Sumitomo Forestry Co. (President: Toshiro Mitsuyoshi; hereinafter "Sumitomo Forestry"), BrainEnergy Inc. (President: Mitsuhiro Kita; hereinafter "BrainEnergy"), and The Jikei University School of Medicine (President: Chiya Matsufuji; hereinafter "Jikei Medical University") have conducted research to clarify the effects of trees on depression and verified the effectiveness of the "Wood Psychotherapy Room". The research was conducted in a wood therapy environment. This study investigates whether a therapeutic environment using wood is effective as an adjunct to psychotherapy and psychotherapy for depressed patients.

Regarding fragrance, the "Tree Psychotherapy Room" confirmed that patients with higher levels of "depression and anxiety" were more likely to respond that fragrance is good for them. In the treatment of depression, how to introduce and continue appropriate treatment is an important factor. The results of this study suggest that a woody environment, especially the scent of wood, is effective in creating a positive impression and encouraging the introduction and continuation of treatment for depression. On the other hand, no difference in "room favorability" was observed between the "wood psychotherapy rooms" and the "regular psychotherapy rooms" with regard to anything other than fragrance.

■ Clinical Trial Summary

・The subjects were 20 patients with depressive disorders attending the Department of Neuropsychiatry, The Jikei University Hospital.

・The floor, walls, and desks of one of the two psychotherapy rooms of the same size in the same department were made of cedar wood.

・The patients were randomly assigned to one of two psychotherapy rooms of the same size in the same department, one of which had cedar wood floors, walls, and desks, and 10 patients each were given cognitive behavioral therapy (CBT) ※2 by a licensed psychologist for 16 weeks.

・The study was conducted by using the Hamilton Depression Rating Scale ※3 and Near Infrared Spectroscopy (NIRS) ※4 to examine the effects of different treatment environments on the effectiveness of psychotherapy and psychotherapy.

・The "desirability of the room" was measured in terms of (1) comfort, (2) aroma, (3) temperature, (4) space, and (5) brightness, each on a 7-point scale.

In recent years, mental disorders have been on the increase worldwide, with depression being one of the major social problems. Although pharmacotherapy such as antidepressants can be very effective when used appropriately, pharmacotherapy is not always proven to be effective for so-called "mild depression. In addition, psychotherapy such as cognitive-behavioral therapy is effective in the recovery phase of depression, and the importance of alternative or adjunctive therapies other than drugs is recognized. Natural elements such as plants and wood are expected to reduce depression and anxiety, and "biophilic design ※5" is attracting attention as a method to support stress improvement.

We will make use of the results of this joint research for further exploration, and aim to provide better services and create more comfortable spaces for a wider range of people.

※1 The Japanese Society of Neuropsychiatry is one of the largest neuropsychiatric societies in Japan with over 20,000 members. The 120th Annual Meeting will be held at the Sapporo Convention Center/Sapporo Industrial Promotion Center on June 20-22, 2024. The annual meeting is attended by more than 7,000 members each year, and the program provides a panoramic view of progress in a wide range of fields of psychiatry.

※2 Cognitive Behavioral Therapy (CBT): A therapy that works on the way one perceives and thinks to create a state of mind that can better cope with stress and enhance adaptability.

※3 Hamilton Depression Rating Scale: A scale to evaluate the severity of depression published by Hamilton in 1960. A psychological test in which doctors and other specialists evaluate each item characteristic of depressive symptoms. It evaluates 17 items including "depressed mood," "guilt," and "difficulty falling asleep.

※4 Near-infrared spectroscopy: A technique that uses near-infrared light to measure changes in the oxygenation state of hemoglobin in the brain and indirectly measure brain function based on changes in blood volume in the brain.

※5 Biophilic design: A technique that incorporates biophilia, the concept that "(humans) have an innate desire to connect with nature," into spatial design.

※6 Positively correlated with the "Depression" item of the Mood Profile Test (POMS) (p = 0.47)

（３） The Jikei University School of Medicine

A private medical school founded in 1881. The university practices patient-centered medicine in accordance with its founding spirit, "Don't diagnose the sick, diagnose the sick.The university is committed to fostering good medical professionals through medical treatment, education, and research. The university has four affiliated hospitals, including the affiliated Kashiwa Hospital (Kashiwa City, Chiba Prefecture), centered on the affiliated hospital (Nishi-Shinbashi, Minato-ku, Tokyo), and aims to be a university and affiliated hospital that leads medical care, education, and research, from community medicine to advanced medical care, and from basic research to clinical research, utilizing its collaborative capabilities with local medical institutions. In this joint research, the University's Department of Psychiatry is primarily responsible for the preparation of the research plan and evaluation of the medical aspects of the research.