Social isolation kills. This is neither a controversial statement, at least among those who have even a passing familiarity with the scientific literature, nor is it, strictly speaking, ‘news’. But new research sheds more light on the mechanism by which loneliness and social isolation impact our health. In a word, it’s inflammation. And this is particularly pertinent given the established link between ‘cytokine storm’ – a flood of inflammatory chemicals that our immune system releases in response to infection – and serious outcomes of SARS-CoV-2 infection.
In 2010, a meta-analytic review of the existing research on the impact of the quality and quantity of individuals’ social relationships on their risk of death, concluded that people with stronger social relationships had a 50% increased likelihood of survival than those with few or weak social ties.
Having strong social ties was found to be more protective against premature death than being a non-smoker, avoiding excessive consumption of alcohol, regular physical activity and maintaining a healthy body weight. And it was far more protective than getting a flu shot or taking high blood pressure drugs.
Why is social isolation so damaging to our health, and even our longevity? The authors of the 2010 review start with the obvious:
“Humans are naturally social.”
Sure, but how does being deprived of the social contact that is so natural to our species, affect our health? There were two prevailing theories back in 2010: The stress buffering hypothesis which proposed that social relationships promote adaptive behavioral or neuroendocrine responses to acute or chronic stressors (e.g., illness, life events, life transitions); and the main effects model which proposed that social relationships directly affect health for example by encouraging or modelling healthy behaviours and by giving individuals meaningful roles that provide self-esteem and a sense of life purpose.
A recently published study slides another piece into the jigsaw puzzle: loneliness and social isolation are linked to increased levels of systemic (body-wide) inflammation.
Chronic inflammation is a key driver of dis-ease processes as diverse as arthritis, obesity and depression (see my article Inflammation: why you’re fat, sick, tired, depressed and in pain… and what to do about it).
The new study, The association between loneliness, social isolation and inflammation: A systematic review and meta-analysis, found that both social isolation – the objective state of being isolated from other people – and loneliness – perceived social isolation – are associated with raised levels of body chemicals associated with inflammation.
Specifically, social isolation was associated with elevated C-reactive protein (CRP), a substance released into the bloodstream within hours of a tissue injury, and increased levels of the glycoprotein fibrinogen, which forms blood clots.
Loneliness, on the other hand, was associated with elevated levels of the inflammatory cytokine interleukin 6 (IL-6).
Why does social isolation fuel the fires of inflammation? The authors of the new systematic review and meta-analysis explain that:
“Alongside biological threats, research shows that an enhanced inflammatory response may also occur in reaction to social stressors and social threats… because humans have evolved to be a socially-oriented species… Contact with society is necessary to provide biological, psychological and social regulation… Perceived social isolation (loneliness) and objective social isolation are proposed to have a biological impact because they act as social stressors and activate the bodies [sic] stress response.”
It’s important to note that IL-6 and CRP levels are both molecular indicators of a cytokine storm – the immune system overreaction that turns infection with SARS-CoV-2 potentially deadly.
Levels of IL-6 and 3 proteins associated with it have been found to be elevated in COVID-19 patients who developed severe or critical infections, while patients who died had increased levels of both IL-6 and CRP. Elevated fibrinogen levels have also been found in COVID-19 patients, creating a hypercoagulable state in which life-threatening blood clots are more likely to form.
There are, of course, many disease conditions that can elevate inflammatory markers including IL-6, CRP and fibrinogen, such as cardiovascular disease and diabetes. However, the people most likely to suffer these disease conditions (the elderly and chronically ill) are also the most likely to suffer from chronic social isolation and loneliness.
Lockdown-induced social isolation may well have been ‘the straw that broke the camel’s back’ for many vulnerable people, perhaps at least partially explaining the fact that 66% of COVID-19 hospitalisations in New York state were in people who were sheltering at home – many of whom have been socially isolating for over a month.
As the review points out,
“Loneliness and social isolation could modify the bodies [sic] response to social and biological stressors, such that when a social or biological challenge occurs that those people who are lonely or socially isolated have an enhanced inflammatory response.”
Our human bodies and minds are built for social contact with others of our kind. There’s a reason why the most serious punishment meted out in prisons is solitary confinement, and why some human rights groups consider it to be a form of torture: being deprived of human contact quite literally drives people mad.
Virtual connection through digital technology is no substitute for in-the-flesh contact with other human beings. People’s brains quite literally synchronise when they touch each other, indicating just how profoundly we are ‘wired’ for physical proximity.
We’re currently being told that in the interests of public health and safety we must embrace a ‘New Normal’ in which the handshake and the hug are outlawed, ‘real life’ conferences must be abandoned and replaced with virtual meetings, and the elderly and vulnerable must be indefinitely isolated. The playgrounds and parks in my area have signs up reminding people to stay away from each other, despite the complete lack of scientific evidence supporting such physical distancing; Professor Robert Dingwall, one of the UK goverment’s top scientific advisors, commented: “I mean the two-metre rule was conjured up out of nowhere.”
Not only is this ‘New Normal’ profoundly inhuman; it’s also scientifically unsupportable. Decades of research show that isolation and loneliness – not viruses – are the most dangerous threats to our health and survival. With apologies to Jesus, “For ye have the germs always with you”. But with strong social connections, our immune systems are far better able to fend off those germs without endangering our own health in the process.
Remember, taking good care of your health is even more important than usual due to the high levels of stress generated by the world’s response to COVID-19, and the fact that people with pre-existing chronic disease are at higher risk of serious complications of any type of infection, including SARS-CoV-2.
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