Multimodal neuroimaging insights into the neurobiology of healthy aging across the lifespan.

PURPOSE: The purpose of this study was to advance our understanding of the neurobiology of healthy aging, which is crucial for improving quality of life and preventing age-related diseases. Despite its importance, a comprehensive investigation of this process has yet to be fully characterized.

METHODS

We used a hybrid PET/MRI scanner to assess neurophysiological parameters in 80 healthy individuals aged 20-78. Cerebral amyloid-beta (Aβ) deposition and glucose metabolism were assessed using PET scans, while participants underwent simultaneous MRI scans.

RESULTS

We found a positive correlation between Aβ-deposition and aging, and a negative correlation between glucose metabolism and aging. The insula showed the strongest negative correlation between glucose metabolism and age (Spearman's r = -0.683, 95% CI [-0.79, -0.54], p < 0.0001), while the posterior cingulate cortex had the strongest positive correlation between Aβ-deposition and age (Spearman's r = 0.479, 95% CI [0.28, 0.64], p < 0.0001). These results suggest a spatially dependent link between Aβ-deposition and metabolism in healthy older adults, indicating a compensatory mechanism in early Alzheimer's. Additionally, Aβ-deposition was linked to changes in interregional neural communication.

CONCLUSIONS

Our study confirms previous findings on aging and offers new insights, particularly on the role of Aβ-deposition in healthy aging. We observed a linear increase in Aβ-deposition, alongside decreases in white matter integrity, cerebral blood flow, and glucose metabolism. Additionally, we identified a complex regional relationship between Aβ-deposition, glucose metabolism, and neural communication, possibly reflecting compensatory mechanisms.