Magnesium, C-reactive protein, and cortisol in drug-naïve patients with short illness-duration, first episode major depressive disorder: possible immunomodulatory role for magnesium.

Plasma magnesium concentration alterations, hypercortisolaemia, and systemic inflammation are observed in major depressive disorder (MDD). This exploratory study examined whether, and to what extent, plasma magnesium is related to C-reactive protein (CRP) levels and cortisolaemia in MDD. The concentrations of plasma magnesium, salivary CRP, and baseline plasma cortisol were studied in 20, treatment-naïve MDD patients with short-illness-duration, first affective episodes and 20 matched controls. Depressed patients showed a basal score higher than 20 on the Hamilton Rating Scale for Depression (HAMD-17). Significantly higher magnesium (p = 0.016) and baseline cortisol (p = 0.01) concentrations were observed in MDD as compared to controls. No significant difference in CRP concentrations between the MDD and control groups was observed. A significant negative correlation was seen between magnesium and CRP in MDD (p<0.01), whereas no correlation was found in controls. A significant positive correlation was found between cortisol and CRP, both in MDD subjects (p = 0.008) and controls (p = 0.004). No significant correlations were observed between magnesium and cortisol levels. The study supports data for hypercortisolaemia in MDD, but provides no evidence of primary hypomagnesaemia or elevated CRP levels in drug-naïve MDD patients with short-illness-duration. The study supports the hypothesis linking hypercortisolaemia to systemic inflammation, with hypermagnesaemia exerting an immunomodulatory action at early stages of the disease.