Transcranial Magnetic Stimulation Induces White Matter Microstructure Alterations in Patients with Mild Cognitive Impairment.

Abstract

Introduction: The aim of this study was to investigate whether exposure to noninvasive brain stimulation with high-frequency repetitive transcranial magnetic stimulation (rTMS) applied over the left dorsolateral prefrontal cortex (DLPFC) can improve memory and regulate white matter (WM) microstructure.

Methods: Twenty-two mild cognitive impairment participants who were randomly assigned to the real and the sham groups received 10 sessions and sham-controlled 10 Hz rTMS over the DLPFC. All patients underwent cognitive assessments and diffusion tensor imaging scans before and after the intervention. Brain regions that showed significant differences in fractional anisotropy (FA) values were selected as the regions of interest to calculate the correlation with cognitive scores.

Results: In the real group, FA values in the left middle frontal gyrus and bilateral parahippocampal gyrus increased and in the right superior frontal gyrus decreased. No significant FA change was detected in the sham group. Furthermore, the FA value of the left middle frontal gyrus was positively correlated with Boston Naming Test (BNT) scores. The change of FA value in the right superior frontal gyrus was positively correlated with the change in the Trail Making Test (TMT-B) score.

Conclusions: This study provides new evidence for rTMS to regulate the abnormal WM microstructure in some special regions and causally ameliorate cognitive performance in MCI, which may be the underlying neural mechanism of intervention.