After p-tau217 abnormality
Should I have a PET scan?
Many people mistakenly believe that "getting senile" is a normal part of aging, unaware that Alzheimers Disease (AD) may already be silently eroding their loved ones memories. The most terrifying aspect of this disease is not the forgetfulness itself, but rather its ability to subtly damage the brain 10-20 years before noticeable symptoms emerge. By the time these changes are detected, it often means that the optimal window for intervention has been missed.
However, traditional diagnostic methods (such as scale assessments and imaging examinations) struggle to detect ultra-early lesions. Blood biomarker detection, with its advantages of non-invasiveness, low cost, and repeatability, has emerged as the most promising early screening tool at present.
Based on the cohort data from our multicenter Chinese Longitudinal Cognitive Decline Study (SILCODE), the consistency between the detection results of only p-tau217 in plasma biomarkers and AβPET is close to 90%, further validating the reliability of the new criteria.
I. Should these people be recommended to undergo blood marker testing as a priority?
Professor Han Yings team, drawing from the latest international guidelines and clinical practices, has identified the following five high-risk groups who require early screening:
Individuals with a family history of AD
Individuals carrying the APOE ε4 allele or having a first-degree relative with Alzheimers Disease (AD) have a 3-5 times higher risk of developing the disease compared to the general population. Among this group, even if asymptomatic, 88%-93% of those with elevated blood p-tau217 levels will test positive for Aβ-PET.
• Patients with mild cognitive impairment (MCI)
MCI is a precursor stage of AD, with approximately 10%-15% of MCI patients progressing to AD each year (the specific risk varies from person to person). Blood tests can accurately distinguish AD-derived MCI from other causes (such as vascular cognitive impairment), avoiding misdiagnosis.
• Individuals exhibiting early suspicious symptoms
If symptoms such as recurrent memory loss, confusion in language and logic, and sudden changes in mood and personality occur, even if they do not affect daily life, blood tests should be conducted to rule out Alzheimers Disease (AD).
• Patients with comorbidities of other neurological diseases
Diseases such as Parkinsons disease and cerebrovascular disease may coexist with AD or accelerate its pathological process. Blood tests can assist in determining whether cognitive decline is primarily caused by AD, thus avoiding missed diagnoses.
• Actively paying attention to the health of middle-aged and elderly people
Individuals aged ≥65 years, with low educational levels, and poor control of long-term hypertension/diabetes can assess their AD risk through blood tests, and combine lifestyle adjustments to delay the onset of the disease.
The Department of Medical Oncology Laboratory in Hainan Province is capable of conducting blood biomarker tests such as p-tau217, Aβ42, Aβ40, and P-tau181. By detecting potential disease changes associated with Alzheimers Disease (AD), it enables screening of high-risk individuals before symptoms appear or in the early stages of the disease.
II. Should a PET scan be performed after abnormal blood test results?
PET examination (such as Aβ-PET, Tau-PET) serves as the "gold standard" for AD diagnosis by visualizing pathological deposition in the brain. However, due to its high cost per procedure, strict control over indications is necessary:
• When the blood test results contradict the clinical manifestations
For example, if plasma p-tau217 is normal but there is significant cognitive impairment, or if blood tests are positive but there are no typical symptoms of Alzheimers Disease (AD), PET is needed to rule out other types of dementia (such as dementia with Lewy bodies and frontotemporal dementia).
• The pathological stage needs to be clarified to guide treatment
If anti-Aβ drugs (such as lencanapril and donanapril) are planned to be used, the degree of Aβ deposition in the brain needs to be confirmed through PET, and APOE gene testing is also required to assess the benefit-risk ratio of treatment.
• Monitor therapeutic efficacy or disease progression
Patients undergoing drug treatment can dynamically observe the clearance effect of Aβ through PET. For example, after six months of using lenvatinib, PET can visually show the reduction of plaques.
• Participate in early intervention clinical trials for AD
Multiple global new drug trials (such as vaccines targeting Aβ protein and tau protein) require participants to confirm their pathological stages through PET. Professor Han Yings team is currently recruiting volunteers and also needs to screen eligible individuals through PET.
The Department of Nuclear Medicine at Hainan Cancer Hospital is currently the only unit in Hainan capable of performing AβPET/CT examinations. To date, over 200 AβPET/CT imaging examinations have been conducted. The results indicate that during the subjective cognitive decline stage of Alzheimers disease, the positive rate of PET/CT diagnosis reaches 50% - 60%, providing a strong basis for early intervention in clinical AD.
III. Screening Guidelines: A Comprehensive Pathway from Blood Testing to PET
Step 1: Prioritize blood screening for initial screening
High accuracy: Our multi-center cohort data from the Chinese Longitudinal Cognitive Decline Study (SILCODE) corroborates the new criteria, indicating that among plasma markers, only p-tau217 has an accuracy that is approximately 90% consistent with AβPET.
Step 2: If the blood test results are abnormal, proceed to PET
Recommended combination: Aβ-PET+Tau-PET, which can comprehensively assess pathological burden.
Note: PET requires the injection of a tracer, and is not recommended for pregnant or lactating women.
Step 3: Develop a plan based on comprehensive evaluation
After obtaining the results, it is essential to seek interpretation from experts at reputable hospitals. Doctors will develop a personalized intervention plan based on symptoms, genetics, imaging, and other information. For early-detected AD patients, a combination of pharmacological treatment and non-pharmacological intervention can delay the progression of the disease by 5-10 years! (The specific effect varies from person to person)
Lastly, the "golden intervention period" for Alzheimers Disease (AD) is 5-10 years before the onset of symptoms. Professor Han emphasized that lifestyle intervention should be initiated for individuals with positive blood test results, even if they are asymptomatic. This includes adopting a Mediterranean diet, engaging in 30 minutes of aerobic exercise daily, and maintaining social interactions.
Hainan Chengmei Hospitals Memory Clinic integrates professional resources from multiple fields to provide patients with comprehensive, precise, and personalized diagnosis and treatment services.
Visiting experts
Clinic Hours: Monday morning
Clinic Hours: Wednesday afternoon
Source | WeChat official account of Professor Han Yings team at Xuanwu Hospital