New research posits that maintaining social interactions with friends and family could be vital for our health. These interactions enhance our immune system and mitigate the risk of diseases like heart disease, stroke, and type 2 diabetes. This insight comes from a collaboration between researchers in the UK and China. They analysed proteins from blood samples of over 42,000 adults registered with the UK Biobank. The study’s findings were published in the Nature Human Behaviour journal.
The significance of social relationships to our overall health is becoming increasingly apparent. Studies consistently show that both social isolation and loneliness correlate with poorer health outcomes and even premature death. However, the specific biological processes by which social connections influence health have been less understood. The researchers tackled this by examining proteins in the blood. Proteins, produced by our genes, are crucial for the proper functioning of our bodies and can also be targeted by drugs to treat diseases.
Led by teams from the University of Cambridge and Fudan University, the study focused on the ‘proteomes’—arrays of proteins found in the blood samples of 42,000 adults aged between 40 and 69 participating in the UK Biobank. This examination helped determine which proteins were more prevalent among those who experienced social isolation or felt lonely and how these proteins are linked to health deterioration. Social isolation was measured objectively—considering factors like living alone, social contact frequency, and participation in social activities—while loneliness was assessed as a subjective feeling.
Upon analysing the proteomes and adjusting for age, sex, and socioeconomic factors, the researchers identified 175 proteins associated with social isolation and 26 with loneliness, noting a significant overlap between the two. These proteins, often produced in response to inflammation or viral infections, are also linked to conditions like cardiovascular disease, type 2 diabetes, stroke, and early mortality.
Using Mendelian randomisation, a method that helps infer causal relationships from genetic associations, the researchers pinpointed five proteins that increased in abundance due to loneliness.
Dr Chun Shen of the University of Cambridge and the Institute of Science and Technology for Brain-Inspired Intelligence at Fudan University remarked on the significance of these findings, noting that specific proteins seemed particularly influential in the health impacts of loneliness.
Professor Jianfeng Feng from the University of Warwick highlighted the role of AI and proteomics in identifying key proteins that can inform the prevention, diagnosis, treatment, and prognosis of many diseases, fundamentally altering our understanding of human health.
One such protein, ADM, known to respond to stress and regulate stress-related and social hormones like oxytocin—the ‘love hormone’—was found in higher levels in lonely individuals. This protein increase is associated with decreased volume in brain areas linked to emotional and social processing and an increased risk of early death. Other proteins identified include ASGR1, linked to higher cholesterol and cardiovascular risk, and others contributing to insulin resistance, arterial disease, and cancer progression.
Professor Barbara Sahakian of the University of Cambridge stressed the importance of social contact for health. With increasing reports of loneliness across ages, the World Health Organization has labelled social isolation and loneliness as significant global public health concerns, underscoring the need for strategies to address this issue and promote social connectivity for better health outcomes.
More information: Chun Shen et al, Plasma proteomic signatures of social isolation and loneliness associated with morbidity and mortality, Nature Human Behaviour. DOI: 10.1038/s41562-024-02078-1
Journal information: Nature Human Behaviour Provided by University of Cambridge
