The Study of Human-Animal Interactions The CAIRC Scholarship Program Summary of the Past Researches
Summary of the Past Scholarship Research
From "Letter from CAIRC" July 2003
Research Theme: "The Relaxation Effect of Companion Animals
on the Patient with Psychosomatic Illness"
By Mutsuhiro Nakao
M.D., Ph.D., an Assistant Professor, Teikyo University Center for Evidence-Based Medicine, Department of Hygiene and Public Health & Division of Psychosomatic Medicine
Despite the fact that the relaxation effect produced by companion animals is increasingly in the media spotlight, there isn’t much research evidence to back it up. The presentation of just such evidence by Nakao, an expert in psychosomatic illness, is therefore all the more important.

“The subject of this case study is a patient in her 30s with systemic lupus erythematosus (SLE), a collagen disease,” noted Dr. Nakao. “Among the characteristics of this disease are both physical and psychological symptoms, including red patches on the face, hypersensitivity to sunlight, inflammation of the joints, hematological abnormalities and delirium. In the case under study, the patient was transferred from the department of internal medicine to the department of psychosomatic illness after complaining of joint pain and depression. Medical examinations subsequently resulted in the diagnosis of SLE, but we also learned that just before the emergence of her illness, she had experienced the death of an indoor pet dog with whom she had been living for many years. After that she had begun living with another indoor dog, whereupon her symptoms had improved before worsening again when that pet was lost. This history led us to believe that companion animals can have a strong influence on SLE symptoms.”

Nakao then obtained the patient’s consent to carry out research on the physiological changes involved in her relaxation response to the presence of a companion animal:

“We began by measuring the frequency and amplitude of the patient’s alpha brain waves, the electrical resistance of her skin, skin temperature, heart rate and respiration rate while at rest. We conducted two measurement sessions in an out-patient examination room. One was taken with the patient resting with her eyes closed. The other was taken while she rested with her eyes closed and concentrated on a mental image of embracing her pet dog. The fluctuations in her heart rate were divided into high (HF) and low frequency (LF) elements, with HF used as an index of the parasympathetic neural function, and LF/HF indicating sympathetic neural function. As a result, we observed significant increases in both alpha brain wave amplitude and the HF indicator of parasympathetic neural function when the subject shifted from an ordinary state of rest to a state of rest in which she imagined embracing her pet. Also, after the first out-patient measurement session, we fitted her with a Holter monitor to measure the fluctuations in her heart rate at home until she went to sleep. This observation revealed an increase in parasympathetic neural activity accompanied by a decrease in sympathetic neural activity while feeding and playing with her dog.

“From these results we learned that not only can interaction with companion animals produce a relaxation effect, but that the effect can be obtained merely by imagining interaction with a pet. However, the data indicated a less potent relaxation effect when pet interaction was merely imagined compared to the results produced when the pet was actually present. This result suggests a need to place utmost importance on designing activities in which patients genuinely physically interact with animals rather than simply looking at or imagining them. The task we now face is establishing the standardized methods for treatment and evaluation that will enable us to begin accumulating high-quality data on the improvement in patients’ physical and psychological states.”

In a question-and-answer session after the presentation, Nakao fielded queries on the healing properties of pets and the damage resulting from the loss of a pet, noting that these are issues that will have to be addressed in the future.