Common Health Issues Can Influence New Blood Tests for Alzheimer’s Disease

Blood-based tests for Alzheimer’s disease are transforming diagnosis by offering a simpler alternative to spinal taps and brain imaging. However, many people evaluated at memory clinics also live with conditions such as diabetes, kidney disease, or high cholesterol, raising concerns about whether these everyday health issues could distort test results and reduce diagnostic accuracy. Addressing this uncertainty is critical as blood biomarkers move into routine clinical use. Now, a new study has found that while some biomarkers are affected by systemic health factors, the most promising marker remains highly reliable.

In the study led by Karolinska Institutet (Stockholm, Sweden), researchers found that several common medical conditions can influence levels of certain Alzheimer’s blood biomarkers, but one key marker continues to perform robustly, supporting its use in clinical practice with appropriate interpretation. The study analyzed blood samples from 311 patients using material from Karolinska’s GEDOC database and biobank. The researchers examined how kidney function, cholesterol levels, diabetes, and vascular conditions were associated with widely used blood-based biomarkers for Alzheimer’s disease.

Image: Everyday health conditions can shape Alzheimer’s blood test results (Photo courtesy of Shutterstock)

By comparing biomarker levels with detailed clinical data, the team assessed whether observed changes reflected Alzheimer’s pathology or were influenced by non-neurological health factors. The analysis showed that conditions such as diabetes and dyslipidemia were linked to changes in amyloid-related biomarkers even after accounting for Alzheimer’s pathology, suggesting effects beyond the brain.

The results, published in the journal Alzheimer’s & Dementia, revealed a clear distinction between biomarkers. Levels of p-tau217, currently considered the most promising blood marker for Alzheimer’s disease, remained highly stable despite variations in kidney function and metabolic health. In contrast, the Aβ42/40 ratio was more sensitive to systemic health influences, and clinical cut-off values shifted when comorbidities were considered.

These findings indicate that most blood biomarkers retain strong diagnostic performance, but interpretation can be improved by factoring in a patient’s overall health profile. Adjusting how results are read may help clinicians avoid misclassification and improve diagnostic precision, especially in patients with multiple chronic conditions.

Going forward, the researchers plan to validate their findings in larger and more diverse populations, including cognitively healthy individuals at increased risk of dementia. The long-term goal is to integrate health-adjusted biomarker models into clinical workflows to support more personalized and accurate Alzheimer’s diagnosis.

“These tests are a big step forward,” said researcher Makrina Daniilidou. “Our results show they are reliable, but also highlight the need for a more personalized approach when interpreting blood biomarkers in patients with other health conditions.”

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Karolinska Institutet