Brain spontaneous activity alterations in patients with Alzheimer's disease and mild cognitive impairment

Abstract

Objective To investigate the functional changes of brain spontaneous activity in patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) using resting-state functional magnetic resonance imaging (fMRI), and evaluate the potential value of fMRI marker in clinical diagnosis of AD and aMCI. Methods Twelve AD patients, 12 aMCI patients and 12 normal controls (NC) were assessed by the Minimum Mental State Examination (MMSE) and scanned using the resting-state fMRI. The fractional amplitude of low-frequency fluctuations (fALFF) method was employed to examine the changes of the brain spontaneous activity among the three groups. Results Significant between-group differences were found in the precuneus and the inferior parietal lobe. In the precuneus, the fALFF value in AD patients (mean±SD: 1.11±0.07) was significantly decreased as compared to NC (1.24±0.11, t=2.89, P=0.012) and aMCI patients (1.34±0.17, t=3.49, P=0.004). The aMCI patients demonstrated numerically largest fALFF in the precuneus. In the inferior parietal lobe, the fALFF values in AD patients (0.96±0.07) were also significantly decreased as compared to NC (1.11±0.07, t=4.31, P=0.001) and aMCI patients (1.09±0.08, t=3.44, P=0.004). Conclusions AD patients were mostly influenced in the specific regions in terms of brain spontaneous activity, while the aMCI patients showed a compensatory tendency in the precuneus. Key words: Alzheimer's disease; Mild cognitive impairment; Nerve net; Magnetic resonance imaging