Could improving gut health also help improve mental health? A small clinical trial suggests that probiotics, often referred to as ‘good bacteria’, may give older people treated for depression an extra boost of energy.
Researchers found that older adults with depression who took daily probiotics alongside regular antidepressant treatment experienced modest but significant improvements in depression and anxiety symptoms compared to older adults who received a placebo. Placebos are inert treatments designed to look just like the real thing.
This study Journal of the American Geriatrics Society.
Exploring the relationship between the intestines and the brain
Scientists are becoming increasingly interested in the relationship between the digestive system and the brain, often referred to as the gut-brain connection. The trillions of microorganisms that live in the human gastrointestinal tract, collectively known as the gut microbiome, can influence mood, behavior, and mental health through a variety of biological pathways.
Probiotics are live microorganisms that help support a healthy balance of bacteria in your gut. Researchers are studying whether these microbes may be able to complement traditional treatments for conditions such as depression and anxiety.
Inside a clinical trial
The pilot study involved 58 adults aged 60 and above with moderate depression in India. All participants continued to receive standard antidepressant treatment.
Volunteers were randomly assigned in a 1:1 ratio to receive either probiotic supplements or a placebo daily for 12 weeks. The researchers then continued to monitor participants for an additional 12 weeks to track long-term results.
Importantly, both groups showed significant improvement over the course of the study. However, symptoms of depression and anxiety were slightly significantly reduced in the probiotic group.
Measuring mental health and biological changes
To assess the effectiveness of the treatment, researchers used several different tools.
They assessed participants using established psychological rating scales designed to measure symptoms of depression and anxiety. They also tested a biomarker known as (serum brain-derived neurotrophic factor levels). Brain-derived neurotrophic factor, often abbreviated as BDNF, is a protein involved in the growth, maintenance, and survival of nerve cells and is frequently studied in mental health research.
In addition, the researchers analyzed the participants’ gut bacteria through fecal microbiota profiling, which allows scientists to examine the composition of microorganisms living in the digestive system.
Taken together, these findings suggested that probiotic therapy contributed to symptom improvement. However, researchers found no clear evidence that probiotics further improved overall quality of life compared to a placebo.
Promising results, but further research required
This is a relatively small pilot study, so the results should be considered preliminary. Larger studies will be needed to determine how much benefit probiotics provide, which patients are most likely to respond, and whether the effects are consistent across a broader population.
Still, the results support the idea that probiotics may serve as a safe and biologically plausible addition to standard depression treatments.
“Our results are novel and our findings are encouraging, so we are now planning a follow-up, large-scale clinical trial,” said co-corresponding author Saibal Das, MBBS, MD, DM, PhD, of the Indian Council of Medical Research (National Institute of Bacterial and Infectious Diseases, Kolkata).
“My vision is to develop affordable healthcare solutions and make them available to more people to have a meaningful impact on public health,” added co-author Abhinava Ghosh (MBBS, MSc, PhD), a physician and neuroscientist at Tata Medical Center in Kolkata.
