Predictors of loneliness in young adults: a systematic review.

Rationale: Loneliness is a cluster of subjective feelings, varying in form, expression, and intensity under different circumstances. Despite this heterogeneity, it is a universal feeling that affects people regardless of age, sex, or culture, and can become a persistent, detrimental state that affects an individual’s well-being. Objectives: By identifying the determinants of loneliness, this study aims to contribute to a deeper understanding of how and why loneliness emerges in young people, thereby guiding future interventions more effectively. Methods: Four databases (PsycINFO, PubMed, Scopus, and Web of Science) were searched for studies published between 2014 and 2024, following PRISMA guidelines. Overall, 56 articles were reviewed. Results: Predictors clustered into 8 domains: (1) sociodemographic variables; (2) social relationships and perceived support; (3) psychological traits; (4) mental health conditions; (5) digital and media influences; (6) lifestyle patterns; (7) contextual and transitional dynamics; and (8) neurobiological insights. A lack of social support consistently emerged as the most significant risk factor. Conclusion: Overall, each domain interacts with the other domains rather than acting in isolation. Because the risk factors are interrelated, interventions should adopt a multifaceted approach that simultaneously strengthens social support and addresses the accompanying psychological, behavioural, and contextual variables that compound loneliness in young adults.