Interactions with friends and family can keep us healthy because they boost our immune system and reduce our risk of diseases such as heart disease, stroke and type 2 diabetes, new research suggests.
Researchers from the United Kingdom and China came to this conclusion after studying proteins from blood samples taken from more than 42,000 adults recruited to the UK Biobank. Their findings are published today in the journal. Nature Human Behavior.
Social relationships play an important role in our well-being. Evidence increasingly shows that both social isolation and loneliness are linked to poorer health and premature death. However, despite this evidence, the underlying mechanisms through which social relationships impact health remain elusive.
One way to explore biological mechanisms is to look at the proteins circulating in the blood. Proteins are molecules produced by our genes and are essential in helping our body function properly. They may also serve as useful drug targets, allowing researchers to develop new treatments to address diseases.
A team led by scientists from the University of Cambridge, UK, and Fudan University, China, examined the “proteomes” (the set of proteins) in blood samples donated by more than 42,000 adults aged 40 to 69 who They participate in the UK Biobank. This allowed them to see which proteins were present at higher levels among socially isolated or lonely people, and how these proteins were linked to poorer health.
The team calculated social isolation and loneliness scores for the individuals. Social isolation is an objective measure that is based, for example, on whether a person lives alone, how often they have social contact with other people, and whether they participate in social activities. Loneliness, on the other hand, is a subjective measure based on whether an individual it feels lonely.
When they analyzed the proteomes and adjusted them for factors such as age, sex, and socioeconomic background, the team found 175 proteins associated with social isolation and 26 proteins associated with loneliness (although there was substantial overlap, with about 85% proteins associated with loneliness). be shared with social isolation). Many of these proteins are produced in response to inflammation, viral infection and as part of our immune responses, and have been linked to cardiovascular disease, type 2 diabetes, stroke and premature death.
The team then used a statistical technique known as Mendelian randomization to explore the causal relationship between social isolation and loneliness, on the one hand, and proteins, on the other. Using this approach, they identified five proteins whose abundance was due to loneliness.
Dr Chun Shen, from the Department of Clinical Neurosciences at the University of Cambridge and the Institute of Science and Technology for Brain-Inspired Intelligence at Fudan University, said: “We know that social isolation and loneliness are linked to poorer health, but we have never understood why. Our work has highlighted a number of proteins that appear to play a key role in this relationship, and the levels of some proteins in particular increase as a direct consequence of loneliness.
Professor Jianfeng Feng from the University of Warwick said: “There are more than 100,000 proteins and many of their variants in the human body. AI and high-throughput proteomics can help us identify some key proteins in prevention, diagnosis, treatment and prognosis in many humans. diseases and revolutionize the traditional view of human health.
“The proteins we have identified give us clues about the biology underlying poor health among socially isolated or lonely people, highlighting why social relationships play such an important role in keeping us healthy.”
One of the proteins produced at higher levels as a result of loneliness was ADM. Previous studies have shown that this protein plays a role in the stress response and in the regulation of stress hormones and social hormones such as oxytocin, the so-called “love hormone”, which can reduce stress and improve mood. cheer up.
The team found a strong association between ADM and the volume of the insula, a brain center for interoception, our ability to sense what is happening inside our body: the higher the levels of ADM, the smaller the volume of this region. . Higher levels of ADM were also linked to lower volume of the left caudate, a region involved in emotional, social, and reward processes. Additionally, higher levels of ADM were associated with a higher risk of premature death.
Another protein, ASGR1, is associated with higher cholesterol and increased risk of cardiovascular disease, while other identified proteins play roles in the development of insulin resistance, atherosclerosis (the lining of the arteries). and cancer progression, for example.
Professor Barbara Sahakian from the Department of Psychiatry at the University of Cambridge said: “These findings highlight the importance of social contact in keeping us well. More and more people of all ages report feeling lonely. That’s why the World Health Organization Health has described “Social isolation and loneliness are a ‘global public health problem’. “We need to find ways to address this growing problem and keep people connected to help them stay healthy.”
The research was supported by the National Natural Science Foundation of China, the China Postdoctoral Science Foundation, the Shanghai Rising-Star Program, the National Key R&D Program of China, the Municipal Science and Technology Major Project of Shanghai, Project 111, Shanghai Brain Science and Technology Center. Inspired Technology and Zhangjiang Laboratory.