RT Journal Article SR Electronic T1 Differential Effects of Tau Stage, Lewy Body Pathology, and Substantia Nigra Degeneration on 18F-FDG PET Patterns in Clinical Alzheimer Disease JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 274 OP 280 DO 10.2967/jnumed.122.264213 VO 64 IS 2 A1 Jesús Silva-Rodríguez A1 Miguel A. Labrador-Espinosa A1 Alexis Moscoso A1 Michael Schöll A1 Pablo Mir A1 Michel J. Grothe A1 for the Alzheimer’s Disease Neuroimaging Initiative YR 2023 UL http://jnm.snmjournals.org/content/64/2/274.abstract AB Comorbid Lewy body (LB) pathology is common in Alzheimer disease (AD). The effect of LB copathology on 18F-FDG PET patterns in AD is yet to be studied. We analyzed associations of neuropathologically assessed tau pathology, LB pathology, and substantia nigra neuronal loss (SNnl) with antemortem 18F-FDG PET hypometabolism in patients with a clinical AD presentation. Methods: Twenty-one patients with autopsy-confirmed AD without LB neuropathologic changes (LBNC) (pure-AD), 24 with AD and LBNC copathology (AD-LB), and 7 with LBNC without fulfilling neuropathologic criteria for AD (pure-LB) were studied. Pathologic groups were compared regarding regional and voxelwise 18F-FDG PET patterns, the cingulate island sign ratio (CISr), and neuropathologic ratings of SNnl. Additional analyses assessed continuous associations of Braak tangle stage and SNnl with 18F-FDG PET patterns. Results: Pure-AD and AD-LB showed highly similar patterns of AD-typical temporoparietal hypometabolism and did not differ in CISr, regional 18F-FDG SUVR, or SNnl. By contrast, pure-LB showed the expected pattern of pronounced posterior-occipital hypometabolism typical for dementia with LB (DLB), and both CISr and SNnl were significantly higher compared with the AD groups. In continuous analyses, Braak tangle stage correlated significantly with more AD-like, and SNnl with more DLB-like, 18F-FDG PET patterns. Conclusion: In autopsy-confirmed AD dementia patients, comorbid LB pathology did not have a notable effect on the regional 18F-FDG PET pattern. A more DLB-like 18F-FDG PET pattern was observed in relation to SNnl, but advanced SNnl was mostly limited to relatively pure LB cases. AD pathology may have a dominant effect over LB pathology in determining the regional neurodegeneration phenotype.