An electric field modeling study with meta-analysis to understand the antidepressant effects of transcranial direct current stimulation (tDCS)

Author(s)

Lais B. Razza ; Miles Wischnewski ^[2] ; Paulo Suen ^[3] ; Stefanie De Smet ; Pedro Henrique Rodrigues da Silva ^[5] ; Beatriz Catoira ; André R. Brunoni ; Marie-Anne Vanderhasselt

• Document type: Journal article
• Source: Revista Brasileira de Psiquiatria; v. 45, n. 6, p. 518-529, 2024-02-12.

Abstract

Objective: Transcranial direct current stimulation (tDCS) has mixed effects for major depressive disorder (MDD) symptoms, partially owing to large inter-experimental variability in tDCS protocols and their correlated induced electric fields (E-fields). We investigated whether the E-field strength of distinct tDCS parameters was associated with antidepressant effect. Methods: A meta-analysis was performed with placebo-controlled clinical trials of tDCS enrolling MDD patients. PubMed, EMBASE, and Web of Science were searched from inception to March 10, 2023. Effect sizes of tDCS protocols were correlated with E-field simulations (SimNIBS) of brain regions of interest (bilateral dorsolateral prefrontal cortex [DLPFC] and bilateral subgenual anterior cingulate cortex [sgACC]). Moderators of tDCS responses were also investigated. Results: A total of 20 studies were included (21 datasets, 1,008 patients), using 11 distinct tDCS protocols. Results revealed a moderate effect for MDD (g = 0.41, 95%CI 0.18-0.64), while cathode position and treatment strategy were found to be moderators of response. A negative association between effect size and tDCS-induced E-field magnitude was seen, with stronger E-fields in the right frontal and medial parts of the DLPFC (targeted by the cathode) leading to smaller effects. No association was found for the left DLPFC and the bilateral sgACC. An optimized tDCS protocol is proposed. Conclusions: Our results highlight the need for a standardized tDCS protocol in MDD clinical trials. Registration number: PROSPERO CRD42022296246. (AU)

• FAPESP's process: 22/03266-0 - Investigation of neuroimaging assessments and current flow modeling as target engagement and predictor biomarkers of convulsive therapies
• Grantee: Pedro Henrique Rodrigues da Silva
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 18/10861-7 - A Phase-I bilateral project using a sham-controlled, factorial design of transcranial direct current stimulation and theta-burst stimulation to investigate the effects on multimodal assessments of prefrontal cortex functioning
• Grantee: Andre Russowsky Brunoni
• Support Opportunities: Regular Research Grants
• FAPESP's process: 19/06009-6 - Non-implantable neuromodulation therapies: a perspective for the depressed brain
• Grantee: Andre Russowsky Brunoni
• Support Opportunities: Research Projects - Thematic Grants