The role of cognitive activity in cognition protection: from Bedside to Bench

How Do Modifiable Risk Factors Affect Alzheimer's Disease Pathology or Mitigate Its Effect on Clinical Symptom Expression?

Epidemiological studies show that modifiable risk factors account for approximately 40% of the population variability in risk of developing dementia, including sporadic Alzheimer's disease (AD). Recent findings suggest that these factors may also modify disease trajectories of people with autosomal-dominant AD. With positron emission tomography imaging, it is now possible to study the disease many years before its clinical onset. Such studies can provide key knowledge regarding pathways for either the prevention of pathology or the postponement of its clinical expression. The former "resistance pathway" suggests that modifiable risk factors could affect amyloid and tau burden decades before the appearance of cognitive impairment. Alternatively, the resilience pathway suggests that modifiable risk factors may mitigate the symptomatic expression of AD pathology on cognition. These pathways are not mutually exclusive and may appear at different disease stages. Here, in a narrative review, we present neuroimaging evidence that supports both pathways in sporadic AD and autosomal-dominant AD. We then propose mechanisms for their protective effect. Among possible mechanisms, we examine neural and vascular mechanisms for the resistance pathway. We also describe brain maintenance and functional compensation as bases for the resilience pathway. Improved mechanistic understanding of both pathways may suggest new interventions.

Multimodal Exercise and Cognitive Training Program Improves Cognitive Function in Amnestic Mild Cognitive Impairment

OBJECTIVE

To investigate the preliminary efficacy of a combined physical exercise + cognitive training intervention for older adults with amnestic mild cognitive impairment (aMCI).

DESIGN

Randomized clinical trial.

SETTING

Veteran Affairs Hospital, Palo Alto, CA.

PARTICIPANTS

Sample included 72 community-dwelling volunteers (mean age 72.4 ± 9.5) diagnosed with aMCI.

INTERVENTION

Participants were randomized to either a combined aerobic and resistance exercise + cognitive training (CARE+CT) or stretching exercise + CT (SE+CT).

MEASUREMENTS

Primary outcomes included intervention specific assessments of word list and name-face recall. Secondary cognitive outcomes included standardized composite scores that reflect cognitive domains (e.g., learning and memory, executive function, processing speed, visuospatial ability, language). Secondary physiological outcomes included VO2 max and functional capacity (e.g., distance walked 6-minute walk test). APOE and BDNF were determined from whole blood samples.

RESULTS

Controlling for age and employment status, linear mixed effects models revealed that all participants experienced significant improvement in the delayed recall of word list, learning and memory and executive function. Only the CARE+CT condition had significant improvement in processing speed and functional capacity. APOE4 status impacted cognitive benefits of those in the SE+CT condition.

CONCLUSIONS

Results provide preliminary support for combined exercise and cognitive training interventions for older adults with aMCI. Further research is needed to understand the mechanisms involved as well as the impact of these interventions in diverse samples.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01962038.

[The psychosocial rehabilitation in addiction medicine]

OBJECTIVES

Addictive behaviors constitute complex behaviors that are usually related to social habits, such as substance use, gambling or gaming activities, or sexual or physical activity. They progressively overrun and stifle the routine habits of the concerned individuals, for example within their occupational or family spheres of life, as well as in their hobbies or in their main physiological functions, such as sleep or eating cycles. The rehabilitation approach of care integrates the objective of restoring the altered habits and functional rhythms, to optimize the clinical outcomes and improve quality of life of the concerned persons.

METHODS

Using a focused and narrative literature review, we aimed to explain what psychosocial rehabilitation consists in, and why this approach is particularly relevant for the addiction care, although to date it has remained insufficiently developed in the routine practice of many facilities.

RESULTS

The "rehab" approach, is first based on a structured and comprehensive assessment of the clinical and functional aspects of the patient, which secondarily allows to frame an individualized project of care that is closely built together with the patient. This project of care can integrate classical pharmacotherapeutic and psychotherapeutic tools, but it also emphasizes wider approaches for restoring some basic social and physiological functions of the concerned person, such as sleep, eating, social functioning, physical activity, or spiritual needs. Priorities among these different dimensions have to be defined by the concerned person.

