Convergent abnormalities of β-amyloid deposition, glucose metabolism, and fMRI activity in the dorsal precuneus in subjective cognitive decline

BackgroundThere has been no report on convergent local abnormalities of multiple functional brain imaging modalities including {beta}-amyloid (A{beta}) deposition, glucose metabolism, and resting-state functional magnetic resonance imaging (RS-fMRI) activities for participants with subjective cognitive decline (SCD). MethodsFifty participants with SCD and 15 normal controls (NC) were scanned with both [18F]-florbetapir positron emission tomography (PET) and [18F]-fluorodeoxyglucose PET, each PET sacn accompanied with simultaneous RS-fMRI. Voxel-wise metrics were analyzed, including A{beta} deposition, glucose metabolism, and three local metrics for RS-fMRI, i.e., amplitude of low frequency fluctuation (ALFF), regional homogeneity (ReHo), and degree centrality (DC). ResultsThe SCD group showed increased A{beta} deposition and increased glucose metabolism (P < 0.05, corrected), as well as decreased ALFF, ReHo, and DC (P < 0.05, uncorrected) in the same area of the left dorsal precuneus (dPCu). The dPCu showed negative resting state functional connectivity (RSFC) with the default mode network (DMN). Regarding global A{beta} deposition positivity, the A{beta} deposition in the dPCu showed a gradient change, i.e., SCD+ > SCD- > NC-. Further, both SCD+ and SCD- showed increased glucose metabolism and decreased RS-fMRI metrics in the dPCu. ConclusionsThe convergent abnormal activities in the dPCu of SCD indicate that the dPCu is an early vulnerable region. The anti-RSFC of the dPCu with DMN supports that the earliest symptoms might be more related to other cognitive functions (e.g., unfocused attention) than episodic memory. (Funded by the National Key Research and Development Program of China and others; ClinicalTrials.gov number, NCT03370744.)