Double-blind, randomized crossover study of intravenous infusion of magnesium sulfate versus 5% dextrose on depressive symptoms in adults with treatment-resistant depression

Aim: Treatment-resistant depression patients are more likely to suffer from comorbid physical and mental disorders, experience marked and protracted functional impairment, and incur higher health-care costs than non-affected individuals. Magnesium sulfate is a treatment option that may offer great potential for patients with treatment-resistant depression based on prior work in animals and humans. Methods: Twelve subjects with mild or moderate treatment-resistant depression were randomized into a double-blind crossover trial to receive an infusion of 4g of magnesium sulfate in 5% dextrose or placebo infusion of 5% dextrose with a 5-day washout in between the 8-day intervention period. Subjects were assessed before and after the intervention for serum and urine magnesium, lipid panel, the Hamilton Rating Scale for Depression, and the Patient Health Questionnaire-9. Results: We found a difference in serum magnesium from day 2 to 8 (pre-infusion) (P< 0.002) and from baseline to day 8 (P< 0.02). No changes were noted on the Hamilton Rating Scale for Depression or the Patient Health Questionnaire-9 24h post-treatment, but as serum magnesium increased from baseline to day 7, the Patient Health Questionnaire-9 decreased from baseline to day 7 (P=0.02). Conclusion: Magnesium sulfate did not significantly affect depression 24h post-infusion, but other results were consistent with the literature. The association between changes in serum magnesium and the Patient Health Questionnaire-9 supports the idea that magnesium sulfate may be used to address treatment-resistant depression, an ongoing medical challenge.