How loneliness accelerates heart disease and lowers immunity: a scientific explanation

Researchers analysed blood samples from more than 42,000 adults aged 40-69, whose data are held in the UK Biobank.

Source: 'Plasma proteomic signatures of social isolation and loneliness associated with morbidity and mortality', Nature Human Behaviour (2025). DOI: 10.1038/s41562-024-02078-1

Experts have paid special attention to the presence in the blood of various proteins (proteins), which are formed in the body and participate in a variety of processes - from immune response to the regulation of inflammation. It turned out that people who experience social isolation (infrequent contact with friends, living alone, lack of participation in social events) or regularly feel lonely have characteristic changes in the set of proteins. And these changes are often correlated with an increased risk of heart disease, stroke, type 2 diabetes and even earlier mortality.

The study distinguished between the concepts of "social isolation" (an objective criterion that takes facts into account) and "loneliness" (a subjective feeling). The scientists found that both were associated with increased levels of proteins responsible for inflammatory and immune responses, as well as with processes associated with atherosclerosis (so-called "clogging" of blood vessels) and risk of premature demise.

To confirm which specific changes can lead to disease, the researchers used the "Mendelian randomisation" method. It allows to reveal what is primary - a violation in the production of proteins or the state of loneliness itself. Thus, one of the proteins, ADM, which strongly influences the regulation of "love hormones" and stress response, increased in response to the feeling of loneliness and, in turn, could negatively affect the brain (for example, reduce the volume of certain areas responsible for emotional regulation).

Social connections turn out to be just as important as good nutrition and physical activity," the researchers emphasise. - An increasing number of people of all ages are experiencing loneliness, and it is our duty to find ways to maintain and strengthen their social contacts in order to protect their health.