America, whose workout schedule sometimes overlaps with mine. We had not met, and out of the blue he came up to me and said, “You are my inspiration. You inspire me to be able to work out like you when I get your age.” Wow! I inspire somebody! Then my balloon popped when I realized that he knew I was old just by looking at me. My body may not look like I’m 83, but I guess hair loss and the lines in my face betray me.

The point of this story is that the bodily organs do not have the same rate of aging. Skin ages rather conspicuously in most older people. Specific organs may age at different rates depending on what they have been exposed to, for example skin and sun, liver and alcohol, lungs and smoking, or fat tissue and too many calories. The brain may age more rapidly than other organs if you damage it with drugs or concussion, or clog its small arteries with high cholesterol, or shrivel its synaptic connections by lack of mental stimulation or not coping with stress.

Is there some biological equivalent to tree rings to show how old your brain actually is?  A scientist at the Imperial College in London, James Cole, is developing an interesting approach for estimating brain age. Moreover, the technique seems to predict approximately when you will die.

In the study thus far, MRI brain scans were taken on 2,001 people between 18 and 90 years of age. A computer algorithm evaluated these scans to construct a frame of reference for what is normal for a given age. Then the scans from 669 adults, all born in 1936, were compared against the norms to determine whether the 81 year-old brains were normal for that age.

The people whose brains were older than normal performed more poorly on fitness measures such as lung function, walking speed, and fluid intelligence. They also had increased risk of dying sooner. Predictions became more reliable when the brain-scan data were combined with the methylation of blood DNA, a marker of life experience effects on gene expression.

Another group of workers at UCLA had determined that these kinds of gene changes predict the risk of mortality. This group, headed by Steve Horvath, evaluated these gene expression changes in various tissues of a 112-year-old woman and found that her brain was younger than her other tissues. A "young" brain will help you to live longer and also have a better quality of life.

There are two take-home implications of such research. The first is that lifestyle and environmental influences affect one's age and that not all tissues age at the same rate. The second is that it may now be possible to test which interventions to slow brain aging actually work. We currently think aging brain is slowed by exercise, by anti-oxidants, by healthy diets, by reducing stress. Having objective measures for aging in general and brain in particular will help us decide how well such preventive measures work. There is also the possibility that such measurement tools may help us identify who is aging too fast and why that is happening, which in turn may lead to better therapy. 

While we wait on technology, there is one symptom of excessive brain aging we can all notice: memory loss. As the title of my book suggests, memory is the canary in your brain's coal mine.

Get the most out of life as you age. You can slow brain aging by following the advice in Memory Medic's inexpensive e-book, "Improve Your Memory for a Healthy Brain. Memory Is the Canary in Your Brain's Coal Mine." It is available in Kindle at Amazon and all formats at Smashwords.com.

Sources:

Kwon, Diana (2017). How to tell a person's "brain age." The Scientist. May 22.

Cole, James H. et al. (2015). Prediction of brain age suggests accelerated atrophy after traumatic brain injury. Annals Neurology.77(4), 571-581.  doi: 10.1oo2/ana.24367.  http://onlinelibrary.wiley.com/doi/10.1002/ana.24367/full

What Happens to Aging Brain

Deterioration of the brain sneaks up on most of us. The first clue might be hearing loss, especially in the higher frequencies. We may be forced into bifocals, even trifocals. But the most serious signs of deterioration occur in the brain.

As we age, our reflexes slow. We walk and act slower. We even talk slower. Our memory starts to fail, especially the short-term form of memory ability that is so crucial for learning new things.

Brain-scan technology reveals aging can cause the brain to shrink. Nerve tracts in the brain shrivel, making the cerebrospinal fluid cavities larger and even leaving gaping holes in the brain. Shriveling occurs in the neuron terminal branches that form the contact points among neurons. People may lose 40% or more of dopamine neurons causing Parkinson’s disease.

These are brutal truths. Whole societies are being affected in major economic and social ways in countries where the population is aging rapidly, such as Japan (23% over 65), Germany (20.5%), Italy (20.4%), and the U.S. (13%). The countries that show that fastest rate of change in population age, in order, are Iran, Vietnam, Mexico, India, and South Korea. The obvious consequences are a shrinking labor force and shifting of a nation’s wealth to health care.

The challenge for aging individuals is to reduce the rate of their decline. This has created a growth anti-aging industry focused on vitamins and supplements, fad diets, gym facilities, mind training programs, and books like my books on memory.  The good news is that these things can work, if they are begun while people are in early middle age.

A likely cause of mental decline in most people is diminished blow flow in small vessels that are easily plugged by cholesterol and fats or ruptured by high blood pressure. These undetected “mini-strokes” are probably quite common as we age, yet they cause cumulative, progressive damage. Another source of damage is the lifetime cumulative effect of oxidative free radicals that result from energy metabolism. The brain consumes about 20% of all the body’s oxygen, even though it only ways about 3.5 pounds.

When brain cells do die or are damaged for any reason, healthy neurons are assaulted by inflammatory chemicals, like cytokines, that are released by the brain’s immune cell system. Brain inflammation is commonly caused by infections such as colds and flu and by diets deficient in anti-oxidants.

We now know brain function need not decline with age, at least for people who stay healthy and mentally active. By the way, research shows that a lifetime of vigorous learning helps prevent or delay Alzheimer’s disease.

Level of education and lifetime of intellectual stimulus of research seem to protect brain against aging.  Here are some examples:

• Leo Tolstoy learned to ride a bicycle at 67
• Queen Victoria began learning Hindustani at 68
• Giuseppe Verdi was still composing operas in his 80s
• Somerset Maugham wrote his last book at 84
• Frank Lloyd Wright designed his last building at 89
• In their 90s, Robert Frost was writing poems and George Bernard Shaw was writing plays, Georgia O’Keefe was painting pictures, and Pablo Casals was playing cello
• Oliver Wendell Holmes was still dominating the Supreme Court until he retired at 91
• Linus Pauling was actively publishing just before his death at age 93.
• Leopold Stokowski recorded 20 albums in his 90s and signed a six-year contract at 96.

Scientists are particularly noted for being sharp and productive long into the late 80s and 90s. The National Science Foundation reports that at age 69 more than 29% of scientists and engineers with PhDs still work full time, compared to 13% of scientists with a M.S. or B.S. degree. Marion Diamond, an active senior scientist at 75, published data showing that brain cells can grow and learning can improve throughout life.

Of course genes and luck have a lot to do with how well one ages. Even so, gene expression is influenced by things like exercise, diet, and mental activity. Two genes have already been identified that become expressed as new memories are formed.

Too many seniors resign themselves to the ravages of age.  They will find, however, large benefits from challenging themselves in new experiences and competencies. Better yet, learning new things makes you feel good about yourself, especially when accomplishing things other people think you can’t do.

Sources:

1. Discover Magazine (2012). Special issue “2062 World Almanac.” October.

2. Rupp, R. (1998) Committed to Memory. New York: Random House.

3. Diamond, Marian (1993). An optimistic view of aging brain. The Free Library. http://www.thefreelibrary.com/An+optimistic+view+of+the+aging+brain.-a013700953

“Dr. Bill,” Senior Professor of Neuroscience at Texas A&M, is author of a new memory improvement book, Memory Power 101 (SkyhorsePublishing.com) and an e-book in multiple formats for students, Better Grades, Less Effort (Smashwords.com).