Psychoneuroimmunology (PNI)

Pyschoneuroimmunology (PNI) is the study of the interactions of psychological processes with the human nervous and immune systems. It is an interdisciplinary study that focuses on how the mental processes and physical health affect one another. PNI focuses on the relationship between mental states, diseases, and healing along with connections between the brain and the immune system. Sometimes known as psychoendoneuroimmunology (PENI), it is an area of research that attempts to find the effects of psychological processes on the immune system and an individual's health.

While interest in the convergence of mind and health has been a subject of interest since the mid-19th century, the actual modern field of PNI dates to 1975 with the work of Robert Ader and his associate Nicholas Cohen, both of Rochester University in New York. This early research dealt chiefly with behavioral research done with rats to measure the relationship of chemical intake (as rewards) and physical health. More recent research has dealt with the interactions between stress and physical health by measuring the release of hormones, neurotransmitters, and other substances into the body.

Studies have shown how stress, anxiety, hostility, and depression can affect the immune system in negative ways. There is also PNI research in regards to optimism and happiness and how it can influence healing in positive ways. The placebo effect is also an area of focus for psychoneuroimmunology.