Can Transcranial Direct-Current Stimulation Alone or Combined With Cognitive Training Be Used as a Clinical Intervention to Improve Cognitive Functioning in Persons With Mild Cognitive Impairment and Dementia? A Systematic Review and Meta-Analysis

Background: Transcranial direct-current stimulation (tDCS) facilitates cognitive improvement in healthy and pathological populations. It has been increasingly used in cases of mild cognitive impairment (MCI) and dementia. Our research question is: Can tDCS serve as a clinical intervention for improving the cognitive functions of persons with MCI (PwMCI) and dementia (PwD)?Objective: This systematic review evaluated the evidence to determine the efficacy of tDCS in improving cognitive outcomes in PwD and PwMCI.Methods: A systematic review was conducted of studies published up to November 2017 involving tDCS in cases of MCI and dementia. Studies were ranked according to the level of evidence (Oxford Center for Evidence-Based Medicine) and assessed for methodological quality (Risk of Bias Tool in the Cochrane Handbook for Systematic Reviews of Interventions). Data was extracted on all protocol variables to establish a reference framework for clinical interventions. Different modalities, tDCS alone or combined with cognitive training, compared with sham tDCS were examined in both short and long-term effects. Four randomized control trials (RCTs) with memory outcomes were pooled using the fixed-effect model for the meta-analysis.Results: Twelve studies with 195 PwD and four with 53 PwMCI met the inclusion criteria. Eleven articles were ranked as Level 1b. The results on the meta-analysis on pooled effects of memory indicated a statistically significant medium effect size of 0.39 (p = 0.04) for immediate effects. This improvement was not maintained in the long term 0.15 (p = 0.44).Conclusion: tDCS improves memory in PwD in the short term, it also seems to have a mild positive effect on memory and language in PwMCI. However, there is no conclusive advantage in coupling tDCS with cognitive training. More rigorous evidence is needed to establish whether tDCS can serve as an evidence-based intervention for both populations

Translation and validation of Chinese version of Problems in Everyday Living (PEDL) test in patients with mild cognitive impairment

Background: Cognitive impairment places older adults at increased risk of functional decline, injuries, and hospitalization. Assessments to determine whether older persons are still capable of meeting the cognitive challenges of everyday living are crucial to ensure their safe and independent living in the community. The present study aims to translate and validate the Chinese version of the Problems in Everyday Living (PEDL) test for use in Chinese population with mild cognitive impairment (MCI).\ud \ud Methods: The cultural relevancy and content validity of the Chinese version of PEDL (C-PEDL) was evaluated by a seven-member expert panel. Forty patients with MCI and 40 cognitively healthy participants were recruited to examine the psychometric properties of C-PEDL.\ud \ud Results: Significant differences in the C-PEDL scores were found between the patients with MCI and the cognitively healthy controls in both educated (F = 9.96, p = 0.003) and illiterate (F = 10.43, p = 0.004) populations. The C-PEDL had excellent test-retest and inter-rater reliabilities, with intraclass correlation coefficient at 0.95 and 0.99 respectively. The internal consistency of C-PEDL was acceptable with Chronbach's α at 0.69. The C-PEDL had moderate correlation with the Mini-Mental State Examination (r = 0.45, p = 0.004) and the Category Verbal Fluency Test (r = 0.40, p = 0.012), and a moderate negative Spearman's correlation with the Global Deteriorating Scale (r = –0.42, p = 0.007).\ud \ud Conclusions: The C-PEDL is a valid and reliable test for assessing the everyday problem-solving ability in Chinese older population with MCI