Factors associated with loneliness and social capital in a large volunteer sample of adults in England

Background Loneliness is a pressing public health concern with wide-ranging impacts on mental, physical and social wellbeing. Building on the Measuring Loneliness in England (INTERACT) Study which represents one of the largest volunteer-based studies of loneliness and social disconnection conducted in the United Kingdom (UK), we explore demographic, social and health-related factors associated with loneliness and social capital, using multiple validated measures. Methods We analysed cross-sectional data from 135,725 community-dwelling adults across England. Loneliness was assessed using both the University of California, Los Angeles (UCLA) 3-item Loneliness Scale and the Office for National Statistics (ONS) Direct Measure of Loneliness (DMOL). Social capital was measured using a composite scale of neighbourhood trust, cohesion and reciprocity. Multivariable ordinal and binary logistic regression models were fitted to summarise mutually adjusted associations within the responding sample. The models were used as exploratory, sample-conditional descriptions and were not intended to estimate population parameters. Results Younger age (particularly 16–25 years old), being single, unemployed or living with disability were consistently associated with higher loneliness across both scales. In contrast, respondents reporting nine or more friends had substantially lower odds of loneliness (UCLA: adjusted odds ratio (aOR) = 0.09, 95% model-based interval (MBI): 0.09–0.10; DMOL: aOR = 0.16, 95% MBI: 0.15–0.17). University education was associated with higher loneliness on the UCLA scale but lower loneliness on the DMOL. High social capital was more frequently reported among older, married and retired respondents. Respondents with long-term conditions or disability had reduced odds of high social capital (long-term conditions: aOR = 0.82, 95% MBI: 0.80–0.85; disability: aOR = 0.77, 95% MBI: 0.74–0.80). Conclusions This study identified several sociodemographic, social and health-related factors associated with loneliness, although some associations varied according to the loneliness measure used. Because participants comprised a non-probability volunteer sample, the estimates should not be interpreted as population parameters, causal effects or confirmatory evidence. The findings are hypothesis-generating and require confirmation in representative, longitudinal and intervention-focused studies.