CONCLUSIONS

The "rehab" approach is particularly relevant in addiction medicine. It represents a more global conception of care that conceives the recovery of social and physiological functioning as a core treatment objective for the concerned persons. The consequences for care organization are that many additional professionals should be integrated into the treatment schemes for addiction, including peer counselors, occupational therapists, physical activity coaches, or dieticians.

Effects of computerized cognitive training on structure‒function coupling and topology of multiple brain networks in people with mild cognitive impairment: a randomized controlled trial

BACKGROUND

People with mild cognitive impairment (MCI) experience a loss of cognitive functions, whose mechanism is characterized by aberrant structure‒function (SC-FC) coupling and topological attributes of multiple networks. This study aimed to reveal the network-level SC-FC coupling and internal topological changes triggered by computerized cognitive training (CCT) to explain the therapeutic effects of this training in individuals with MCI.

METHODS

In this randomized block experiment, we recruited 60 MCI individuals and randomly divided them into an 8-week multidomain CCT group and a health education control group. The neuropsychological outcome measures were the Montreal Cognitive Assessment (MoCA), Chinese Auditory Verbal Learning Test (CAVLT), Chinese Stroop Color-Word Test (SCWT), and Rey-Osterrieth Complex Figure Test (Rey CFT). The brain imaging outcome measures were SC-FC coupling and topological attributes using functional MRI and diffusion tensor imaging methods. We applied linear model analysis to assess the differences in the outcome measures and identify the correspondence between the changes in the brain networks and cognitive functions before and after the CCT.

RESULTS

Fifty participants were included in the analyses after the exclusion of three dropouts and seven participants with low-quality MRI scans. Significant group × time effects were found on the changes in the MoCA, CAVLT, and Rey CFT recall scores. The changes in the SC-FC coupling values of the default mode network (DMN) and somatomotor network (SOM) were higher in the CCT group than in the control group (P(unc.) = 0.033, P(unc.) = 0.019), but opposite effects were found on the coupling values of the visual network (VIS) (P(unc.) = 0.039). Increasing clustering coefficients in the functional DMN and SOM and subtle changes in the nodal degree centrality and nodal efficiency of the right dorsal medial prefrontal cortex, posterior cingulate cortex, left parietal lobe, somatomotor area, and visual cortex were observed in the CCT group (P < 0.05, Bonferroni correction). Significant correspondences were found between global cognitive function and DMN coupling values (P(unc.) = 0.007), between immediate memory and SOM as well as FPC coupling values (P(unc.) = 0.037, P(unc.) = 0.030), between delayed memory and SOM coupling values (P(unc.) = 0.030), and between visual memory and VIS coupling values (P(unc.) = 0.007).

CONCLUSIONS

Eight weeks of CCT effectively improved global cognitive and memory functions; these changes were correlated with increases in SC-FC coupling and changes in the topography of the DMN and SOM in individuals with MCI. The CCT regimen also modulated the clustering coefficient and the capacity for information transformation in functional networks; these effects appeared to underlie the cognitive improvement associated with CCT.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR2000034012. Registered on 21 June 2020.

Tai Chi enhances cognitive training effects on delaying cognitive decline in mild cognitive impairment

INTRODUCTION

Cognitive training and physical exercise have shown positive effects on delaying progression of mild cognitive impairment (MCI) to dementia.

METHODS

We explored the enhancing effect from Tai Chi when it was provided with cognitive training for MCI. In the first 12 months, the cognitive training group (CT) had cognitive training, and the mixed group (MixT) had additional Tai Chi training. In the second 12 months, training was only provided for a subgroup of MixT.

RESULTS

In the first 12 months, MixT and CT groups were benefited from training. Compared to the CT group, MixT had additional positive effects with reference to baseline. In addition, Compared to short-time training, prolonged mixed training further delayed decline in global cognition and memory. Functional magnetic resonance imaging showed more increased regional activity in both CT and MixT.

DISCUSSION

Tai Chi enhanced cognitive training effects in MCI. Moreover, Tai Chi and cognitive mixed training showed effects on delaying cognitive decline.

