Cognitive Improvement Via Left Angular Gyrus-Navigated Repetitive Transcranial Magnetic Stimulation Inducing the Neuroplasticity of Thalamic System in Alzheimer’s Disease Spectrum Patients

Abstract

Background: Stimulating superficial brain regions highly associated with the hippocampus by repetitive transcranial magnetic stimulation (rTMS) may improve memory of Alzheimer disease (AD) spectrum patients. Methods: We recruited 26 mild cognitive impairment (MCI) and AD patients. All the patients were stimulated to the left angular gyrus, which was confirmed a strong link to the hippocampus through neuroimaging studies, by the neuro-navigated rTMS for four weeks. Automated fiber quantification (AFQ) using diffusion tensor imaging (DTI) metrics and graph theory analysis on functional network were employed to detect the neuroplasticity of brain networks. Results: After neuro-navigated rTMS intervention, the episodic memory and language function of patients were significantly improved. Increased white matter integrity of right anterior thalamic radiation among MCI patients, while decreased functional network properties of thalamus subregions were observed. It is worth noting that the improvement of cognition was associated with the neuroplasticity of thalamic systemConclusions: We speculated that the rTMS intervention targeting left angular gyrus may be served as a strategy to improve cognitive impairment in AD spectrum patients, supporting by the neuroplasticity of thalamic system, especially in the early disease process at the stage of MCI.