Social isolation and loneliness trigger changes in blood proteins

Loneliness and social isolation are more than just feelings – they’re silent threats to our health.

A recent study from researchers at the University of Cambridge and Fudan University reveals a direct link between our social lives and the proteins in our blood, shedding light on why staying connected may protect against serious illnesses.

Published in the journal Nature Human Behaviour, the study analyzed blood samples from over 42,000 adults in the UK Biobank.

Dr. Chun Shen, a researcher in Cambridge’s Department of Clinical Neurosciences, is the study’s lead author.

“We know that social isolation and loneliness are linked to poorer health, but we’ve never understood why. Our work has highlighted a number of proteins that play a key role in this relationship,” explained Dr. Shen.

Why loneliness and isolation matter

Loneliness and social isolation impact health differently. Isolation is an objective condition – living alone or rarely interacting socially.

Loneliness, however, is subjective and hinges on an individual’s sense of connection. Both states have been linked to chronic conditions like heart disease, type 2 diabetes, and stroke, but the biological mechanisms behind these links remained elusive until now.

The study’s approach was innovative: researchers analyzed “proteomes,” or the collection of proteins in the bloodstream, to identify changes associated with social factors.

Proteins, which govern critical functions in the body, often serve as indicators of health and potential drug targets.

Proteins link loneliness to poor health

The study identified 175 proteins associated with social isolation and 26 linked to loneliness, with substantial overlap between the two.

Many of these proteins are tied to inflammation, immune responses, and conditions like cardiovascular disease and diabetes. The team used Mendelian randomization, a robust statistical method, to confirm causal links between loneliness and specific proteins.

One standout protein was ADM (adrenomedullin), which regulates stress responses and influences oxytocin – a hormone known to reduce stress and enhance mood.

“Levels of some proteins, including ADM, increase as a direct consequence of loneliness,” said Dr. Shen.

High ADM levels were linked to structural changes in the brain’s insula and caudate regions, essential for emotional and social processing, and were associated with a higher risk of early death.

Other proteins, such as ASGR1, were linked to cholesterol regulation and cardiovascular risk. Several proteins played roles in insulin resistance, arterial health, and even cancer progression. These findings highlight the far-reaching effects of social isolation on physical health.

Why social bonds protect health

“AI and high-throughput proteomics can pinpoint key proteins in preventing and diagnosing diseases, revolutionizing our understanding of health,” noted Professor Jianfeng Feng from the University of Warwick.

The connection between social relationships and health isn’t new. However, this study offers unprecedented insight into the biological pathways at play.

It highlights how proteins, as mediators of biological processes, may bridge the gap between social experiences and physical outcomes.

Cost of social isolation and loneliness

The findings come at a critical time. Professor Barbara Sahakian from Cambridge’s Department of Psychiatry noted that more and more people – of all ages – are reporting feeling lonely.

“That’s why the World Health Organization describes social isolation and loneliness as a ‘global public health concern,’” said Professor Sahakian.

The urgency is clear: without intervention, the ripple effects of loneliness may strain individuals and healthcare systems alike.

Moving forward: What can we do?

So, how do we tackle this pressing issue? Solutions must address both personal and societal levels. Promoting social activities, community engagement, and using technology to connect isolated individuals are vital.

Policymakers and healthcare providers must collaborate to create environments that encourage social bonding.

Dr. Shen’s team also calls for more research into targeted therapies. The proteins identified could pave the way for treatments that mitigate the impact of loneliness on the body. By developing interventions that focus on these biological markers, we may help those most at risk.

The evidence is clear: our social lives profoundly influence our physical health. This study doesn’t just illuminate the biological roots of loneliness – it also challenges us to rethink how we value relationships.

As the world grapples with increasing isolation and loneliness, these findings serve as a timely reminder of the power of social connection.

The study is published in the journal Nature Human Behaviour.

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