Resting-State and Task-State Dual-Paradigm fNIRS Study Reveals Dynamic Alterations in Brain Network Activity in Alzheimer's Disease With Behavioural and Psychological Symptoms.

BACKGROUND

Alzheimer's disease (AD) frequently presents with behavioural and psychological symptoms of dementia (BPSD), severely impacting prognosis. The dynamic brain network mechanisms remain unclear, and traditional neuroimaging faces limitations. Functional near-infrared spectroscopy (fNIRS) offers a unique approach to explore these mechanisms under natural conditions.

OBJECTIVE

To systematically compare brain region activation, signal complexity and network topology in AD patients with and without BPSD using resting-state and verbal fluency task (VFT) fNIRS paradigms.

METHODS

This cross-sectional study enrolled 48 AD patients (24 with BPSD, 24 without) and 25 normal controls (NC). fNIRS recorded hemodynamic changes in the frontal, temporal, parietal and occipital lobes during rest and VFT. Analyses included activation, time-frequency characteristics, functional connectivity and network topology. Partial correlations assessed links between fNIRS metrics and neuropsychological scores.

RESULTS

In resting state, AD-BPSD showed altered coefficient of variation in left premotor and somatosensory cortices, and elevated information entropy in left dorsolateral prefrontal cortex (lDLPFC), versus NC and AD-non-BPSD. Functional connectivity abnormalities emerged between right frontal eye field-left somatosensory cortex, and right dorsolateral prefrontal cortex (rDLPFC)-left superior temporal gyrus (lSTG) (p < 0.05). During VFT, AD-BPSD had significantly lower lDLPFC and left somatosensory activation versus NC (p < 0.05), but increased signal fluctuation and power in right primary motor cortex (rM1) (p < 0.05), alongside reduced whole-brain clustering coefficient (p = 0.023).

CONCLUSIONS

AD-BPSD was associated with altered brain functional patterns across resting and task states, involving sensorimotor and executive networks as well as altered interhemispheric coordination. These fNIRS-derived alterations provide exploratory evidence of altered brain functional patterns associated with BPSD and warrant further investigation in larger longitudinal studies.