The impact of anodal tDCS on attentional networks as a function of trait anxiety and depressive symptoms: A preregistered double-blind sham-controlled experiment

Attention is a multifaceted construct, including three distinct attentional networks: the alerting, orienting, and executive conflict networks. Recently, researchers have started to envision strategies to enhance the attentional networks, and transcranial Direct Current Stimulation (tDCS) has emerged as a promising tool to do so, especially regarding the executive conflict network. On the other hand, other research lines have suggested that anodal tDCS might yield more substantial impacts among depressive and anxious participants. In this preregistered study, we thus examined two questions. First, we wanted to replicate previous observations and tested whether anodal tDCS does improve the executive conflict network's efficiency. Second, we set out to clarify the impact of anxiety and depressive symptoms on this effect. To do so, we adopted a double-blind within-subject protocol in an unselected sample (n = 50) and delivered a single session of anodal— applied over the dorsolateral part of the left prefrontal cortex—versus sham tDCS during the completion of a task assessing the attentional networks. We assessed anxiety and depressive symptoms at baseline. Although there were no significant direct effects of tDCS on the attentional networks, we found that the higher the levels of depression and trait anxiety, the larger the executive conflict network's enhancement during tDCS. By highlighting the importance of trait anxiety and depression when considering the impact of tDCS on the attentional networks, this study fulfills a valuable niche in clinical neuroscience, wherein preclinical data provide critical clues for larger, more definitive future translational efforts.

注意力是一个多维度结构，包括三个独立的注意力网络：警觉、定位和执行冲突网络。近期，研究人员开始构思提升注意力网络的策略，而经颅直流电刺激（tDCS）已崭露头角，成为实现此目标的潜在工具，尤其在增强执行冲突网络方面。另一方面，其他研究路径表明，阳极tDCS可能在抑郁和焦虑参与者中产生更为显著的影响。在本项预注册研究中，我们因此探讨了两个问题。首先，我们旨在复现先前的观察结果，并测试阳极tDCS是否能够提升执行冲突网络的效率。其次，我们旨在阐明焦虑和抑郁症状对此效果的影响。为此，我们采用了一种双盲的受试者内设计，在未进行选择的样本（n = 50）中，进行了一次的阳极tDCS——作用于左侧前额叶皮层的背外侧部分——与安慰剂tDCS的对比，在完成一项评估注意力网络的任务期间实施。我们在基线时评估了焦虑和抑郁症状。尽管tDCS对注意力网络没有产生显著的直接影响，但我们发现，抑郁和特质焦虑的水平越高，在tDCS期间执行冲突网络的增强效果越显著。通过强调特质焦虑和抑郁在考虑tDCS对注意力网络影响时的关键作用，本研究在临床神经科学领域填补了一个宝贵的空白，其中临床前数据为更大规模、更具决定性的未来转化研究提供了关键的线索。