Association of Plasma Levels of Angiotensin-Converting Enzyme and Cytokines with Recurrent Depression : A Preliminary Study

ABSTRACT

OBJECTIVES: Angiotensin-converting enzyme (ACE) gene and plasma levels of cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-4 (IL-4), interleukin-6 (IL-6), interleukin-10 (IL-10), have previously been determined to be associated with depression. The purpose of this study was to investigate the association of plasma levels of ACE and cytokines with recurrent depression. METHODS: A total of 52 participants (14 male, 38 female, aged 43.9 ± 14.0 years) were enrolled after being diagnosed with depression by experienced psychiatrists using the Mini International Neuropsychiatric Interview from the outpatient clinic of the Department of Psychiatry, CHA Bundang Medical Center. The participants completed blood sampling, the Hamilton Depression Rating Scale (HAMD), the Beck Depression Inventory, the Beck Anxiety Inventory, and the Scale for Suicidal Ideation. RESULTS: ACE plasma levels are higher in patients with recurrent depression (27.4 ± 10.4 U/L) than in patients with newly diagnosed depression (19.1 ± 7.7 U/L) (p = 0.004). The levels of cytokines, such as TNF-α, IL-4, IL-6, IL-10, are not significantly different between the two groups. Additionally, the ACE plasma level is negatively correlated with a reduction in the HAMD over six weeks (r = −0.429, p = 0.046, n = 22). CONCLUSIONS: The current findings show that plasma ACE levels may be associated with recurrent depression and further suggest that the renin-angiotensin system could play a role in recurrent depression.