The Brain

  What happens to my hearing?

  The aging auditory system develops a general loss of hearing but mostly of higher frequencies (around 3–7 KHz); sadly, the consequence of losing these frequencies is a reduced ability to perceive speech. The hearing loss is due mostly to degenerative changes occurring in an inner ear structure called the cochlea. For people living in noisy environments or using earbuds to listen to loud music, the energy of the sound is conducted into the inner ear, leading to actual cell death of sound-receptor cells.

  What happens to my balance?

  The vestibular system, which monitors your body’s angular acceleration, as well as its sense of gravity and tilt, also resides within your inner ear. Without doubt, the most bothersome age-related problem that most people complain about is a loss of balance. This occurs in about one third of all people 40 years and older; the degeneration of vestibular nerves contributes to the high number and frequency of falls in the elderly. Dizziness is often the most common complaint that elderly patients mention to their doctors. Why? The number of neurons originating within the vestibular system in the inner ear of a 20-year-old person is about 19,000; this number declines to about 18,000 by age 60 years. Apparently, the loss of only about 5% of these neurons is sufficient to cause vertigo and problems with balance. Vertigo, a sensation that either you or the room is spinning, is a complaint of about 90% of patients seen in geriatric clinics.

  What happens to the taste of food?

  Your sense of taste is handled by your gustatory system. With normal aging, the absolute threshold of taste increases. Essentially, what this means is that you require more spices and more intense flavorings to enjoy your food. Your taste perception also declines with age; some familiar or favorite foods simply lose their complexity and pleasure. Part of this loss is due to degenerative changes occurring in the olfactory system within your nose. Your ability to identify unique smells peaks between age 20 and 40 years, declining slowly with normal aging. Interestingly, your ability to smell sweet and fruity odors is most vulnerable to age-related changes, while your ability to smell musky or spicy odors remains relatively stable with age.

  Why do things feel differently?

  Finally, your sense of touch exhibits the following changes with normal aging. More pressure must be exerted to report tactile sensation. Sensory discrimination decreases. Using a two-point threshold discrimination task, that is, how far apart do two pressure points need to be in order for you to detect two distinct points, subjects between 20 years and 36 years of age could distinguish two points 6.3 mm apart on their palms and 2.2 mm apart on their thumbs. Subjects between 63 years and 78 years of age could distinguish two points 7.8 mm apart on their palms and 3.9 mm apart on their thumbs. Clearly, just about every aspect of your aging nervous system changes with age—which raises the next most important question.

  What can you do to slow aging?

  Stop eating so much! Especially avoid red meat and dairy products. There are many other healthier dietary sources for iron and calcium. The benefits are now well known: dietary restriction slows brain aging and protects against many neurodegenerative diseases. The exact biological mechanisms underlying the beneficial effects of dietary restriction are not completely understood, even though the effects have been observed in many species, ranging from worms to monkeys. As already discussed, the current evidence suggests that a reduction in free radical formation and subsequent inflammatory processes, as well as alterations in the expression of genes that regulate our circadian rhythm, underlies at least part of dietary restriction’s beneficial effects.

  How much should you restrict your diet?

  Not that much. In a recent study, a large group of monkeys, ranging in age from middle-aged adults to the quite elderly, were fed 70% of their free-feeding diet for about 15 years. This study is valuable because it investigated the effects of a reasonable reduction in total calorie intake and the monkeys were on this restricted diet for a significant portion of their lives. Essentially, for a normal human male eating 2,000 calories per day, this would be about 600 fewer calories per day. For comparison, 600 calories would be about one cup of roasted almonds, or a typical 100 gram bar of dark chocolate, or a typical Cold Stone Creamery dessert (with the M & M’s of course!). Obviously, the monkeys were not on a starvation diet.

  Because they consumed 30% fewer calories, the brains and bodies of the monkeys on the restricted diet aged significantly more slowly. Although several brain regions showed benefits, those brain regions that evolved most recently, such as the frontal lobes, which also tend to be more vulnerable to the consequences of aging, showed the greatest beneficial response to the dietary restriction. Monkeys on the restricted diet developed fewer age-related diseases, had no indication of diabetes, exhibited almost no age-related muscle atrophy, and lived much longer than their free-feeding compatriots.

  Take note of the crucial fact that these monkeys did not exercise their weight off; they simply consumed fewer calories. Exercising is never going to be as beneficial to your brain and body as restricting the number of calories you consume! By now you can probably guess why—exercising involves lots and lots of breathing and encourages you to consume lots of energy.

  What is the consequence of being overweight as I get older?

