Repetitive Transcranial Magnetic Stimulation Improves Hippocampal N-Acetlaspartate Levels and Visual Memory Scores in Alzheimer's Disease

Abstract

The latest research into the pathophysiology of Alzheimer's Disease (AD) has included several cognitive deficits related to hippocampal functioning. However, current clinical research fails to consider the full extent of the heterogeneous cognitive spectrum of AD, resulting in a lack of the specific methods required to draw definitive diagnostic and therapeutic conclusions. This also includes in-vivo metabolic measurements for tailoring the diagnostic and therapeutic regimens in humans with AD. Magnetic resonance spectroscopy and repetitive transcranial magnetic stimulation (rTMS) are two novel diagnostic and therapeutic approaches that must be modified to treat AD. In the present study, we aimed to investigate the underlying therapeutic role of rTMS in humans with AD by evaluating the in-vivo hippocampal metabolites before and after rTMS treatment. Based on the data obtained using the fMRI data in our previous study and on the references reported in the literature, in the present study, we decided to use hippocampal NAA data after rTMS stimulation and found a significant increase in NAA levels. To the best of our knowledge, no other study has evaluated the effect of rTMS on hippocampal metabolites in humans with AD.

Keywords: AD; MRS; NAA; hippocampus; rTMS.

Figure 1

Axial T1 weighted magnetic resonance image from an AD subject illustrating the location of single voxel H-MRS voxels in the left hippocampus.