Neuro-navigated rTMS Targeting Left Angular Gyrus Promotes White-Gray Matter Remodelling to Improve Cognitive Function in Amnestic Mild Cognitive Impairment Patients: Evidence for Early Alzheimer's Intervention.

INTRODUCTION

Repetitive Transcranial Magnetic Stimulation (rTMS), a non-invasive neuromodulation technique, has been increasingly applied in early intervention for amnestic Mild Cognitive Impairment (aMCI). However, the mechanism of changes in brain structure after rTMS treatment remains unclear.

METHODS

A total of 54 aMCI patients received neuro-navigation rTMS targeting the left angular gyrus for 4 weeks (rTMS group: n=28; sham group: n=26). All participants received multimodal MRI and cognitive assessments before and after rTMS. A white matter network was constructed, and Local Diffusion Homogeneity (LDH) was calculated to analyse white matter differences. Surface- based morphometry was used to detect cortical changes. In addition, the correlation between these structural alterations and improved cognitive function was analysed.

RESULTS

After rTMS, general cognitive function and episodic memory of aMCI patients significantly improved. Assortativity improved (P=0.039) while hierarchy decreased (P=0.036). Lower LDH was detected in the right hippocampus cingulum fasciculus, left inferior longitudinal fasciculus, right inferior/superior cerebellar peduncle, and right cingulum gyrus. The sulcus depth of the left medial orbitofrontal cortex, left superior frontal/parietal cortex, left middle/inferior temporal cortex, and right lateral occipital cortex was decreased. Improved general cognition was negatively correlated with decreased sulcus depth in left inferior temporal cortex (R=-0.585, P=0.001) and left superior parietal cortex (R=-0.447, P=0.017). Improved memory was negatively correlated with altered LDH in the right inferior cerebellar peduncle (R=-0.427, P=0.037).

DISCUSSION: Our study shows that neuro-navigated rTMS targeting the left angular gyrus can improve cognitive function and mood symptoms in aMCI patients by impacting brain structures, offering new biological evidence for its potential as an early AD intervention.

CONCLUSION

Neuro-navigated rTMS targeting the left angular gyrus improves aMCI cognition, linked to specific brain structural changes, supporting its early intervention value.