Efficacy of Pediococcus acidilactici CCFM6432 in alleviating anhedonia in major depressive disorder: A randomized controlled trial.

Background: Anhedonia, a hallmark symptom of major depressive disorder (MDD), is often resistant to common antidepressants. Preliminary evidence indicates that Pediococcus acidilactici (P. acidilactici) CCFM6432 may offer potential benefits in ameliorating this symptomatology in patients with MDD.

Aim: To further assess the efficacy of P. acidilactici CCFM6432 in alleviating anhedonia in patients with MDD, using a combination of objective and subjective assessment tools.

Methods: Adult patients with MDD exhibiting anhedonic symptoms were enrolled and randomly assigned to two treatment groups: One receiving standard antidepressant therapy plus P. acidilactici CCFM6432, and the other receiving standard antidepressant treatment along with a placebo, for 30 days. Assessments were conducted at baseline and post-intervention using the Hamilton Depression Rating Scale (HAMD), Temporal Experience of Pleasure Scale (TEPS), and synchronous electroencephalography (EEG) during a "Doors Guessing Task." Changes in both clinical outcomes and EEG biomarkers, specifically the stimulus-preceding negativity (SPN) and feedback-related negativity amplitudes, were analyzed.

Results: Of the 92 screened participants, 71 were enrolled and 55 completed the study (CCFM6432 group: n = 27; Placebo group: n = 28). No baseline differences were noted between the groups in terms of demographics, clinical assessments, or EEG metrics. A mixed-design analysis of variance revealed that the CCFM6432 group showed significantly greater improvements in both HAMD and TEPS scores compared to the Placebo group. Moreover, the CCFM6432 group demonstrated a significant increase in SPN amplitudes, which were inversely correlated with the improvements observed in HAMD scores. No such changes were observed in the Placebo group.

Conclusion: Adjunctive administration of P. acidilactici CCFM6432 not only augments the therapeutic efficacy of antidepressants but also significantly ameliorates the symptoms of anhedonia in MDD.