No evidential value in samples of transcranial direct current stimulation (tDCS) studies of cognition and working memory in healthy populations
No evidential value in samples of transcranial direct current stimulation (tDCS) studies of cognition and working memory in healthy populations
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DOI：
10.1016/j.cortex.2017.06.021
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发表时间：
2017-09-01
期刊：
影响因子：
3.6
通讯作者：
Cason, Samuel
中科院分区：
文献类型：
--
作者：
Medina, Jared;Cason, Samuel
过去十年发表了大量研究，声称经颅直流电刺激 (tDCS) 可以影响认知任务的表现。然而，人们对经颅直流电刺激 (tDCS) 的功效存在一些怀疑，荟萃分析的证据也参差不齐。这些荟萃分析的一个主要弱点是它们仅检查已发表研究中的结果。鉴于科学文献中对发表阳性结果存在偏见，tDCS 文献中可能存在大量未发表的阴性结果的“文件抽屉”。此外，多个研究人员自由度也会夸大已发表的 p 值。最近，Simonsohn、Nelson 和 Simmons (2014) 创建了一种新颖的荟萃分析工具，用于检查文献中显着 p 值的分布，并将其与具有不同效应大小的预期分布进行比较。使用这一工具，人们可以评估所选研究是否具有证据价值。因此，我们在最近发表的荟萃分析中随机选择了一些使用 tDCS 来改变认知任务表现的研究，以及 tDCS 对工作记忆的研究（Mancuso 等人，2016）。使用 p 曲线分析，我们没有发现任何证据表明 tDCS 研究具有证据价值（33% 功效或更高），认知研究的这些研究的统计功效估计约为 14%，工作记忆研究的统计功效约为 5%（随机生成的数据的预期）。以前的 tDCS 研究很可能严重不足，我们为未来的研究提供建议，以增加未来 tDCS 研究的证据价值。 (C) 2017 Elsevier Ltd. 保留所有权利。
A substantial number of studies have been published over the last decade, claiming that transcranial direct current stimulation (tDCS) can influence performance on cognitive tasks. However, there is some skepticism regarding the efficacy of tDCS, and evidence from meta-analyses are mixed. One major weakness of these meta-analyses is that they only examine outcomes in published studies. Given biases towards publishing positive results in the scientific literature, there may be a substantial "file-drawer" of unpublished negative results in the tDCS literature. Furthermore, multiple researcher degrees of freedom can also inflate published p-values. Recently, Simonsohn, Nelson and Simmons (2014) created a novel meta-analytic tool that examines the distribution of significant p-values in a literature, and compares it to expected distributions with different effect sizes. Using this tool, one can assess whether the selected studies have evidential value. Therefore, we examined a random selection of studies that used tDCS to alter performance on cognitive tasks, and tDCS studies on working memory in a recently published meta-analysis (Mancuso et al., 2016). Using a p-curve analysis, we found no evidence that the tDCS studies had evidential value (33% power or greater), with the estimate of statistical power of these studies being approximately 14% for the cognitive studies, and 5% (what would be expected from randomly generated data) for the working memory studies. It is likely that previous tDCS studies are substantially underpowered, and we provide suggestions for future research to increase the evidential value of future tDCS studies. (C) 2017 Elsevier Ltd. All rights reserved.