Patty Wooten presents ... 
Psychoneuroimmunology of
Laughter: An Interview with
Lee Berk, Dr. PH
From Journal of Nursing Jocularity, Fall 1997, 7(3), pp 46-47.
Lee Berk, Dr. PH is a psychoneuroimmunologist, professor and medical research scientist in the School of Medicine and Public Health at Loma Linda University. He is the leader and pioneer in conducting scientific research in the psychoneuroimmunology of mirthful laughter.
Patty Wooten: Dr. Berk could you give us a brief history and overview of your research in mirthful laughter?
Lee Berk: Our research began back in 1983 at Loma Linda University in southern California. At that time, volumes of scientific research existed confirming that physical and psychological stress produced chemical and neurological changes. The bulk of this research focused on negative stress or distress.
Surprisingly, very few studies investigated the impact of eustress or positive emotional states. My colleague, Stanley Tan MD, PhD, and I decided to study the biochemical changes that occur relative to the eustress state of mirthful laughter. Our first study found significant changes in neuroendocrine and stress hormones in response to mirthful laughter. The next logical step was to ask, "Could we measure the impact of these neuroendocrine changes on the immune system?" After all, if, as the bible says, "A merry heart does good like a medicine," we wondered, "Would mirthful laughter stimulate any changes to the system that monitors for various pathogenic processes?"
PW: Dr. Berk, can you describe your research design and methodology?
LB: First of all, I would like to emphasize that all of our research was scrupulously controlled for extraneous variables. We used state of the art methods to quantify measurements and employed sophisticated statistical multivariate analysis of variance (MANOVA) to interpret the results. Our subjects were medical students. The stimulus for the mirthful laughter was a videotape entitled, "Over Our Head" (pre-selected by the subjects), featuring the comedian Gallagher. Blood samples for both the experimental and control groups were gathered before, during and immediately after the video was viewed. We also collected blood samples the next day. Samples were obtained through an indwelling intravenous angiocatheter, using a stopcock and saline drip to keep the vein open. We carefully controlled for food intake, medications and exercise. All subjects were non-smokers, received no exercise the day before and the day of the experiment, and could not be taking any medication. We insured that the subjects were well rested and not physically or mentally stressed.
The control group sat in a separate room and had everything occur just as with the experimental group, except they did not view any video tape. If we had shown any other film, say a travel film, it would be possible that some subjects could have found it enjoyable or exciting while others would find it boring or distressful. By maintaining a neutral environment we avoided contaminating our data.
PW: Dr. Berk, please explain the results of your studies and the implications they have to your hypothesis that, "A merry heart does good like a medicine."
LB: First, we found that for the experimental group, those exposed to the humorous film, there was an increase in the number of activated T-cells (T lymphocytes). Apparently during mirthful laughter, there is a chemical stimulus that tells these lymphocytes to become active, to get prepared for combat with a potential virus, bacteria or foreign protein. Next, we saw an increase in the T-cells that had the helper/suppressor receptors or markers. Each cell in our body has numerous receptors that neurotransmitters, such as cytokines, plug into. As a consequence of these chemicals plugging into that specific receptor, the cell changes its metabolic activity.
We also saw an increase in the numbers of natural killer cells (NK cells) which are very important for immune surveillance. Natural killer cells are a type of immune cell that attack viral infected cells and some types of cancer or tumor cells. Natural killer cells do not appear to need prior sensitization or communication to be activated. They know and recognize when another cell is aberrant or infected. Every day, cells in our body undergo a lot of change, creating potential carcinogenic cells. Fortunately, when our immune system is functioning properly, the natural killer cells destroy aberrant cells. Natural killer cells are significant in terms of immunosurveillance. Our research shows that not only does the activity of the natural killer cells increase during mirthful laughter, but the actual number of natural killer cells increases as well.
We also saw an increase in the antibody immunoglobulin A (IgA). IgA is an immunoglobulin that resides, in part, in the mucosal areas. It helps us fight upper respiratory tract insults and infections.
We also noted an increase in IgM during the intervention of mirthful laughter. IgM is the immunoglobulin or antibody, which arrives first with respect to the humoral immune response.
We also noted an increase in immunoglobulin G (IgG). The IgG takes off after the IgM does its initial work. IgG is what gives us that long-term immunity.
We also saw an increase in the number of B cells (B lymphocytes) which goes along with the immunoglobulins increasing.
In addition, we found an increase in a substance called Complement 3. This substance helps the antibodies pierce the cell open when the cell is dysfunctional or infected and needs to be disrupted or broken. Complement 3 was found to be increased both during recovery and the next day.
Our most recent research was presented at the Psychoneuroimmunology Research Society meeting in April 1996. We found significant increases in gamma interferon (IFN). The precise role of IFN in human diseases and therapy is not completely understood. However, we know that it is clearly involved in the defense against parasites, viruses and possible tumor cells. A deficiency in the production of gamma interferon has been related to persistent viral infections. Our studies showed that gamma interferon levels not only increased during the humor intervention, but also lasted into recovery and through the next day. It should be noted that plasma volume, hematocrit and total serum protein showed no significant change over these time points. It is well known that interferon plays important roles in the growth and differentiation of cytotoxic T cells, activation of natural killer cells and functions as B-cell maturation factor. Based upon this understanding, it is reasonable to propose that there indeed may be a correlative relationship at a molecular level between the presence of gamma interferon and other components of the immune system.
PW: Dr. Berk, how might you summarize what you have discovered about the connection between laughter and health?
LB: Essentially, we found that mirthful laughter serves to modulate specific immune system components. By modulate, we mean that chemicals released during the emotional experience of mirth can connect to receptors on the surface of the immune cells. This connection stimulates a change in the molecular machinery inside the cell. Specific molecules known as immunoregulators are like plugs that fit into receptors and subsequently increase or decrease the immune cell activity.
One metaphor for modulation of immune activity is the conductor of an orchestra. Although the conductor does not actually play an instrument, he influences the tempo, harmony and volume of the music produced by the orchestra. Mirthful laughter would be like the conductor who enhances sonic integration and brings out melodious harmony. Whereas distressful emotions would be like the conductor who brings out harsh, disharmonious sounds. Emotions, like a conductor, modulate the activity and effectiveness of the immune cells although they do not directly protect the body from insult or infection.
The results of our studies validate the existence of our eustress paradigm which links the brain, behavior and immune function in a positive manner. As a medical scientist, it is gratifying and fulfilling to continue to discover objective, scientific data to support beliefs that many have held intuitively for centuries. "A merry heart does good like a medicine." (Proverbs 17:22)
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This article was originally published in "Jest for the Health of It", a regular feature in the Journal of Nursing Jocularity.
Feature columnist Patty Wooten, BSN, is also a past President of the American Association for Therapeutic Humor, author of two books related to humor, and a national speaker presenting on the benefits of humor.
