Metabolic connectivity has greater predictive utility for age and cognition than functional connectivity

Area of Science:

• Neuroscience
• Medical Imaging
• Gerontology

Background:

• Functional (18F)-fluorodeoxyglucose positron emission tomography (fPET) measures brain metabolism in vivo at the post-synaptic neuron.
• Functional magnetic resonance imaging (fMRI) reflects combined metabolic, haemodynamic, and vascular components of neuronal activity.
• The comparative value of fPET versus fMRI for studying brain aging and cognition remains unclear.

Purpose of the Study:

• To compare metabolic (fPET) and functional (fMRI) connectivity in younger and older adults.
• To assess the predictive ability of fPET and fMRI connectivity for age and cognitive performance.
• To investigate age-related alterations in brain metabolic and functional connectivity.

Main Methods:

• Simultaneous fPET/fMRI acquisition in 40 younger and 46 older adults.
• Cross-sectional comparison of whole-brain fPET and fMRI connectomes.
• Analysis of within- and between-network connectivity and graph metrics.

Main Results:

• fPET and fMRI connectomes exhibited moderate topological similarity.
• fPET revealed more age-related connectivity and graph metric differences than fMRI.
• fPET connectivity predicted performance across more cognitive domains than fMRI.

Conclusions:

• Brain aging is associated with metabolic connectivity reconfiguration distinct from haemodynamic changes.
• Metabolic connectivity, measured by fPET, offers greater predictive utility for age and cognition than functional connectivity (fMRI).
• Glucodynamic changes measured by fPET show promise as a biomarker for age-related cognitive decline.