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Loneliness may not be a direct cause of illness
Last reviewed: 02.07.2025
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Managing risk factors associated with loneliness can still improve long-term health outcomes, researchers say.
In a recent study published in the journal Nature Human Behaviour, researchers assessed whether the associations between loneliness and the risk of various diseases correlated with causal effects.
Loneliness is social isolation resulting in a discrepancy between desired social relationships and actual social connections. It can trigger complex biochemical and behavioral mechanisms such as excessive stress response, inflammation, and suppressed motivation that worsen overall health and increase vulnerability to various diseases.
Health professionals view loneliness as a health risk factor, although its causal effects remain unclear. Observational studies show an increased risk of mental and physical illness, as well as premature mortality. However, most of these studies focus on specific diseases, and the links between loneliness and serious illnesses such as chronic kidney disease remain unclear.
In this study, the researchers assessed whether genetic and observational data converge regarding the relationship between loneliness and the risk of developing multiple diseases.
They used hospital admission, behavioural and genetic data from the UK Biobank to identify associations between loneliness and a range of health conditions. Mendelian randomisation (MR) methods were used to assess genetic data. Questions to assess loneliness were taken from the University of California, Los Angeles (UCLA) Loneliness Scale.
Of 476,100 people (mean age 57, 55% women), 5% reported feeling lonely. People who felt lonely were more likely to be physically inactive, overweight, and have a lower education level. Over 12 years of follow-up, loneliness was associated with an increased risk for 13 disease categories, including mental and behavioral disorders, infections, respiratory diseases, nervous system diseases, and others (hazard ratio [aHR], 1.1–1.6).
Loneliness has been linked to an increased risk of a variety of health conditions, including behavioral and mental health disorders, infections, and respiratory diseases. However, most of these associations were not causal, suggesting that loneliness may be more of a marker than a direct risk factor for most of the diseases studied.