  Obesity leads to brain shrinkage and increases your risk of developing dementia. One recent study demonstrated that being obese at midlife is a strong predictor of dementia in later life. The obese elderly also have more impaired learning and memory abilities than thin elderly people. Patients with Alzheimer’s disease who are obese develop more pathology in their brains and demonstrate a very rapid decline in mental function. How does obesity contribute to brain shrinkage and dementia? Fat cells in the body produce inflammation by releasing specialized proteins called cytokines. The more fat cells you have, the more cytokines are released into your blood every hour of every day. Cytokines induce shrinkage of brain regions that are required for making new memories and for recalling old ones. If the obesity-induced inflammation lasts for many decades, there is more brain shrinkage and greater memory loss.

  Fortunately, the sooner one loses the body fat, the sooner the brain can begin to recover. The true culprit is body fat. Older people who have relatively more visceral fat than subcutaneous fat, and thus might appear to be thin, are also at increased risk for diabetes, metabolic syndrome, and increased mortality. What would happen if these harmful fat cells were simply removed? Exercise can shrink fat cells, but only liposuction can remove them from the body. A group of scientists investigated this question by conducting three very clever experiments on obese and normal-weight mice. Mice demonstrate an identical vulnerability to the negative consequences of body fat on brain health as humans. First, a group of obese mice exercised on a treadmill. As expected, these mice reduced belly fat, reduced the level of inflammation in their body, and significantly restructured how their brains functioned at the cellular level, leading to greatly improved memory.

  In the second study, the scientists surgically removed abdominal fat pads from a similar group of obese mice; that is, the mice underwent a standard liposuction procedure. The results were identical to those produced by running on the treadmill: inflammation was reduced and the mice became significantly smarter. These findings confirm many recent studies that have documented the ability of fat cells to impair brain function and accelerate aging.

  In the third study, the scientists did something truly astonishing; they transplanted fat pads into normal, healthy-weight mice. The impact of the additional fat cells was immediately obvious: the mice showed increased signs of brain and body inflammation, and they developed harmful changes in brain structure and function that led to a significant memory impairment.

  Today, an overwhelming amount of scientific evidence across a wide spectrum of medical disciplines strongly argues that obesity accelerates the aging process, impairs overall cognitive function and, ultimately, is responsible for numerous metabolic proce
sses that ultimately kill us.

  What can you do about your aging brain?

  As you have just discovered, medical research has found some great answers. To save you the time it would take to search through a diverse collection of epidemiological studies (some of which have already been discussed), here is a compilation of the best scientifically defendable advice for living a long life and having a healthy brain: be female, drink lots of coffee, choose your parents carefully, eat as little as possible, breathe as little as possible, move as little as possible, be born in May, be tall and have a large head, develop arthritis so that you can justify taking lots of anti-inflammatories, and drink moderate amounts of beer every day. If you must eat, then only dine during the early part of your daily biorhythm.

  Do miracle cures for brain aging exist?

  In the void of what we have yet to discover about brain aging lie numerous unanswered questions and unproven theories. Unfortunately, countless myths have been invented to fill this void of ignorance; among these myths are those concerning age- or disease-related mental decline and the benefits of alternative, nonscientific remedies purported to restore, or even enhance, brain function. A truly remarkable variety of medical interventions have been concocted out of uneducated interpretations of genuine scientific facts and promoted by people who become victims of their own wishful thinking. We have all encountered these people; they are sincere but appear deluded and fixated on eccentric theories—and always, without fail, they are confident that their knowledge will revolutionize science or society if only somebody would just listen to them. We ourselves are vulnerable to these misconceptions because we desperately want them to be true.

  Inevitably, we become dreadfully disappointed when our expectations are not met. Maybe the problem was you, maybe you were not sufficiently persuaded by all of those wonderful claims by your friends on the Internet. As Tinker Bell said, “You just have to believe!” Shouldn’t your good thoughts and a positive attitude be sufficient? No. Results of many carefully controlled studies have failed to show that psychological interventions, such as simply being happier, practicing positive thinking, or receiving the prayers of devout friends, have any impact on the survival of cancer patients.

  Today, the Internet, magazines, and slick television infomercials are using sloppy interpretations of questionable scientific studies to mislead desperate people. Usually, the only consequence for exploited victims is the loss of money or a delay in seeking treatment that might offer some true medical benefits.

  Our brains change throughout our lives, and not always for the better. Why do they change? There are many causes of cognitive decline, including the long-term consumption of some drugs—both licit and illicit, dementia and various diseases of the brain and body, head injury, hormone imbalance, dietary nutrient deficiency or excess, heavy-metal toxicity, sleep deprivation, and prolonged stress, to name only a few. The treatments are as varied as the causes. Some modern treatments for many of these ailments are relatively effective for many people. In contrast, no treatments currently available can reverse one of the biggest causes of cognitive decline: normal aging.

