Preclinical Evidence for the Mechanisms of Transcranial Direct Current Stimulation in the Treatment of Psychiatric Disorders; A Systematic Review

Abstract

Backgrounds. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique for the treatment of several psychiatric disorders, eg, mood disorders and schizophrenia. Although tDCS provides a promising approach, its neurobiological mechanisms remain to be explored. Objectives. To provide a systematic review of animal studies, and consider how tDCS ameliorates psychiatric conditions. Methods. A literature search was conducted on English articles identified by PubMed. We defined the inclusion criteria as follows: (1) articles published from the original data; (2) experimental studies in animals; (3) studies delivering direct current transcranially, ie, positioning electrodes onto the skull. Results. 138 papers met the inclusion criteria. 62 papers deal with model animals without any dysfunctions, followed by 52 papers for neurological disorder models, and 12 for psychiatric disorder models. The most studied category of functional areas is neurocognition, followed by motor functions and pain. These studies overall suggest the role for the late long-term potentiation (LTP) via anodal stimulation in the therapeutic effects of tDCS. Conclusions. tDCS Anodal stimulation may provide a novel therapeutic strategy to particularly enhance neurocognition in psychiatric disorders. Its mechanisms are likely to involve facilitation of the late LTP.

Mathematical Model Insights into EEG Origin under Transcranial Direct Current Stimulation (tDCS) in the Context of Psychosis

“…Long duration a-tDCS stimulation is known to yield cognitive enhancement [ 69 ], induces LTP [ 10 ] and may serve an important role in clinical psychiatry in the future [ 15 , 16 , 17 , 70 ]. To describe the involved plasticity, we have developed a model that relates tDCS duration and plasticity effect.…”

“…However, we argue that we are interested in the general underlying neural mechanism of tDCS and its impact in psychosis valid for unspecific mammalian subjects. Since tDCS in different subjects of different mammalian species trigger similar EEG neural responses [ 6 , 11 , 70 , 71 ], it is important to choose a general rather simplistic population model that captures essential neural features and hence is independent of specific model choices. Here, the essential features are the nonlinear transfer function between synaptic input and population firing rate, realistic synaptic response models and a brain network topology of realistic polarity, i.e., with realistic excitation and inhibition.…”

Transcranial Direct Current Stimulation on the Left Superior Temporal Sulcus Improves Social Cognition in Schizophrenia: An Open-Label Study

“…Improvements of cognitive symptoms by multisession tDCS may be mediated through several mechanisms, including long-term potentiation (LTP), continuous enhancement of signal transduction between neurons, and related neural events ( 14 , 34 , 35 ). Specifically, LTP has been shown to enhance the synthesis of various proteins, e.g., neurotransmitter synthases, receptors, ion channels, and intracellular signal proteins, thus facilitating the efficiency of neurotransmissions in cortical circuits ( 14 , 34 , 35 ). Moreover, improvement in cognitive function becomes more apparent a few weeks after administration of tDCS ( 36 ), suggesting that tDCS may induce LTP.…”

Transcranial direct current stimulation in the treatment of anxiety and depression in patients with oral cancer during perioperative period

“…[11][12][13][14] Transcranial direct current stimulation (tDCS) is a safe, noninvasive, and painless treatment technique. [15][16][17][18] It applies low-intensity direct current using scalp electrodes overlying targeted cerebral cortical areas through the scalp. [15][16][17] Although a variety of studies have reported tDCS for anxiety and depression relief, [19][20][21][22][23][24][25] there are still insufficient data to investigate the efficacy of tDCS in the treatment of anxiety and depression in patients with OC during PPP.…”