Temporal cortex direct current stimulation enhances performance on a visual recognition memory task in Alzheimer disease
- 1Center for Health and Biological Sciences, Mackenzie Presbyterian University, São Paulo, Brazil
- 2Estância Vale Verde, Guararema, Brazil
- 3Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
- Dr P S Boggio, Center for Health and Biological Sciences, Mackenzie Presbyterian University, Rua da Consolação, 930, prédio 38, CEP 01302–907, São Paulo, SP, Brazil;
- Received 7 December 2007
- Revised 20 May 2008
- Accepted 17 June 2008
- Published Online First 31 October 2008
Several studies have reported that transcranial direct current stimulation (tDCS), a non-invasive method of neuromodulation, enhances some aspects of working memory in healthy and Parkinson disease subjects. The aim of this study was to investigate the impact of anodal tDCS on recognition memory, working memory and selective attention in Alzheimer disease (AD). Ten patients with diagnosis of AD received three sessions of anodal tDCS (left dorsolateral prefrontal cortex, left temporal cortex and sham stimulation) with an intensity of 2 mA for 30 min. Sessions were performed in different days in a randomised order. The following tests were assessed during stimulation: Stroop, Digit Span and a Visual Recognition Memory task (VRM). The results showed a significant effect of stimulation condition on VRM (p = 0.0085), and post hoc analysis showed an improvement after temporal (p = 0.01) and prefrontal (p = 0.01) tDCS as compared with sham stimulation. There were no significant changes in attention as indexed by Stroop task performance. As far as is known, this is the first trial showing that tDCS can enhance a component of recognition memory. The potential mechanisms of action and the implications of these results are discussed.
Competing interests: None.
Funding: This work was supported by a grant from CNPq (401701/2007-7) to PSB. LPK was supported by a research grant from CNPq, São Paulo, Brazil (PIBIC—CNPq). DCSM was supported by a research grant from Mackenzie, São Paulo, Brazil (PIBIC—Mackenzie). ECM is supported by a CNPq grant (305356/2005-4). FF is supported by an AHA grant (0735535T).
Ethics approval: Ethics approval was provided by the Institutional Ethics Committee from Mackenzie Presbyterian University, Brazil.
Patient consent: Obtained.