A large number of various types of bacteria make up the human gut microbiome. Intestinal barriers are critical to separate the physiological environment of the gut lumen from the rest of the body. Intestinal epithelial cells are firmly joined with tight junctions and are covered with a mucus layer that contains secretory immunoglobulin A (s-IgA) and antimicrobial proteins, which work as physical and immunological barriers, respectively. Dendritic cells in the epithelium and s-IgA-producing immune cells in the epithelium and sub-epithelium work as an immunological barrier. Such a defense mechanism may be impaired by aging or psycho-socio-environmental stress, leading to a leaky gut status. A leaky gut may cause psychoneurological, gastrointestinal, metabolic, and autoimmune disorders. Inflammation, the invasion or absorption of unfavorable bacterial metabolites, and immune responses may cause such pathologies. The pathophysiology of psycho-neurological disorders involves inflammatory processes that may destroy the blood-brain barrier, leading to neuroinflammation. Meanwhile, neurotoxic molecules may be absorbed and then transported to the brain through efferent nerves, leading to degenerative neurological diseases. Therapeutic approaches to such conditions have been extensively investigated. Phychobiotics is one of the important topics in this field of study.

The biopsychosocial model is the foundation of psychosomatic medicine’s clinical and practical activities. However, the position of social factors has not been thoroughly discussed in psychosomatic medicine, although research and education focusing on mind−body connections have been mainstream. For example, as of October, our official journal BioPsychoSocial Medicine has published 331 articles, with 142 (43%) pertaining to the biological/psychosomatic domain, 120 (36%) pertaining to the psychological domain, 51 (15%) pertaining to social medicine, and 18 (5.4%) in “others” (Nakao M, Komaki G, Yoshiuchi K, Deter HC, Fukudo S. BioPsychoSoc Med 2020, 14 : 30).

The purpose of this symposium was to delve deeper into the social aspects of psychosomatic medicine. As social medicine encompasses a vast wide range of fields, we invited behavioral medicine specialists familiar with society so that they could shed light on what social medicine is and how psychosomatic medicine can incorporate it. In the symposium, we discussed how psychosomatic medicine could contribute to social medicine. Psychosocial factors that affect psychosomatic disorders are plagued by problems that cannot be understood until the individual, their family, job, and social structure are considered.

Psychosomatic medicine is a major academic field that encompasses both medical care and health. Clinical medicine is closely linked to the public health approach, and medical practices should be undertaken with the limited human, time, and financial resources available. In addition to a high-risk approach for those who suffer from or are likely to suffer from illnesses, a population approach emphasizing health communication, a health program, and the health system should be employed to maintain people’s health (Biopsychosoc Med. 2010 ; 4 : 19). In this way, psychosomatic medicine helps create a bridge between clinical medicine and public health.

The World Health Organization defines social determinants of health (SDH) as the circumstances in which people are born, grow, live, work, and age. These circumstances are shaped by the global, national, and local distribution of money, power, and resources. The social determinants of health are mostly responsible for health inequities, which are unfair and avoidable differences in health status within and between countries. Socioeconomic status―such as income, education, and occupation―is often operationalized as a constructive mediator between SDH and their health effects. The mechanisms through which socioeconomic status affects people’s health involve psychosocial and biological pathways. Several successful interventions were considered, as they could reduce social and organizational health inequalities. In certain clinical settings, socioeconomic status is beginning to be measured for the precise evaluation of patients and, if necessary, patients are referred to a link employee who can help them by connecting them with the appropriate social resources to resolve their problems (social prescribing). However, if no solution is provided, screening patients with a low socioeconomic status can be unethical. Thus, the Bio-Psycho-Socio-Ethical model, the foundation of psychosomatic medicine, can address health inequality.

