It feels as though the Covid pandemic has made virologists and epidemiologists of all us (except those who deny it’s happening of course). Suddenly people are following vaccine development with sport-like attention and discussing the difference between cytokine and bradykinin storms at the bus-stop. Or perhaps that’s just my circle of hypervigilant friends…
This interest is of course highly practical, since returning to any semblance of normal life depends to a great extent on success in a vaccination program. But I sense there’s another dimension to it: it makes us feel better when we understand what’s happening to us, gives us a sense (perhaps illusory) of control. This effect of increased confidence can in some cases affect our real bodily functions, when it’s referred to as ‘the placebo effect’.
Medical science has only fairly recently started to take the placebo effect seriously, and its power appears more remarkable the more is discovered. The effect was dismissed for a long time for the very good reason that it appears to conflict with the central dogma that separates science from magic, namely that the mind cannot *directly* affect matter (without which we’d still be using Eye Of Newt instead of dexamethasone). That’s changing as we learn about the real material pathways that exist between software processes in the brain (that is, thoughts) and bodily processes. These pathways are mostly chemical rather than electrical, depending upon hormones and neurotransmitters distributed via the bloodstream. Incidentally, this is one more reason why the pursuit of Artificial Intelligence will remain stunted so long as it treats intelligence solely as a computational function of the brain, ignoring the intimate two-way communication between brain and the rest of the body’s organs.
Acceptance of the placebo effect grew with the pharmaceutical industry as it introduced drug trials and discovered that a placebo (from the Latin ‘to please’) – that is a fake pill, often just sugar – could sometimes produce an effect similar to the real drug. At first explanations were purely psychological, concerned with expectation: if you *expect* a pill to cure your headache then it might. The placebo effect was and remains a problem for drug trials, since untangling it from the real drug effect is difficult. There’s also an opposite, ‘nocebo effect’ where patients who are informed of possible side effects of a drug can experience or intensify them.
Psychological explanations raise the difficult question over whether such effects are ‘merely’ imaginary, or are physical, a question that also arises about illnesses that medicine suspects may be ‘psychosomatic’. The emphasis nowadays is shifting, not to discount psychological explanation entirely but to reveal how mind actually affects bodily systems. Placebo analgesia occurs when the mental expectation of relief stimulates the limbic system to release hormones called endorphins which behave like opiates. Expecting an antidepressant effect can release dopamine and thus improve mood, ditto for insulin and blood sugar or vasopressin and blood pressure. It’s even been demonstrated that patients can be conditioned, Pavlov-style: administer a drug in a drink with a distinctive taste, and if the drug is removed merely tasting the drink may produce its effect. In short, the placebo effect reveals yet another bodily system – like the immune, muscular and gastro-intestinal systems – that functions as a computational control system separate from and in parallel with the brain.
These placebo pathways can be trained and nurtured to an extraordinary extent, so that they become the basis of practices like yoga and acupuncture, or even the source of what would have once been called ‘miracles’. Wim Hof, a 60-year old Dutchman, can immerse himself in ice water for 45 minutes and swim under 50 yards under the ice of a frozen lake, by conditioning his breath control. Free divers train themselves into feats of breath-holding approaching 20 minutes. Similar feats of ‘mental’ pain relief are routinely reported both in wartime and among marathon runners. An Italian placebo scientist called Fabricio Benedetti gave weightlifters what he told them was a performance-enhancing drug, actually a placebo. He also secretly gave them lighter weights, which convinced them that the drugs were working. When he surreptitiously replaced the normal weights, the muscular force they were able to exert increased while their perceived fatigue remained the same.
I suspect there’s a lot more yet to discover about the placebo effect and its pathways, with enormous consequences not just for medicine but for sport, and everyday life. There’s already evidence that it can even stimulate the immune system, though whether it could ever be trained to resist infections like coronavirus seems pretty unlikely at the moment. Such slim hopes are certainly no excuse either to slacken the effort to develop vaccines, nor to stop persuading anti-vaxxers that they will need to accept them.
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