Potential of Transcranial Direct Current Stimulation in Alzheimer's Disease: Optimizing Trials Toward Clinical Use

Abstract

Transcranial direct current stimulation (tDCS) is a safe and well-tolerated noninvasive method for stimulating the brain that is rapidly developing into a treatment method for various neurological and psychiatric conditions. In particular, there is growing evidence of a therapeutic role for tDCS in ameliorating or delaying the cognitive decline in Alzheimer's disease (AD). We provide a brief overview of the current development and application status of tDCS as a nonpharmacological therapeutic method for AD and mild cognitive impairment (MCI), summarize the levels of evidence, and identify the improvements needed for clinical applications. We also suggest future directions for large-scale controlled clinical trials of tDCS in AD and MCI, and emphasize the necessity of identifying the mechanistic targets to facilitate clinical applications.

Keywords: Alzheimer disease; clinical trial; transcranial direct current stimulation.

Fig. 1. Transcranial direct current stimulation (tDCS) equipment, working principle, and modeling of the electric field distribution. (1) tDCS device: programmable session type (active or sham), stimulation duration, and current intensity. (2) Dorsolateral prefrontal cortex (DLPFC) electrode montage (left to right, F3-F4 according to the international 10-20 system). (3) Sponge electrodes.