My soon to be 86-year-old grandmother was in particularly high spirits when I saw her last weekend. She was in no pain after experiencing weeks of enduring nerve agony in her left leg. Being pain free meant that she didn’t need to take her prescription morphine, which she explained tastes awful. In passing, Mardie (the nickname her 14 grandchildren and four great grandchildren have given her) mentioned that she’d needed to eat jellybeans just to wash the hideous taste out of her mouth. Then, with a twinkle in her eye and a conspiratorial tone, she revealed that one-day she had taken a jellybean without the morphine and that alone had made the pain go away.  

At first you might be tempted to dismiss a story like this and put it down to Mardie’s age. But I can assure you there is not one whiff of fuddy-duddy behaviour emanating from my fiercely independent grandmother. Mardie is in fact sharper than many younger people I know. How then can we explain the story of jellybeans as a remedy for chronic, severe nerve pain? It turns out; Mardie’s story can be explained by science.  

More than 40 years ago a researcher named Robert Ader was studying taste aversion in rats at the University of Rochester when he began to form a theory that the mind could significantly affect the ability of the immune system to fight disease. His colleagues greeted the idea with skepticism but nevertheless in the mid 1970s, he conducted a water tight, game changing experiment that proved he could suppress the immune system of rats by making them think they had been given a drug.^⁠  

He did this by giving the rodents sweetened water and injecting them with a drug that induced a stomach upset and suppressed their immune system. The rats soon learned to avoid drinking the water, associating it with sickness. Ader then stopped giving the rats the drug but continued to force-feed them the sugar solution by dropping it in their eyes. He was stunned to find that the rats began to die and realised that in addition to training the rats to avoid the sugar water, he was also training their immune systems to become suppressed with the mere taste of the sugar water. With stifled immune systems, the rats succumbed to infections and died.  

The effect is known as classical conditioning and Ader’s research was one of the first scientific clues proving the brain and the immune system were connected. It launched the field of psychoneuroimmunology - the study of interactions between our thoughts, brain and immune system - and showed that our mind can have profound effects on our body’s unconscious functions.  

Ader’s work is still the backbone of many research papers today and in 2002 researchers showed they could reproduce classical conditioning in humans. Ader also continued the research himself and in 2009, a year before his death at aged 79, he published a paper in which he and his fellow researchers at the University of Rochester Medical Center used classical conditioning to successfully treat people with psoriasis with a quarter to a half of the usual dose of a widely used steroid medication^⁠. “Our study provides evidence that the placebo effect can make possible the treatment of psoriasis with an amount of drug that should be too small to work,” Ader said at the time^⁠. “While these results are preliminary, we believe the medical establishment needs to recognise the mind’s reaction to medication as a powerful part of many drug effects, and start taking advantage of it.”  

It’s early days for practical use of classical conditioning in clinical settings and there are some major ethical hurdles to be overcome before it can be used widely in doctor’s clinics but the real world potential is nevertheless exciting. Perhaps some of the leading scientists could take a hint from my grandmother who seems to have stumbled across a way to practically use classical conditioning to treat severe nerve pain? It might be best to keep this one a secret though because we’d hate for the price of jellybeans to skyrocket if word got out.