A simple blood test marker may help identify people at increased risk of developing dementia, according to a large study using routine clinical data.
Researchers analyzed the neutrophil-to-lymphocyte ratio (NLR) – a measure of inflammation calculated from standard complete blood counts – in more than 370,000 patients from two US health systems. Follow-up data were assessed over time to assess whether higher NLR levels were linked to future diagnoses of Alzheimer’s disease and related dementias.
They found that individuals with higher NLR values had a greater risk of developing dementia in both datasets. The association was consistent across different patient groups and showed a dose–response pattern, meaning that risk increased as NLR rose.
NLR testing is already widely available in clinical practice, as it is derived from routine blood tests. This makes it a practical marker that could be incorporated into risk assessment models without additional testing.
However, NLR is not specific to dementia. It reflects general inflammation and can be influenced by many conditions, including cardiovascular disease and infection. The study also does not show that inflammation directly causes dementia, only that there is an association.
The findings highlight the potential value of routinely collected hematology data beyond immediate clinical use. NLR could contribute to identifying patients at higher risk when used alongside other clinical and biomarker information.
Further research is needed to understand how this marker could be used in practice, including whether tracking changes in NLR over time adds predictive value and how it integrates with established dementia biomarkers.
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