The Mind-Immune System Connection:“Psycho-neuro-immunology”


School of Medicine and Dentistry at the University of Rochester Medical Center


University Rochester Professor Emeritus of Psychiatry Robert Ader, Ph.D. (deceased), Professor of Microbiology and Immunology Nicholas Cohen, Ph.D. and Neuroscientist David Felton, Ph.D. (currently of Oakland University).


Ader and his colleagues transformed the way physicians think about the relationship between life events and the environment, and how the human body responds biologically. This work continues to have extraordinary implications, not only for understanding immunological responses to stress and disease, but also for appreciating the potentially powerful positive effects of what’s known as the ‘placebo effect.’ Ader created the field of psychoneuroimmunology (PNI).


In the early 1970s, Ader was studying taste aversion conditioning in rats. In the experiment, rats drank different volumes of a saccharin solution and also were injected with a dose of Cytoxan, an immunosuppressive drug that induces gastrointestinal upset. The rats “learned” or were conditioned to avoid consuming the solution. When he stopped giving the rats the drug but continued to give them the saccharin solution, not only did the rats avoid drinking the solution, some of the animals died. The magnitude of the avoidance response of the rats was directly related to the volume of solution consumed. The mortality rate also varied with the amount of solution consumed. The critical discovery of the mind-immune system connection in 1974 led to subsequent research by his colleagues into just how they were connected.  In 1981 Felton looked at a tissue sample from the spleen and there saw nerve fibers from the central nervous system (the wiring that leads to the brain), together with white blood cells (key players in the immune system).  Further Rochester research has documented how the brain sends signals to the immune system—by finding receptors on the surface of immune-system cells that act as keyholes to accept chemical neurotransmitters released by the nervous system. Emotional stress can trigger the release of nerve-fiber chemicals, which then tell the immune-system cells what to do. Rochester scientists also found the reverse true: chemicals from immune-system cells have an effect on the brain, causing, for example, drowsiness and an elevated temperature when the body needs to fight illness.