Enriched environment ameliorates propagation of tau pathology and improves cognition in rat model of tauopathy

Introduction

The typical symptoms of Alzheimer’s disease (AD) are cognitive impairment, disrupted spatial orientation, behavioral and psychiatric abnormalities, and later motor deficits. Neuropathologically, AD is characterized by deposits of pathological forms of endogenous proteins – amyloid-β, and neurofibrillary tau protein pathology. The latter closely correlates with brain atrophy and clinical impairment. Pharmacological therapies for these pathologies are largely absent, raising the question whether non-pharmacological interventions could be efficacious. Environmental factors can play a role in the manifestation of AD. It is unknown whether enriched environment (EE) can ameliorate the propagation of protein aggregates or their toxic components.

Methods

We injected insoluble tau extracts from human brains with AD (600 or 900 ng per animal) into hippocampi of SHR72 transgenic rats that express non-mutated truncated human tau 151-391/4R, but usually do not develop hippocampal tangles. The rats had either standard housing, or could access an EE 5×/week for 3 months. Behavioral analysis included the Morris Water Maze (MWM). Histological analysis was used to assess the propagation of tau pathology.

Results

Animals exposed to EE performed better in the MWM (spatial acquisition duration and total distance, probe test); unexposed animals improved over the course of acquisition trials, but their mean performance remained below that of the EE group. Enriched environment abrogated tau propagation and hippocampal tangle formation in the 600 ng group; in the 900 ng group, tangle formation was ∼10-fold of the 600 ng group, and unaffected by EE.

Conclusion

Even a small difference in the amount of injected human AD tau can cause a pronounced difference in the number of resulting tangles. EE leads to a noticeably better spatial navigation performance of tau-injected animals. Furthermore, EE seems to be able to slow down tau pathology progression, indicating the possible utility of similar interventions in early stages of AD where tangle loads are still low.

Decreased kynurenine pathway potentiate resilience to social defeat effect on cocaine reward

The kynurenine (KYN) pathway of tryptophan (TRP) degradation is activated by stress and inflammatory factors. It is now well established that social stress induces the activation of the immune system, with central inflammation and KYN metabolism being two of the main factors linking stress with depression. The aim of the present study was to evaluate the long-lasting changes in the KYN pathway induced by social defeat (SD) associated with the resilience or susceptibility to an increase in the conditioned rewarding effects of cocaine. Mice were exposed to repeated SD and 3 weeks later, a conditioned place preference (CPP) induced by a subthreshold dose of cocaine (1.5 mg/kg) was developed. KYN levels in plasma, cerebellum, hippocampus, striatum and limbic forebrain were studied at the end of the CPP procedure. Changes in the KYN pathway after exposure to pharmacological (oxytocin and indomethacin) and environmental interventions (environmental enrichment) were also evaluated. Our results showed that defeated susceptible (SD-S) mice had higher conditioning scores than resilient mice (SD-R). In addition, although KYN concentration was elevated in all defeated mice, SD-R mice showed smaller increases in KYN concentration in the cerebellum than SD-S mice. Oxytocin or Indomethacin treatment before SD normalized cocaine-induced CPP, although the increase in the KYN pathway was maintained. However, environmental enrichment before SD normalized cocaine-induced CPP and prevented the increase in the KYN pathway. The present study highlights the role of the KYN pathway and anti-inflammatory drugs acting on TRP metabolism as pharmacological targets to potentiate resilience to social stress effects.

