Indahlastari Aprinda, Hardcastle Cheshire, Albizu Alejandro, Alvarez-Alvarado Stacey, Boutzoukas Emanuel M, Evangelista Nicole D, Hausman Hanna K, Kraft Jessica, Langer Kailey, Woods Adam J
Center for Cognitive Aging and Memory, McKnight Brain Institute, University of Florida, Gainesville, FL, USA.
Department of Clinical and Health Psychology, University of Florida, Gainesville, FL, USA.
Neuropsychiatr Dis Treat. 2021 Mar 29;17:971-990. doi: 10.2147/NDT.S259499. eCollection 2021.
Transcranial direct current stimulation (tDCS) has been proposed as a possible method for remediating age-associated cognitive decline in the older adult population. While tDCS has shown potential for improving cognitive functions in healthy older adults, stimulation outcomes on various cognitive domains have been mixed.
A systematic search was performed in four databases: PubMed, EMBASE, Web of Science, and PsychInfo. Search results were then screened for eligibility based on inclusion/exclusion criteria to only include studies where tDCS was applied to improve cognition in healthy older adults 65 years and above. Eligible studies were reviewed and demographic characteristics, tDCS dose parameters, study procedures, and cognitive outcomes were extracted. Reported effect sizes for active compared to sham group in representative cognitive domain were converted to Hedges' g.
A total of thirteen studies involving healthy older adults (n=532, mean age=71.2+5.3 years) were included in the meta-analysis. The majority of included studies (94%) targeted the prefrontal cortex with stimulation intensity 1-2 mA using various electrode placements with anodes near the frontal region. Across all studies, we found Hedges' g values ranged from -0.31 to 1.85 as reported group effect sizes of active stimulation compared to sham.
While observed outcomes varied, overall findings indicated promising effects of tDCS to remediate cognitive aging and thus deserves further exploration. Future characterization of inter-individual variability in tDCS dose response and applications in larger cohorts are warranted to further validate benefits of tDCS for cognition in healthy older adults.
经颅直流电刺激（tDCS）已被提议作为一种可能改善老年人群与年龄相关认知衰退的方法。虽然tDCS已显示出改善健康老年人认知功能的潜力，但在各个认知领域的刺激效果却参差不齐。
在四个数据库中进行了系统检索：PubMed、EMBASE、科学网和心理信息数据库。然后根据纳入/排除标准对检索结果进行筛选，仅纳入将tDCS应用于改善65岁及以上健康老年人认知功能的研究。对符合条件的研究进行综述，并提取人口统计学特征、tDCS剂量参数、研究程序和认知结果。将代表性认知领域中活性组与假手术组相比报告的效应量转换为Hedges' g。
共有13项涉及健康老年人（n = 532，平均年龄 = 71.2 ± 5.3岁）的研究纳入荟萃分析。大多数纳入研究（94%）以额叶前皮质为靶点，刺激强度为1 - 2 mA，采用各种电极放置方式，阳极靠近额叶区域。在所有研究中，我们发现与假刺激相比，活性刺激的组效应量报告的Hedges' g值范围为 - 0.31至1.85。
虽然观察到的结果各不相同，但总体研究结果表明tDCS对改善认知老化有显著效果，因此值得进一步探索。未来有必要对tDCS剂量反应的个体间变异性进行特征描述，并在更大的队列中应用，以进一步验证tDCS对健康老年人认知的益处。
