Why We Forget and How to Remember Better, page 22
Vitamin D
Vitamin D is essential for your brain health. If children don’t receive enough vitamin D it can cause rickets, a disease that commonly affects bones and brain. Adults with low levels of vitamin D are about twice as likely to develop Alzheimer’s disease compared with those whose levels are normal.11 Many people don’t have enough vitamin D. Although you can actually make this vitamin through your skin, you need to spend sufficient time outside without sunblock—which we don’t recommend.
Because of how serious its deficiency is, vitamin D is one of the few nutrients that we recommend you take as a supplement pill. A daily dose of 2,000 IU of vitamin D3 is the right amount for most people. You can also get vitamin D from fatty fish (such as salmon), portobello mushrooms grown under an ultraviolet light, and foods fortified with vitamin D, including milk, cereals, and orange juice. Note that there are some important interactions between vitamin D and certain prescription medications, so you should speak with your doctor prior to taking vitamin D supplements.
B Vitamins
The B vitamins are another group in which supplements are sometimes helpful. As we mentioned in Chapter 14, low levels of vitamin B12 (cyanocobalamin) can cause depression, anxiety, and psychosis in addition to impairment of memory and thinking. Liver and clams have the most B12, although fish and other shellfish, meats, milk, and yogurt also have some. Many people have trouble absorbing enough B12 from foods as they get older, but by taking a supplement as well (such as 250 or 500 micrograms daily) they can usually overcome this problem and get enough into their body. Some individuals, however, cannot absorb the vitamin at all and will need injections. The best way to determine if you need supplemental B12 pills or injections is to work with your doctor and get your level checked.
Thiamine (vitamin B1) deficiency can cause a form of potentially reversible memory loss and confusion called Wernicke’s encephalopathy, as well as a devastating, permanent loss of memory called Korsakoff syndrome (or Korsakoff amnesia), which is often associated with alcoholism. Thiamine-rich foods include whole grains, legumes, fruit, and yeast. However, if one has alcoholism, we recommend taking 100 milligrams of thiamine daily.
Although deficiencies of B6 and folate (vitamin B9) are uncommon, they can cause confusion and impaired memory, and are sometimes seen in the elderly and those with kidney problems, autoimmune disorders, and alcoholism. Low levels of B6 and folate have also been associated with an increased risk of developing Alzheimer’s disease. Foods rich in B6 include chickpeas, tuna, salmon, potatoes, bananas, turkey, marinara sauce, beef, pistachios, and dark chocolate. Foods rich in folate include dark green leafy vegetables, fruits, nuts, beans, peas, seafood, eggs, dairy products, meat, poultry, and grains. You can also get B6 and folate from a B-complex vitamin or separate pills. Note, however, that too much B6 is highly toxic (it can cause a severe neuropathy), so we do not recommend more than 50 milligrams daily. For folate we do not recommend more than 1,000 micrograms daily, unless you are pregnant or planning to get pregnant (in which case you should speak with your doctor).
Once-in-a-While Foods
Now that you know the foods that are good for you are on a Mediterranean-style menu, you may be wondering which foods are not so good for you. Which ones are they? Well . . . they’re almost everything else. The following foods should be infrequently eaten:
• Red meats
• Butter and margarine
• Fried foods
• Fast foods
• Highly processed foods
• Pastries and sweets
• White bread, white flour, and white rice
• Most pasta
• Regular sodas and juices as well as diet sodas and juices with artificial sweeteners
Wondering what’s wrong with diet sodas and juices? It turns out that the artificial sweeteners mimic sugar so well that they actually cause a spike in insulin in your body. This is detrimental for two reasons. The first is that these high insulin spikes are not good for the brain. The second is that the insulin spike makes you hungry, and you end up eating more than if you drank water without the artificial sweetener.
What to Drink?
Speaking of water, plain water is one of the best beverages to drink with your food. If you prefer bubbles, soda/seltzer water is fine too. Coffee and tea—in moderation because of the caffeine—are also good to drink. Decaffeinated coffee and tea and herbal teas are a nice way to enjoy these drinks without the caffeine. Chilled water that is flavored with mint, other herbs, herbal teas, a bit of fruit, or even vegetables can be delicious and good for you. (We will discuss alcoholic beverages in Chapter 19.)
What About Dessert?
Some of you are probably thinking that, given the evidence, you should never eat dessert again. Not true! First, berries and other fruits are nutritious and make a terrific dessert. Second, chocolate, in small amounts, has been shown to benefit thinking, memory, and mood. Just remember that the benefit comes from the actual raw cocoa, so the darker the chocolate the better.
In the United States, dark chocolate has a minimum of 35% cocoa, sweet chocolate a minimum of 15%, and milk chocolate a minimum of 10%—meaning that even dark chocolate may not have a lot of cocoa in it. Look for the amount on the package; some dark chocolate is 60% to 90% cocoa. The recommended daily amount of chocolate is between 0.35 and 1.6 ounces, which is about one-third of a typical chocolate bar. Remember not to overdo it—chocolate is high in calories, fat, and sugar, and so too much of it can be detrimental to your health.
