Prevalence of Alzheimer's Disease Pathology in the Community – The HUNT Study

The prevalence of Alzheimer’s disease neuropathological changes (ADNC), the leading cause of cognitive impairment, remains uncertain. Recent blood-based biomarkers enable scalable assessment of ADNC. Here, we measured phosphorylated tau at threonine 217 in 11,486 plasma samples from a population-based cohort of individuals >57 years. The prevalence of ADNC increased with age, from 10% in people 58-69.9 years to 64.9% in those over 90. In the 70+ population, 11.4% had preclinical AD, 10.8% had prodromal AD, and 7.4% had AD dementia. Furthermore, among those 70+, ADNC was present in 57.7% of people with dementia, in 31% of those with mild cognitive impairment and in 22.6% of the cognitively unimpaired group. Our findings suggest a higher prevalence of AD dementia in older individuals and a lower prevalence of preclinical AD in younger groups than previously estimated. Ten percent of the 70+ group met the present eligibility criteria for monoclonal antibody AD treatments.