Before you make the synaptic leap from megadosing with neurotransmitter precursors to cognitive superiority, consider this: All effects so far depend on the context. Neurotransmitter supplementation improves cognitive performance only in the face of a deficit caused by environmental stress or aging. No one yet knows whether supplementation can improve performance in people who have normal levels of neurotransmitter precursors. "Whether or not you'll sustain a benefit depends on where you start off," says Strupp. "If you have a deficit of a certain neurotransmitter precursor, then you may benefit."
To complicate matters, precursor amino acids normally compete with each other to cross the blood-brain barrier. If you eat a protein-rich meal, amino acid are delivered to the brain in an acceptable pattern. But when you take supplements of individual amino acids, in attempts to bolster a specific neurotransmitter, you monopolize the transport system. That may be counterproductive, throwing off the balance of neurotransmitters needed for all-around mental performance and well-being. To date, the best way to get the right mix of neurotransmitter precursors, along with other nutrients that are turned into brain chemicals, "is the way they come in food," says Strupp.
Still, taking extra choline may not hurt. Since it's not an amino acid, choline has no competition crossing from blood to brain, and therefore it doesn't interfere with the absorption of other nutrients. It seems to be safe in the doses used in studies—around 5 grams per day—according to Strupp. If you don't regularly eat egg yolks, organ meats, and legumes, you can get choline from lecithin. But keep in mind that choline is a fat and thus adds calories.
A Jolt of Java
Looking for a quick cognitive boost? Go ahead, fill up your coffee mug.
Psychologist Harris Lieberman, Ph.D., of the U.S. Army Research Institute of Environmental Medicine, in Natick, Massachusetts, has been studying how to maintain alertness in soldiers. Caffeine works, says Lieberman, by blocking the neurotransmitter adenosine, which normally calms the brain. "The clearest effect of caffeine on cognition is its ability to enhance vigilance." Caffeine helps sustain attention during performance of various cognitive tasks for long periods of time.
Used in moderation, caffeine appears to be safe, Lieberman says. Unless pregnant, the average person can safely use coffee and tea as a habitual wake-up call, up to his or her personal "jitter threshold."
Does Sugar Make You Sharp?
The brain's source of energy is, almost exclusively, glucose, a simple sugar to which all dietary sugars and other carbohydrates are ultimately broken down. Hormones that aid memory do it by raising glucose levels. According to University of Virginia psychology professor Paul Gold, Ph.D., studies of rats and people show that glucose, whether given after a fast or after a meal, whether consumed as food or injected directly into the brain (in rats), in fact improves long-term memory.
In a study, Gold and colleagues gave college students a lemonade drink containing 50 grams of glucose—200 calories' worth of pure sugar—and then subjected them to a battery of cognitive tests. Gold found that glucose measurably enhanced the students' performance, most notably in a reading retention task.
Which leads directly to the question: Should you chug a glucose-laced sports drink such as Gatorade to boost your brain power a quarter of an hour before your Mensa test? Perhaps, but the amount you need to drink is still something of a crapshoot. Your optimum dose of glucose at any one time depends on several factors: current blood glucose level, physical and mental stressors, previous dietary patterns, individual metabolism, and other variables that neither you nor medical science can readily evaluate at this time.
To further complicate matters, the dose you take doesn't always match the response you want. Too much glucose can actually prompt a hypoglycemic response. Blood sugar levels soar, then plummet; in response to the sudden sugar flood, insulin rushes into the blood and mops up the excess, worsening mental performance.
Still, a glucose drink specifically tailored more for brain boosts than for physical performance is already available in England and might reach American markets within the next few years, according to Gold. Most likely it will be initially targeted for the elderly, and those with Alzheimer's disease, Down's syndrome, and head injuries, all of whom perform substantially better on cognitive tests when given glucose.
How best to stoke your brain with glucose? "The variety of carbohydrate foods found in a balanced diet will take care of the brain's energy needs," says Gold. "The brain is selfish, and takes care of itself," having first dibs on any glucose present in the bloodstream. Or it may force the conversion of other nutrients into glucose.
Mood: A Serotonin Solution?
Carbohydrates not only influence cognitive performance, they play a major role in your mood, contends Judith Wurtman, Ph.D., research scientist at the Massachusetts Institute of Technology. She finds that a diet rich in carbohydrates can help you feel anxiety-free and relaxed, by giving the amino acid tryptophan preferential access to the brain.
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