There are over a dozen substances, including both nutrients and certain prescription drugs, that have been shown to increase intelligence in animals and man. When we refer to intelligence, we are talking about a wide range of cognitive abilities, including information processing of various types and memory. A particular intelligence-increasing substance does not increase the entire range of intelligence but only certain specific aspects of it. Increasing human intelligence is no longer simply science fiction. It is fact.
In last month's column, we discussed choline, lecithin, and Deanol. At the proper dosages, these substances have all been shown to increase human intelligence, particularly memory. In this column, we discuss the amino acid nutrients phenylalanine and tyrosine.
Norepinephrine is an important brain chemical used by many brain cells to stimulate each other. It appears to play an important role in learning and memory. Learning can be blocked in experimental animals by administering drugs that selectively deplete norepinephrine in the brain. In one study, a drug was given to rats to prevent their brains from making norepinephrine. (Norepinephrine is also called noradrenaline, the brain's version of adrenaline.) These rats were able to retain a newly learned response for only a short time. Injection of norepinephrine into their brains restored the long-term retention of the learned response.
Phenylalanine and tyrosine, amino acids, are used by the brain to manufacture norepinephrine. Many popular stimulant drugs—including cocaine, amphetamines, Ritalin®, and magnesium pemoline—initially increase norepinephrine levels but prevent the brain cells that secrete norepinephrine from recycling it, resulting eventually in the depletion of norepinephrine. Depression and difficulties in learning and memory then occur.
Depression is a common life event that has serious side effects both on mental function and survival itself. For example, in a study of 4,500 British widowers 55 years of age or older, 213 died during the first six months after the death of their wife. This is 40 percent higher than would be expected in this age group. After the initial six-month surge, the death rate returned to normal. In another study, investigators found a higher level of cervical cancer developing in women who had experienced a significant emotional loss in the previous six months.
Two thousand years ago, the father of modern medicine, the Greek physician Galen, observed that habitually melancholy women had a higher incidence of breast cancer than women who were emotionally "up." Biological research scientists have found that the body's immune system—the mechanisms that identify and kill invaders such as bacteria, viruses, and cancer cells and destroy atherosclerotic plaques—decreases in effectiveness during periods of depression. Thus, depressed persons are more likely to contract serious illnesses, including cancer, or even to die.
The perception of helplessness or being out of control of one's life can lead to serious depression and an inability to act in both animals and humans. Experimental animals can be made "helpless" (unable to act) by subjecting them to inescapable, mild electric shock. Helpless animals subsequently exposed to escapable shock often are unable to simply move away a short distance to escape the shock.
An important finding of scientists has been an association of helpless depressed behavior and mental performance in animals with a decrease in brain norepinephrine. Treatment of such animals with nutrients that stimulate the brain to make norepinephrine can prevent the helplessness, depression, and inability to act that normally follows norepinephrine depletion. When you feel drained of energy by long, hard, stressful mental work, you may well be suffering from norepinephrine depletion.
Phenylalanine, an amino acid found in such foods as cheese, milk, eggs, and meats, is used by the brain to make norepinephrine. It is effective in blocking the development of helplessness in the type of animal experiments described. In humans, phenylalanine has been used to significantly improve motivation (ability to act) and subsequent intellectual performance. In addition, phenylalanine is an extremely powerful antidepressive nutrient that has been used successfully to treat people for a variety of depression problems, such as that which might result from cocaine or amphetamine abuse (these drugs deplete norepinephrine), schizophrenic depression, etc. Effective doses were in the 100-500 milligram per day range for a period of two weeks.
Since phenylalanine in large dosages (usually larger than that recommended here) can increase blood pressure, it is wise for those with hypertension to use this nutrient under the supervision of their physician and to take their own blood pressure on a daily basis for a period of time to ascertain any changes. (We recommend such a procedure regardless of whether or not you have a problem or you use phenylalanine, since blood pressure is often a barometer of biochemical changes in the body that can then be determined and corrected.)
Tyrosine is also a nutrient precursor to norepinephrine and has also been shown to be an effective antidepressant in humans at similar doses to that of phenylalanine. In preliminary experiments, tyrosine appears to have a normalizing effect on blood pressure, reducing it when too high and increasing it when too low. Nevertheless, hypertension patients should follow the same precautions as for phenylalanine. Warning: Do not use either phenylalanine or tyrosine with MAO (monamine oxidase) inhibitor antidepressants, since this combination can cause extreme hypertension!
For best results, the psychoactive amino acids should be taken on an empty stomach to avoid the competition for transport sites that carry amino acids across the blood-brain barrier into the brain. Start with a small initial dose, such as 50 milligrams per day. Vitamins B-6 and C are required for the conversion of these nutrient precursors to norepinephrine.
While norepinephrine precursors such as phenylalanine and tyrosine are well suited to anergic depression, agitated or violent depression is better dealt with by supplements of tryptophan (see a forthcoming column for more about this).
You no longer have to be helpless when you feel drained of mental energy resulting from emotional stresses or overwork. Your solution may simply be improved nutrition.
A list of scientific literature on this topic is available through REASON. Send a stamped, self-addressed envelope and ask for H&W references, October.
Durk Pearson and Sandy Shaw are consulting scientists and authors. Their book, Life Extension, was recently published by Warner Books. Copyright © 1982 by Durk Pearson and Sandy Shaw.