Scalable biological-cognitive profiling for Alzheimer's disease in the population

Plasma phosphorylated tau217 has been suggested as a core biomarker for establishing biological Alzheimers disease diagnosis. This blood biomarker has not been studied together with scalable cognitive assessment tools in population-based samples. We investigated the prevalence of cognitive and Alzheimers disease biomarker abnormality and associations between plasma phosphorylated tau217 and remotely measured cognitive function in individuals without dementia. We used a population-based cross-sectional sample of 65-85-year-olds (n=692, 57% females) excluding those with previously diagnosed Alzheimers disease or other dementia-causing neurodegenerative disease. Cognition was measured with telephone-administered word list recall task (episodic memory) and animal naming (semantic fluency). Plasma phosphorylated tau217 was determined with the ALZpath assay. The prevalence of individuals with abnormalities in tests measuring episodic memory, semantic fluency and plasma phosphorylated tau217 was 10-13%. Higher plasma phosphorylated tau217 was related to lower scores in telephone-administered cognitive tests. We found a substantial minority of a population-based sample of individuals without a clinical diagnosis of Alzheimers disease to have cognitive and plasma phosphorylated tau217 profiles suggesting underlying Alzheimers disease. Combining plasma phosphorylated tau217 with remote cognitive assessment could be a scalable, accessible, and cost-effective protocol for screening individuals with undiagnosed or risk for Alzheimers disease.