Investigating the relationship between Major Depressive Disorder, aggression and inflammation in adolescents: a cross-sectional study

Introduction: Previous research in blood plasma has revealed a potential relationship between depression and the immune system. A similar relationship between aggressive behavior and the immune system suggests that the three phenomena are interconnected in some way. To date, this interaction has not been researched in adolescents. The current study investigates the relationship between adolescent depression and immune markers (IL-6, IL-1β, TNF-α and CRP), and examines aggressive behavior as a potential moderator in this relationship. Immune markers were measured in salivary samples, contributing to the incorporation of a novel, non- invasive way to assess inflammation in mental health research. Methods: A total of 114 adolescents with and without clinically diagnosed depression were included in the present study (32 depressed, 76 healthy controls; 32.4% males; mean age 15.91 years old, ranging from 12-18). Participants provided 2ml saliva via passive drool, in which IL6, IL-1β and...Show moreIntroduction: Previous research in blood plasma has revealed a potential relationship between depression and the immune system. A similar relationship between aggressive behavior and the immune system suggests that the three phenomena are interconnected in some way. To date, this interaction has not been researched in adolescents. The current study investigates the relationship between adolescent depression and immune markers (IL-6, IL-1β, TNF-α and CRP), and examines aggressive behavior as a potential moderator in this relationship. Immune markers were measured in salivary samples, contributing to the incorporation of a novel, non- invasive way to assess inflammation in mental health research. Methods: A total of 114 adolescents with and without clinically diagnosed depression were included in the present study (32 depressed, 76 healthy controls; 32.4% males; mean age 15.91 years old, ranging from 12-18). Participants provided 2ml saliva via passive drool, in which IL6, IL-1β and TNF-α were analyzed with the Luminex Human Discovery Assay (Bio-Techne), and CRP was analyzed with an ELISA Kit Generation II (Salimetrics). Parents of the participating adolescents filled in the Child Behavior Checklist-questionnaire on aggressive behavior. Results: In an analysis of covariance no significant associations were found between depression and levels of IL-6, IL-1β, TNF-α and CRP. In addition, no significant moderating effects of aggressive behavior on this relationship were found. Conclusion: Despite earlier evidence nudging towards a relationship between depression and the immune system, this study has not obtained similar results. Future studies on the matter are warranted, preferably with simultaneous advancement of salivary measurement technologies.Show less

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Investigating the relationship between Major Depressive Disorder, aggression and inflammation in adolescents: a cross-sectional study