Early Alzheimer's diagnosis is now closer than ever

Mayo Clinic researchers have validated a blood test's high precision for diagnosing patients with cognitive impairment.This non-invasive, cost-effective breakthrough, detailed in Alzheimer's & Dementia, offers much-needed hope for earlier intervention and better management.

Alzheimer's disease, a devastating neurological condition characterised by progressive memory loss and cognitive decline, affects millions worldwide. The profound impact extends beyond patients to their families and caregivers. While new treatments are emerging for individuals in the early stages of the disease, a critical challenge remains: the need for accessible, cost-effective, and accurate diagnostic tools to identify Alzheimer's sooner.

In a significant stride forward, Mayo Clinic researchers have validated the accuracy of an FDA-approved blood test that promises to revolutionise Alzheimer's diagnosis. This accessible test, suitable for use in outpatient memory clinics, demonstrated high accuracy in diagnosing the disease across a spectrum of cognitive impairments. The groundbreaking findings are published in Alzheimer's & Dementia: The Journal of the Alzheimer's Association.

Traditionally, diagnosing Alzheimer's disease has relied on methods such as positron emission tomography (PET) scans and spinal taps, which measure the buildup of toxic proteins in the brain. However, these procedures are often expensive and invasive, limiting their widespread applicability. The urgent need for more accessible, non-invasive, and cost-effective biomarkers – measurable indicators of a disease – has been a driving force in Alzheimer's research. This new blood test addresses that critical need, paving the way for improved diagnoses in diverse clinical settings.

The research team highlights the immense potential of their findings, stating that this blood test can significantly contribute to better identifying research participants with Alzheimer's disease brain changes, efficiently screening and selecting patients with Alzheimer's disease for clinical trials, and more effectively assessing patient response to therapy in clinical trials.

The study involved over 500 patients receiving treatment for various memory issues at the outpatient Memory Disorder Clinic at the Mayo Clinic in Florida. The diverse patient cohort included individuals with early- and late-onset cognitive impairment, typical and atypical Alzheimer's disease, Lewy body dementia, and vascular cognitive impairment. Patients ranged in age from 32 to 89, with the average age of symptom onset at 66. Alzheimer's disease was determined to be the underlying cause of symptoms in 56% of the participants. The research team also conducted serum tests to measure kidney disease, a factor that can influence plasma biomarker concentrations.

Mayo Clinic Laboratories conducted tests for two key proteins in blood plasma associated with amyloid plaque buildup, the hallmark of Alzheimer's disease: Aβ42/40 and p-tau217. The results revealed significantly higher levels of p-tau217 in patients diagnosed with Alzheimer's disease compared to those without the condition. Importantly, the researchers also observed that higher plasma p-tau217 concentrations were associated with impaired kidney function, underscoring the importance of considering this factor when interpreting blood test results.

Out of 509 patients, plasma p-tau217 concentrations were positive in 267 individuals. Notably, this included 233 out of 246 patients (95%) whose cognitive impairment was attributed to Alzheimer's disease, demonstrating the test's remarkable accuracy.

The study's compelling findings were prominently featured at the American Academy of Neurology Annual Meeting in April, generating significant interest within the medical community. This research builds upon a previous study by the Mayo Clinic Laboratories team, which demonstrated the utility of these blood tests in comparison to amyloid PET scans in research participants.

Looking ahead, Dr. Day, a lead researcher on the study, emphasised the next crucial steps. The team plans to evaluate blood-based testing in more diverse patient populations and in individuals with early Alzheimer's disease who may not yet exhibit cognitive symptoms. Furthermore, they aim to investigate disease-specific factors that could potentially alter biomarker accuracy in clinical trials.

This breakthrough in blood testing offers a promising future for Alzheimer's diagnosis, enabling earlier intervention, facilitating more effective clinical trials, and ultimately providing new hope for patients and their families.

Copied