Sixty-year-old Anjali Mukherjee of Kolkata began feeling a persistent heaviness in her chest two years ago—a quiet sadness that lingered through mornings and dulled her once-vibrant love for gardening. Like thousands of older adults in India, she was diagnosed with moderate depression and started standard antidepressant treatment. But in 2024, she became one of 58 participants in a small but groundbreaking trial that offered something extra: a daily probiotic capsule. By week 12, her mood scores had improved meaningfully, and her anxiety had eased—changes mirrored across half the study group who, like her, received live bacterial strains alongside their medication.
Depression in older adults is a growing global health concern, often resistant to standard therapies and compounded by stigma and limited access to mental health care. In India, where geriatric mental health services remain sparse, innovative and affordable solutions are urgently needed. The PRODG trial—Efficacy of Adjunct PRObiotics in Moderate Unipolar Depression in Geriatric Patients—offered a promising clue: the gut might be a new frontier in treating the mind. Conducted in Kolkata, the randomized, double-blind study assigned adults aged 60 and older to receive either a daily probiotic blend or a placebo for 12 weeks, all while continuing their prescribed antidepressants. Researchers tracked changes using psychological assessments, blood biomarkers like serum brain-derived neurotrophic factor (BDNF), and gut microbiome analysis.
The results, published in the Journal of the American Geriatrics Society, revealed that the probiotic group experienced modest but statistically significant reductions in depressive and anxiety symptoms compared to the placebo group. While both groups improved—underscoring the value of standard care—the addition of probiotics tipped the scale in favor of faster, more pronounced symptom relief. Notably, the treatment was safe, with no serious adverse effects reported, and biologically plausible: shifts in gut microbiota composition correlated with clinical improvements, and BDNF levels, linked to brain plasticity, showed favorable trends.
Though quality of life measures didn’t differ significantly between groups, the study’s implications are resonant. “The results of our study are novel, and we are now planning a follow-up, larger-scale clinical trial due to the encouraging findings,” said Dr. Saibal Das of the Indian Council of Medical Research-National Institute for Research in Bacterial Infections, Kolkata. Co-corresponding author Dr. Abhinaba Ghosh, a physician-neuroscientist at Tata Medical Center, envisions a future where low-cost, accessible interventions like probiotics become part of mainstream mental health care in underserved communities.
This pilot study doesn’t promise a cure, but it opens a door—one that could lead to gentler, more holistic ways of healing the aging brain. As research expands, the humble probiotic may become more than a gut health supplement: a quiet ally in the fight against late-life depression.