The relationship between population density and suicide: a systematic review and meta-analysis

Background: Higher rates of suicide have been reported in rural areas in some countries suggesting that low population density may be associated with a higher risk of suicide. We examined the relationship between population density and suicide rates across different countries worldwide, and evaluated possible moderating effects by sex and age. Methods: A systematic review was conducted by searching the PubMed, Embase and PsychINFO databases for relevant publications following a pre-registered protocol and standard PRISMA methods. A meta-analysis was conducted with the available data. Results: From the 10,916 original non-duplicate articles initially identified, 80, published between 1932 and 2023 and covering time-periods ranging from 1890 to 2019 met the selection criteria. Of them, 83.8 % indicated that lower levels of population density were associated with higher suicide rates. A meta-analysis, based on the data from 8 publications, confirmed a statistically significant association between higher suicide rate and lower population density (OR = 1.87; 95 % CI: 1.53–2.30, z = 6.05, p < 0.001). This association was observed in males (p = 0.009), but not in females (p = 0.091). No consistent age or time effects were found. Context-specific differences in suicide methods were identified. Conclusions: Across diverse socio-economic and cultural settings in the world, living in less densely populated areas involves a higher risk of suicide in the male population. Men are more sensitive to the suicide risk factors associated with less populated areas and should be a target of preventive interventions. Prospero registration number: CRD42022345279.