Song Jianmeng, Torres-Carmona Edgardo, Abdolizadeh Ali, Kambari Yasaman, Amaev Aron, Ueno Fumihiko, Koizumi Teruki, Remington Gary, Deluca Vincenzo, Graff-Guerrero Ariel, Gerretsen Philip
Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health (CAMH), Toronto, ON, Canada.
Institute of Medical Science, University of Toronto, Toronto, ON, Canada.
Brain Topogr. 2025 Aug 28;38(5):60. doi: 10.1007/s10548-025-01140-z.
Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation that delivers a constant low electric current through electrodes placed on the scalp. A significant amount of research has explored the clinical potential of tDCS in psychiatric disorders. However, the mechanism of tDCS' behavioural effects remains largely unknown. Cerebral blood flow (CBF) is a surrogate marker of neural activity and has been used as an index of brain dysfunction in various psychiatric disorders. Studies have shown that single-session tDCS can modulate regional CBF in humans, however, these results as yet have not been systematically reviewed. The primary objective of this systematic review and meta-analysis was to evaluate the immediate effects of single-session tDCS on regional CBF. A literature search of English language publications in humans was conducted through Ovid database using Medline, Embase, and PsycINFO (last search in August 2023). The following search terms were used: (transcranial direct current stimulation or tDCS) and (cerebral blood flow or cerebrovascular circulation). Studies that reported sufficient data for calculating the pooled effect size of regional CBF change from baseline to immediately post-tDCS were included. The analysis was separated by anodal, cathodal, and sham stimulation. The search identified 188 English language publications. Four papers were deemed eligible for the analysis, while two of them were based on the same sample. Studies varied in terms of tDCS montage, stimulation protocol, and population studied. The meta-analysis found a decrease in regional CBF following single-session cathodal tDCS stimulation (n = 34) and no effect of single-session anodal (n = 58) or sham tDCS (n = 52). However, increased regional CBF following anodal tDCS was significantly associated with older age, sex (% male), and higher current intensity and density based on the results of exploratory moderator and subgroup analyses. The results of this meta-analysis contribute to the growing body of knowledge investigating the cerebral mechanisms of tDCS. Given the limited number and heterogeneity of available studies, further investigation into the effects of single- and multi-session tDCS on regional CBF in clinical or healthy participant samples is warranted to gain a better mechanistic understanding of tDCS' therapeutic effects.
经颅直流电刺激（tDCS）是一种非侵入性脑刺激形式，通过放置在头皮上的电极传递恒定的低电流。大量研究探索了tDCS在精神疾病中的临床潜力。然而，tDCS行为效应的机制在很大程度上仍然未知。脑血流量（CBF）是神经活动的替代指标，已被用作各种精神疾病中脑功能障碍的指标。研究表明，单次tDCS可以调节人类的局部CBF，然而，这些结果尚未得到系统的综述。本系统综述和荟萃分析的主要目的是评估单次tDCS对局部CBF的即时影响。通过Ovid数据库使用Medline、Embase和PsycINFO（最后一次搜索于2023年8月）对人类英文出版物进行文献检索。使用了以下搜索词：（经颅直流电刺激或tDCS）和（脑血流量或脑血管循环）。纳入了报告了足够数据以计算从基线到tDCS后即刻局部CBF变化的合并效应大小的研究。分析按阳极、阴极和假刺激进行分类。搜索共识别出188篇英文出版物。四篇论文被认为符合分析条件，其中两篇基于相同样本。研究在tDCS电极放置方式、刺激方案和研究人群方面存在差异。荟萃分析发现，单次阴极tDCS刺激后（n = 34）局部CBF下降，单次阳极（n = 58）或假tDCS（n = 52）无影响。然而，根据探索性调节因素和亚组分析结果，阳极tDCS后局部CBF增加与年龄较大、性别（男性百分比）以及较高的电流强度和密度显著相关。该荟萃分析的结果有助于增加对tDCS脑机制的认识。鉴于现有研究数量有限且存在异质性，有必要进一步研究单次和多次tDCS对临床或健康参与者样本中局部CBF的影响，以更好地从机制上理解tDCS的治疗效果。
