Loneliness is associated with health behaviour: A Danish population study of 122.258 individuals

BACKGROUND: Loneliness is steadily being recognized as a public health concern due to its association with increased morbidity and mortality. Health behaviour has been proposed as a key mechanism that influences this association. The objective of the present study is to provide a comprehensive account of the relationship between loneliness and adverse health behaviour, including daily smoking, alcohol consumption, physical inactivity, unhealthy dietary habits and obesity. METHODS: We conducted a cross-sectional study using data from the 2017 Danish National Health Survey. Loneliness was assessed using a Danish version of the Three-Item Loneliness Scale. We analysed the association between loneliness and multiple forms of adverse health behaviour in 122.258 individuals aged 16 years and older using logistic regression models adjusting for sex, age, educational attainment, country of origin and cohabitation status. Stratified analyses was conducted to investigate potential differences by sex and age. RESULTS: Loneliness was associated with a greater risk of smoking (AOR=1.30; 95% CI: 1.21-1.40), physical inactivity (AOR=1.87; 95% CI: 1.75-1.99), unhealthy diet (AOR=1.58; 95% CI: 1.47-1.70), and obesity (AOR=1.60; 95% CI: 1.49-1.72). Conversely, loneliness was associated with a lower risk of weekly alcohol consumption (AOR=0.91; 95% CI: 0.83-0.98). CONCLUSIONS: Our study provides evidence that loneliness is associated with an increased risk of adverse health behaviour, such as smoking, physical inactivity and unhealthy dietary intake, across the life span. These results suggest that adverse health behaviors may influence the association between loneliness and poor health. Longitudinal studies are needed to clarify causal relationships underlying these associations. KEY MESSAGES: • Loneliness is strongly associated with adverse health behaviour across the life span. • Our study supports the theory that health behaviour is a key mechanism on the relationship between loneliness and morbidity.