A double-blind randomized clinical trial on the efficacy of cortical direct current stimulation for the treatment of Alzheimer's disease.

Eman M Khedr,Anwer M Ali,Noha Abo El-Fetoh,Mostafa Noaman,Elham M Ahmed,Nageh F El Gamal,Ahmed Abd El-Baki,Hosam Khalifa,Ahmed A Karim

doi:10.3389/fnagi.2014.00275

Eman M Khedr, Anwer M Ali + Show 7 more

Open Access

https://doi.org/10.3389/fnagi.2014.00275

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Abstract

Background: The purpose of this study was to investigate the long-term efficacy of transcranial direct current stimulation (tDCS) in the neurorehabilitation of Alzheimer’s disease (AD).Methods: Thirty-four AD patients were randomly assigned to three groups: anodal, cathodal, and sham tDCS. Stimulation was applied over the left dorsolateral prefrontal cortex for 25 min at 2 mA, daily for 10 days. Each patient was submitted to the following psychometric assessments: mini-mental state examination (MMSE) and Wechsler adult intelligence scale-third edition at base line, at the end of the 10th sessions and then at 1 and 2 months after the end of the sessions. Motor cortical excitability and the P300 event-related potential were assessed at baseline and after the last tDCS session.Results: Significant treatment group × time interactions were observed for the MMSE and performance IQ of the WAIS. Post hoc comparisons showed that both anodal and cathodal tDCS (ctDCS) improved MMSE in contrast to sham tDCS. Whereas, this was only true for ctDCS in the performance IQ. Remarkably, tDCS also reduced the P300 latency, but had no effect on motor cortex excitability.Conclusion: Our findings reveal that repeated sessions of tDCS could not only improve cognitive function but also reduce the P300 latency, which is known to be pathologically increased in AD.

Highlights

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder (Alzheimer’s Association et al, 2011) that causes deficits in many cognitive activities such as memory, language, and executive function including working memory, cognitive flexibility (Monsell, 2003), planning (Chan et al, 2008), and abstract reasoning (Bruce and Jeffrey, 2007)
Post hoc comparisons showed that both anodal and cathodal transcranial direct current stimulation (tDCS) improved mini-mental state examination (MMSE) in contrast to sham tDCS
This was only true for cathodal tDCS (ctDCS) in the performance IQ

Summary

Introduction

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder (Alzheimer’s Association et al, 2011) that causes deficits in many cognitive activities such as memory, language, and executive function including working memory, cognitive flexibility (Monsell, 2003), planning (Chan et al, 2008), and abstract reasoning (Bruce and Jeffrey, 2007). Given the limited efficacy of pharmacological treatments (Birks, 2006), non-pharmacological approaches in AD are of great interest. One approach that has been used in several centers is repetitive transcranial magnetic stimulation (rTMS), a noninvasive form of brain stimulation that produces after-effects on cortical excitability thought to involve forms of long-term potentiation/depression (LTP/LTD) at central synapses. RTMS has been targeted over the dorsolateral prefrontal cortex (DLPFC), given its recognized role in executive function, and has been reported to improve memory, language, and executive functions for several weeks after a period of treatment (Cotelli et al, 2006, 2008, 2011; Ahmed et al, 2012). The purpose of this study was to investigate the long-term efficacy of transcranial direct current stimulation (tDCS) in the neurorehabilitation of Alzheimer’s disease (AD)

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