Stephens Jaclyn A, Berryhill Marian E
Department of Psychology, Program in Cognitive and Brain Sciences, University of Nevada, Reno, NV 89557.
Department of Psychology, Program in Cognitive and Brain Sciences, University of Nevada, Reno, NV 89557.
Brain Stimul. 2016 Jul-Aug;9(4):553-9. doi: 10.1016/j.brs.2016.04.001. Epub 2016 Apr 21.
Aging is associated with decline in executive function (EF), upper-level cognitive abilities such as planning, problem solving, and working memory (WM). This decline is associated with age-related volume loss and reduced functional connectivity in the frontal lobes. Cognitive training interventions aim to counter these losses, but often fail to elicit benefits beyond improvements on trained tasks. Recent interventions pairing WM training with transcranial direct current stimulation (tDCS) have improved WM and elicited transfer to untrained EF tasks. Limitations in previous work include exclusive use of laboratory-based computer training and testing and poor characterization of the mechanism(s) of durable tDCS-linked change.
OBJECTIVE/HYPOTHESIS: To determine if tDCS-linked WM training improves performance on ecologically valid transfer measures administered in participants' homes. To explore intervention-based changes using neuroimaging (fNIRS) and genotyping (COMT val158met).
90 healthy older adult participants completed 5 sessions of WM training paired with tDCS (Sham, 1 mA tDCS, 2 mA tDCS; 15 min). At follow-up, we assessed performance change on laboratory-based and ecologically valid tasks.
All participants showed improvement on trained tasks. Importantly, 2 mA of tDCS induced significantly greater far transfer gains after 1 month without contact. Gains were observed on standard far transfer tasks along with ecologically valid far transfer tasks, and stimulation was well tolerated by all participants. FNIRS and genotyping results were less conclusive, but provide promising avenues for future research initiatives.
These findings highlight the translational value for tDCS-based interventions in healthy older adults interested in maintaining cognitive function.
衰老与执行功能（EF）下降相关，执行功能是诸如计划、问题解决和工作记忆（WM）等高级认知能力。这种下降与年龄相关的额叶体积减少和功能连接性降低有关。认知训练干预旨在对抗这些损失，但往往未能在训练任务之外带来益处。最近将工作记忆训练与经颅直流电刺激（tDCS）相结合的干预措施改善了工作记忆，并引发了向未训练的执行功能任务的迁移。以往研究的局限性包括仅使用基于实验室的计算机训练和测试，以及对与tDCS相关的持久变化机制的描述不足。
目的/假设：确定与tDCS相关的工作记忆训练是否能提高在参与者家中进行的生态有效迁移测量任务上的表现。使用神经成像（功能性近红外光谱，fNIRS）和基因分型（儿茶酚-O-甲基转移酶val158met，COMT val158met）探索基于干预的变化。
90名健康的老年参与者完成了5次与tDCS（假刺激、1毫安tDCS、2毫安tDCS；15分钟）相结合的工作记忆训练。在随访时，我们评估了基于实验室和生态有效的任务上的表现变化。
所有参与者在训练任务上都有改善。重要的是，2毫安的tDCS在1个月无接触后诱导出显著更大的远迁移增益。在标准远迁移任务以及生态有效远迁移任务上都观察到了增益，并且所有参与者对刺激的耐受性良好。功能性近红外光谱和基因分型结果的结论性较差，但为未来的研究计划提供了有前景的途径。
这些发现突出了基于tDCS的干预措施对有兴趣维持认知功能的健康老年人的转化价值。
