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Blood tests versus spinal fluid tests for Alzheimer's: what the studies report
Spinal fluid tests for amyloid and tau have been the laboratory standard for years; blood tests now aim to replace them. This page shows the library studies that measured both.
- 1,040studies in the library match, of 29,780
- 154name it in the title
- 1985–2026years published
- 1,008peer-reviewed articles
The query: title or abstract mentions "plasma", "blood" or "serum" AND "CSF" or "cerebrospinal fluid", matched case-insensitively against each record's title and abstract (its summary field) in alzhub's library of 29,780 study records, as of 2026-11-09. Every count on this page comes from that match. The matched list as JSON.
Cerebrospinal fluid is collected by lumbar puncture and bathes the brain directly, so its levels of amyloid-beta and phosphorylated tau track brain pathology closely. Blood is far easier to take but the same proteins are present at tiny concentrations and are diluted by the rest of the body, so blood tests needed more sensitive assays before they could compete.
The studies on this page measured both fluids in the same people, or compared each against a reference such as amyloid PET or autopsy. They report how often the two agree, which blood markers come closest to spinal fluid, and where blood tests still fall short, including in people with kidney disease or other conditions that alter blood levels.
This page describes what published research in alzhub's library reports. It is not medical advice and does not apply to any one person: a doctor who knows the person's history is the only one who can say what a result or a treatment means for them.
What the studies report, in their own words
Whole sentences copied from the abstract or key findings of the highest-scoring matched studies, chosen because they mention the subject and give a figure. 8 of the 1,040 matched records are quoted; each links to its study page and from there to the paper.
“Serum inflammatory markers were not affected. 11C-PK11195 binding and increased BBB permeability are present in SVD; minocycline did not reduce either process.”
“In meta-analysis of unadjusted correlation coefficients, kidney function (primarily eGFR) was inversely associated with concentrations of blood NfL, GFAP, Aβ40, β-amyloid 1-40 (A β 40), β-amyloid 1-42, and phosphorylated tau (p-tau181).”
“Reduction was seen in plasma NF-L (emm = -0.15 log pg/mL, CI [-0.27, -0.03], p = 0.0139).”
“Conclusions and relevance This study found that a commercially available plasma p-tau217 immunoassay accurately identified biological AD, comparable with results using CSF biomarkers, with reproducible cut-offs across cohorts.”
“The core biomarkers differentiated Alzheimer's disease from controls with good performance: CSF T-tau (average ratio 2·54, 95% CI 2·44-2·64, p<0·0001), P-tau (1·88, 1·79-1·97, p<0·0001), and Aβ42 (0·56, 0·55-0·58, p<0·0001).”
“CSF Aβ40 and plasma Aβ40 levels declined more in the placebo group than the resveratrol-treated group, resulting in a significant difference at week 52.”
“Exposure Plasma Aβ42 and Aβ40 were measured at 12 months for 448 participants (92.8%) and at 24 months for the rest.”
“Individuals with poor sleep quality exhibited greater PET Aβ burden and higher Aβ42 levels in plasma than those with good sleep quality.”
What kind of evidence it is
By study design
| Design (as recorded) | Studies |
|---|---|
| Systematic review or meta-analysis | 41 |
| Randomised controlled trial | 5 |
| Other clinical trial | 23 |
| Cohort or longitudinal study | 133 |
| Case-control study | 10 |
| Cross-sectional study | 77 |
| Other recorded design | 11 |
| No design recorded | 740 |
The design is the one named in alzhub's record for the study; a record with none is counted as "no design recorded".
By year
| Year | Studies | Share |
|---|---|---|
| 2026 | 70 | |
| 2025 | 181 | |
| 2024 | 105 | |
| 2023 | 85 | |
| 2022 | 79 | |
| 2021 | 70 | |
| 2020 | 57 | |
| 2019 | 67 | |
| 2018 | 36 | |
| 2017 | 35 | |
| 2016 and earlier | 255 |
Other counts within the matched set
| Peer-reviewed articles | 1,008 |
| Marked open access in the record | 449 |
| Rated "high" evidence strength in alzhub's summary | 79 |
| Rated "moderate" evidence strength in alzhub's summary | 315 |
| Rated "low" evidence strength in alzhub's summary | 637 |
| No evidence-strength rating | 9 |
| Records stating a participant count | 451 |
| Median participants (those records) | 163 |
| Largest participant count | 62,503 |
Within the 1,040 matched studies
| Studies… | Count | Rule |
|---|---|---|
| …that mention p-tau217 | 136 | the abstract also contains "p-tau217" |
| …that mention the amyloid-beta 42/40 ratio | 86 | the abstract also contains "Aβ42/40" or "42/40 ratio" |
| …that mention neurofilament light | 215 | the abstract also contains "neurofilament" or "NfL" |
| …that use amyloid PET as the reference | 89 | the abstract also contains "amyloid PET", "PET positivity" or "Centiloid" |
| …that report agreement, concordance or a correlation | 326 | the abstract also contains "concordance", "agreement" or "correlation" |
The 10 highest-scoring matched studies
Title matches first, then by alzhub's usefulness score, which rates a study's design, journal, evidence and recency, not whether its result is good news.
