Interplay between social isolation and loneliness and chronic systemic inflammation during the COVID-19 pandemic in Japan: Results from U-CORONA study

Abstract

In the face of the global coronavirus disease 2019 (COVID-19) pandemic, billions of people were forced to stay at home due to the implementation of social distancing and lockdown policies. As a result, individuals lost their social relationships, leading to social isolation and loneliness. Both social isolation and loneliness are major risk factors for poor physical and mental health status through enhanced chronic inflammation; however, there might be an interplay between social isolation and loneliness and the association with chronic inflammation. We aimed to clarify the link between social relationship and inflammation in the context of the COVID-19 pandemic by distinguishing whether social isolation only, loneliness only, or both were associated with chronic inflammation markers among community-dwelling adults. The data of 624 people (aged 18-92 years, mean 51.4) from the Utsunomiya COVID-19 seROprevalence Neighborhood Association (U-CORONA) study, which targeted randomly sampled households in Utsunomiya city, Japan, were analyzed. Social isolation was assessed as a structural social network by asking the number of social roles they have on a daily basis. Loneliness was measured with the UCLA loneliness scale. As chronic inflammation biomarkers, neutrophil-to-lymphocyte ratio (NLR) and the concentration of high-sensitivity C-reactive protein (CRP) were measured. Generalized estimating equations method was employed to take into account the correlations within households. Isolated-Lonely condition (i.e., being both socially isolated and feeling lonely) was associated with higher NLR among men (B = 0.141, 95%CI = -0.01 to 0.29). Interestingly, Nonisolated-Lonely condition (i.e., not socially isolated but feeling lonely) was associated with lower CRP among women (B = -0.462, 95%CI = -0.82 to -0.10) and among the working-age population (B = -0.495, 95%CI = -0.76 to -0.23). In conclusion, being both social isolated and feeling lonely was associated with chronic inflammation. Assessing both social isolation and loneliness is critical for proper interventions to mitigate the impact of social relationship on health, especially in the context of the COVID-19 pandemic.

Loneliness during the COVID-19 Pandemic: A Comparison between Older and Younger People

“…The uncertainties and mitigating measures surrounding the pandemic have changed peoples' normal lifestyle and social relationships in such a way that their psychological conditions and loneliness have become vulnerable. The concern about loneliness among older people is particularly worrying due to their living status, need for long-term care, and vulnerable physical and mental health conditions [8][9][10].…”

Threats to Belonging and Health: Understanding the Impact of the COVID‐19 Pandemic using Decades of Research

“…It is thus not surprising that there are increases in both threats to belonging and mental health problems during the pandemic; they are intricately linked to each other. In fact, data collected during the pandemic replicate data from the pre‐pandemic literature: people experiencing a threat to belonging are at increased risk for mental health problems, particularly depression and anxiety (Birditt et al., 2021; Bulbulia et al., 2020; Koyama et al., 2021; Pieh et al., 2020; Quintana et al., 2021). Thus, it is critical that policymakers attend to the impact that the COVID‐19 pandemic has had and may continue to have on people's relationships.…”

The Immunomodulatory Effects of Social Isolation in Mice are Linked to Temperature Control

“…A very large body of evidence suggests that a heightened basal level of immune activation might be responsible for the development of neurodegenerative diseases, psychiatric conditions and autoimmune disorders (138)(139)(140)(141). This basal level of undetectable inflammation -also known as meta-inflammation-has been described to be most prevalent in subjects experiencing loneliness and social isolation (92,142,143). Secondly, we have not fully explored the link between immune cells, fat and heat regulation.…”