Cognitive training in MCI may stimulate pre-existing neural reserves or recruit neural circuitry as “compensatory scaffolding” prompting neuroplastic reorganization to meet task demands (Reuter-Lorenz & Park, 2014). However, existing systematic reviews and meta-analytic studies exploring the benefits of cognitive interventions in MCI have been mixed. An updated examination regarding the efficacy of cognitive intervention in MCI is needed given improvements in adherence to MCI diagnostic criteria in subject selection, better defined interventions and strategies applied, increased use of neuropsychological measures pre- and post-intervention, as well as identification of moderator variables which may influence treatment. As such, this meta-analytic review was conducted to examine the efficacy of cognitive intervention in individuals diagnosed with mild cognitive impairment (MCI) versus MCI controls based on performance of neuropsychological outcome measures in randomized controlled trials (RCT). RCT studies published from January 1995 to June 2017 were obtained through source databases of MEDLINE-R, PubMed, Healthstar, Global Health, PSYCH-INFO, and Health and Psychological Instruments using search parameters for MCI diagnostic category (mild cognitive impairment, MCI, pre-Alzheimer’s disease, early cognitive decline, early onset Alzheimer’s disease, and preclinical Alzheimer’s disease) and the intervention or training conducted (intervention, training, stimulation, rehabilitation, or treatment). Other inclusion and exclusion criteria included subject selection based on established MCI criteria, RCT design in an outpatient setting, MCI controls (active or passive), and outcomes based on objective neuropsychological measures. From the 1199 abstracts identified, 26 articles met inclusion criteria for the meta-analyses completed across eleven (11) countries; 92.31% of which have been published within the past 7 years. A series of meta-analyses were performed to examine the effects of cognitive intervention by cognitive domain, type of training, and intervention content (cognitive domain targeted). We found significant, moderate effects for multicomponent training (Hedges’ g observed = 0.398; CI [0.164, 0.631]; Z = 3.337; p = 0.001; Q = 55.511; df = 15; p = 0.000; I ² = 72.978%; τ ² = 0.146) as well as multidomain-focused strategies (Hedges’ g = 0.230; 95% CI [0.108, 0.352]; Z = 3.692; p < 0.001; Q = 12.713; df = 12; p = 0.390; I ² = 5.612; τ ² = 0.003). The effects for other interventions explored by cognitive domain, training type, or intervention content were indeterminate due to concerns for heterogeneity, bias, and small cell sizes. In addition, subgroup and meta-regression analyses were conducted with the moderators of MCI category, mode of intervention, training type, intervention content, program duration (total hours), type of control group (active or passive), post-intervention follow-up assessment period, and control for repeat administration. We found significant overall effects for intervention content with memory focused interventions appearing to be more effective than multidomain approaches. There was no evidence of an influence on outcomes for the other covariates examined. Overall, these findings suggest individuals with MCI who received multicomponent training or interventions targeting multiple domains (including lifestyle changes) were apt to display an improvement on outcome measures of cognition post-intervention. As such, multicomponent and multidomain forms of intervention may prompt recruitment of alternate neural processes as well as support primary networks to meet task demands simultaneously. In addition, interventions with memory and multidomain forms of content appear to be particularly helpful, with memory-based approaches possibly being more effective than multidomain methods. Other factors, such as program duration, appear to have less of an influence on intervention outcomes. Given this, although the creation of new primary network paths appears strained in MCI, interventions with memory-based or multidomain forms of content may facilitate partial activation of compensatory scaffolding and neuroplastic reorganization. The positive benefit of memory-based strategies may also reflect transfer effects indicative of compensatory network activation and the multiple-pathways involved in memory processes. Limitations of this review are similar to other meta-analysis in MCI, including a modest number studies, small sample sizes, multiple forms of interventions and types of training applied (some overlapping), and, while greatly improved in our view, a large diversity of instruments used to measure outcome. This is apt to have contributed to the presence of heterogeneity and publication bias precluding a more definitive determination of the outcomes observed.

