By Stephen Beech
Socializing with friends and family helps protect people from a heart attack and illnesses such as flu, according to new research.
Loneliness is linked to a higher risk of heart disease and stroke and susceptibility to infection, say scientists.
But the new study suggests that interactions with friends and family may keep people healthy because they boost the immune system and reduce the risk of diseases such as heart disease and type 2 diabetes.
Researchers from Cambridge University along with colleagues in China came to the conclusion after studying proteins in blood samples taken from more than 42,000 adults recruited to the UK Biobank.
The team says 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 early death.
But the underlying mechanisms through which social relationships impact health have remained elusive until now.
The researchers explained that one way to explore biological mechanisms is to look at proteins circulating in the blood.
Proteins are molecules produced by our genes and are essential for helping our bodies function properly.
They can also serve as useful drug targets, allowing scientists to develop new treatments to tackle diseases.
The Cambridge team and scientists at Fudan University in China, examined the ‘proteomes’ – the suite of proteins – in blood samples donated by more than 42,000 British adults aged 40 to 69.
That allowed them to see which proteins were present in higher levels among people who were socially isolated or lonely, and how these proteins were connected to poorer health.
The team calculated social isolation and loneliness scores for individuals in the study, published in the journal Nature Human Behavior.
The researchers explained that social isolation is an objective measure based on, for example, whether someone lives alone, how frequently they have contact with others socially, and whether they take part in social activities.
Loneliness, on the other hand, is a subjective measure based on whether an individual feels lonely.
When they analyzed the proteomes and adjusted for factors including age, sex and socio-economic background, the team found 175 proteins associated with social isolation and 26 proteins associated with loneliness.
The team said many of the proteins are produced in response to inflammation, viral infection and as part of our immune responses, as well as having been linked to cardiovascular disease, type 2 diabetes, stroke, and early death.
They then used a statistical technique to explore the causal relationship between social isolation and loneliness on the one hand, and proteins on the other.
Using that approach, they identified five proteins whose abundance was caused by loneliness.
Dr. Chun Shen said: “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.
Dr. Jianfeng Feng, of 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 pinpoint some key proteins in prevention, diagnosis, treatment and prognosis in many human diseases and revolutionize the traditional view of human health.
“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.”
One of the proteins produced in higher levels as a result of loneliness was ADM.
Previous studies have shown that ADM plays a role in responding to stress and in regulating stress hormones and social hormones such as oxytocin – known as the “love hormone” – which can reduce stress and improve mood.
The team found a “strong” association between ADM and the volume of the insula, a brain hub for interoception, our ability to sense what’s happening inside our body.
The greater the ADM levels, the smaller the volume of the region.
Higher ADM levels were also linked to lower volume of the left caudate, a region involved in emotional, reward, and social processes.
Higher levels of ADM were also linked to an increased risk of dying young.
The researchers said another of the proteins, ASGR1, is associated with higher cholesterol and an increased risk of cardiovascular disease, while other identified proteins play roles in the development of insulin resistance, “furring” of the arteries) and cancer progression.
Cambridge University Professor Barbara Sahakian said: “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.'”
She added: “We need to find ways to tackle this growing problem and keep people connected to help them stay healthy.”
