Duffy Michelle J, Feltman Kathryn A, Kelley Amanda M, Mackie Ryan
U.S. Army Aeromedical Research Laboratory, Fort Novosel, AL, United States.
Oak Ridge Institute for Science and Education, Oak Ridge, TN, United States.
Front Hum Neurosci. 2024 Jul 26;18:1444450. doi: 10.3389/fnhum.2024.1444450. eCollection 2024.
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method, popular due to its low cost, ease-of-application, and portability. As such, it has gained traction in examining its potential for cognitive enhancement in a diverse range of populations, including active-duty military. However, current literature presents mixed results regarding its efficacy and limited evaluations of possible undesirable side-effects (such as degradation to cognitive processes).
To further examine its potential for enhancing cognition, a double-blind, randomized, sham-controlled, within-subjects design, was used to evaluate both online active-anodal and -cathodal on several cognitive tasks administered. Potential undesirable side effects related to mood, sleepiness, and cognitive performance, were also assessed. Active tDCS was applied for 30 min, using 2 mA, to the left dorsolateral prefrontal cortex with an extracephalic reference placed on the contralateral arm of 27 (14 males) active-duty Soldiers.
We report mixed results. Specifically, we found improvements in sustained attention (active-anodal) for males in reaction time ( = 0.024, η = 0.16) and for sensitivity index in females ( = 0.013, η = 0.18). In addition, we found faster reaction time ( = 0.034, η = 0.15) and increased accuracy ( = 0.029, η = 0.16) associated with executive function (active-anodal and -cathodal), and worsened working memory performance (active-cathodal; = 0.008, η = 0.18). Additionally, we found increased risk-taking with active-anodal ( = 0.001, η = 0.33).
tDCS may hold promise as a method for cognitive enhancement, as evidenced by our findings related to sustained attention and executive function. However, we caution that further study is required to better understand additional parameters and limitations that may explain results, as our study only focused on anode vs. cathode stimulation. Risk-taking was examined secondary to our main interests which warrants further experimental investigation isolating potential tradeoffs that may be associated with tDCS simulation.
经颅直流电刺激（tDCS）是一种非侵入性脑刺激方法，因其成本低、易于应用和便携性而受到欢迎。因此，它在研究其对包括现役军人在内的各种人群认知增强潜力方面获得了关注。然而，目前的文献对于其疗效呈现出不一致的结果，并且对可能的不良副作用（如认知过程退化）的评估有限。
为了进一步研究其增强认知的潜力，采用了双盲、随机、假对照、被试内设计，以评估在线主动阳极和阴极刺激对多项认知任务的影响。还评估了与情绪、嗜睡和认知表现相关的潜在不良副作用。对27名（14名男性）现役士兵的左侧背外侧前额叶皮层施加30分钟、2毫安的主动tDCS，将头皮外参考电极置于对侧手臂。
我们报告了不一致的结果。具体而言，我们发现男性在持续注意力方面（主动阳极刺激）反应时间有所改善（p = 0.024，η² = 0.16），女性在敏感性指数方面有所改善（p = 0.013，η² = 0.18）。此外，我们发现与执行功能相关的反应时间更快（p = 0.034，η² = 0.15）和准确性提高（p = 0.029，η² = 0.16）（主动阳极和阴极刺激），以及工作记忆表现恶化（主动阴极刺激；p = 0.008，η² = 0.18）。此外，我们发现主动阳极刺激下冒险行为增加（p = 0.001，η² = 0.33）。
tDCS作为一种认知增强方法可能具有前景，我们关于持续注意力和执行功能的研究结果证明了这一点。然而，我们提醒需要进一步研究以更好地理解可能解释结果的其他参数和局限性，因为我们的研究仅关注阳极与阴极刺激。冒险行为是在我们主要兴趣之后进行研究的，这需要进一步的实验研究来分离可能与tDCS模拟相关的潜在权衡。
