Threats to Belonging, Immune Function, and Eating Behavior: an Examination of Sex and Gender Differences

Loneliness, social network size and mortality in older adults: a meta-analysis

Loneliness and social network size have been found to be predictors of mortality in older adults. The objective of this study was to investigate whether loneliness and small social network size are associated with an increased mortality risk and to review the evidence for either network size, or loneliness that constitutes the higher mortality risk. A systematic literature search was performed in PubMed, EMBASE and PsychInfo in January/February 2018 and March/April 2021. Studies that mentioned outcome data were included in the meta-analysis and coded using the Newcastle-Ottawa Quality Assessment Scale for Cohort Studies. The meta-analysis showed that both loneliness and small social network size are associated with mortality risk in older adults (Hazard Ratio 1.10 (95% Confidence Interval 1.06-1.14) for loneliness and 0.96 (95% Confidence Interval 0.93-0.99) for larger network size). Sensitivity analyses according to the Newcastle-Ottawa Quality Assessment Scale yielded varying results. Heterogeneity was large. In conclusion, both loneliness and small social network size in older adults are associated with increased mortality, although the effect size is small. Targeting subjective and objective aspects of older adults' social contacts should be on the agenda of preventive as well as personalized medicine. In order to be able to compare the association between loneliness and network size and mortality, more studies are needed that include both these risk factors.

Loneliness: An Immunometabolic Syndrome

Loneliness has been defined as an agonizing encounter, experienced when the need for human intimacy is not met adequately, or when a person’s social network does not match their preference, either in number or attributes. This definition helps us realize that the cause of loneliness is not merely being alone, but rather not being in the company we desire. With loneliness being introduced as a measurable, distinct psychological experience, it has been found to be associated with poor health behaviors, heightened stress response, and inadequate physiological repairing activity. With these three major pathways of pathogenesis, loneliness can do much harm; as it impacts both immune and metabolic regulation, altering the levels of inflammatory cytokines, growth factors, acute-phase reactants, chemokines, immunoglobulins, antibody response against viruses and vaccines, and immune cell activity; and affecting stress circuitry, glycemic control, lipid metabolism, body composition, metabolic syndrome, cardiovascular function, cognitive function and mental health, respectively. Taken together, there are too many immunologic and metabolic manifestations associated with the construct of loneliness, and with previous literature showcasing loneliness as a distinct psychological experience and a health determinant, we propose that loneliness, in and of itself, is not just a psychosocial phenomenon. It is also an all-encompassing complex of systemic alterations that occur with it, expanding it into a syndrome of events, linked through a shared network of immunometabolic pathology. This review aims to portray a detailed picture of loneliness as an “immunometabolic syndrome”, with its multifaceted pathology.

Altered immunoemotional regulatory system in COVID-19: From the origins to opportunities

The emergence of the novel coronavirus (SARS-CoV-2) and the worldwide spread of the coronavirus disease (COVID-19) have led to social regulations that caused substantial changes in manners of daily life. The subsequent loneliness and concerns of the pandemic during social distancing, quarantine, and lockdown are psychosocial stressors that negatively affect the immune system. These effects occur through mechanisms controlled by the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenocortical (HPA) axis that alter immune regulation, namely the conserved transcriptional response to adversity (CTRA), which promotes inflammation and diminishes antiviral responses, leading to inadequate protection against viral disease. Unhealthy eating habits, physical inactivity, sleep disturbances, and mental health consequences of COVID-19 add on to the pathological effects of loneliness, making immunity against this ferocious virus an even tougher fight. Therefore, social isolation, with its unintended consequences, has inherently paradoxical effects on immunity in relation to viral disease. Though this paradox can present a challenge, its acknowledgment can serve as an opportunity to address the associated issues and find ways to mitigate the adverse effects. In this review, we aim to explore, in detail, the pathological effects of the new social norms on immunity and present suggested methods to improve our physical, psychological, and healthcare abilities to fight viral infection in the context of the COVID-19 pandemic.