Home › Research › Tau biomarkers
National trends in cerebrospinal fluid biomarker testing for Alzheimer's disease in Japan
Masanori Kurihara, Ryoko Ihara, Kenichiro Sato, Atsushi Iwata. Journal of Alzheimer's disease reports, 2025-12-22
Topic: Plasma and spinal-fluid biomarkers
The annual number of health insurance claims for p-tau181 testing gradually increased from 1358 (2014) to 3420 (2023); 79-86% of claims were from inpatient settings throughout the study period. The number of claims was highest in the 75-79 age group and higher in women in older age. Regional variances were identified. The number of claims for CSF Aβ42/40 ratio testing in its first 3 months (December 2023 to March 2024) was 729; 56% of claims were from outpatient settings. Although the number of health insurance claims for CSF p-tau181 testing has gradually increased, this number is low compared with the previously estimated annual diagnosis of AD. Tests are often performed in inpatient settings and regional inequity exists, whereas CSF Aβ42/40 ratio testing is slightly more often performed in outpatient settings. These data are important for understanding the current situation before the implementation of biomarker-based AD diagnosis in Japan.
Key findings
- The annual number of health insurance claims for p-tau181 testing gradually increased from 1358 (2014) to 3420 (2023); 79-86% of claims were from inpatient settings throughout the study period.
- The number of claims was highest in the 75-79 age group and higher in women in older age.
- The number of claims for CSF Aβ42/40 ratio testing in its first 3 months (December 2023 to March 2024) was 729; 56% of claims were from outpatient settings.
- Although the number of health insurance claims for CSF p-tau181 testing has gradually increased, this number is low compared with the previously estimated annual diagnosis of AD.
- Tests are often performed in inpatient settings and regional inequity exists, whereas CSF Aβ42/40 ratio testing is slightly more often performed in outpatient settings.
New to this subject? Start with our plain-English guide: Blood tests & biomarkers →
Study details
- Evidence strengthLow
How this study scored 43/100
Published in a peer-reviewed journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record, multi-centre collaboration and free to read, so those were left out: it earned 24 of the 56 points we could judge it on, which is 43 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Journal of Alzheimer's disease reports) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 4 / 5 | 2025 — within 3 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 41445784) |
| Free to read | — / 2 | Access not recorded — left out of this score |
| Points | 24 / 56 | Scored on 10 of 20 parts. We have no data for the rest, so they are left out: 24 of the 56 points we could judge it on is 43 out of 100. |
| Total | 43 / 100 | — |
What each of these 20 components measures, and what this score is not →
Read the original
Free copy unknown: no free-copy check has an answer for this record yet. That does not mean it is paywalled.
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. Check the citation against the original before you use it.
APA 7th
Kurihara, M., Ihara, R., Sato, K., & Iwata, A. (2025). National trends in cerebrospinal fluid biomarker testing for Alzheimer's disease in Japan. Journal of Alzheimer's disease reports. https://doi.org/10.1177/25424823251410102
Vancouver
Kurihara M, Ihara R, Sato K, Iwata A. National trends in cerebrospinal fluid biomarker testing for Alzheimer's disease in Japan. Journal of Alzheimer's disease reports. 2025. doi:10.1177/25424823251410102. PMID: 41445784.
BibTeX
@article{kurihara2025-41445784,
author = {Kurihara, Masanori and Ihara, Ryoko and Sato, Kenichiro and Iwata, Atsushi},
title = {{National trends in cerebrospinal fluid biomarker testing for Alzheimer's disease in Japan}},
journal = {Journal of Alzheimer's disease reports},
year = {2025},
doi = {10.1177/25424823251410102},
pmid = {41445784},
url = {https://doi.org/10.1177/25424823251410102}
}