Probiotic effects on brain function, as measured by resting state functional connectivity, persist 4-6 weeks after discontinuation in healthy older adults.
This RCT found that some brain-related effects of probiotics, particularly changes in resting state functional connectivity between the left superior parietal lobule and right occipital/cuneal/intracalcarine/supracalcarine cortex, persisted 4-6 weeks after cessation of a 6-week supplementation period. Additionally, significant time*group interaction effects were observed for Hospital Anxiety and Depression Scale Total Score and Anxiety Subscore between weeks 10-12 and week 6, but not from baseline. The study involved 32 healthy older adults (mean age 68.0 years) and compared two probiotic formulations of Lacticaseibacillus rhamnosus HN001 against placebo.
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Probiotic effects on brain function, as measured by resting state functional connectivity, persist 4-6 weeks after discontinuation in healthy older adults. The current body of evidence comprises 1 study, including 1 randomized controlled trial. EvidenceHub rates the overall confidence at 44/100 (low).
The Claim
Probiotic effects on brain function, as measured by resting state functional connectivity, persist 4-6 weeks after discontinuation in healthy older adults.
This conclusion is most relevant to: 32 community-dwelling self-reported healthy older adults (mean age 68.0 ± 5.4 years, 21 female/11 male) without contraindications for study examinations..
What the Research Shows
The conclusion draws on 1 linked study. Highlights from the cited literature:
- ▸Probiotic effects on brain health are both transient and sustained for several weeks after discontinuation: a randomised controlled trial. (Communications medicine, 2026) —
How It Works
The proposed biological pathway:
- ▸Daily probiotic supplementation with Lacticaseibacillus rhamnosus HN001 modulates gut-brain axis
- ▸Alters resting state functional connectivity patterns and anxiety symptom scores immediately post-intervention
- ▸Some connectivity changes (e.g., left superior parietal lobule to occipital/cuneal cortex) persist 4-6 weeks after discontinuation
- ▸Suggests longer-lasting gut-brain axis effects than previously presumed
Who Might Benefit
Evidence fit by population:
- ▸32 community-dwelling self-reported healthy older adults (mean age 68.0 ± 5.4 years, 21 female/11 male) without contraindications for study examinations.
Recommended Dose
N/A (specific dose not reported in abstract)
Limitations & Caveats
Important context when interpreting this evidence:
- ▸Small sample size (n=32 total, with uneven group sizes: 8, 12, 12 per group at follow-up)
- ▸Exploratory nature of outcomes (brain function as exploratory outcome of main study, psychological assessments as exploratory)
- ▸High attrition from randomization to analysis (e.g., 29 randomized to encapsulated group but only 8 analyzed)
Frequently Asked Questions
How long do probiotic effects on the brain last after stopping intake?▼
This study suggests some effects, particularly on resting state functional connectivity, persist for at least 4-6 weeks after discontinuation of a 6-week probiotic regimen.
What specific brain changes were observed with probiotics?▼
Significant differences in connectivity between the left superior parietal lobule and right occipital/cuneal/intracalcarine/supracalcarine cortex were found, along with changes in anxiety and depression scores.
Who was studied in this probiotic brain health trial?▼
The study included 32 community-dwelling healthy older adults with an average age of 68 years, mostly female (21 out of 32).
What type of probiotic was used in this study?▼
The probiotic used was Lacticaseibacillus rhamnosus HN001, tested in both encapsulated and non-encapsulated formulations.
References
- 1.Hutchinson AN, Brummer RJ, Rode J. “Probiotic effects on brain health are both transient and sustained for several weeks after discontinuation: a randomised controlled trial..” Communications medicine, 2026. PMID: 42521749 DOI: 10.1038/s43856-026-01800-6