Effect of Minocycline on Inflammation in Depressed Patients

The study aims to evaluate or to assess: * An improvement in the peripheral inflammatory levels in depressed patients after 8 weeks of treatment with Minocycline in addition to their current antidepressant treatment; * Any improvements in depressive symptoms after 8 weeks of treatment with Minocycline given as adjuvant to the current antidepressant treatment; * Changes in the inflammatory status in the brain (in terms of microglia activation with 11C PK PET) after 8 weeks of treatment with Minocycline in addition to the current patient's treatment; * Possible structural and functional brain changes evaluated by MRI after 8 weeks of treatment with Minocycline given as adjuvant to the current patient's treatment; * Whether changes in MRI, in microglia activation, and peripheral inflammation correlate with the improvement in depressive symptoms. In order to achieve these, a total of 60 patients, male and female, aged 25-45, who have not responded to their pharmacological treatment and who have medium-high levels of inflammation (with CRP\> 2 mg/L) will be included in the study. Enrolled patients will receive, in addition to their current antidepressant treatment, Minocycline (200 mg/day as total dosage) for 8 weeks. Patients will be subjected to blood collection and clinical evaluations at baseline and after 8 weeks of treatment with Minocycline. A subgroup of patients will be subjected to MRI and 11C PK PET assessment at baseline and after 8 weeks of treatment with Minocycline.