Abstract
Aims: The results of our pilot study suggested that one session of high frequency rTMS applied over the left dorsolateral prefrontal cortex (DLPFC) might induce measurable positive effects on executive functioning in patients with mild cognitive impairment of the vascular type without dementia (MCI-V). The aims of the current study were to replicate the results of our pilot study using a frameless stereotaxy as opposed to the standard and routinely used procedure. We also studied the effects of low frequency rTMS. Patients and method: Seven patients with MCI-V participated in a randomized, controlled, blind study with a crossover design. Each patient received 10 Hz and 1 Hz stimulation over the left DLPFC (an active stimulation site) or the motor cortex (MC; a control stimulation site). Frameless stereotaxy was used to target the DLPFC. The order of sites and frequencies was randomized. A short battery of neuropsychological tests was performed to evaluate executive function, working memory, and psychomotor speed. Results: One session of both high and low frequency rTMS was well tolerated and safe in terms of the cognitive after-effects in patients with MCI-V. We did not observe any significant frequency dependent or stimulation site-dependent cognitive effects of rTMS. Conclusion: We found neither positive nor negative significant effect of either low or high frequency rTMS applied over the DLPFC or the MC, while a mild positive site-specific effect of 10 Hz rTMS was observed in our pilot study on the Stroop interference results. These results suggested that MCI-V is a heterogeneous and poorly defined entity and, thus, rTMS might be useful in a subpopulation of this group of patients.
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