A blood test that measures plasma phosphorylated tau 217 is capable of predicting future Alzheimer’s disease onset in cognitively normal older adults even when positron emission tomography scans do not show amyloid or tau build up in the brain. “We used to think that positron emission tomography (PET) scan detection was the earliest sign of Alzheimer’s disease progression, revealing amyloid accumulation in the brain 10 to 20 years...
