"Positive" but Symptoms Undetermined? The Cutting Edge of Blood Biomarkers: Hope and Confusion Intertwine in the "Future Diagnosis of the Brain"

1. Prologue - On the Same June 2025, Rio and Tokyo Were Abuzz

On June 16, the US FDA granted the world's first approval to Fujirebio's plasma p-Tau217/βA42 testbloomberg.co.jp. Ten days later, Brazil's major portal UOL VivaBem reported "Detecting Alzheimer's with a Blood Test: When Should It Be Used?" which spread on social mediauol.com.br. These two pieces of news reflect the "temperature difference" in super-aged societies across the Atlantic.

2. Brazil's Current Position

2-1 Price and Access to PrecivityAD2™

The Fleury Group in São Paulo has been offering PrecivityAD2™ since 2023,with a fee of R$ 3,600 (approximately 100,000 yen)fleury.com.br. A doctor's referral is required for the request, and results are available 20 days later. The bill PL 3210/24, which mandates introduction to SUS, is under deliberation in Congress, with the focus on whether it will be publicly fundedcamara.leg.br.

2-2 Number of Patients and Diagnosis Rate

8.5% of those over 60 (about 1.8 million people) have dementia, but reports indicate the diagnosis rate is only 20%gov.brwww1.folha.uol.com.br. Blood tests carry the expectation of "unearthing potential patients."

3. Japan's Current Position

3-1 Timeline for Approval and Insurance Coverage

Fujirebio's Lumipulse G p-Tau217/βA42 Plasma Ratio is expected to apply for domestic approval in the summer of 2025, following FDA approvalnakamaaru.asahi.com. However, it is expected to take several years to be included in insurance coverage, with current insurance covering only PET and CSFroche-diagnostics.jphealthist.net.

3-2 Cost Comparison

• PET Scan: 150,000 to 300,000 yen per sessionhealthist.net

• CSF Test: Approximately 70,000 to 100,000 yen if paid out-of-pocket

• Blood Test (Estimated): 50,000 to 80,000 yen converted from Western prices
  In terms of cost, there is little difference from Brazil, but in Japan, the "30% co-payment" causes the out-of-pocket amount to vary.

4. Guidelines and Experts' Stance

The "Guidelines for Appropriate Use of Blood Biomarkers" published in March 2025 by the Japan Dementia Societylimits use to determining treatment policies for mild cognitive impairment (MCI) and mild AD patients, prohibiting screening for asymptomatic individualsbri.niigata-u.ac.jp. The Brazilian Neurology Society also emphasized in an interview with UOL that "positive does not equal onset"uol.com.br.

5. Temperature Difference on Social Media

6. Linkage with Therapeutic Drugs

Lecanemab has been approved in both Japan and Brazil between 2023 and 2024, butproof of brain amyloid is essential for administration. In Brazil, it is not covered by insurance, resulting in a significant out-of-pocket cost, while in Japan, it is priced at 2.98 million yen annuallymitsui.comnakamaaru.asahi.com. As blood tests become more widespread, reliance on PET may decrease, improving access to medication, but there are many concerns about increased treatment costs.

7. Public Health Impact

• Brazil: The Ministry of Health has announced an estimate that testing and intervention could reduce the number of dementia patients by 10% from 2.8 million by 2030.

• Japan: In 2025, the era of 7 million dementia patients and 10 million including MCI will begindock-tokyo.jpu-tokyo.ac.jp. Blood tests have the potential to become a hub for early intervention, butintegration with community-based care is a prerequisite.

8. Future Challenges

1. Insurance Reimbursement: SUS Bill and Japan's Chuikyo Deliberations

2. Management of False Positives/Negatives: Adherence to Guidelines and Re-examination Protocols

3. Psychological Support: Mental Care System at the Time of Positive Notification

4. Education: Public Awareness and Training for Physicians in Image Reading and Interpretation

9. Conclusion - More Than Technological Disparity, Operational Disparity

Blood biomarkers are becoming widespread across borders, but"When and to whom should they be conducted, and how should the results be utilized?" is the operational design that determines the outcome. The common challenge faced by Japan and Brazil, two super-aged societies, is whether they can incorporate testing into a total plan of treatment, care, and life support while keeping cost burdens low.