Food Supplements and Cognition
Advertisers offer a range of food supplements that supposedly will make you smarter, improve your memory, help you think more clearly, and so on. Unfortunately, though, these supplements have usually not been tested in any systematic way. (In the United States and in many other countries, new medicines are tested before they are put on the market, but new food supplements are not.) In most cases, then, the claims made about these supplements are unsupported by evidence.
One supplement, though, has been widely endorsed and rigorously tested; this supplement is Ginkgo biloba , an extract derived from a tree of the same name and advertised as capable of enhancing memory. Is Ginkgo biloba effective? The answer begins with the fact that, for its normal functioning, the brain requires an excellent blood flow and, with that, a lot of oxygen and a lot of nutrients. Indeed, it is sometimes estimated that the brain, constituting just 2% of our body weight, consumes 15% percent of our body’s energy supply!
It’s not surprising, therefore, that the brain’s operations are impaired if some change in your health interferes with the flow of oxygen or nutrients. If (for example) you’re ill, or not eating enough, or not getting enough sleep, these conditions will affect virtually all aspects of your biological functioning. However, since the brain is so demanding of nutrients and oxygen, it’s one of the first organs to suffer if the supply of these necessities is compromised. This is why poor nutrition, or poor health, almost inevitably undermine your ability to think, to remember, to pay attention, and more.
Of course, the opposite is also true: A healthy diet, adequate exercise, and regular sleeping hours will improve the performance of all your bodily systems; but again, since the brain is so expensive to maintain, these different aspects of a healthy lifestyle are especially important for making sure your brain has the resources it needs to function well. The implications of this for students are clear.
But what about Ginkgo biloba? Evidence suggests that Ginkgo extract may improve blood circulation, reduce some sorts of bodily inflammation, and protect the nervous system from several types of damage. This is why researchers are examining this extract as a possible treatment for people who have troubles with blood circulation or who are at risk for nerve damage. In fact, results suggest that patients with Huntingdon’s disease, Alzheimer’s disease, and several other conditions may be helped by this food supplement—and, in particular, helped to remember more, and to think more clearly. Let’s be clear, though, that Ginkgo is not making these patients “smarter” in any direct fashion. Instead, the Ginkgo is broadly improving the patients’ blood circulation and the health status of their nerve cells, allowing these cells to do their work.
What about healthy people—people who are not suffering from bodily inflammations or damage to their brain cells? Will Ginkgo help them? Here the evidence is mixed. Some reviews offer the tentative conclusion that Ginkgo may improve the cognitive functioning of healthy young adults, but many studies have failed to observe any benefit from this food supplement, suggesting that Ginkgo’s effects, if they exist at all in healthy adults, are so small that they are difficult to detect.
Are there other steps that are more promising—steps that will improve the mental functioning of healthy young adults? We’ve already indicated part of a positive answer: Overall, good nutrition, plenty of sleep, adequate exercise, and so on will keep your blood supply in good condition, and this will help your brain to do its job. In addition, there may be something else you can do: The brain’s functioning depends on an adequate fuel supply, and that fuel supply comes from the sugar glucose. Crucially, the body’s neurons have no way to store glucose, and so, for their moment-by-moment functioning, they depend on the bloodstream to deliver a steady supply of this fuel.
You can protect yourself, therefore, by making sure that your brain has all the glucose it needs. This is not a recommendation to jettison all other aspects of your diet and eat nothing but chocolate bars. In fact, most of the glucose your body needs doesn’t come from sugary foods; most comes from the breakdown of carbohydrates, and so you get it from the grains, dairy products, fruits, and vegetables you eat. Thus, it might be a good idea to have a slice of bread and a glass of milk just before you take an exam, or just before you walk into a particularly challenging class. These steps will help ensure that you’re not caught by a glucose shortfall that could interfere with your brain’s functioning.
We need to be cautious, though, in how we think about these points. As one concern, you don’t want to gulp down too much sugar. If you do gobble up a candy bar just before your exam, or gulp down a large glass of sugary lemonade, you might produce an upward spike in your blood glucose followed by a sudden drop, and this can produce problems of its own. In addition, we should emphasize that the benefits of ingesting carbohydrates—even if you get the “dose” right—may be relatively small. This is because the glucose supply for the brain is tightly controlled by a number of different mechanisms inside the body, and these mechanisms usually guarantee that your brain gets the sugar it needs. As a result, the extra glucose you might obtain from a fast snack may just get “set aside” by the liver and not be sent to the brain at all.
In short, then, the evidence suggests that food supplements offer no “fast track” toward better cognition. Ginkgo is helpful, but mostly for special populations. A high-carb snack may help, but will be of little value if you’re already adequately nourished. Thus, on all these grounds, the best path toward better cognition seems, in some ways, to be the one that common sense would already recommend—a balanced diet, a good night’s sleep, and paying careful attention during your studies.
Critical Questions
1. fiogf49gjkf0d Why might the effects of Ginkgo biloba on cognitive functioning be rather indirect? |
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2. fiogf49gjkf0d What are some changes that you can make to your day-to-day lifestyle to improve the functioning of your brain? |
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3. Although our brains depend heavily on glucose for energy, we do not have to eat sugary foods to maintain healthy levels of glucose in the blood. Spend a few minutes researching the dietary sources of glucose. |
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The So-Called “Smart Pills”
In the previous essay, we looked at one means of enhancing cognition—through food supplements such as Ginkgo biloba. There is, however, another strategy that people have tried but that has been deeply controversial: the use of stimulants. Students working through the night have often turned to caffeine and nicotine to help them stay awake—drinking yet another cup of coffee, or smoking a cigarette. The same is true for military personnel who need to remain alert for a long mission; they, too, have turned to these stimulants. And, in recent years, grocery stores have been offering other (more potent) means of getting the same effects, in the form of heavily caffeinated “energy drinks” (and “energy bars,” caffeinated candy, and even a caffeinated inhalant).
