Loneliness, social isolation and psychiatric disorders: insights from the National Mental Health Survey in Korea

Background Loneliness and social isolation pose significant public health concerns globally, with adverse effects on mental health and well-being. Although the terms are often used interchangeably, loneliness refers to the subjective feeling of lacking social connections, whereas social isolation is the objective absence of social support or networks. Aims To investigate the prevalence of loneliness and social isolation and their associations with psychiatric disorders. Method This study used data from the Republic of Korea National Mental Health Survey 2021, a nationally representative survey. A total of 5511 adults aged 18–79 residing in South Korea participated in the survey. Loneliness and social isolation were assessed using the Loneliness and Social Isolation Scale, whereas psychiatric disorders were evaluated using the Korean version of the Composite International Diagnostic Interview. Multivariate logistic regressions were performed after adjustment for sociodemographic variables. Results Among the participants, 11.8% reported experiencing loneliness, 4.3% reported social isolation and 3.4% reported both. Co-occurrence of loneliness and social isolation was significantly associated with psychiatric disorders (adjusted odds ratio (AOR) 7.59, 95% CI: 5.48–10.52). Loneliness alone was associated with greater prevalence and higher probability of psychiatric disorders (AOR 3.12, 95% CI: 2.63–3.71), whereas social isolation did not show any significant association (AOR 0.88, 95% CI: 0.64–1.22). Conclusion The co-occurrence of loneliness and social isolation is particularly detrimental to mental health. This finding emphasises the need for targeted interventions to promote social connection and reduce feelings of isolation.