Nutrients Without Evidence
We wanted to mention a few of the diets, foods, and spices that are advocated for by some but that we don’t recommend. Because fish and other seafood are so good for you, you might think that fish oil would be good for you too. Unfortunately, there are no studies to support supplementation with fish oil. Similarly, although some have claimed that coconut oil improves memory, brain health, and one’s risk of Alzheimer’s, there are no scientific studies to support such claims. Ginkgo biloba was also thought to be helpful, but subsequent studies showed no benefit on cognition or on reducing one’s risk of cognitive decline, Alzheimer’s disease, or other dementias.1213
Resveratrol
Resveratrol is found in blueberries and red wine and was hypothesized to be the brain protective factor in those foods. Because of this, a carefully conducted year-long study gave people with mild to moderate Alzheimer’s disease 2,000 milligrams daily—the amount of resveratrol in 60 tons of blueberries or 186 bottles of red wine. Although resveratrol was safe and well tolerated, no clear beneficial effects were observed.14 So, although it won’t hurt you, we do not recommend resveratrol.
Curcumin
We love spicy curries and are always hoping to open our clinical and scientific journals to read about a large, well-conducted study showing that curcumin—one of the components in the curry spice turmeric—benefits memory, thinking, or brain health in any way. Unfortunately, such studies are still lacking. So, if you like spicy curry dishes—enjoy them. But we don’t recommend adding more curries to your weekly menu to improve your memory given the available evidence at this time.
Ketogenic Diet
The ketogenic diet is a high-fat, low-carbohydrate, adequate-protein diet that has been successfully used to control seizures in some children whose epilepsy could not otherwise be controlled. Two small studies with 20 or fewer subjects have suggested that the ketogenic diet can improve memory or blood flow to the brain in individuals with Alzheimer’s disease. Larger studies are needed, however, before we would recommend this diet. Although it can promote weight loss, which may be beneficial in some people, it also has serious side effects, including constipation, hypoglycemia (low blood sugar), elevated cholesterol, and kidney stones.
Prevagen
Prevagen is an over-the-counter supplement containing a protein found in jellyfish called apoaequorin. Its advertising boasts that it is “the leading memory support and brain health supplement in America,” which certainly may be true given how much is sold. But does it work? Not at all. In fact, the U.S. Federal Trade Commission charged its makers with false and deceptive advertising.15 Don’t waste your money.
Never Too Late to Start Eating Healthy
Perhaps by now we’ve convinced you that eating a Mediterranean-style menu of whole, minimally processed foods is good for you and your memory. Are you worried that you’re too old for a change in your eating to improve your brain health? The good news is that it’s not too late. One study found that even 55- to 80-year-old adults showed benefits by switching to a Mediterranean menu.16
You Don’t Have to Be Perfect
Don’t worry about trying to be perfect. There is ample evidence that just making some healthy choices regarding what you eat will benefit your memory and thinking and reduce your risk of Alzheimer’s disease. For example, although those who followed the MIND diet (described earlier in this chapter) “rigorously” showed a 53% reduction in their risk of developing Alzheimer’s disease, those who followed the diet “moderately well” still showed a 35% reduction in risk—quite a large amount.4
Eat Healthy on a Budget
Want to eat healthy on a budget? Here are a few tips.
• Buy the fresh fruits and vegetables that are in season; they’ll be less expensive and more likely to be locally produced.
• Buy local fish (if available); it will likely be less expensive and fresher.
• Buy store brands.
• To avoid expensive and unhealthy impulse buys, shop using a list and don’t go to the grocery store hungry.
• Buy enough ingredients to cook more than one meal and refrigerate or freeze additional portions for another night.
Eat for Brain Health
Keep your memory strong by providing your body with good nutrition.
• Maintain a healthy weight in the normal range for your height, which means a body mass index of 18.5 to 24.9.
• Eat a Mediterranean menu of foods: fish, olive oil, avocados, vegetables, fruits, berries, nuts, beans, whole grains, and poultry.
• Foods to be eaten rarely include red meats, butter, margarine, fried foods, fast foods, highly processed foods, pastries, sweets, white bread, white flour, white rice, most pasta, regular sodas, diet sodas, and juices.
19
This is your brain on alcohol, cannabis, and drugs
You open your eyes slowly and look around in the dim light, seeing empty bottles of beer, wine, and liquor littering the floor. Your gaze falls on the nightstand covered with drug paraphernalia, empty bags, and crumpled papers. As you continue to look around, you realize that you have no idea where you are, how you got there, or anything that happened last night. You can remember getting ready for the party, but everything is a haze after that. You wonder what you might have drunk, smoked, snorted, ingested, or injected that left you with such a hole in your memory.
We hope you’ve never had an experience like this one, a “blackout” period when you couldn’t remember anything. As we will discuss, alcohol, cannabis, and drugs (both legal and illegal) can impair your memory. Their effects are typically more subtle than the complete blackout in our story, but they are every bit as real. In this chapter we’ll review the data to answer questions such as: Should you drink red wine or abstain from alcohol? Does cannabis help your memory or harm it? Are illegal drugs as bad as those old television messages—“This is your brain on drugs?”—or is that all hype?
