Transcranial direct current stimulation (tDCS) in elderly with mild cognitive impairment: A pilot study

ABSTRACT. Transcranial direct current stimulation (tDCS) is a non-invasive, painless and easy-to use-technology. It can be used in depression, schizophrenia and other neurological disorders. There are no studies about longer usage protocols regarding the ideal duration and weekly frequency of tDCS. Objective: to study the use of tDCS twice a week for longer periods to improve memory in elderly with MCI. Methods: a randomized double-blind controlled trial of anodal tDCS on cognition of 58 elderly aged over 60 years was conducted. A current of 2.0 mA was applied for 30 minutes for 10 sessions, twice a week. The anode was placed over the left dorsolateral prefrontal cortex (LDLFC). Subjects were evaluated before and after 10 sessions by the following tests: CAMCOG, Mini-Mental State Examination (MMSE), Trail Making, Semantic Verbal Fluency (Animals), Boston naming, Clock Drawing Test, Word list memory (WLMT), Direct and Indirect Digit Order (WAIS-III and WMS-III) and N-back. Results: After 10 sessions of tDCS, significant group-time interactions were found for the CAMCOG - executive functioning (χ2 = 3.961, p = 0.047), CAMCOG - verbal fluency (χ2 = 3.869, p = 0.049), CAMCOG - Memory recall (χ2 = 9.749, p = 0.004), and WMLT - recall (χ2 = 7.254, p = 0.007). A decline in performance on the CAMCOG - constructional praxis (χ2 = 4.371, p = 0.037) was found in the tDCS group after intervention. No significant differences were observed between the tDCS and Sham groups for any other tasks. Conclusion: tDCS at 2 mA for 30 min twice a week over 5 consecutive weeks proved superior to placebo (Sham) for improving memory recall, verbal fluency and executive functioning in elderly with MCI.

摘要。经颅直流电刺激（transcranial direct current stimulation, tDCS）是一种非侵入式、无痛且操作简便的技术，可用于抑郁症、精神分裂症及其他神经系统疾病的干预。目前尚无针对经颅直流电刺激理想治疗时长与每周使用频率的长期应用方案相关研究。
研究目的：探讨每周两次、长期使用经颅直流电刺激对轻度认知障碍（mild cognitive impairment, MCI）老年群体记忆功能的改善效果。
研究方法：本研究开展一项随机双盲对照试验，纳入58名60岁以上老年人，评估阳极经颅直流电刺激对其认知功能的影响。以2.0 mA的电流持续刺激30分钟，共10个疗程，每周治疗两次。刺激阳极置于左侧背外侧前额叶皮层（left dorsolateral prefrontal cortex, LDLFC）。分别于干预前后，采用以下量表与测试对受试者进行评估：剑桥认知检查（CAMCOG）、简易精神状态检查表（Mini-Mental State Examination, MMSE）、连线测验、语义言语流畅性测验（动物命名版）、波士顿命名测验、画钟测验、词语列表记忆测验（Word list memory, WLMT）、韦氏成人智力量表第三版（WAIS-III）与韦氏记忆量表第三版（WMS-III）中的顺背及倒背数字广度测验，以及N-back任务。
研究结果：经10个疗程的经颅直流电刺激后，在CAMCOG执行功能（χ²=3.961, p=0.047）、CAMCOG言语流畅性（χ²=3.869, p=0.049）、CAMCOG记忆回忆（χ²=9.749, p=0.004）以及WLMT回忆（χ²=7.254, p=0.007）指标上，均观察到显著的组间-时间交互效应。干预后，经颅直流电刺激组在CAMCOG结构性运用能力（χ²=4.371, p=0.037）上出现成绩下降。其余测试任务中，经颅直流电刺激组与假刺激组均未观察到显著差异。
研究结论：以2 mA电流、每次30分钟、每周两次、连续5周的经颅直流电刺激方案，在改善轻度认知障碍老年群体的记忆回忆、言语流畅性与执行功能方面，效果优于安慰剂（假刺激）对照。