Supplementary Material for: Differential Effects of Inflammatory and Psychosocial Stress on Mood, Hypothalamic-Pituitary-Adrenal Axis, and Inflammation in Remitted Depression

<p><b><i>Background/Aims:</i></b> Major depressive disorder (MDD) is highly recurrent. This may be due to increased stress sensitivity after remission. Both inflammatory and psychosocial stressors are implicated in the pathogenesis of MDD, but the additive or differential effect is unclear. <b><i>Methods:</i></b> We conducted a single-blind placebo-controlled study to investigate the effects of inflammatory stress (i.e., typhoid vaccination), psychosocial stress (i.e., Trier Social Stress Test [TSST]), or a combination of both in women (25-45 years old) with (partially) remitted recurrent MDD (<i>n</i> = 21) and healthy female controls (<i>n</i> = 18). We evaluated the effect on mood measured by the Profile of Mood States, markers of the hypothalamic-pituitary-adrenal (HPA) axis activity, and inflammatory system activation. The study was performed during 2 testing days, separated by a washout of 7-14 days. In a crossover design, subjects received one of the interventions on one day and placebo on the other. <b><i>Results:</i></b> A lowering of mood was seen in patients (β [95% CI] = -4.79 [-6.82 to -2.75], <i>p</i> < 0.001) only after vaccination, but not after the TSST or the combination; this effect was not observed in controls. Controls experienced a significantly different response on adrenocorticotropic hormone (ACTH) after vaccination, with a general rise in ACTH not observed in patients. In both groups, the TSST activated the HPA axis and suppressed the inflammatory parameters. <b><i>Conclusions:</i></b> There is a differential effect of inflammatory and psychosocial stress on mood and HPA axis activation in patients with remitted recurrent MDD. This may be an interesting treatment target in MDD.</p>