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).