People diagnosed with Down syndrome face a high risk of Alzheimer’s disease. Despite this, they have been mostly excluded from the recent proliferation of blood tests aimed at detecting Alzheimer’s. A recent study, however, suggests a shift in this trend. The study revealed that two blood tests, already in use for Alzheimer’s detection, were successful in identifying Alzheimer’s-related changes in individuals with Down syndrome. These were nearly as accurate as in the general population. Published in Communications Medicine, these findings could simplify and widen access to Alzheimer’s screening for this group, which currently relies on more invasive tests.
Blood Tests Indicating Promise for Down Syndrome Patients
The study evaluated two tests: Lumipulse G p-tau217/β-Amyloid 1-42 and PrecivityAD2. These tests detect amyloid buildup and abnormal tau proteins in the brain, both of which are linked to Alzheimer’s. Blood tests are gaining attention for their simplicity compared to brain scans or spinal taps. Historically, individuals with Down syndrome have been excluded from studies testing these methods. Michael Rafii, a clinical neurology professor at the Keck School of Medicine of USC, noted the importance of including this group due to their high Alzheimer’s risk.
Researchers found almost all individuals with Down syndrome have amyloid plaques by age 40, though not all develop Alzheimer’s dementia. The risk of developing the disease exceeds 90 percent. Genetic changes causing Down syndrome lead to increased amyloid accumulation, characteristic of Alzheimer’s.
Challenges in Diagnosing Alzheimer’s in Down Syndrome Cases
Dr. Yıldız Değirmenci from Medicana Health Group stated that diagnosing Alzheimer’s in those with Down syndrome is challenging. New cognitive declines must be distinguished from lifelong intellectual disabilities, as the disease often presents differently in this group. Typical early changes include shifts in executive functioning, personality, or behavior, unlike the memory loss common in late-onset Alzheimer’s.
Researchers analyzed 39 individuals with Down syndrome, employing both blood testing and positron-emission tomography (PET) scans. Both blood tests accurately identified participants with abnormal brain amyloid levels. They also established preliminary thresholds to differentiate between cases with and without Alzheimer’s-related brain pathology in this population. This suggests a future where a simple blood draw may indicate Alzheimer’s presence before resorting to complex testing. Current diagnostic options can be hard to access, as amyloid PET scans are mainly available at large medical facilities, and lumbar punctures require specialized care.
Zinayida Schlachetzki, the study’s first author, explained that the blood test is more accessible as a screening method. It is easier, cost-effective, and less burdensome for patients. Değirmenci warned that blood biomarkers should be complemented by clinical history and cognitive assessments, not used alone.
Future Prospects for Blood Testing
Researchers suggested these tests may offer advantages beyond just identifying Alzheimer’s. Symptoms like memory issues and behavioral changes could have multiple origins. A reliable way to exclude Alzheimer’s might guide doctors toward alternative explanations, like untreated depression or sleep apnea.
Study authors acknowledged the need for further research before wide application. They aim to test these methods in a larger Down syndrome population. Michael S. Rafii highlighted the necessity for validation, stating the findings are promising but require more diverse and longitudinal studies to confirm thresholds and interpretation alongside cognitive, behavioral, and functional changes.
Challenges remain, including regulatory reviews, insurance coverage, lab access, clinician education, and equitable access to specialists. Testing should be paired with effective counseling, as Alzheimer’s biological markers can be detected long before dementia symptoms appear. Upcoming research already plans to use blood-based screening to select participants for a clinical trial of the Alzheimer’s treatment donanemab in the Down syndrome community.
Rafii emphasized the importance of inclusion in research. Despite contributing significantly to the understanding of Alzheimer’s biology, individuals with Down syndrome are often absent from trials. Recognizing their contribution is both a scientific and ethical obligation. It highlights the importance of inclusivity in advancing medical understanding.
Reference: Study co-authors include Oliver Langford, Michael Donohue, Xiaoyu Zhou, Sonal Sukreet, Sara Abdel-Latif, Robert Rissman, Matthew Zammit from University of Wisconsin–Madison, and Joel Braunstein from C2N Diagnostics. Supported by the National Institutes of Health [R61AG066543]. DOI: 10.1038/s43856-026-01709-0
Leave a Reply