38. The effect of repetitive transcranial magnetic stimulation on attention and psychomotor speed in patients with mild cognitive impairment and early Alzheimer’s disease

Abstract

Introduction Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive tool to study and modulate cortical plasticity and brain processes in healthy and diseased brain. Study objectives The aim of this study was to investigate the effects of one session of high-frequency rTMS on cognitive functions in patients with mild cognitive impairment (MCI) and early stages of Alzheimer's disease (AD). Based on our pilot study results (Eliasova et al., 2014) we were particularly interested in modulating attention and psychomotor speed domain by applying rTMS over the right inferior frontal gyrus (IFG) and the right superior temporal gyrus (STG). Methods Altogether 20 right-handed patients (11 women, 9 men; age 73.0±6.9years; 12 mild AD, 8 MCI) participated in the placebo-controlled study. Each patient received 3 sessions of 10Hz rTMS applied over the IFG, STG and vertex (a control stimulation site). A frameless stereotaxy was used for the coil navigation. A total of 2250 stimuli were delivered per session at 90% intensity of resting motor threshold. The order of stimulation sites was randomized. The Trail making test (TMT) and the Stroop test (ST) were used to evaluate attention and psychomotor speed prior to and immediately after each session. The Wilcoxon paired test and Linear mixed models were used for data analyses. Results rTMS of both IFG and STG induced significant improvement in the Word part of the ST (Wilcoxon paired test; p =0.023 and 0.033, respectively), while the IFG stimulation induced additional enhancement in the TMT A and B (Wilcoxon paired test; p =0.002 and 0.005, respectively). When controlling for placebo effects improvement in the ST (Word part) remained significant after both IFG and STG stimulation. Conclusions rTMS of the right IFG and the right STG enhanced psychomotor speed and attention in patients with early stages of AD and may thus have a therapeutic potential that has to be further tested using a multiple-sessions rTMS protocol.