16S rRNA Next Generation Sequencing Analysis Shows Bacteria in Alzheimer's Post-Mortem Brain.
Level 4 - case-series / case-control
Case-control study using post-mortem human brain tissue
PubMed 28676754 · doi:10.3389/fnagi.2017.00195
What was done
Researchers extracted DNA from post-mortem brain tissue (both frozen and formaldehyde-fixed sections) from a small cohort of individuals with Alzheimer's disease and cognitively unimpaired controls. They performed 16S ribosomal RNA gene-specific next-generation sequencing to profile and compare bacterial species content between the two groups.
What was found
The abstract reports no numerical values, effect sizes, or specific statistical test results. The authors state qualitatively that bacterial populations were increased in Alzheimer's disease brain tissue compared with cognitively unimpaired normal brain tissue.
Why it matters
This study provides exploratory sequence-based evidence supporting the hypothesis that microbial infiltration and neuroinflammation may be present in Alzheimer's disease pathology.
Limits
The abstract describes only a small cohort and omits the exact sample size, patient characteristics, statistical significance levels, and specific identified bacterial taxa. Post-mortem tissue sequencing is highly vulnerable to post-mortem interval artifacts, tissue handling contamination, and fixative-induced degradation.
Cited by
- partial Individuals with dementia have up to fourfold more bacteria in their brain compared to people without dementia.