Increased immune activation in persons with major depressive disorder (MDD) could be due to childhood trauma along with current and long-term stress, according to a study published in the Journal of Affective Disorders.
The investigators of the study recruited 44 participants who were diagnosed with MDD with a mean score of 18.9 (SD 6.4) on the Hamilton Depression Rating Scale, which indicates moderate to severe depression. Controls (n=44) matched for age and sex were also recruited.
To measure inflammatory markers, plasma was separated from the venous blood sample and the concentration of interleukin 6 (IL-6) and interleukin 10 (IL-10) was evaluated by different enzyme-linked immunosorbent assay tests. Stress levels were assessed through clinical interviews using standardized psychiatric ratings, questionnaires, and instruments. The German version of Cohen’s Perceived Stress Scale was used for testing current stress levels. The List of Threatening Experiences Questionnaire was used to detect stressful life events. The Childhood Trauma Questionnaire (CTQ) was used to gather information on negative childhood experiences. CTQ is a retrospective questionnaire that collects and grades this information on 5 subscales: emotional neglect, emotional abuse, physical neglect, physical abuse, and sexual abuse.
The investigators found that persons diagnosed with MDD in the study showed immune activation in response to stress. The patients with MDD, when compared with controls, showed significantly higher scores on the List of Threatening Experiences Questionnaire (2.7 vs 1.1; P=.001) and had significantly higher scores than the control group on CTQ Emotional Abuse (P =.048) and Physical Neglect (P =.002). Similarly, Perceived Stress Scale values were also higher in the patient group when compared with the control group (35.2 vs 15.5; P <.001). The investigators also reported higher levels of pro-inflammatory cytokine IL-6 and anti-inflammatory cytokine IL-10.
Some of the major limitations of the study are that the sample size was small and it did not evaluate causal relationships. The investigators also mentioned that nearly all patients with MDD were treated with antidepressants when cytokines were measured, which could result in altering the level of IL-6 and IL-10.
The investigators conclude that childhood adversity along with current and long-term stress are related to and may result in inflammation in depression. They suggest that “future prospective longitudinal studies should address the phenotype wherein inflammation possibly induced by stress/trauma and depression co-occur.”
Müller N, Krause D, Barth R, et al. Childhood adversity and current stress are related to pro- and anti-inflammatory cytokines in major depression [published online April 22, 2019]. J Affect Disord. doi: 10.1016/j.jad.2019.04.088