To evaluate a blood test measuring amyloid beta aggregation seeding activity for distinguishing Alzheimer’s disease and mild cognitive impairment from normal cognition and other dementias.
Approach:
Study Design: Researchers recruited 549 patients at Xuanwu Hospital, assessing a blood test in a discovery group of 120 patients and a validation group of 429 patients.
Test Methodology: The test utilized protein misfolding cyclic amplification to detect misfolded amyloid beta in plasma, measuring aggregation with a fluorescent dye.
Sample Testing: Each sample was tested twice, with laboratory investigators blinded to patients' clinical information.
Key Findings:
The assay distinguished Alzheimer’s disease from normal cognition with an area under the curve of 0.93.
For mild cognitive impairment due to Alzheimer’s disease, the area under the curve was 0.92.
The plasma assay outperformed cerebrospinal fluid biomarkers in distinguishing Alzheimer’s disease from non-Alzheimer’s dementia.
Interpretation:
Higher plasma seeding activity correlated with poorer cognitive performance and greater dementia severity.
Limitations:
Diagnoses were based on clinical criteria without neuropathologic confirmation.
The study did not compare the assay with established plasma biomarkers such as phosphorylated tau 217.
The cross-sectional design limited assessment of the test’s predictive ability for disease progression.
Validation in populations outside of China is necessary.
Conclusion:
The blood test shows promise as a biomarker for Alzheimer’s disease and related conditions, but further validation is needed.
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