Social interactions with loved ones boost our immune system and lower the risk of cardiovascular problems, stroke, and diabetes, according to a study published in the journal Nature Human Behavior.
A team of UK researchers from the University of Cambridge analysed blood samples from more than 42,000 adults and found that specific proteins present in the blood of people who are lonely and isolated are associated inflammation and can cause certain diseases, such as diabetes and cardiovascular problems.
Researchers know social interactions are vital for our well-being, and isolation is linked with poorer health and early death. However, the underlying biological mechanisms remain elusive.
To unveil these mechanisms, the team examined the ‘proteomes’—the suite of proteins—in blood samples from adult participants in the UK Biobank. The aim was to identify which proteins were present at higher levels among socially isolated people and how these proteins were connected to poorer health.
The team assessed each individual’s social isolation and loneliness. Social isolation can be objectively measured based on how frequently an individual has contact with others and whether they take part in social activities, for example. Loneliness, on the other hand, is more subjective and based on whether an individual feels lonely.
The authors found 175 proteins associated with social isolation and 26 associated with loneliness. There was a substantial overlap, and about 85% of the loneliness-related proteins were shared with social isolation. After analysing the functions of these proteins, it turned out that many of them are produced in response to inflammation, viral infection, and as part of our immune responses. They are also linked to cardiovascular disease, type 2 diabetes, stroke, and early death.
“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 appear to play a key role in this relationship, with levels of some proteins, in particular, increasing as a direct consequence of loneliness,” said Dr. Chun Shen from the Department of Clinical Neurosciences at the University of Cambridge.
“The proteins we’ve identified give us clues to the biology underpinning poor health among people who are socially isolated or lonely, highlighting why social relationships play such an important part in keeping us healthy,” added Professor Jianfeng Feng from the University of Warwick.
For example, one of the proteins identified in this study was ADM, which plays a role in responding to stress and regulating stress hormones and social hormones such as oxytocin – the so-called ‘love hormone’ – which can reduce stress and improve mood. High levels of ADM are associated with a smaller insula, which is a part that allows us to sense what’s happening inside our body. Higher ADM levels are also linked with a smaller left caudate volume, a region involved in emotional, reward, and social processes. In addition, higher levels of ADM are linked to an increased risk of early death.
“These findings drive home the importance of social contact in keeping us well. More and more people of all ages are reporting feeling lonely. That’s why the World Health Organization has described social isolation and loneliness as a ‘global public health concern.’ We need to find ways to tackle this growing problem and keep people connected to help them stay healthy,” concluded Professor Barbara Sahakian from the Department of Psychiatry at the University of Cambridge.
Shen, C et al. Plasma proteomic signatures of social isolation and loneliness associated with morbidity and mortality. Nat Hum Behav; 3 Jan 2025; DOI: 10.1038/s41562-024-02078-1