Interactions with friends and family may 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.
More and more people of all ages are reporting feeling lonely. We need to
find ways to tackle this growing problem and keep people connected to help them
stay healthy
Barbara Sahakian
Researchers
from the UK and China drew this conclusion after studying proteins from blood
samples taken from over 42,000 adults recruited to the UK Biobank. Their
findings are published today in the journal Nature Human
Behaviour.
Social relationships play an important role in our wellbeing. Evidence
increasingly demonstrates that both social isolation and loneliness are linked
to poorer health and an early death. Despite this evidence, however, the
underlying mechanisms through which social relationships impact health remain
elusive.
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 researchers to develop new treatments to tackle diseases.
A team led by scientists at the University of Cambridge, UK, and Fudan
University, China, examined the ‘proteomes’ – the suite of proteins – in blood
samples donated by over 42,000 adults aged 40-69 years who are taking part in
the UK Biobank. This 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. 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 analysed the proteomes and adjusted for factors such as age, sex
and socioeconomic background, the team found 175 proteins associated with
social isolation and 26 proteins associated with loneliness (though there was
substantial overlap, with approximately 85% of the proteins associated with
loneliness being shared with social isolation). Many of these 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.
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 caused by 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, Fudan University, 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.
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 pinpoint some key proteins in
prevention, diagnosis, treatment and prognosis in many human diseases and
revolutionise 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 this protein plays a role in responding
to stress and in regulating stress hormones and social hormones such as
oxytocin – the so-called ‘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 this
region. Higher ADM levels were also linked to lower volume of the left caudate,
a region involved in emotional, reward, and social processes. In addition,
higher levels of ADM were linked to increased risk of early death.
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, atherosclerosis (‘furring’
of the arteries) and cancer progression, for example.
Professor Barbara Sahakian from the Department of Psychiatry at the
University of Cambridge 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’.
We need to find ways to tackle this growing problem and keep people connected
to help them stay healthy.”
Source: https://www.cam.ac.uk/research/news/loneliness-linked-to-higher-risk-of-heart-disease-and-stroke-and-susceptibility-to-infection
Journal
article: https://www.nature.com/articles/s41562-024-02078-1
Source: Loneliness
linked to higher risk of heart disease and stroke and susceptibility to
infection – Scents of Science
