HQ Team
January 9, 2024: Loneliness may contribute to a higher risk of heart disease, stroke and susceptibility to infections, according to a study conducted by the University of Cambridge and Fudan University involving 42,000 adults.
The researchers examined blood proteins to understand how social isolation and loneliness affected health outcomes. They identified 175 proteins linked to social isolation and 26 to loneliness, many related to inflammation and immune responses.
Five proteins were identified that increase in abundance due to loneliness. Adrenomedullin (ADM) was linked to stress regulation and emotional responses.
“ADM emerged as the primary mediator linking loneliness to various health outcomes, including cardiovascular disease (8.3%), dementia (4.4%), stroke (7.8%) and mortality (16.3%),” the researchers wrote in Nature Human Behaviour.
Social relationships and health
Higher levels of ADM correlated with reduced brain volume in areas associated with emotion and social processing, as well as an increased risk of early death, according to the researchers.
Proteins, as the final products of gene expression, serve as the main functional components of biological processes and represent a major source of drug targets.
“Therefore, understanding the proteomic associations of social isolation and loneliness becomes imperative for unravelling the biology underpinning the effects of social relationships on health,” the researchers stated.
The 42,062 participants (aged 56.4 ± 8.2 years, 52.3% female) from the UK Biobank had quality-controlled proteomic data and complete behavioural data, including social isolation, loneliness and all covariates. They were observed for almost 14 years.
Morbidity, mortality
More than half of the 2,920 plasma proteins analysed in the participants were prospectively linked to cardiovascular diseases, diabetes, dementia and depression.
At the end of the study, on November 22, 2,695 participants developed cardiovascular disease, 892 developed all-cause dementia, 1,703 developed type 2 diabetes, 1,521 developed depression, 983 developed stroke and 4,255 passed away.
“Collectively, these findings support the idea that social relationships indirectly influence morbidity and mortality through peripheral physiological pathways,” the researchers said.
“They may impact health through distinct pathways, for instance, objective social engagement and loneliness exhibit different associations with neuroimmune markers in older age.”
‘Targeted prevention’
Social isolation and loneliness, acting as social stressors, can trigger stress responses leading to altered immune function.
The findings emphasise the importance of maintaining social connections for overall health, as loneliness is increasingly recognised as a global public health issue.
The study can help bridge the link between social relationships and morbidity and mortality.
“Comprehending the biology underlying the impact of social relationships on health, particularly the peripheral changes preceding disease, may provide new opportunities for targeted prevention and effective intervention.”
