While antibiotics are widely used to treat bacterial infections and other illnesses, a new research suggested that minocycline, an antibiotic with anti-inflammatory properties, improved depressive symptoms in patients with low-grade peripheral inflammation. The findings of the study were published in the journal 'Neuropsychopharmacology'. According to the study led by King's College London researchers minocycline helped in improving depressive symptoms in patients with treatment-resistant depression with low-grade peripheral inflammation. In a four-week randomised clinical MINDEP (MINocycline in DEPression) trial, 39 patients with major depressive disorder were recruited from services linked to South London and Maudsley NHS Foundation Trust (SLaM) and via public advertisement. The trial took place at the NIHR/Wellcome Trust King's Clinical Research Facility at King's College Hospital. The patients, who were taking their routine antidepressant treatment, were split into two groups, one group took daily a placebo (sugar pill) tablet while the other group took daily minocycline alongside their routine treatment for 4 weeks. Both groups showed similar, significant improvement in depressive symptoms as measured by the Hamilton Depression (HAM-D) Rating Scale. However, patients with higher C-reactive protein (CRP) levels, indicating low-grade inflammation, showed greater improvement in their depressive symptoms when taking minocycline.