The Effect of Cognitive Intervention on Cognitive Function in Older Adults With Alzheimer's Disease: A Systematic Review and Meta-Analysis

Cognitive intervention includes cognitive stimulation, cognitive training, and cognitive rehabilitation. This systematic review was performed to re-assess the efficacy of cognitive intervention for the patients with Alzheimer's disease (AD). Twenty studies (2012 participants) were eventually included. For global cognitive function, the combined mean difference (MD) in eight studies was 1.67 (95% Confidence Interval: 0.45, 2.89, p = 0.007; Q = 33.28, df = 8, p < 0.0001, τ² = 2.17, I² = 76%) for the short term. The pooled standardized mean difference (SMD) of six RCTs was 1.61 (95% Confidence Interval: 0.65, 2.56, p = 0.0009; Q = 127.66, df = 6, p < 0.00001, τ² = 1.56, I² = 95%) for the medium term. The pooled SMD of seven studies was 0.79 (95% Confidence Interval: 0.33, 1.25, p = 0.0008; Q = 35.10, df = 7, p < 0.0001, τ² = 0.33, I² = 80%) for the long term. For depression, the pooled SMD of two trials was -0.48 (95% Confidence Interval: -0.71, -0.24; p < 0.0001, I² = 4%) for the short term. Cognitive training may show obvious improvements in global cognitive function whether after short, medium, or long-term interventions and in depression after short term intervention. However, the positive effect of the intervention on general cognitive function or depression did not seem to persist after intervention ended. There is still a lack of reliable and consistent conclusions relevant to the effect of cognitive stimulation and cognitive rehabilitation on observed outcomes, cognitive training for memory or other non-cognitive outcomes. PROSPERO registration number: CRD42019121768.

Are There Any Cognitive Benefits of Computer-Based Foreign Language Training for Healthy Elderly People? - A Mini-Review

The purpose of this mini-review is to investigate if there are any cognitive benefits of computer-based foreign language training for healthy older individuals aged 55+ years. The author conducted a literature search of peer-reviewed English written research articles found in Pub Med, Web of Science and Scopus. The findings of this mini-review reveal that the research on the cognitive benefits of computer-based foreign language training for healthy older individuals is small-scale. The limited research findings of only three relevant studies indicate that these computer-based foreign language training programs may bring cognitive benefits for healthy elderly people, especially as far as the enhancement of their cognitive functions such as working memory are concerned. In addition, the authors of these studies suggest that foreign language learning is a useful activity for healthy older adults since it has the benefits of being meaningful (an advantage over other cognitive training approaches) and provides the chance for acquiring important skills that can benefit other aspects of life, such as travel or communication. In conclusion, the author of this mini-review also provides several implications for practice and future research.

Effectiveness of an Innovative Cognitive Treatment and Telerehabilitation on Subjects With Mild Cognitive Impairment: A Multicenter, Randomized, Active-Controlled Study

Background

In recent years, the potential usefulness of cognitive training procedures in normal aging and mild cognitive impairment (MCI) have received increased attention.

Objective

The main aim of this study was to evaluate the efficacy of the face-to-face cognitive virtual reality rehabilitation system (VRRS) and to compare it to that of face-to-face cognitive treatment as usual for individuals with MCI. Moreover, we assessed the possibility of prolonging the effects of treatment with a telerehabilitation system.

Methods

A total of 49 subjects with MCI were assigned to 1 of 3 study groups in a randomized controlled trial design: (a) those who received face-to-face cognitive VRRS (12 sessions of individualized cognitive rehabilitation over 4 weeks) followed by telerehabilitation (36 sessions of home-based cognitive VRRS training, three sessions for week); (b) those who received face-to-face cognitive VRRS followed by at-home unstructured cognitive stimulation (36 sessions of home-based unstructured cognitive stimulation, three sessions for week); and (c) those who received face-to-face cognitive treatment as usual (12 sessions of face-to-face cognitive treatment as usual).

Results

An improvement in memory, language and visuo-constructional abilities was observed after the end of face-to-face VRRS treatment compared to face-to-face treatment as usual. The application of home-based cognitive VRRS telerehabilitation seems to induce more maintenance of the obtained gains than home-based unstructured stimulation.

Discussion

The present study provides preliminary evidence in support of individualized VRRS treatment and telerehabilitation delivery for cognitive rehabilitation and should pave the way for future studies aiming at identifying optimal cognitive treatment protocols in subjects with MCI.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier NCT03486704.

