title: A double-blind randomized clinical trial on the efficacy of cortical direct current stimulation for the treatment of Alzheimer's disease.
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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Neurology, Assiut University Hospital , Assiut , Egypt.
authors.forename: Eman M
authors.initials: EM
authors.lastname: Khedr
authors.affiliation: Department of Neurology, Assiut University Hospital , Assiut , Egypt.
authors.forename: Nageh F El
authors.initials: NF
authors.lastname: Gamal
authors.affiliation: Department of Neurology, Assiut University Hospital , Assiut , Egypt.
authors.forename: Noha Abo
authors.initials: NA
authors.lastname: El-Fetoh
authors.affiliation: Department of Neurology, Assiut University Hospital , Assiut , Egypt.
authors.forename: Hosam
authors.initials: H
authors.lastname: Khalifa
authors.affiliation: Department of Neurology, Assiut University Hospital , Assiut , Egypt.
authors.forename: Elham M
authors.initials: EM
authors.lastname: Ahmed
authors.affiliation: Department of Neurology, Assiut University Hospital , Assiut , Egypt.
authors.forename: Anwer M
authors.initials: AM
authors.lastname: Ali
authors.affiliation: Department of Neurology, Assiut University Hospital , Assiut , Egypt.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Noaman
authors.affiliation: Department of Neurology, Assiut University Hospital , Assiut , Egypt.
authors.forename: Ahmed Abd
authors.initials: AA
authors.lastname: El-Baki
authors.affiliation: Department of Prevention and Health Psychology, University of Riedlingen , Riedlingen , Germany ; Department of Psychiatry and Psychotherapy, University Clinic Tübingen , Tübingen , Germany.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Karim
keywords: Alzheimer’s disease; Wechsler Adult Intelligent Scale; auditory event-related potentials (P300); cognitive function; cortical excitability; cortical plasticity; transcranial direct current stimulation