- Kidney Function and Blood and Cerebrospinal Fluid Biomarkers in Alzheimer's Disease and Related Dementias: Systematic Review and Meta-Analysis
- CSF and blood biomarkers for the diagnosis of Alzheimer's disease: a systematic review and meta-analysis
- Differences Between Plasma and Cerebrospinal Fluid Glial Fibrillary Acidic Protein Levels Across the Alzheimer Disease Continuum
- Combining CSF MTBR-tau243 and plasma pTau217 ratio enhances the prediction of continuous regional tau PET burden in early Alzheimer's disease
- Highly accurate blood test for Alzheimer's disease is similar or superior to clinical cerebrospinal fluid tests
- The Associations of Phosphorylated Tau 181 and Tau 231 Levels in Plasma and Cerebrospinal Fluid with Cognitive Function in Alzheimer's Disease: A Systematic Review and Meta-Analysis
- The diagnostic performance of neurofilament light chain in CSF and blood for Alzheimer's disease, frontotemporal dementia, and amyotrophic lateral sclerosis: A systematic review and meta-analysis
- Neurofilament Light Chain in Cerebrospinal Fluid and Blood as a Biomarker for Neurodegenerative Diseases: A Systematic Review and Meta-Analysis
- Association of CSF, Plasma, and Imaging Markers of Neurodegeneration With Clinical Progression in People With Subjective Cognitive Decline
- Association of Plasma Amyloid, P-Tau, GFAP, and NfL With CSF, Clinical, and Cognitive Features in Patients With Dementia With Lewy Bodies
Systematic reviews and meta-analyses in the set
41 of the matched records are recorded as a systematic review, meta-analysis or umbrella review; the highest-scoring not already listed above:
- Proteomic landscape of Alzheimer's Disease: novel insights into pathogenesis and biomarker discovery
- The FDA-approved anti-amyloid-β monoclonal antibodies for the treatment of Alzheimer's disease: a systematic review and meta-analysis of randomized controlled trials
- Prospective biomarkers of Alzheimer's disease: A systematic review and meta-analysis
- Cerebrospinal Fluid Inflammatory Cytokine Aberrations in Alzheimer's Disease, Parkinson's Disease and Amyotrophic Lateral Sclerosis: A Systematic Review and Meta-Analysis
- Meta-analysis of amyloid-cognition relations in cognitively normal older adults
Newest matched studies
- CSF Alzheimer’s Disease Biomarkers in Relation to Functional Status and Tofersen Treatment Response in ALS
- α-Synuclein Seed Amplification Status Modifies the Relationship Between Plasma p-tau217, Amyloid and Fibrillar Tau
- Clinical Factors Associated With Discordant Plasma P-Tau217 and Established Alzheimer Disease Biomarkers
- APOE Genotype and Fluid Biomarkers of Blood-Brain Barrier Integrity: A Systematic Review and Meta-Analysis
- Neurodegeneration-inducing macromolecules exit the brain via nanovascular conduits formed by reticular fibroblasts
Journals with the most matched studies
| Journal | Studies |
|---|---|
| Alzheimer's & dementia : the journal of the Alzheimer's Association | 77 |
| Alzheimer's research & therapy | 55 |
| Journal of Alzheimer's disease : JAD | 55 |
| Neurology | 47 |
| Alzheimer s & Dementia | 20 |
Questions
- Can a blood test replace a lumbar puncture for Alzheimer's?
- For some markers, in some settings, the newest blood tests perform close to spinal fluid, and guidelines are beginning to allow them as a first step with spinal fluid or PET to confirm uncertain results. The studies quoted here give the agreement figures that support or qualify that.
- How many studies on blood vs csf biomarkers does alzhub hold?
- 1,040 of the 29,780 study records in alzhub's library match the query "title or abstract mentions "plasma", "blood" or "serum" AND "CSF" or "cerebrospinal fluid""; 154 of them name it in the title. Counted from the records when this page was built.
- What kinds of study are they?
- 41 systematic review or meta-analysis, 5 randomised controlled trials, 23 other clinical trials, 133 cohort or longitudinal studys, 10 case-control studys, 77 cross-sectional studys; 740 record no design.
- What is the most recent study in the set?
- "CSF Alzheimer’s Disease Biomarkers in Relation to Functional Status and Tofersen Treatment Response in ALS" (medRxiv, 2026), the newest by publication date among the matched records.
- Which journals publish most on it?
- Alzheimer's & dementia : the journal of the Alzheimer's Association (77); Alzheimer's research & therapy (55); Journal of Alzheimer's disease : JAD (55), counted across the matched records.
Read on
- Biomarkers explainedBlood, spinal fluid and imaging tests in plain language.
- Blood tests for Alzheimer'sThe blood-test studies on their own.
- p-tau217The blood marker that comes closest to spinal fluid.
- Amyloid PET scan resultsThe imaging reference many of these studies use.