P.G. Wodehouse’s character Bertie Wooster was convinced that the superior intelligence of his manservant Jeeves was maintained by eating large amounts of fish. Could this be true? Can you boost your intelligence, or arrest its decline, by eating the right diet?
There are at least three contemporary examples of such claims. First, a number of scientific studies have given rise to reports that vitamin supplements can improve children’s intelligence. Second, so called smart drugs and smart nutrients, many of them based on chemicals that occur in the brain, are sold by health-food shops and mail order organisations using claims that they enhance intelligence and memory. Finally, most seriously of all, a number of medical practitioners in Europe and the United States are treating children who have Down’s syndrome with huge doses of vitamins and dietary supplements that allegedly boost these children’s intellectual development.
Sadly, cruelly even, all these claims are unfounded. According to Steven Rose, professor of biology at The Open University, and a world leader in research on the biochemistry of memory “There is absolutely no evidence that, for people in normal health, any food acts as a cognitive enhancer. It is distressing that, among the good things they do, health food shops participate in this con.”
Why then, if the claims are baseless, do they persist? A large part of the answer lies in Rose’s chosen word “con”. Confidence, whether it is other people’s confidence in you or your own self-confidence, motivates you to perform better. If you take a pill that you believe will make you work better, even if the pill itself has no effect, your belief will inspire you. Similarly, a child whose family are convinced that he or she will develop well is bound to do better than one whose family have low expectations.
Consequently, in order to show whether a smart drug or dietary supplement has any real effect, a group of people taking it must be compared with an otherwise identical group taking a substance known to have no effect, a placebo. The recipients of the drug may even respond to the expectations of those administering it, so the test must be double blind: neither the people participating in the trial, nor those running it, should know who is taking the placebo and who is taking the substance under test. The tests of intelligence or memory must be carried out both before and after taking the drug.
Double blind trials are a lot of trouble, but they are the acid test of the effectiveness of a drug or dietary supplement. So far their use in this field has been both limited and discouraging. Trials of the effect of vitamin supplements on schoolchildren’s intelligence showed that some children improve on some tests. But repeated trials found different results, and some found no improvements at all. Current opinion is sharply divided on whether there is a small effect of vitamin supplements on intelligence in a subset of children, presumed to be those with a diet deficient in vitamins, or whether there is no effect at all. Direct evidence that dietary deficiencies impair intelligence is difficult to find because children who have a poor diet usually also lack intellectual stimulation.
Most of the smart drugs and dietary supplements sold by health food shops have never been rigorously tested in normal humans. A report published by the Consumer Association failed to find any justification for claims that smart drugs improve the intelligence or memory in normal healthy people. Some smart drugs improve memory in rats when injected, some of them directly into the brain. The likelihood that similar effects will be found in humans taking the drug in tablet form is remote. Worryingly, some products available by mail-order are prescription-only drugs used to treat conditions like dementia, and known to have potentially severe side-effects.
Side-effects are also a huge potential problem for the nutritional treatments for Down’s syndrome. According to Anna Khan, director of the Down’s Syndrome Association, “high dosages of vitamins and minerals …can cause liver damage. The Association is also concerned that parents of children with Down’s syndrome are vulnerable to possible exploitation by those professing to have discovered a treatment or therapy that can dramatically improve the intelligence of their child.”
One such treatment, based on a dietary supplement called “Hap Caps” has been in the public eye recently. According to Khan, dietary treatments for Down’s Syndrome crop up every few years, but their effectiveness has never been tested in double blind clinical trials. A report last year in “Smart Drug News” said that the team that developed Hap Caps could not carry out a trial using a placebo because they are completely convinced that the treatment is beneficial, and consider it unethical to withhold treatment from the group taking the placebo.
Unfortunately, until double blind trials are carried out, the convictions of the Hap Caps team should be given no more weight than those of Bertie Wooster.