Background: Major depressive disorder (MDD) is inconsistently associated with elevations in proinflammatory cytokines and neuropeptides. We used a skin sweat patch, recently validated in healthy control subjects, and recycling immunoaffinity chromatography to measure neuroimmune biomarkers in patients with MDD mostly in remission.
Methods: We collected blood at 8:00 am and applied skin sweat patches for 24 hours in 21- to 45-year-old premenopausal women (n = 19) with MDD (17/19 in remission) and age-matched healthy controls (n = 17) participating in the POWER (Premenopausal, Osteopenia/Osteoporosis, Women, Alendronate, Depression) Study.
Results: Proinflammatory cytokines, neuropeptide Y, substance P, and calcitonin-gene-related peptide were significantly higher and vasoactive intestinal peptide, a marker of parasympathetic activity, was significantly lower in patients compared to controls, and depressive symptomatology strongly correlated with biomarker levels. All analytes were strongly correlated in the skin sweat patch and plasma in patients (r = .73 to .99; p < .0004).
Conclusions: The skin sweat patch allows detection of disrupted patterns of proinflammatory cytokines and neuropeptides in women with MDD in clinical remission, which could predispose to medical consequences such as cardiovascular disease, osteoporosis, and diabetes. This method permits measurement of cytokines in ambulatory settings where blood collection is not feasible.