Would transcranial direct current stimulation (tDCS) enhance the effects of working memory training in older adults with mild neurocognitive disorder due to Alzheimer's disease: study protocol for a randomized controlled trial.

Calvin P W Cheng,Lin Shi,Arthur D P Mak,Linda Chiu-Wa Lam,Defeng Wang,Sandra S M Chan,Sheung Tak Cheng,Wai Chi Chan

doi:10.1186/s13063-015-0999-0

Abstract

BackgroundThere has been longstanding interesting in cognitive training for older adults with cognitive impairment. In this study, we will investigate the effects of working memory training, and explore augmentation strategies that could possibly consolidate the effects in older adults with mild neurocognitive disorder. Transcranial direct current stimulation (tDCS) has been demonstrated to affect the neuronal excitability and reported to enhance memory performance. As tDCS may also modulate cognitive function through changes in neuroplastic response, it would be adopted as an augmentation strategy for working memory training in the present study.Methods/DesignThis is a 4-week intervention double-blind randomized controlled trial (RCT) of tDCS. Chinese older adults (aged 60 to 90 years) with mild neurocognitive disorder due to Alzheimer’s disease (DSM-5 criteria) would be randomized into a 4-week intervention of either tDCS-working memory (DCS-WM), tDCS-control cognitive training (DCS-CC), and sham tDCS-working memory (WM-CD) groups. The primary outcome would be working memory test – the n-back task performance and the Chinese version of the Alzheimer’s Disease Assessment Scale – Cognitive Subscale (ADAS-Cog). Secondary outcomes would be test performance of specific cognitive domains and mood. Intention-to-treat analysis would be carried out. Changes of efficacy indicators with time and intervention would be tested with mixed effect models.DiscussionThis study adopts the theory of neuroplasticity to evaluate the potential cognitive benefits of non-invasive electrical brain stimulation, working memory training and dual stimulation in older adults at risk of cognitive decline. It would also examine the tolerability, program adherence and adverse effects of this novel intervention. Information would be helpful for further research of dementia prevention studies.Trial registrationChiCTR-TRC-14005036 Date of registration: 31 July 2014.

Highlights

There has been longstanding interesting in cognitive training for older adults with cognitive impairment
This study adopts the theory of neuroplasticity to evaluate the potential cognitive benefits of non-invasive electrical brain stimulation, working memory training and dual stimulation in older adults at risk of cognitive decline
Information would be helpful for further research of dementia prevention studies

Summary

Discussion

The present study aims to examine the cognitive effects of working memory training in older adults with MND-AD, and to evaluate whether the effects would be transferrable to other cognitive domains. We hope to examine if adjuvant electrical stimulation would consolidate the brain response through manipulation of neuroplasticity. This would provide directions for research in the neurophysiological basis of synergistic brain stimulation of different modalities. The current proposal would serve as a Phase 2 non- pharmacological intervention It would examine the potential efficacy of cognitive training, electrical brain stimulation, and dual mental and electrical brain stimulation. If the findings suggest potential positive benefits, and with low risks, the proposed intervention would provide a solid basis for further evaluation by further Phase 3 clinical trials with implementation in clinical settings for dementia prevention.

Background

Findings