Clinical utility of loneliness as a symptom of major depression in youth

Background: This study aims to examine the utility of adding loneliness as a symptom of major depressive disorder (MDD).Methods: We used data from the 2018-2019 wave of the Brazilian High-Risk Cohort Study, involving 1,905 participants aged 14-23. We evaluated the centrality of loneliness within the depressive symptom network. Finally, we used adjusted multiple regression (sociodemographic factors and social isolation) to examine the association of 1) loneliness alongside classical symptoms of MDD and 2) clinical groups (including or excluding loneliness), with a composite of life-threatening events (suicide attempt, self-harm, psychiatric admission, or emergency room visits), poor life-chance events (criminal convictions, substance use, and school dropout), and well-being.Results: Loneliness was part of the depressive construct and the most central symptom in the network structure of depressive symptoms. It was independently associated with life-threatening events (OR: 1.754; 95% CI: 1.187, 2.590), life chance impoverishment events (OR: 1.446; 95% CI: 1.065, 1.963), and well-being (B: -2.681; 95% CI: -3.792, -1.569). Lastly, the group with MDD that included loneliness as a symptom had a higher risk for life-threatening events (OR: 3.168; 95% CI: 2.039, 4.976) and had lower scores on well-being (B: -3.474; 95% CI: -5.085, -1.862), compared to those with MDD without loneliness. Conclusion: Loneliness is a constitutive symptom of depression that serves as an indicator of severity in MDD. The operationalization of loneliness as a clinical criterion of MDD is expected to improve clinical care of young people with depression.