Blood Test Detects Early Signs of Alzheimer’s Disease

Researchers from the University of California, San Francisco published a study in The Lancet showing that blood biomarkers—beta‑amyloid Aβ42, Aβ40 and p‑tau—correlate with subtle cognitive changes in middle‑aged adults without dementia. The analysis of 1,350 participants in the United States, average age 61, found higher biomarker levels linked to slower processing speed and reduced executive function. The results suggest that a simple blood test could identify Alzheimer’s pathology decades before clinical symptoms appear, potentially allowing earlier intervention that might prevent or delay up to 40% of dementia cases. Independent experts cautioned that such tests may generate false‑positive results in younger, asymptomatic populations and warned they are not suitable for large‑scale, untargeted screening without additional diagnostic criteria.

The study underscores the promise of blood‑based diagnostics for neurodegenerative disease while highlighting the need for careful clinical validation before widespread use.