Comparison of Brain Amyloid Deposition and Cortical Glucose Metabolism Between Clinic- and Community-Based Cohort.

Background: The differences in positron emission tomography (PET) imaging among older adults with mild cognitive impairment (MCI), according to the recruitment source, remain unclear.

Objective: To investigate the differences in brain amyloid deposition and cortical glucose metabolism according to recruitment source among older adults with MCI.

Methods: Participants in the clinic-based MCI cohort, who were referred to Oita University Hospital for cognitive decline, consisted of 90 adults with MCI. The community-based MCI cohort, which participated in a prospective cohort study, consisted of 118 adults with MCI. Participants underwent cognitive function evaluation, 11C-Pittsburgh compound B (PiB)-PET, and 18F-fluorodeoxyglucose (FDG)-PET. The prevalence of amyloid positivity and mean PiB and FDG uptake values were compared between the cohorts. Moreover, a voxel-by-voxel group study was performed to determine the areas with significant differences between the clinic- and community-based MCI cohorts.

Results: The prevalence of amyloid positivity and mean PiB uptake value in the clinic-based MCI cohort were significantly higher than those in the community-based MCI cohort (p < 0.001 and p < 0.001, respectively). The mean FDG uptake value in the clinic-based MCI cohort was significantly lower than that in the community-based MCI cohort (p < 0.001). SPM 8 analysis showed significantly increased PiB uptake in the precuneus and parietotemporal lobe and significantly decreased FDG uptake in the posterior cingulate in the clinic-based MCI cohort compared to the community-based MCI cohort.

Conclusion: The prevalence and severity of amyloid pathology in older adults with MCI varied depending on the recruitment source.