I’ve made an infographic explaining conditioned immunosuppression. This was first established in rodents in the 1980s but also shown to be operative many, many times in humans.
Here’s a brief article here explaining a few things about this pathway and its importance.
The pathway for conditioned immunosuppression is thought to operate through the amygdala, insula, and part of the prefrontal cortex. This was first shown in 2002, but much work in subsequent years has explained the pathway in more detail.
After the signal is processed in the brain, a nerve from the brain that innervates the spleen and gives the signal to the spleen then modulates immunity. See above. Very little is understood about the input to the brain, i.e. how the brain “knows” to send an immunosuppression signal to the spleen.
This isn’t the only pathway that does this. Cortisol, growth hormone, and other pathways can also be modulated in what is thought to be a similar fashion, but through their own particular, distinctive pathways. This does not at present seem to be well-understood.
Allergies can also be modulated in this way, with basophilic activity changing in response to conditioned immunosuppression.
Here’s the kicker. This is not the same thing as the placebo effect. In fact, the placebo effect is probably at least two separate phenomena.
1. This one, which is strictly a matter of physiological conditioning and is not mediated by expectation or cognition.
2. And another one, which is mediated by expectation or cognition. Parkinson’s symptoms, for instance, can be reduced by influencing a subject to believe that they will improve; dopamine in the brain then increases, reversing Parkinson’s symptoms physically. (The mechanisms for this are not well-understood.)
Likewise, depression can be treated in this way, as can allergies, pain, and a whole host of other symptoms. Use a placebo, get a response. But again, expectation is not the same as conditioned immunosuppression… When you use placebo with allergies, you can reduce symptoms without changing the immunological profile of the person. But only when you use conditioned immunosuppression do you get a drop in basophils, etc.
Could this kind of conditioning also work with foods? Hard to say. Suffice to say: placebo is one hell of a drug.
For now, I need to be working on other things. I will return to this later. Thanks for reading.