The study investigates the efficacy and tolerability of probiotics as a complementary treatment for patients with major depressive disorder (MDD) who respond inadequately to antidepressants. In a double-blind, placebo-controlled pilot study, 50 participants aged 18 to 55 years took probiotics (8 billion colony-forming units from 14 bacterial strains) or a placebo daily for 8 weeks in addition to their antidepressant therapy.
The results show that probiotics can bring about significant improvements in depression symptoms (measured using the Hamilton Depression Rating Scale [HAMD-17] and the Inventory of Depressive Symptomatology [IDS]) and anxiety symptoms. The effect on symptoms was already visible after 4 weeks and intensified by the 8th week. The treatment was well tolerated, with high adherence (97%) and no serious side effects.
Conclusion: Probiotics could be a safe and promising addition to conventional depression treatment. Further, more extensive studies are needed to confirm these results and evaluate the long-term effect.
Background:
Major depressive disorder (MDD) affects millions of people worldwide and places a significant burden on the healthcare system. Although antidepressants are the mainstay of treatment, around 60% of patients do not fully respond. The microbiota-gut-brain axis is a promising target for novel therapies, including the use of probiotics, which could potentially influence the balance of gut flora and alleviate depressive symptoms.
Aims of the study:
The aim was to evaluate the acceptance, tolerability and potential efficacy of probiotics as an add-on therapy for MDD and to collect data for future, larger efficacy studies.
Methodology:
The double-blind, placebo-controlled pilot study included 50 adults with MDD who did not fully respond to stable doses of antidepressants. Participants were randomly assigned to either a probiotic (14 strains, 8 billion colony-forming units daily) or placebo group. The treatment duration was 8 weeks, and the main evaluations included depression and anxiety ratings using the HAMD-17, IDS, Hamilton Anxiety Rating Scale (HAMA) and General Anxiety Disorder Scale (GAD-7).
Results:
Of the 50 participants, 46 completed the study. The probiotics group showed significant improvements in depression and anxiety symptoms compared to the placebo group. After 8 weeks, the effect on depressive symptoms (HAMD-17) was a standardized effect of 0.70 (95% CI: 0.01-0.98) and on anxiety symptoms (HAMA) 0.79 (95% CI: 0.06-1.05). Probiotics appeared to be particularly effective in patients with severe anxiety symptoms. There were no serious side effects and adherence was 97%. The treatment was rated as well tolerated.
Conclusion:
Probiotics could be a promising adjunct to depression treatment, especially for patients with incomplete response to antidepressants. The results of this pilot study provide important information for future research, including larger, long-term studies to confirm the efficacy, safety and mechanisms of this form of therapy.