A daily probiotic capsule taken alongside prescribed antidepressants produced larger drops in depression and anxiety symptoms over 12 weeks than a placebo did in older adults, a pilot clinical trial in the Journal of the American Geriatrics Society reports.
The double-blind study followed 58 adults aged 60 and older with moderate depression for a total of 24 weeks. All continued their standard antidepressant care and were randomly assigned to add either the probiotic or a matching placebo for the first 12 weeks.
The capsule combined two well-studied strains, Lactobacillus helveticus and Bifidobacterium longum. Researchers were probing the gut-brain axis, the two-way signaling between the digestive tract and the brain through nerves, hormones and immune messengers.
The probiotic group also showed higher levels of brain-derived neurotrophic factor, or BDNF, a protein that helps brain cells grow and function and is often linked to recovery from depression.
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What the numbers showed
On the Montgomery-Åsberg Depression Rating Scale, the standard clinician-rated measure of depression severity, the probiotic group scored consistently lower across the trial than the placebo group.
Anxiety symptoms, measured with the General Anxiety Disorder 7-item questionnaire, or GAD-7, also fell further in the probiotic arm. Both differences were statistically significant, though the authors describe the overall edge as modest rather than transformative.
Both groups improved substantially on their standard antidepressant treatment. The added probiotic did not produce clear additional gains in quality-of-life scores.
More than half of the participants dropped out over the 24-week study, a common problem in geriatric trials that limits how firmly a 58-person pilot can generalize.
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A cautious signal, not a prescription
The research team called adjunctive probiotics "a safe, biologically plausible adjunct to standard care" and reported no serious psychiatric side effects.
Co-corresponding author Dr. Saibal Das of the Indian Council of Medical Research's National Institute for Research in Bacterial Infections in Kolkata said the group is now planning a larger follow-up trial "due to the encouraging findings."
The trial does not tell readers to swap antidepressants for a supplement or to pick a probiotic off the shelf. Depression in later life can interact with medications, chronic illnesses and sleep problems, and dosing and strain matter for any probiotic evidence to translate.
Older adults already on antidepressants who are curious about adding a probiotic should raise it with the doctor who manages the prescription before buying a capsule.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.