Sex- and Age-Related Differences in Brain FDG Metabolism of Healthy Adults: An SPM Analysis

BACKGROUND AND PURPOSE The purpose of our study was aimed to analyze the sex- and age-related differences of brain metabolism in healthy individuals. METHODS Consecutive 100 healthy subjects, 50 males and 50 females, undergoing routine 2-[ 18 F]fluoro-2-deoxy-d-glucose positron emission tomography (FDG PET) for health checkup in our hospital were retrospectively enrolled in this study. Statistical parametric mapping (SPM) was used for analyses of the FDG PET images to disclose the possible effects of age on brain metabolism in males and females as well as the differences of brain metabolism between male and female groups. RESULTS In males and females, decreased brain metabolism with aging is found in bilateral lateral orbital prefrontal and right anterior cingulate cortices. In comparisons between sexes, males are found to have more brain metabolism than females in bilateral visual cortices and cerebellum. CONCLUSIONS Our report discloses different sex- and age-related brain metabolism. Decreased brain metabolism with aging in males and females is similar to findings reported in previous literatures. However, whether declined brain function or volume with aging causing metabolic changes is unknown and should be further evaluated. Nevertheless, the sexrelated differences are possibly compatible with the historical observation of better performance in visual-spatial tasks in males than females.