中文翻译：

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认知干预在轻度认知障碍（MCI）中的功效：对神经心理学测量结果的荟萃分析

MCI的认知训练可能会刺激先前存在的神经储备，或以“补偿性脚手架”的形式招募神经回路，从而促进神经塑性重组以满足任务要求（Reuter-Lorenz＆Park，2014）。然而，现有的系统综述和荟萃分析研究对认知干预在MCI中的益处进行了混合研究。鉴于在选择受试者时要遵守MCI诊断标准，改善定义的干预措施和策略，增加干预前和干预后神经心理措施的使用以及识别主持人的方法，需要对MCI认知干预的有效性进行更新检查可能影响治疗的变量。因此，这项荟萃分析旨在根据随机对照试验（RCT）中神经心理学结果指标的执行情况，对诊断为轻度认知障碍（MCI）与MCI对照的个体进行认知干预，以评估其有效性。1995年1月至2017年6月发布的RCT研究是通过MEDLINE-R，PubMed，Healthstar，Global Health，PSYCH-INFO和Health and Psychological Instruments的来源数据库使用MCI诊断类别（轻度认知障碍，MCI， -阿尔茨海默氏病，早期认知能力下降，阿尔茨海默氏病和临床前阿尔茨海默氏病的早期发作）以及进行的干预或培训（干预，培训，刺激，康复或治疗）。其他纳入和排除标准包括根据既定的MCI标准进行的受试者选择，门诊环境中的RCT设计，MCI对照（主动或被动）以及基于客观神经心理学指标的结果。在确定的1199个摘要中，有26篇文章符合在十一（11）个国家/地区完成的荟萃分析的纳入标准；其中92.31％已在过去7年内发表。进行了一系列荟萃分析，以按认知领域，培训类型和干预内容（针对认知领域）检查认知干预的效果。我们发现多分量训练具有明显的中等效果（Hedges's 在确定的1199个摘要中，有26篇文章符合在十一（11）个国家/地区完成的荟萃分析的纳入标准；其中92.31％已在过去7年内发表。进行了一系列荟萃分析，以按认知领域，培训类型和干预内容（针对认知领域）检查认知干预的效果。我们发现多分量训练具有明显的中等效果（Hedges's 在确定的1199个摘要中，有26篇文章符合在十一（11）个国家/地区完成的荟萃分析的纳入标准；其中92.31％已在过去7年内发表。进行了一系列荟萃分析，以按认知领域，培训类型和干预内容（针对认知领域）检查认知干预的效果。我们发现多分量训练具有明显的中等效果（Hedges's实测值g＝ 0.398；实测值＝ 0.398。CI [0.164，0.631]；Z  = 3.337；p  = 0.001；Q  = 55.511; df  = 15；p  = 0.000；I ²  = 72.978％；τ ²  = 0.146）以及多域为中心的策略（树篱克 = 0.230; 95％CI [0.108，0.352]; Z = 3.692; p <0.001; Q  = 12.713; DF  = 12; p  = 0.390;我 ²  = 5.612; τ ² = 0.003）。由于对异质性，偏倚和小细胞大小的关注，通过认知领域，训练类型或干预内容探讨的其他干预措施的效果不确定。此外，还对MCI类别，干预模式，培训类型，干预内容，计划持续时间（总时数），对照组（主动或被动），干预后随访的主持人进行了亚组和元回归分析。延长评估期，并控制重复给药。我们发现干预内容具有显着的总体效果，其中以记忆为中心的干预措施似乎比多域方法更有效。没有证据显示其他协变量对结果有影响。全面的，这些发现表明，接受多成分培训或针对多个领域（包括生活方式改变）的干预措施的MCI患者易于表现出干预后认知结果指标的改善。这样，干预的多成分和多域形式可能会提示募集其他神经过程，并支持主要网络同时满足任务需求。此外，对内存和多域内容形式的干预似乎特别有帮助，基于内存的方法可能比多域方法更有效。其他因素，例如计划的持续时间，似乎对干预效果的影响较小。鉴于此，尽管在MCI中创建新的主要网络路径似乎很麻烦，基于记忆或多域形式的内容的干预可能有助于补偿性支架的部分激活和神经塑性重组。基于内存的策略的积极优势还可能反映出转移效应，该效应表明补偿性网络激活以及内存过程中涉及的多种途径。该评价的局限性与MCI中的其他荟萃分析相似，包括数量不多的研究，较小的样本量，多种形式的干预措施和所应用的培训类型（有些重叠），尽管我们认为这有很大的改进，但差异很大用于衡量结果的工具。这容易导致异质性和出版偏见的存在，从而排除了对观察到的结果的更确定的确定。