[Heterogeneity of aging brain: a preliminary comparative study of functional magnetic resonance imaging in elderly people].

OBJECTIVE: To explore the heterogeneity of aging brain.

METHODS: Blood oxygenation level dependent functional magnetic resonance imaging was performed on 10 subjects meeting the standards of successful aging (SA), 9 subjects meeting the standards of usual aging (UA), and 9 subjects meeting the criteria of mild cognitive impairment (MCI), all age, and sex-matched, under stimulation of verbal fluent test (VFT). The activation level of different regions of interest (ROI), laterality index, and the activation level of occipital lobe were analyzed.

RESULTS: The achievement in VFT of the SA group was greater than that of the UA group, and much greater than that of the MCI group with significant differences between any 2 groups (all P < 0.05) except in the task of "names of vegetables". The activation volume of the SA group was greater than that of the UA group, and much greater than that of the MCI group. The main activated regions of the SA and UA groups included left precuneus, anterior cingulate gyrus, middle frontal gyrus, superior frontal gyrus and inferior parietal lobule, and bilateral occipital lobes. The main activated regions of the MCI group included the bilateral prefrontal lobe. The intensity of activation was not significantly different between the SA and UA groups, however, was significantly different between the SA and MCI groups and between the UA and MCI groups. The laterality index (LI) was 0.46 in the SA group, significantly higher than those of the UA group (-0.12) and MCI group (-0.06) (both P < 0.01), however, without a significant difference between the UA group and MCI group. The activation of left prefrontal lobe in the SA group was more obvious than that in the UA group, and much more obvious than that in the MCI group with a significant difference between the UA and MCI groups as well (all P < 0.01). The activation volume of the left dorsal lateral prefrontal cortex (DLPFC) in the SA group was 787 voxels, significantly greater than that in the UA group (292 voxels) and MCI group (0 voxel) (all P < 0.01).

CONCLUSION: Heterogeneity exists in the course of aging, associated with complicated brain mechanism. The activation level of DLPFC and LI may be used as sensitive indexes in evaluation of the brain function of the elderly.