Loneliness and social isolation are linked to specific proteins – novel research

Human beings are social by nature. We develop through connections, communication and shared experiences that facilitate shape our identity and strengthen our sense of belonging. However, in an increasingly digital and lively world, feelings of loneliness and social isolation have become alarmingly common.

The World Health Organization (WHO) has stated that these feelings are common. About 25% of older people experience social isolation and 5-15% of teenagers feel lonely.

These numbers are significant because published research has shown that social isolation and loneliness are associated with an increased risk of disease and death. Indeed, our own study published in 2022found that social isolation in older adults carries a 26% increased risk of developing dementia. We also found that loneliness was associated with depression.

We wanted to follow up our previous study by trying to understand the basic biological processes underlying the link between social isolation, loneliness and health. Why is loneliness so harmful to our bodies and minds?

Protein discovery

We focused on proteomics, the study of proteins. This is because we know that proteins play a role in gene expression, the process by which information encoded in a gene is converted into biological activity. Proteins are also a major source of drug targets in drug development.

In this collaborative study between the University of Cambridge and Fudan University, published in Nature Human behaviorwe used data from 42,062 participants from the UK Biobank and examined 2,920 plasma proteins.

We examined the association between proteins and self-reported loneliness and social isolation. We found that proteins significantly associated with loneliness and social isolation are also involved in inflammation and antiviral and immune responses.

Specifically, our study suggests that loneliness may lead to increases in the levels of five specific proteins expressed in the brain (known as GFRA1, ADM, FABP4, TNFRSF10A, and ASGR1). In other words, all of the proteins we identified as associated with loneliness were “positively associated,” meaning that people who feel lonely tend to have higher levels of the protein compared to those who do not feel lonely.

We also analyzed approximately 14 years of health data from our participants. More than half of the proteins were found to be linked to cardiovascular disease, type 2 diabetes, stroke and death.

Our findings show that having good social relationships and not feeling lonely may promote health by reducing levels of certain harmful proteins. However, proteins can only partially explain the link between loneliness and health. Other potential pathways, such as social stress, may also play a role.

To our knowledge, this may be the first demonstration of how loneliness influences morbidity and mortality through association with these five key proteins.

Social effects

Social isolation and loneliness affect all ages and genders and lead to stern mental and physical health problems. This study helps to understand how this happens at a biological level.

It shows how vital it is to connect with others through social activities, such as volunteering or playing a team sport. This may reduce the impact of social isolation and loneliness on basic biological processes vital for health outcomes.

While technology offers novel ways to stay connected, sometimes it can lead to superficial connections that leave us feeling more disconnected than ever. This paradox – being surrounded by digital interactions and yet feeling profoundly alone – highlights the importance of deep, meaningful social connections.

Face-to-face social interactions where you also experience non-verbal communication often foster better connections. Indeed, one study found that partners communicate face-to-face had more positive impressions than people communicating via computer.

Social interactions are ultimately vital to our well-being, improving physical and mental health. Social connections reduce stress, lower blood pressure and support immune function. They also improve cognitive health and improve brain health. Additionally, they can foster empathy and understanding, strengthen our minds, and provide emotional resilience.

Of course, to support a flourishing society, we need to build meaningful connections with each other.