Endocrinology of Loneliness and Social Isolation

In the last decades, loneliness (the subjective feeling of being isolated) and social isolation (an objective lack of social contact with others) are becoming major concerns as they are strongly linked to poor physical and mental health outcomes. Both social isolation and loneliness are considered potent chronic emotional stressors, disrupting the normal functioning of the neuroendocrine and the immune systems and leading to the appearance of adverse health outcomes. In this regard, epidemiological studies indicate that social isolation and loneliness are important risk factors for morbidity and mortality.

Dysregulation of different endocrine systems and hormone production, and the interaction with the immune system, are potential pathways through which loneliness and social isolation can exert a negative impact on the brain, physiological functioning of the body, and behavior. Significant progress has been made in recent years in our understanding of the alteration of endocrine and immune system in socially isolated subjects, although there are partially controversial results in the literature. Thus, animal studies have indicated that short- and long-term social isolation during adolescence or adulthood can lead to distinct neuroendocrinological alterations, depending on the species, sex, and age of the subjects. Similarly, human epidemiological and clinical studies have revealed age- and gender-related differences in the hormonal dysfunctions (including altered levels of oxytocin, glucocorticoids, estradiol, testosterone, ghrelin, etc.) and dysregulation of inflammation in individuals under social isolation or feeling lonely. Therefore, we consider that basic and translational studies are needed to further our understanding and to unravel the complex endocrine changes associated with loneliness and social isolation during childhood, adolescence, adulthood, and aging.

This Research Topic aims to assemble contributions that will showcase and advance our current understanding of the role of hormones on loneliness and/or social isolation. All types of papers are welcome; i.e., empirical papers, targeted reviews, meta-analyses, and opinion pieces. Work can cover studies in animals and/or humans, as well as theoretical concepts dealing with the interplay between loneliness and/or social isolation and hormones in health and diseases, including but not restricted to the following themes:
- Endocrine and immune biomarkers of loneliness in childhood, adolescence, adulthood, and/or aging;
- Impact of social isolation on endocrine function;
- Mechanistic insight into the interplay between hormones and social isolation;
- Role of genetic and epigenetic factors including lifestyle, and endocrine disruptors in the risk modification and etiology of loneliness and social isolation;
- Gender differences in the association between hormones and social isolation or loneliness.