Alcohol
Have you experienced difficulty remembering information, perhaps someone’s name, after a drink or two? Although there are individual differences between one person and another, it is well established that alcohol interferes with both procedural memory and episodic memory.
Procedural Memory
While you might first think of party games such as “beer pong” when considering how alcohol interferes with procedural memory (Chapter 2), probably the most important—and terrible—example is the fact that drunk drivers are involved in one-quarter of all motor vehicle fatalities. Procedural memory is critical for your reaction time, your routine driving actions such as turns and lane changes, and your automatic responses to situations such as the car in front of you suddenly slowing down. Alcohol disrupts several brain regions critical for procedural memory, including the cerebellum (the “little brain” in the back and bottom part of your head). In fact, when used habitually, alcohol can damage the cerebellum—permanently impairing procedural memory.
Episodic Memory
Alcohol’s effects on episodic memory are especially notable during the encoding (learning) process. Individuals who drink too much alcohol in an evening can experience alcoholic blackouts in which they wake up the next morning not remembering what happened the night before. But less alcohol consumption can also interfere with learning and memory.
In order to understand more about how alcohol interferes with learning, a group of researchers in Toronto put healthy young adults into a magnetic resonance imaging (MRI) scanner after consuming orange juice spiked with either a large amount of alcohol (the “alcohol group”) or just enough alcohol to taste it (the “placebo group”). While their brains were being scanned, both groups had to learn pairs of objects and names of people. The researchers found that, after consuming alcohol, parts of the prefrontal cortex (your central executive, see Chapters 3 and 4) were less active, as were regions neighboring the hippocampus—all brain areas typically active when you are building your memories (see Part 2). Perhaps not surprisingly, when they were tested 24 hours later outside of the scanner, memory for both the pairs of objects and the names of people was impaired in the alcohol group compared to the placebo group.1
In another study, college students learned some information on day 1 to about 90% accuracy. The participants were then divided into three groups. The control group had their memory tested on day 7; they were still about 90% accurate. The members of the second group were given enough alcohol to make them a little drunk just before bed on day 1; on day 7 their memory accuracy dropped below 50%. The members of the third group were given enough alcohol to make them a little drunk just before bed on day 3; by day 7 their memory accuracy dropped to about 60%. This surprising result means that not only will alcohol interfere with your memory when you are intoxicated, but it will also interfere with your retention of information you learned earlier in the day—or earlier in the week. Why is this the case? Because alcohol interferes with sleep, and sleep—as we will discuss in Chapter 20—plays a critical role in memory.
Is Drinking in Moderation Good or Bad?
So, alcohol interferes with memory function—you knew that already, right? But is drinking in moderation good for the brain? After all, red wine is a traditional part of the Mediterranean menu. Some studies have, in fact, found that one alcoholic beverage daily can reduce one’s risk of dementia.2 Other papers, however, have questioned this finding, suggesting that some of the prior studies showing a benefit of alcohol consumption on dementia risk were flawed.3 An extensive review of the available data on alcohol consumption found that it is the leading risk factor for disease burden worldwide, noting that “the safest level of drinking is none.”4 Some researchers have suggested that the small correlations observed between moderate drinking and health are attributable to the fact that when people become ill they generally stop drinking, arguing that it isn’t that drinking keeps you healthy, it’s just that unhealthy people don’t drink.
Our Recommendations
First, don’t fool yourself. Whether it is a 12-ounce beer, a 5-ounce glass of wine, or 1 ounce of liquor in a cocktail, even a single alcoholic drink will impair your episodic and procedural memory to some degree. That doesn’t mean you shouldn’t have one, but if you are trying to learn the names of a dozen people you’re meeting in a party, you’ll be more likely to remember them if you don’t drink. You’ll also be more likely to remember information you learned during the week if you don’t get drunk on the weekend. And do not have more than one drink and drive or engage in other procedural memory tasks where safety is an issue, such as biking or downhill skiing. (No one should have more than one drink in these circumstances, but note that everyone’s tolerance for alcohol is different. Know yourself. Some people will be impaired drivers after a single drink.)
Second, our reading of the clinical and scientific literature is that a single alcoholic beverage daily neither helps nor harms your brain. So, if you enjoy a glass of wine with dinner or a beer with the ballgame, go right ahead. However, we would strongly recommend limiting yourself to no more than two drinks per day and seven in a given week.
Third, we would never recommend that you start drinking for your health. If you currently abstain, there is no evidence that starting to drink will benefit your brain.
Lastly, if you have a history of drinking problems, don’t drink.
Cannabis
Cannabis (also known as marijuana) is now legal for recreational use in more than a dozen U.S. states and is legal in some form for medical use in all but two. It is also legal for recreational use in Canada and several other countries, and decriminalized or otherwise tolerated in almost 50 others. Does this mean science has shown that it does not impair brain function? Unfortunately not. As we learned with alcohol (and junk food), the legality of a substance does not mean that it is good for you.
