Longitudinal effects of aging on 18 F-FDG distribution in cognitively normal elderly individuals.

Previous studies of aging effects on fluorine-18-labeled fluorodeoxyglucose ( ¹⁸ F-FDG) distribution have employed cross-sectional designs. We examined aging effects on ¹⁸ F-FDG distribution using both cross-sectional and longitudinal assessments. We obtained two ¹⁸ F-FDG positron emission tomography scans at two different time points from 107 cognitively normal elderly participants. The participants' mean ages at baseline and second scans were 67.9 and 75.7, respectively. The follow-up period ranged from 4 to 11 years with a mean of 7.8 years. The voxel-wise analysis revealed significant clusters in which ¹⁸ F-FDG uptake was decreased between baseline and second scans (p < 0.05, family-wise error corrected) in the anterior cingulate cortex (ACC), posterior cingulate cortex/precuneus (PCC/PC), and lateral parietal cortex (LPC). The cross-sectional analysis of ¹⁸ F-FDG uptake and age showed significant correlations in the ACC (p = 0.016) but not the PCC/PC (p = 0.240) at baseline, and in the ACC (p = 0.004) and PCC/PC (p = 0.002) at the second scan. The results of longitudinal assessments suggested that ¹⁸ F-FDG uptake in the ACC, PCC/PC, and LPC decreased with advancing age in cognitively normal elderly individuals, and those of the cross-sectional assessments suggested that the trajectories of age-associated ¹⁸ F-FDG decreases differed between the ACC and PCC/PC.