The controversy in this area, however, has focused on a different type of stimulation: In the last dozen years or so, people have turned to the (typically illegal) use of various prescription drugs to enhance their performance in school and in the workplace. Many of these drugs are stimulants used widely for treatment of attention--deficit/hyperactivity disorder (ADHD). These same drugs—including methylpenidate (marketed as Ritalin or Concerta) and various forms of amphetamine (e.g., Adderall)—have become popular, though, as “cognitive enhancers.”
These drugs are effective as stimulants, and so, plausibly, do help to keep people alert as they work or study. Even so, many researchers are deeply troubled about the increasing use of these prescription medications. As one concern, many of the commonly taken drugs have side effects, including gastrointestinal upset or nausea, and these side effects can offset any potential benefits from the drug. (The drug might perk you up, but that’s not going to be helpful if you’re focusing all your attention on not vomiting.) In addition, people often come “crashing down” when the drug effects wear off, so whatever gain in productivity they experienced while influenced by the drug is canceled out by the loss in productivity they’ll experience in the next few days, while dealing with the “crash.”
More troubling, many individuals use these drugs repeatedly over long periods of time, and we know little so far about the long-term problems that this use may create. We do know that there’s a risk of addiction associated with these medications, and that’s certainly a substantial concern. It’s also important that individuals who receive these drugs with a doctor’s prescription (e.g., for ADHD) are given clear information about dosages, and they receive follow-up from the doctor. In contrast, individuals who use these drugs as stimulants often obtain the drugs through means other than a prescription, and so they improvise on the dose and receive no follow-up—-factors that magnify any concerns about side effects and undetected drug dependence. Related, a doctor prescribing these medications would be alert to factors that, for that individual, might argue against using these drugs (so-called “contraindications,” including other medical conditions the person might have, or other drugs the person might be taking). This safety net is obviously not in place if someone obtains these drugs without a doctor.
Ironically, alongside of these potential problems, the possible benefits of these drugs are questionable. We certainly know that getting information into memory requires that you pay attention and engage the material somehow, and this mental “work” won’t happen if you’re sleepy and unfocused. On that basis, a stimulant might help you to learn new material. Likewise, judgment and reasoning often depend on mental shortcuts that are efficient but open to error. To avoid these shortcuts, you need to rely on (what we’ll call, in Chapter 11) System 2 thinking, and this sort of thinking is less likely if you’re sleepy. So here, too, a stimulant might help you. And, for that matter, in Chapter 12, we’ll distinguish between fluid and crystallized intelligence. Fluid intelligence is what you need for working on novel problems, especially problems that require some mental flexibility—and fluid intelligence is compromised when you are tired.
There’s really no debate, therefore, about whether being alert and awake is helpful for cognition. There’s likewise no debate about whether a stimulant helps you to be alert; plainly, it does. The question, then, is whether these prescription medications are superior to, say, caffeine in offering this stimulation, and also whether the prescription medications might offer other benefits beyond stimulation. If the answer to these questions is “no,” then the prescription drugs are surely a bad bet—providing no benefits beyond caffeine, but with greater risk of side effects, and greater risk of drug dependence.
What is the evidence on these points? One recent report offers the encouraging (but “provisional”) conclusion that the prescription stimulants help with the consolidation of memories. In other words, the stimulants enhance the processes that take place in the hours after a learning episode, processes that serve to “cement” a memory in place (Smith & Farah, 2011). There’s indication, though, that this benefit for consolidation emerges only if just the right dose of the drug is delivered, at just the right moment. Otherwise, the drugs do little to help (and might even disrupt) consolidation. Indeed, these specifics might lead us to expect that any benefits of the drugs will be difficult to document, and that expectation is correct. One summary of the evidence, for example, concluded that the “use of stimulants in college students did not promote learning or academic achievement. Overall, it is still uncertain whether the medical use of stimulants enhances academic achievement” (Swanson, Wigal & Volkow, 2011, p. 745). Another 2011 paper argues that a conclusion offered by Rasmussen (2008) is still in line with the evidence: “Enhancements with stimulants are hard to demonstrate, especially when compared to caffeine, and seem to relate more to individual perception of increased ability rather than to objective improvement of function” (Elliott & Elliott, 2011).
Where, then, does this leave us? Many people (including your textbook’s author!) can do little intellectual work prior to their morning’s coffee. Intellectual work is “work” and requires an alert brain. Caffeine—a mild stimulant—helps promote this alertness, and so do the prescription stimulants. Whether the prescription stimulants can do more than this—and whether they can promote memory consolidation, or the brain’s executive functioning, or some other specific process—is (at best) not yet clear. At the same time, the potential problems associated with the prescription meds are well documented. As a result, most researchers would advise against the use of these pills. The drug benefits are questionable, and their problems are real, and so there are surely better, healthier, safer ways to promote alertness and enhance your mental life.
Critical Questions
1. What are some safe and legal changes that you can make to your day-to-day lifestyle to improve the functioning of your brain? |
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2. fiogf49gjkf0d Spend a few minutes researching the side effects of caffeine. How do they compare with the side effects of using prescription stimulants? |
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3. fiogf49gjkf0d What are some of the legal and political difficulties with regulating use of prescription stimulants? |
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