Association between 18F – FDG uptake and global cognitive performance in individuals at risk of dementia

Abstract

AbstractBackgroundCardiometabolic disorders (CMD) and Mild Cognitive Impairment (MCI) have been associated with an increased risk of developing dementia. However, brain glucose metabolism has not been compared between patients with CMD and MCI, and little is known about its associations with global cognitive performance. Here we examined regional brain 18F – FDG uptake in patients with CMD and MCI, and analyzed its potential associations with global cognitive performance.Methods55 patients with increased risk for developing dementia were recruited (MCI = 22; CMD = 33) in this cross‐sectional study. As a measure of brain glucose metabolism, PET/CT was performed and the mean uptake value in brain regions of interest (ROI) was obtained and standardized by whole brain uptake. Global cognitive performance was examined using the Mini‐Mental State Examination (MMSE). Group differences in brain metabolism and cognitive performance were examined. We conducted separate linear regression models considering standardized MMSE as the dependent variable, and mean 18F – FDG uptake in each of the ROI (and its CMD/MCI group‐interactions) as independent variables. Our models were adjusted by age, gender, years of education, and presence of at least one APOE e4 allele, and corrected for multiple testing with the False Discovery Ratio (FDR < 0.01).ResultsThe CMD and MCI groups were comparable in age, gender, education, and mean 18F‐FDG uptake across all the ROIs, but significantly different in MMSE (Table 1). Adjusted models for global cognitive performance showed significant group interactions with the mean 18F – FDG uptake in bilateral caudate and hippocampus, as well as in left‐hemisphere amygdala, cuneus, fusiform gyrus, and opercular part of the inferior frontal gyrus. Thus, significant negative associations of 18F – FDG uptake in the above ROIs and cognitive performance was observed in the MCI group (Figure 1 & Table 2).ConclusionsIn MCI patients, reduced global cognitive performance was significantly associated with high brain glucose metabolism in bilateral caudate and hippocampus, and with the left fusiform gyrus, cuneus, and inferior frontal gyrus (opercular part). These asymmetric associations between high metabolism and low cognitive performance could suggest compensatory effects in MCI patients but further research is needed to confirm this hypothesis.