A routine blood test might spot Alzheimer’s risk long before symptoms begin.
Neutrophils are a type of white blood cell that serve as rapid responders in the immune system. Their levels rise quickly during infection or inflammation, which changes the balance between neutrophils and other immune cells circulating in the blood.
Doctors can measure this balance using the neutrophil to lymphocyte ratio (NLR). This value comes from a standard complete blood count, a routine test commonly used to detect infections and assess immune function.
A new study led by researchers at NYU Langone Health suggests that this simple ratio could do more than reflect current health. It may help identify people who are at risk of developing Alzheimer’s disease and related dementias before any signs of cognitive decline appear. The research included nearly 400,000 patients across two major healthcare systems.
Large Study Links Blood Marker to Dementia Risk
“Our study is the first large-scale investigation showing that neutrophil metrics are associated with increased risk of dementia in humans,” said study first author Tianshe (Mark) He, PhD, a data scientist in the Department of Psychiatry at NYU Grossman School of Medicine. “Neutrophil elevation is happening before any evidence of cognitive decline, which makes a compelling case for studying whether neutrophils are actively contributing to disease progression.”
Dr. He and co-senior author Jaime Ramos-Cejudo, PhD, an assistant professor in the Departments of Psychiatry and Neurology at NYU Grossman School of Medicine, are both affiliated with the VA Boston Healthcare System’s Cooperative Studies Program.
Published in Alzheimer’s & Dementia, the study analyzed data from nearly 285,000 patients treated at four NYU Langone hospitals and about 85,000 patients within the Veterans Health Administration.
To carry out the analysis, researchers selected the earliest NLR measurement that met their criteria for each patient. These measurements had to fall within the study period, be taken when patients were at least 55 years old, and occur before any diagnosis of Alzheimer’s or dementia. The team then tracked whether those individuals later developed dementia during the study window.
Higher NLR Associated With Increased Alzheimer’s Risk
The findings showed a consistent pattern across both populations. Individuals with higher NLR values had a significantly greater likelihood of developing Alzheimer’s or other dementias, both in the near term and over longer periods. High NLR levels were defined using the median value, meaning half of the participants fell above that point and half below it.
The relationship between NLR and dementia risk was stronger in certain groups. Hispanic patients showed a higher level of risk associated with elevated NLR, although it remains unclear whether this is due to genetic influences or social factors such as differences in access to healthcare. Women in both healthcare systems also showed increased risk linked to higher NLR values.
Why This Common Blood Test Matters
Dr. Ramos-Cejudo explained that the results are important for two key reasons. First, while an elevated NLR alone is unlikely to predict dementia with certainty, it could become useful when combined with other known risk factors. This approach may help identify individuals who should receive further testing or early interventions before symptoms appear.
Second, the findings support growing evidence that neutrophils may not just reflect disease risk but could be involved in the progression of Alzheimer’s itself.
Possible Role of Neutrophils in Brain Damage
Neutrophils play a crucial role in fighting infection and repairing tissue, but they can also contribute to damage under certain conditions. In Alzheimer’s and other dementias, this damage may affect blood vessels and brain tissue. Signs of neutrophil-related inflammation have been observed in the brains of people with Alzheimer’s, and studies in mice suggest these cells can speed up disease progression.
Aging may further complicate this process. Changes in how the body clears out old neutrophils could lead to buildup or dysfunction, potentially causing tissue damage when normal removal processes are disrupted.
Even so, researchers caution that a direct cause-and-effect link has not yet been proven. One challenge is that neutrophils have a short lifespan and must be studied using fresh blood samples, unlike other cell types that can be stored for later analysis.
Ongoing Research on Diagnosis and Treatment
Dr. Ramos-Cejudo said his team at the Vascular and Immune Dysfunction in Aging and Alzheimer’s Disease (VIDA) lab is continuing to explore whether neutrophils actively contribute to cognitive decline. Their work combines measurements of neutrophil activity with advanced imaging methods (such as PET and diffusion MRI) along with cognitive testing.
“These and future studies will show whether neutrophils are just a marker of Alzheimer’s disease or are actively causing dementia progression — in which case, they could make a compelling therapeutic target,” said Dr. Ramos-Cejudo. “In the meantime, we hope the neutrophil to lymphocyte ratio can contribute to gateway diagnostic tools for people at risk of developing Alzheimer’s and dementia, so they can get more in-depth testing and interventions long before they experience cognitive decline.”
Reference: “Neutrophil inflammation metrics are associated with the risk of future dementia in large data from NYU Langone Hospitals and the Veterans Health Administration” by Tianshe He, Rebecca A. Betensky, Ricardo S. Osorio, Kaitlin Swinnerton, Chunlei Zheng, Tovia Jacobs, Alok Vedvyas, Karyn Marsh, Joshua Chodosh, Ula Y. Hwang, Natalia Sifnugel, Omonigho M. Bubu, Thomas Wisniewski, Mary Brophy, Nhan V. Do, Nathanael R. Fillmore and Jaime Ramos-Cejudo, 3 April 2026, Alzheimer’s & Dementia.
DOI: 10.1002/alz.71335
The study was supported by National Institutes of Health grants R01AG092953, R01AG070821, R01AG079282, P30AG066512, K23AG068534, R01AG082278, and RF1AG083975. Additional funding came from the National Alzheimer’s Coordinating Center, the VA Boston Healthcare System’s Cooperative Studies Program, Alzheimer’s Association grant AARG-21-848397, and BrightFocus Foundation grant A2022033S.
Other NYU researchers involved in the study were Rebecca A. Betensky, PhD; Ricardo S. Osorio, MD; Tovia Jacobs; Alok Vedvyas, MS, MSJ; Karyn Marsh, PhD; Joshua Chodosh, MD; Ula Y. Hwang, MD, MPH; Natalia Sifnugel, MPH; Omonigho M. Bubu, MD, PhD, MPH; and Thomas Wisniewski, MD.
Additional co-investigators included Chunlei Zheng, PhD; Kaitlin Swinnerton, MIDS; Mary Brophy, MD; and Nhan V. Do, MD, from the VA Boston Healthcare System’s Cooperative Studies Program (MAVERIC). Nathaniel Fillmore, PhD, at Harvard Medical School, also served as co-senior author.
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