A recent scientific investigation, published on December 3, 2025, in the esteemed journal Neurology, has illuminated a critical nuance in the interpretation of Alzheimer’s disease biomarkers detected in blood samples. The research indicates that individuals experiencing compromised kidney function may exhibit elevated levels of these biochemical markers, a phenomenon that does not necessarily correlate with an increased predisposition to developing dementia. This critical observation underscores the necessity for healthcare professionals to consider a patient’s renal status when evaluating the significance of blood-based Alzheimer’s indicators.
The study meticulously examined a cohort of 2,279 adults, whose average age was approximately 72 years, and none of whom presented with dementia at the commencement of the observation period. Over an average follow-up duration of eight years, participants underwent comprehensive medical evaluations, including cognitive assessments and precise blood analyses. These analyses were designed to quantify both kidney function and the concentrations of several key proteins associated with Alzheimer’s pathology. Among the biomarkers scrutinized were tau and amyloid-beta proteins, crucial elements in the pathological cascade of Alzheimer’s, as well as neurofilament light chain and glial fibrillary acidic proteins, which serve as indicators of neuronal damage and neuroinflammation, respectively.
A fundamental aspect of the study’s findings is the observed correlation between diminished kidney efficiency and heightened concentrations of the majority of Alzheimer’s-related biomarkers. The kidneys, vital organs responsible for filtering waste products and toxins from the circulatory system and excreting them via urine, play a crucial role in maintaining the body’s chemical balance. When this filtering capacity is impaired, certain substances that would normally be cleared from the blood may persist at higher levels. The research team specifically noted that this association remained consistent even after excluding individuals who developed dementia during the study’s progression, suggesting that the link between impaired kidney function and biomarker levels is a persistent phenomenon.
While the study established a clear association, it is paramount to clarify that it did not assert a direct causal relationship where diminished kidney function actively precipitates an increase in Alzheimer’s biomarker levels. Rather, the findings suggest that reduced renal clearance mechanisms may contribute to the accumulation of these proteins in the bloodstream, leading to potentially misleadingly high readings. This distinction is vital for accurate diagnostic interpretation.
Intriguingly, the research also explored the interplay between kidney health, biomarker levels, and the eventual development of dementia. The data revealed that among the 1,722 participants with unimpaired kidney function, 221 individuals were diagnosed with dementia over the eight-year monitoring period. In contrast, within the group of 557 individuals exhibiting impaired kidney function, 141 developed dementia. When researchers meticulously adjusted their analysis for confounding factors such as age, sex, and the presence of APOE ε4, a well-established genetic determinant of increased Alzheimer’s risk, no statistically significant elevation in the overall likelihood of developing dementia was found for individuals with impaired kidney function compared to their counterparts with healthy kidneys.
However, a particularly significant subgroup emerged from the analysis: individuals who possessed both compromised kidney function and elevated levels of neurofilament light chain proteins. This specific group demonstrated a nearly doubled risk of developing dementia when compared to individuals with preserved kidney function who also exhibited high levels of the same biomarker. This finding suggests a more nuanced interaction, where kidney health might influence the tempo or onset of dementia in individuals already predisposed by elevated biomarker levels, even if it doesn’t initiate the underlying pathological process or increase the overall lifetime risk. Dr. Francesca Gasparini, the lead author of the study and an investigator at Karolinska Institutet in Stockholm, Sweden, emphasized this point, stating that impaired kidney function may accelerate the progression of dementia in individuals who already present with elevated biomarker concentrations.
The implications of these findings are substantial for the clinical application of emerging blood-based Alzheimer’s diagnostics. As these tests become more widely adopted for early detection and risk assessment, it is imperative that clinicians adopt a holistic approach to interpretation. Dr. Gasparini highlighted the importance of this integrated perspective, asserting that "When looking at these biomarkers in older adults, keeping an eye on kidney health may be more important than one might think." The study advocates for the routine monitoring of renal health alongside Alzheimer’s biomarker testing, particularly in older populations where both conditions may be more prevalent. This dual monitoring strategy could empower clinicians to more accurately interpret biomarker results and to better identify individuals who may be at risk for a more rapid decline, thus enabling more timely and targeted interventions.
Despite the valuable insights gained, the research acknowledges certain limitations. A key constraint is that the Alzheimer’s-related biomarkers were quantified only once for each participant. This singular measurement means the study could not definitively ascertain how dynamic changes in kidney function over time might dynamically influence biomarker concentrations. Longitudinal studies tracking both kidney function and biomarker levels would be necessary to fully elucidate this complex relationship. Furthermore, the study’s participant pool was largely composed of highly educated individuals residing in urban areas of Sweden. Consequently, the generalizability of these findings to more diverse demographic and socioeconomic populations may be limited, necessitating further research across broader populations to confirm these associations and their implications. The quest for accurate and reliable Alzheimer’s diagnostics continues, with this research adding a crucial layer of complexity and a call for greater clinical vigilance in considering multifactorial influences on diagnostic markers.
About the Author
