Hanna Al-Shaikh, Fadi S

AbstractIntroductionComparison of tau (flortaucipir) positron emission tomography (FTP‐PET) to autopsy is important to demonstrate the relationship of FTP‐PET to neuropathologic findings.MethodsAutopsies were performed on 26 participants who had antemortem FTP‐PET. FTP‐PET standardized uptake value ratios (SUVRs) were compared to autopsy diagnoses and Braak tangle stage. Quantitative tau burden was compared to regional FTP‐PET signal.ResultsParticipants with Braak stages of IV or greater had elevated FTP‐PET signal. FTP‐PET was elevated in participants with Alzheimer's disease. An FTP‐PET SUVR cut point of 1.29 was determined to be optimal. Quantitative measurements of hippocampal and temporal lobe tau burden were highly correlated to FTP‐PET signal (rho's from 0.61 to 0.70, P ≤ .02).DiscussionElevated FTP‐PET reflects Braak IV or greater neuropathology. Participants with primary age‐related tauopathy and hippocampal sclerosis did not show elevated FTP‐PET signal. Secondary neuropathologic diagnoses of Alzheimer's disease neuropathologic change can lead to borderline elevated FTP‐PET signal.

AbstractIntroductionOur primary goal was to examine demographic and clinicopathologic differences across an ethnoracially diverse autopsy‐confirmed cohort of Alzheimer's disease cases.MethodsA retrospective study was conducted in the Florida Autopsied Multi‐Ethnic cohort on 1625 Alzheimer's disease cases, including decedents who self‐reported as Hispanic/Latino (n = 67), black/African American (n = 19), and white/European American (n = 1539).ResultsHispanic decedents had a higher frequency of family history of cognitive impairment (58%), an earlier age at onset (median age of 70 years), longer disease duration (median of 12 years), and lower MMSE proximal to death (median of 4 points) compared with the other ethnoracial groups. Black decedents had a lower Braak tangle stage (stage V) and higher frequency of coexisting hippocampal sclerosis (21%); however, only hippocampal sclerosis differences survived adjustment for sex, age at onset, and disease duration. Neither Thal amyloid phase nor coexisting Lewy body disease differed across ethnoracial groups.DiscussionDespite a smaller sample size, Hispanics demonstrated longer disease duration with Alzheimer's disease, but not greater lifespan. Neuropathologic differences across ethnoracial groups supported differences in tau pathology distribution and coexisting hippocampal sclerosis, which may impact biomarker studies.