Noninvasive brain stimulation in psychiatric disorders: a primer

Abstract

Objective:Noninvasive brain stimulation (NIBS) techniques, such as transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS), are increasingly being used to treat mental disorders, particularly major depression. The aim of this comprehensive review is to summarize the main advances, limitations, and perspectives of the field.Methods:We searched PubMed and other databases from inception to July 2017 for articles, particularly systematic reviews and meta-analyses, evaluating the use of NIBS in psychiatric disorders.Results:We reviewed the mechanisms of action, safety, tolerability, efficacy, and relevant clinical parameters of NIBS. Repetitive TMS is already an established technique for the treatment of depression, and there is theoretically room for further methodological development towards a high-end therapeutic intervention. In contrast, tDCS is a technically easier method and therefore potentially suitable for wider clinical use. However the evidence of its antidepressant efficacy is less sound, and a recent study found tDCS to be inferior to antidepressant pharmacotherapy. Clinical trials using rTMS for other mental disorders produced mixed findings, whereas tDCS use has not been sufficiently appraised.Conclusion:The most promising results of NIBS have been obtained for depression. These techniques excel in safety and tolerability, although their efficacy still warrants improvement.

Precision non-implantable neuromodulation therapies: a perspective for the depressed brain

“…39 Notably, anodal tDCS and high-frequency rTMS usually increase cortical excitability, although the net effect is also influenced by the underlying cortical activity. 15 This rationale has been supported to some extent by neuroimaging studies in depressed patients receiving rTMS 21,40 and by recent validation studies. 41 In turn, ECT and MST -both of which are performed in a controlled environment, under general anesthesiainduce seizures via depolarization of neuronal networks.…”

“…They do not require surgery, are less invasive, and involve less risk than implantable techniques, such as deep brain stimulation and vagus nerve stimulation. 22 They can be categorized into subconvulsive and convulsive modalities, the former also often described as ''non-invasive brain stimulation'' (NIBS), which include TMS and tDCS, 15 while the convulsive modalities include ECT and MST. 23 Compared to the convulsive modalities, NIBS does not require sedation or anesthesia, and presents excellent safety and tolerability profiles.…”

“…25,26,28 The most common side effects include itching and tingling at the scalp application sites. 15 Skin burns are uncommon, and the risk can be further reduced with proper soaking of the electrodes, customized sponges, and adequate use of saline solution. 71 Due to its portability and ease of use, tDCS has been investigated as an augmentative and substitute treatment for antidepressant medications.…”

“…6 Non-implantable neuromodulation (NIN) interventions, such as transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), electroconvulsive therapy (ECT), and magnetic seizure therapy (MST), are non-pharmacological, non-psychotherapeutic interventions with distinct efficacy, safety, tolerability, and availability profiles. [14][15][16] These techniques have been developed over multiple decades to bridge the efficacy and safety gaps of traditional antidepressant treatments, with concrete results. 17 Nevertheless, major caveats remain, such as limited efficacy and significant adverse effects.…”

Transcranial direct current stimulation (tDCS) for preventing major depressive disorder relapse: Results of a 6-month follow-up

“…For these reasons, the technique is being intensively investigated in psychiatry disorders, notably for MDD (for a review, see Brunoni et al. ()). Recent clinical trials in depression have typically administered tDCS at between 1 and 2.5 mA current intensity, 10–30 min per session, either once or twice daily over several weeks (Brunoni et al., ).…”