Purpose: Our earlier investigation assessed the correlation between regional accumulations of a tau positron emission tomography (PET) tracer (THK5351) and cognitive dysfunction in the Alzheimer's disease (AD) continuum brain. We reported significant correlations between bilateral parietotemporal and left posterior cingulate/precuneus THK5351 accumulations and Mini-Mental State Examination (MMSE)/Alzheimer Disease Assessment Scale-Cognitive Subtest (ADAS) scores. Herein, we explored the relationship between these variables in non-AD pathologic brains. Methods: Thirty-one subjects with non-AD pathologic changes (mean age: 64.6 ± 11.3 yrs) underwent three-dimensional MRI, fluoro-2-deoxyglucose (FDG)-(PET), Pittsburgh compound B (PiB)-amyloid PET, and THK5351-tau PET. All subjects completed the MMSE (mean ± SD score: 27.0 ± 4.1), and 20 subjects (mean age: 63.8 ± 11.9 yrs) also completed the ADAS (9.7 ± 9.3). A voxel-wise statistical analysis using statistical parametric mapping determined the correlations between each subject's FDG and THK imaging results and their MMSE and ADAS scores. Results: The voxel-wise statistical analysis revealed that FDG accumulations in the left temporal cortices were significantly positively correlated with the subjects' MMSE scores and significantly negatively correlated with their ADAS scores. A negative correlation was observed between the subjects' MMSE scores and THK5351 accumulations in the left temporal and medial frontal cortices and the right temporal pole. A positive correlation was observed between the subjects' ADAS scores and THK5351 accumulations in the left temporal cortices and the right anterior temporal lobe. Conclusions: Compared to FDG accumulation, THK5351 accumulations correlated more strongly with neuropsychological test scores in non-AD pathologic brains, likely due to THK5351's affinity for both tau and monoamine oxidase-B. THK5351 measurements may be valuable for clarifying the pathophysiology of non-AD pathologic changes in the brain.
Sugimoto et al. (2024) studied this question.