Transcranial direct current stimulation (tDCS) is a promising method for altering cortical excitability with clinical implications. It has been increasingly used in neurodevelopmental disorders, especially attention-deficit hyperactivity disorder (ADHD), but its efficacy (based on effect size calculations), safety, and stimulation parameters have not been systematically examined. In this systematic review, we aimed to (1) explore the effectiveness of tDCS on the clinical symptoms and neuropsychological deficits of ADHD patients, (2) evaluate the safety of tDCS application, especially in children with ADHD, (3) model the electrical field intensity in the target regions based on the commonly-applied and effective versus less-effective protocols, and (4) discuss and propose advanced tDCS parameters. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses approach, a literature search identified 14 empirical experiments investigating tDCS effects in ADHD. Partial improving effects of tDCS on cognitive deficits (response inhibition, working memory, attention, and cognitive flexibility) or clinical symptoms (e.g., impulsivity and inattention) are reported in 10 studies. No serious adverse effects are reported in 747 sessions of tDCS. The left and right dorsolateral prefrontal cortex are the regions most often targeted, and anodal tDCS the protocol most often applied. An intensity of 2 mA induced stronger electrical fields than 1 mA in adults with ADHD and was associated with significant behavioral changes. In ADHD children, however, the electrical field induced by 1 mA, which is likely larger than the electrical field induced by 1 mA in adults due to the smaller head size of children, was sufficient to result in significant behavioral change. Overall, tDCS seems to be a promising method for improving ADHD deficits. However, the clinical utility of tDCS in ADHD cannot yet be concluded and requires further systematic investigation in larger sample sizes. Cortical regions involved in ADHD pathophysiology, stimulation parameters (e.g. intensity, duration, polarity, and electrode size), and types of symptom/deficit are potential determinants of tDCS efficacy in ADHD. Developmental aspects of tDCS in childhood ADHD should be considered as well.

中文翻译：

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ADHD 中的经颅直流电刺激：对有效性、安全性和协议引起的电场建模结果的系统评价。

经颅直流电刺激 (tDCS) 是一种具有临床意义的改变皮质兴奋性的有前途的方法。它越来越多地用于神经发育障碍，尤其是注意力缺陷多动障碍 (ADHD)，但其功效（基于效应量计算）、安全性和刺激参数尚未得到系统研究。在本系统评价中，我们旨在 (1) 探讨 tDCS 对 ADHD 患者临床症状和神经心理缺陷的有效性，(2) 评估 tDCS 应用的安全性，尤其是在 ADHD 儿童中，(3) 模拟电场基于普遍应用的有效与低效协议的目标区域的强度，以及 (4) 讨论和提出先进的 tDCS 参数。使用系统评价和元分析方法的首选报告项目，文献搜索确定了 14 项研究多动症中 tDCS 效应的实证实验。10 项研究报告了 tDCS 对认知缺陷（反应抑制、工作记忆、注意力和认知灵活性）或临床症状（例如，冲动和注意力不集中）的部分改善作用。在 tDCS 的 747 次会议中没有报告严重的不良反应。左和右背外侧前额叶皮层是最常被针对的区域，而阳极 tDCS 是最常应用的协议。在患有 ADHD 的成年人中，2 mA 的强度会诱导比 1 mA 更强的电场，并且与显着的行为变化有关。然而，在 ADHD 儿童中，1 mA 感应的电场，由于儿童的头部尺寸较小，这可能大于成人 1 mA 感应的电场，足以导致显着的行为改变。总体而言，tDCS 似乎是改善 ADHD 缺陷的一种很有前途的方法。然而，tDCS 在 ADHD 中的临床效用尚未得出结论，需要在更大的样本量中进行进一步的系统研究。ADHD 病理生理学中涉及的皮层区域、刺激参数（例如强度、持续时间、极性和电极大小）和症状/缺陷类型是 ADHD 中 tDCS 功效的潜在决定因素。还应考虑儿童 ADHD 中 tDCS 的发育方面。tDCS 似乎是改善 ADHD 缺陷的一种很有前途的方法。然而，tDCS 在 ADHD 中的临床效用尚未得出结论，需要在更大的样本量中进行进一步的系统研究。ADHD 病理生理学中涉及的皮层区域、刺激参数（例如强度、持续时间、极性和电极大小）和症状/缺陷类型是 ADHD 中 tDCS 功效的潜在决定因素。还应考虑儿童 ADHD 中 tDCS 的发育方面。tDCS 似乎是改善 ADHD 缺陷的一种很有前途的方法。然而，tDCS 在 ADHD 中的临床效用尚未得出结论，需要在更大的样本量中进行进一步的系统研究。ADHD 病理生理学中涉及的皮层区域、刺激参数（例如强度、持续时间、极性和电极大小）和症状/缺陷类型是 ADHD 中 tDCS 功效的潜在决定因素。还应考虑儿童 ADHD 中 tDCS 的发育方面。症状/缺陷的类型和类型是 ADHD 中 tDCS 疗效的潜在决定因素。还应考虑儿童 ADHD 中 tDCS 的发育方面。症状/缺陷的类型和类型是 ADHD 中 tDCS 疗效的潜在决定因素。还应考虑儿童 ADHD 中 tDCS 的发育方面。