This article discusses the mental health of workers, with an emphasis on work-life balance. Traditional measures for workers’ mental health, especially primary prevention, have focused on work environment and individual work styles, and have conducted supervisor training, work environment improvement, and self-care support. However, workers’ mental health is affected not only by the work environment and individual work styles but also by factors outside of work, such as work-life balance and leisure time activities. In 2008, the authors launched the TWIN (Tokyo Work-life Interface) study, a large cohort study of dual-earning couples with preschool children. This study aimed to examine the effects of work-life balance on the health of self and partner in TWIN study Ⅰ, and on the health of self, partner, and children in TWIN study Ⅱ. In addition, in TWIN study Ⅲ, we developed a new support program and conducted a randomized controlled trial to evaluate its effectiveness.

We expect this paper to foster collaboration among psychosomatic medicine, social medicine, and psychology to maintain and improve workers’ physical and mental health.

The health benefits of physical activity are well documented ; however, many people still struggle to make it a habit. Although psycho-behavioral methods have been used to promote physical activity, the Japanese physical activity level continues to decline. Since 2000, neighborhood environments that support physical activity have been the subject of study and research. Walkability was originally proposed as being directly related to density, mixed land use, and street connectivity. Areas with high walkability have high physical activity and low obesity among local residents. With mounting evidence, Japan has witnessed a number of policy shifts. One of the goals set in the physical activity area of Health Japan 21 (the second term) is to “increase the number of local governments that offer community development and environment to promote physical activity.” The Ministry of Land, Infrastructure, Transport, and Tourism (MLIT) is also interested in this area. National land development will make cities more compact and create areas where people can live their daily life on foot. Sociological factors, along with biological and psychological factors, shape people’s habits and determine their health status. The Japanese Society of Behavioral Medicine comprises specialists in the three fields of clinical medicine, behavioral psychology, and social medicine and provides a forum for research within the framework of the bio-psycho-social model. Collaboration between psychosomatic medicine and social medicine will allow for the resolution of numerous health issues.

Background : Currently, an objective measure of stress is unavailable in socially vulnerable children. In recent years, hair cortisol concentration (HCC) has attracted attention as a medium- to long-term stress assessment index. Studies have suggested that HCC is associated with low socioeconomic status and a difficult nurturing environment and may provide useful information regarding stress-related health issues in children. Additionally, estimation of other indicators, such as the dehydroepiandrosterone (DHEA) concentration, which reduces cortisol concentration and shows antistress effects, as well as the DHEA/cortisol ratio used as a resilience indicator, have attracted widespread attention and are shown to be negatively correlated with stressful life events and their perceptions. In this study, we measured concentrations of hormones in children’s hair to investigate gender-based and developmental differences and also to confirm the association between biological and subjective indices.

Methods : This study included 58 children (9-15 years) in the prepubertal to adolescent age groups. We measured HCC and DHEA (an antistress indicator) concentrations and the DHEA/HCC ratio (a resilience indicator) as biological indicators. We used the Public Health Research Center’s version of the Stress Inventory (PSI) as a subjective indicator of the correlation between biological indicators and factors associated with the stress response, stressors, and social support.

Results : We observed a moderate correlation between HCC and DHEA concentrations. HCC concentrations increased with age, and the DHEA concentration and DHEA/HCC ratio were lower in middle school students. Overall, we observed a weak association between biological and subjective indices. However, we observed significant gender-based differences in the aforementioned associations ; boys showed a moderate-to-high positive correlation between DHEA, DHEA/HCC and subjective stress, with no such association observed in girls.

Conclusions : The significant correlation between HCC and DHEA suggests the importance of DHEA as a stress hormone. Analysis of developmental differences based on hormone concentrations in hair highlights the role of hair as a bioindicator of some aspects of psychological issues in children and adolescents and may contribute to a better understanding of stress in children. DHEA concentrations and the DHEA/HCC ratio were significantly correlated with subjective stress in boys, which suggests the significance of focusing on DHEA in addition to HCC in this population. We observed no correlation between biological and subjective indices in girls, which emphasizes the need for future investigation using other psychological indicators. Considering the small sample size of this study, further large-scale research with subjects spanning a wider age range is warranted in addition to establishment of standard values for each developmental stage.