Researchers associated increased blood p-tau181 levels with cognitive decline and neurodegeneration in Alzheimer's disease-characteristic brain areas among individuals with elevated amyloid-beta levels, while higher plasma neurofilament light chain levels correlated with cognitive impairment and neurodegeneration among those with and without amyloid-beta accumulation, researchers reported in JAMA Neurology. The study "is a major step forward showing that blood tests for tau pathology and neurodegeneration have clinical value to track disease progression in patients with Alzheimer's disease," said researcher Dr. Kaj Blennow.