Lancet study shows blood test may detect early Alzheimer

A new study suggests that a blood test may be able to detect biological changes linked to Alzheimer's disease in middle-aged adults decades before clear symptoms emerge. The research, published in The Lancet, found that a small percentage of cognitively healthy individuals in their early 60s showed elevated levels of key Alzheimer's-related proteins in their blood, which were associated with subtle but measurable cognitive differences.

The study involved 1,350 participants without dementia, with an average age of 61. Researchers measured blood levels of biomarkers for amyloid and tau, the hallmark proteins that abnormally accumulate in the brains of people with Alzheimer's. They found that 86 participants, or 6% of the cohort, had high levels of these biomarkers. Crucially, these individuals scored lower on tests of verbal memory and processing speed at the study's outset and showed accelerated cognitive decline over a five-year period compared to those without elevated biomarkers.

Lead author Kristine Yaffe of the University of California San Francisco stated that the findings support the concept that Alzheimer's disease begins decades before clinical symptoms emerge and...