Distinct Reserve Capacity Impacts on Default-Mode Network in Response to Left Angular Gyrus-Navigated Repetitive Transcranial Magnetic Stimulation in the Prodromal Alzheimer Disease

Abstract

Default-mode network (DMN) may be the earliest affected network and is associated with cognitive decline in Alzheimer’s disease (AD). Repetitive transcranial magnetic stimulation (rTMS) may help to modulate DMN plasticity. Still, stimulation effects substantially vary across studies and individuals. Higher global connectivity of the left frontal cortex, a substitute for reserve capacity, may contribute to the heterogeneous physiological effects of neuro-navigated rTMS. This study investigated the effects of left angular gyrus-navigated rTMS on DMN connectivity in different reserve capacity participants. Global left frontal cortex (gLFC) connectivity, was computed through resting-state fMRI correlations. Thirty-one prodromal AD patients were divided into low connection group (LCG) and high connection group (HCG) by the median of gLFC connectivity. Distinct reserve capacity impacts on DMN in response to rTMS were identified in these two groups. Then, brain-behavior relationships were examined. gLFC connectivity within a certain range is directly proportional to cognitive reserve ability (i.e ., LCG), and the effectiveness of functional connectivity beyond this range decreases (i.e, HCG). Moreover, LCG exhibited increased DMN connectivity and significantly positive memory improvements, while HCG showed a contrary connectivity decline and maintained or slightly improved their cognitive function after neuro-navigated rTMS treatment. The prodromal AD patients with the distinct reserve capacity may benefit differently from left angular gyrus-navigated rTMS, which may lead to increasing attention in defining personalized medicine approach of AD.

Note:
Funding Information: This work was supported partly by grants from the National Natural Science Foundation of China (No. 82071186; 81822013).

Conflict of Interests: The authors declare no competing interests.

Ethical Approval: We have got the informed consent written by all subjects. The Ethics Committee of Nanjing Drum Tower Hospital has agreed this study.

Keywords: Alzheimer's disease, reserve capacity, neuro-navigated, repetitive transcranial magnetic stimulation, default-mode network