Probiotic use linked to lower odds of Parkinson’s and Alzheimer’s
Probiotic medication users had lower odds of a first Parkinson or Alzheimer diagnosis than nonusers in Japanese insurance records, with an odds ratio of 0.56.
Our read
Populations- Studied:
- Case-control study of adults aged 20-74 years, against nonusers
- What changed:
- Odds of a first Parkinson or Alzheimer diagnosis were lower in probiotic medication users than nonusers (odds ratio of 0.56)
- The catch:
- Differences in users' health or health care use may have contributed to the association
- Stake:
- An author works for Daiichi Sankyo.
- In the record:
- The 90th paper on probiotics with results in people; 460 on record in all.
Editor of record: Boris Djordjevic · AgingResearch.News
Japanese adults aged 20–74 with a first Parkinson or Alzheimer diagnosis—20,322 cases—were compared with 60,966 controls in a nested case-control study. Cases averaged 51.7 years old, and 52.1% were male. The analysis used insurance claims from January 2005 through April 2025. Controls matched cases by age, sex and duration of insurance enrollment.
The researchers identified probiotic medication use from outpatient prescriptions during a period ending two years before the diagnosis month or corresponding month for controls. Probiotic use was associated with lower odds of either diagnosis after statistical adjustments. The association also appeared separately for Parkinson disease, with an odds ratio of 0.54, and Alzheimer disease, with an odds ratio of 0.63.
Why it matters
Parkinson and Alzheimer disease involve neurodegeneration, the damage to or loss of nerve cells. The authors said the findings support the potential relevance of the intestinal environment to this process.
Caveats
Prescription claims do not establish whether people took the medication, and differences in users’ health or health care use may have contributed to the association. The analysis covered Japanese adults aged 20–74, leaving older adults outside its scope.
- Probiotics
- Microbiome composition
- Parkinson's disease
- Alzheimer's disease
- Neurodegenerative disease
- Humans
The paper
Ehime University Hospital
Journal of Neurology, May 30, 2026
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