Association Between Neuropsychological Test Performance and Neuroimaging Findings in Cognitive Impairment: A Retrospective Cohort Study

BACKGROUND: Structural magnetic resonance imaging (MRI) and [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) provide different information about cognitive impairment, but the additional contribution of FDG-PET beyond MRI across cognitive outcomes remains unclear. This study examined associations between neuropsychological performance and MRI/FDG-PET findings. METHODS: This retrospective cohort included 200 patients with mild cognitive impairment or dementia. Neuropsychological assessment covered global cognition and memory, executive, visuospatial and language domains. Structural MRI was evaluated using the Modified Visual Magnetic Resonance Rating Scale; FDG-PET data were available for 68 patients. MRI-only, FDG-PET-only and combined models were compared. RESULTS: Structural MRI abnormalities showed broad associations with global and domain-level cognitive performance. Sulcal and ventricular atrophy were associated with multiple cognitive domains, while regional FDG-PET findings aligned with corresponding domains. The additional contribution of FDG-PET beyond MRI appeared most evident for global cognition, more modest for executive performance and limited for several other outcomes. CONCLUSIONS: Structural MRI showed broad multidomain associations, while regional FDG-PET findings corresponded to cognitive performance. The additional explanatory contribution of FDG-PET appeared to vary across cognitive outcomes, warranting cautious interpretation and further evaluation.