Aberrant Brain Entropy in Alzheimer's Disease: Evidence From a Resting-State fMRI Study

The neurodegenerative disorder, Alzheimer's disease (AD), is typified by insidious onset and increasing prevalence with advancing age. It primarily causes comprehensive functional decline in memory, language, and executive control. The scarcity of reliable imaging biomarkers has led to resting-state functional magnetic resonance imaging (rs-fMRI) becoming a seminal tool for investigating functional alterations in neurological disorders. Brain entropy (BEN) is an indicator derived from rs-fMRI data, quantifying the complexity of functional brain activity and the uncertainty of spontaneous activity. This study aims to utilize BEN technology to elucidate the spatial distribution characteristics of functional complexity within the brains of AD patients.

The present study comprised 30 patients diagnosed with AD and 46 healthy controls recruited from the same center. A comprehensive neuropsychological assessment and rs-fMRI data acquisition were carried out for all participants. Intergroup comparisons were conducted using voxel-level BEN value maps. To this end, a partial correlation analysis was conducted with the objective of ascertaining the association between BEN values in regions exhibiting significant intergroup differences and cognitive function scores.

This study found significantly decreased BEN in the right superior temporal gyrus, right inferior frontal gyrus, and left posterior parietal gyrus among patients with AD, which was significantly correlated with MMSE and MoCA cognitive scores. Exploratory analyses also revealed abnormal trends in the precuneus, cuneus, and left frontotemporal pole.

A widespread reduction in BEN was observed in cerebral regions implicated in language memory, processing, and integrative functions, consistent with cognitive decline in AD. As a sensitive and noninvasive metric, BEN shows promise as an imaging marker for early screening and monitoring of AD.