Do Age and Sex Moderate the Mediating Role of Perceived Stress in the Association Between Loneliness and Depression? A Population-Based Study With Finnish Adults

Loneliness is a global issue with numerous negative health outcomes, depression being among the most well-documented. However, the mechanisms underlying this connection remain poorly understood. Recent research and theory suggest perceived stress may mediate the relationship between loneliness and depression. Using data from a Finnish population-based sample of 9,752 adults (age range: 18–88; women: 66.4%), we examined whether perceived stress mediated this relationship using causal mediation analysis methods, and whether age or sex moderated either the direct effect or mediating effect. Our findings showed that women report more loneliness, perceived stress, and depressive symptoms than men. We also found a direct effect of loneliness on depressive symptoms, and a statistical mediating effect of stress on this association. We found this pattern across ages and both sexes. However, the statistical mediation effect was strongest among young women and weakest among older adults. We discuss whether differences in mediation strength may be associated with social support, social network, coping styles, and neuroticism. This study highlights the interplay between loneliness, perceived stress, and depressive symptoms, and further clarifies how this interplay varies by age and sex. Further studies should investigate these mechanisms using longitudinal data.