COPENHAGEN, Denmark ― Probiotics may be effective in reducing core depressive symptoms in treatment-naive patients with a mild to moderate form of the disorder, results of a new pilot study suggest.
Investigators led by Caroline Wallace, PhD candidate, Queen’s University, Kingston, Ontario, Canada, found that symptoms of mood, anhedonia, and sleep disturbance were significantly reduced with probiotic therapy after just 4 weeks, with results maintained at 8 weeks.
The findings are of particular interest because probiotics are not associated with any of the adverse effects of current antidepressant therapies and can be safely taken over long periods.
These results, the investigators note, “suggest that probiotics may be effective in alleviating depressive symptoms such as mood, anhedonia, and sleep quality.”
Nevertheless, they acknowledge that the open-label nature of the study means that “these findings are susceptible to bias; thus, further blinded studies are warranted.” To address these limitations plans for a larger randomized controlled trial are underway.
Results from preclinical and clinical studies suggest that probiotics improve symptoms of depression. The hypothesis is that the effects are mediated via the gut-brain axis by reducing inflammation and increasing serotonin levels.
To assess the efficacy of probiotics in treatment-naive patients with depression, the researchers carried out a pilot study using Probio’Stick, a probiotic supplement that combines two different strains known to act on the gut-brain axis ― Lactobacillus helveticus R0052and Bifidobacterium longum R0175.
The 8-week, single-arm, open-label intervention pilot study involved 10 treatment-naive patients with major depressive disorder who were experiencing a current episode of depression.
After an initial screening period, the participants were assessed for a range of clinical symptoms of depression, including mood, anhedonia, anxiety, and subjective sleep disturbance, at baseline and at weeks 2, 4, and 8 using the Canadian Biomarker Integration Network in Depression protocol.
Molecular markers of inflammation were assessed and tryptophan and serotonin levels were determined. The patients underwent polysomnographic assessment to measure objective sleep.