Frequency of biologically-defined AD in relation to age, sex, APOEε4 and cognitive impairment in a prospective cohort study

Objective:  To assess the frequency of biologically-defined Alzheimer’s disease (AD) in relation to age, sex and APOEε4, as well as rates of discordance between clinically- and biologically defined AD.

Methods: We assessed cognitively unimpaired (CU) elderly (n=166), amnestic MCI (n=77) and probable AD dementia (n=62) subjects who underwent evaluation by dementia specialists and neuropsychologists in addition to amyloid-PET with [18F]AZD4694 and tau-PET with [18F]MK6240. Individuals were grouped according to their AD biomarker profile. Positive predictive value for biologically-defined AD was assessed in relation to clinical diagnosis. Frequency of AD biomarker profiles were assessed using logistic regressions with odds ratios and 95% CIs.

Results: The clinical diagnosis of probable AD dementia demonstrated good agreement with biologically-defined AD (positive predictive value: 85.2%). 7.88% of CU elderly subjects were positive for both amyloid-PET and tau-PET. Frequency of biolo...