  Once again, the failure of modern science to provide an effective intervention has left a void of ignorance. This has been filled by con artists, who offer usually harmless products for sale and claim that these enhance brain function as we age. The most distinctive feature of any useless elixir is that it is always 100% effective. In contrast, no scientifically tested drug would or could ever make such a claim. In general, most of these unproven elixirs contain common stimulants such as caffeine or sugar in order to enhance one’s level of arousal. Unfortunately, stimulants only enhance performance, not true intelligence. The classic brain stimulants already discussed—coffee or nicotine—might improve performance, engaging certain neurotransmitters in the process, but they do not raise one’s IQ score, and they do not stop normal age-related cognitive decline.

  Thus far, however, no one has been able to design a drug therapy that can make a person smarter in any significant way. If you look at the so-called memory boosters and cognitive enhancers on the market today, you will find that they contain caffeine and sugar and some peculiar amino acids and a few vitamins that together do nothing except make you a little poorer. At this point in time in the 21st century, nothing—let me repeat that, nothing—can truly make you smarter; thus, do not waste your money on any product that promises to do so.

  One thing, however, is certain: someone, somewhere is now selling “the cure” for mental decline. Everyone would prefer to defy the aging process by simply taking a pill and being able to eat with impunity everything we desire rather than following the standard prosaic advice about moderate, healthy eating. The fact that science has not yet invented a true brain enhancer has not stopped people from selling drugs, ancient elixirs, unusual therapies with mystical names, and hundreds of books that all boast of the properties of this or that miraculous, age-defying brain booster. If someone stands to gain financially from your gullibility, then what he or she is selling is probably useless, and there is no guarantee that it is safe. Any cursory search on the web brings up countless potions containing useless, scientifically discredited but rather harmless ingredients.

  Why do so many people fall under the spell of charlatans?

  Why do people believe that these magical elixirs are effective for them? The answer is easily summarized in three little words—the placebo effect. Essentially, we very badly want these elixirs to do something, anything, to slow down the aging of our brain; so we fool ourselves into thinking that they do. After all, you have just spent a lot of money on this pill! Placebos, of course, must be expensive. No one would ever believe in the effectiveness of an inexpensive magical elixir; after all, they are special and, therefore, must be expensive. When challenged, spokespersons for these fraudulent products often claim that medical science has ignored their wonderful product because doctors simply do not want you to be healthy. Not true. Scientists have spent years testing many of these compounds; their conclusion is that these products are as useless as they are expensive. Fortunately, most of them are so utterly inactive that they will not harm you. One of the best examples of a useless antiaging product is an extract from the Ginkgo biloba plant.

  What about Ginkgo?

  The first challenge in using Ginkgo or any other plant product is knowing how much to use and which component of the extract is most effective. When ancient Chinese herbalists recommended that their patients take Ginkgo biloba, or any number of other plant extracts that have been prescribed during the last two millennia, they always estimated dosage based on past experience. But plants are complicated organisms that produce a large variety of molecules, some of which are active in the brain, some of which are not active in the brain but are quite nutritious, and some of which are simply inactive. Therefore, how much of any particular extract should be taken by a person who seeks the benefit that Ginkgo might offer? No one knows! The studies necessary to establish a truly effective dose are exceptionally expensive and, therefore, have never been performed rigorously. In order to avoid such expensive testing, the manufacturers, with the help of politicians, have had their products designated as nutritional supplements rather than as drugs.

  Studies conducted on these nutritional supplements are often poorly designed and have various methodological problems, such as inadequate sample size (the number of subjects in the study) and lack of a double-blind, placebo-controlled paradigm, the gold standard of modern scientific research. This paradigm means that no one involved in a drug trial—including its investigators and its subjects—knows which tested substance, whether an active drug or a placebo (usually an inactive form of the drug under study or a sugar pill), is being administered. The purpose of this approach has to do, again, with bias: to keep investigator and subject bias from influencing the trial’s results. In fact, on the rare occasion that this standard has been applied to studies on alternative medicines such as Gingko biloba, the res
ults have been negative. For example, a pair of very large clinical trials that followed the health of more than 3,000 people of various ages for eight years clearly demonstrated that Gingko biloba cannot influence the development of age-related memory problems. Another trial indicated that the use of Gingko may actually be harmful and increase an individual’s risk of stroke (i.e., when a blood vessel in the brain becomes blocked and shuts off blood flow). These are, however, just a handful of studies, and much more high-quality research needs to occur before the effectiveness of Gingko biloba and other herbal products is irrefutably proven or disproven.

  In the meantime, most manufacturers of these products prefer to err on the side of selling diluted samples, thereby avoiding any toxic side effects and potential lawsuits from people who survive the experience. But this is still no guarantee that the samples are safe. Unacceptably high levels of pesticides and carcinogens have, for example, been found in a large percentage of imported samples of Gingko biloba and many other herbal medications. These concerns aside, many people are convinced that they benefit from substances like Gingko biloba or the countless other useless products on the market, such as extracts of deer antlers or sea horses, that promise enhanced cognitive function. Why? Because they want these drugs to do something and, therefore, fool themselves into thinking that they do. We all are subject to this faulty thinking from time to time.