rTMS regulates homotopic functional connectivity in the SCD and MCI patients

Honglin Ge; ShanShan Chen; Zigang Che; Huimin Wu; Xinyi Yang; Meizhao Qiao; Lei Chi; Jia Fan; Yeming Zhong; Caiyun Zou; Xingjian Lin; Jiu Chen

doi:10.3389/fnins.2023.1301926

rTMS regulates homotopic functional connectivity in the SCD and MCI patients

Front Neurosci. 2023 Nov 23:17:1301926. doi: 10.3389/fnins.2023.1301926. eCollection 2023.

Authors

Honglin Ge^#¹, ShanShan Chen^#², Zigang Che³, Huimin Wu², Xinyi Yang², Meizhao Qiao², Lei Chi², Jia Fan⁴, Yeming Zhong³, Caiyun Zou³, Xingjian Lin², Jiu Chen^{1

5}

Affiliations

¹ Department of Neurosurgery, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.
² Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.
³ Department of Radiology, Nanjing Tongren Hospital, School of Medicine, Southeast University, Nanjing, China.
⁴ Department of Human Biology, University of Cape Town Faculty of Health Sciences, Cape Town, South Africa.
⁵ Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China.

^# Contributed equally.

Abstract

Objective: Impaired interhemispheric connectivity and corpus callosum atrophy have been linked to cognitive impairment in Alzheimer's disease (AD). Existing evidence indicates that repetitive transcranial magnetic stimulation (rTMS) targeting the bilateral precuneus may enhance cognitive function in AD. This study aims to investigate the effects of precuneus rTMS on cognitive function, as well as alterations in interhemispheric functional connectivity (FC) and its structural basis in patients with subjective cognitive decline (SCD) and mild cognitive impairment (MCI).

Methods: A total of 14 patients with SCD and 16 patients with MCI were enrolled in this study and received 10 Hz rTMS intervention on the bilateral precuneus for 2 weeks. Neurocognitive scales, structural and functional magnetic resonance imaging were collected at enrollment and after the rTMS intervention. Interhemispheric FC was assessed using mirror homotopic functional connectivity (VMHC), while the structural equation modeling (SEM) was employed to analyze the relationship between corpus callosum volume, interhemispheric connectivity, and cognitive function after rTMS intervention.

Results: The precuneus rTMS not only enhanced episodic memory in SCD, but also improved multiple cognitive domains in MCI. Post-rTMS intervention, decreased VMHC values in the lingual cortex, middle occipital gyrus, putamen, and fusiform gyrus were observed in SCD, and an increased VMHC value in the postcentral gyrus along with reduced VMHC value in the cerebellum and putamen in MCI. After intervention, more brain regions show decreased FC in SCD and MCI patients, suggesting that precuneus rTMS may protect cerebral cortical plasticity by reducing excessive functional compensation, and thus improve cognitive function. The SEM indicated that the corpus callosum serves as the structural foundation for rTMS regulation of interhemispheric FC to further improve cognitive function.

Conclusion: 10 Hz rTMS in the bilateral precuneus could be a promising strategy to improve cognitive function in patients with SCD and MCI. Our study implies that improvements in cognition brought about by precuneus rTMS may result from the remodeling of interhemispheric FC, with the corpus callosum possibly acting as the anatomical basis for functional modulation.

Keywords: VMHC; functional magnetic resonance imaging; mild cognitive impairment; repetitive transcranial magnetic stimulation; subjective cognitive decline.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study was supported by Clinical Research Special Funded Project of Nanjing Drum Tower Hospital (No. 2023-LCYJ-MS-11), Special Funded Project of Nanjing Drum Tower Hospital (No. RC2022-023), Development Plan (Social Development) Project of Jiangsu Province (No. BE2022679), Natural Science Foundation of Jiangsu Basic Research Program (No. BK20221185).