Temporal Dynamic Changes of Intrinsic Brain Activity Associated with Cognitive Reserve in Prodromal Alzheimer's...

Cognitive reserve (CR) is an important protective factor for Alzheimer's disease (AD), yet its mechanism has not been fully elucidated.

To explore the effect of CR on resting and dynamic brain intrinsic activity in patients with mild cognitive impairment (MCI).

65 amyloid-β PET-negative (Aβ-) normal controls (NC) and 30 amyloid-β PET-positive (Aβ+) MCI patients underwent resting-state functional magnetic resonance imaging were included from Alzheimer's Disease Neuroimaging Initiative. According to the years of education, the subjects were divided into high education group and low education group. A two-way analysis of variance was employed for the fractional amplitude of low-frequency fluctuation (fALFF) and dynamic fALFF (dfALFF) comparisons among the four groups. Moreover, the interaction effect of neuroimaging×pathology on clinical cognitive function was tested with linear regression analysis.

The value of fALFF in the left prefrontal lobe was increased in Aβ+ MCI patients compared to Aβ- NC. The significant interactive effect between disease state and education (binary factor) was observed in the right parahippocampal gyrus (PHG) for fALFF, the right PHG and the right inferior parietal lobule for dfALFF. While no significant results between education (continuous factor) and brain activity was found in voxel-by-voxel analysis. For MCI patients, a significant fluorodeoxyglucose hypometabolic convergence index×right PHG dfALFF interaction was found, indicating the maintenance of executive function at higher levels of dfALFF in the right PHG.

High CR can alleviate the impairment of hypometabolism on executive function in MCI patients, which is partially achieved by regulating the dynamic brain activity in the right PHG.