In another study, the efficacy of Bacillus coagulans administration on MDD in IBS patients was tested and revealed an improvement in HAM-D, Montgomery-Asberg Depression Rating Scale (MADRS), Center for Epidemiological Studies Depression Scale (CES-D) as well as reduced serum myeloperoxidase, an inflammatory biomarker (Majeed et al., 2018). Here, MPO is linked to major depressive disorder.