A small randomized clinical trial published in the Journal of the American Geriatrics Society suggests that probiotic therapy may provide additional benefits in the treatment of depression among older adults, although the effect appears to be modest.

The study involved 58 participants in India aged 60 years and older who had moderate depression. All participants received standard antidepressant treatment and were then randomly assigned to one of two groups: one received daily probiotic supplements, while the other received a placebo. The intervention lasted 12 weeks, followed by an additional 12-week observation period.

Researchers assessed outcomes using clinical measures of depression and anxiety, blood levels of brain-derived neurotrophic factor (BDNF), and analyses of gut microbiota composition. Compared with the placebo group, participants receiving probiotics experienced greater reductions in symptoms of both depression and anxiety. However, differences in quality-of-life measures between the two groups were less pronounced.

Importantly, both groups showed substantial overall improvement during the study period, underscoring the effectiveness of standard antidepressant treatment and suggesting that probiotics may offer a limited but potentially meaningful additional benefit.

The authors note that probiotic therapy appears to be a safe and biologically plausible adjunctive approach that may influence the so-called gut–brain axis. However, they emphasize that larger and longer-term clinical trials are needed before firm conclusions can be drawn.

According to the study’s co-authors, including Saibal Das and Abhinaba Ghosh of Tata Medical Center, further studies are already being planned and could eventually lead to the development of accessible and scalable supportive treatments for depression.

While the findings are encouraging, the researchers stress that probiotics should currently be viewed as a complement to established treatments rather than a replacement for antidepressant therapy or psychological care.