Thirty five years ago, Robert Ader, PhD serendipitously discovered a key part of our physiology that was not thought to exist. The story begins with rats drinking water sweetened with saccharine. Half the rats were simultaneously given low doses of Cytoxan to cause stomach pain. (Cytoxan is a chemotherapy drug for cancer.) It was no surprise that soon the rats associated the sweetened water with the pain and refused to drink it.
The experiment, conducted at the University of Rochester in New York State, then continued without the Cytoxan and Dr Ader gave these rats the water using an eye-dropper. The rats who had never received Cytoxan continued to drink the sweetened water normally. Unexpectedly, the rats previously treated with Cytoxan began to die from infections at a rate significantly higher than the rats who had never received it. Considerable investigation was needed to reveal the cause.
Cytoxan, in addition to causing stomach discomfort, suppresses the immune system. Dr Ader’s work revealed that, after the cytoxan injections, the saccharine water alone suppressed the immune system. More experiments confirmed that tasting the saccharine triggered the nervous system to suppress the immune system. Prior to this work, no such neuro-immune connection was thought to exist. The process was analogous to the placebo effect where taking a sugar tablet you expect to relieve pain triggers changes in the brain that do relieve pain.
This work became the foundation of the field of psychoneuroimmunology which is beginning to unravel the connections between stress, the nervous system, the immune system and diseased organs. In a cautionary tale for those of us who treat patients with psychophysiologic disorders (PPD), Dr Ader had to defend his work against people who drew unwarranted, unscientific conclusions from his findings.
Sadly, Dr Ader died recently, a few months short of his 80th birthday. There is more information about his life and career in the New York Times obituary.