Current approaches to modeling the virtual reality in rodents for the assessment of brain plasticity and behavior

Virtual reality (VR) and augmented reality (AR) have become valuable tools to study brains and behaviors resulting in development of new methods of diagnostics and treatment. Neurodegenerаtion is one of the best examples demonstrating efficacy of VR/АR technologies in modern neurology. Development of novel VR systems for rodents and combination of VR tools with up-to-date imaging techniques (i.e. MRI, imaging of neural networks etc.), brain electrophysiology (EEG, patch-clamp), precise analytics (microdialysis) allowed implementing of VR protocols into the animal neurobiology to study brain plasticity, sensorimotor integration, spatial navigation, memory, and decision-making. VR/AR for rodents is а young field of experimental neuroscience and has already provided more consistent testing conditions, less human-animal interaction, opportunities to use a wider variety of experimental parameters. Here we discuss present and future perspectives of using VR/AR to assess brain plasticity, neurogenesis and complex behavior in rodent and human study, and their advantages for translational neuroscience.

Study protocol of the self-monitoring activity program: Effects of activity on incident dementia

Introduction

Numerous studies have focused on nonpharmacological interventions on cognitive function and the effects of cognitive function on daily living. However, effects of behavior change techniques that promote physical, cognitive, and social activities on cognitive function and incident dementia in the elderly are yet to be elucidated. In this study, we aimed to design a single-blind, randomized controlled trial to study dementia prevention effects of behavior change techniques, using an accelerometer and a newly developed daily activity booklet in community-living older adults.

Methods

The study cohort comprised 5390 individuals aged 65 years and older who were randomized into one of the following three groups: accelerometer group (n = 1508), accelerometer and daily activity booklet group (n = 1180), or a control group (n = 2702; vs. accelerometer group [n = 1509] vs. accelerometer and daily activity booklet group [n = 1193]). Incident dementia was diagnosed based on the Japanese Health Insurance System data. The participants without dementia at baseline, who are diagnosed with dementia over a 36-month follow-up period, are considered to have incident dementia. The participants of the accelerometer group were asked to wear the accelerometer everyday and visit a site having data readers to download the accelerometer data every month. The subjects of the booklet group were requested to not only wear the accelerometer but also record the physical, cognitive, and social activities. The participants receive a feedback report from the data of the accelerometer and booklet.

Discussion

The study has the potential to provide the first evidence of effectiveness of the self-monitoring tools in incident dementia. In case our trial results suggest a delayed dementia onset upon self-monitoring interventions, the study protocol will provide a cost-effective and safe method for maintaining a healthy cognitive aging.

•

We aim to study dementia prevention effects of behavior change techniques.

•

The study may shed light on the effect of self-monitoring in dementia prevention.

•

The findings may provide a safe method for maintaining a healthy cognitive aging.

Computerized cognitive training for Chinese mild cognitive impairment patients: A neuropsychological and fMRI study

BACKGROUND

Computerized multi-model training has been widely studied for its effect on delaying cognitive decline. In this study, we designed the first Chinese-version computer-based multi-model cognitive training for mild cognitive impairment (MCI) patients. Neuropsychological effects and neural activity changes assessed by functional MRI were both evaluated.

METHOD

MCI patients in the training group were asked to take training 3-4 times per week for 6 months. Neuropsychological and resting-state fMRI assessment were performed at baseline and at 6 months. Patients in both groups were continuously followed up for another 12 months and assessed by neuropsychological tests again.

RESULTS

78 patients in the training group and 63 patients in the control group accomplished 6-month follow-up. Training group improved 0.23 standard deviation (SD) of mini-mental state examination, while control group had 0.5 SD decline. Addenbrooke's cognitive examination-revised scores in attention (p = 0.002) and memory (p = 0.006), as well as stroop color-word test interference index (p = 0.038) and complex figure test-copy score (p = 0.035) were also in favor of the training effect. Difference between the changes of two groups after training was not statistically significant. The fMRI showed increased regional activity at bilateral temporal poles, insular cortices and hippocampus. However, difference between the changes of two groups after another 12 months was not statistically significant.

CONCLUSIONS

Multi-model cognitive training help MCI patients to gained cognition benefit, especially in memory, attention and executive function. Functional neuroimaging provided consistent neural activation evidence. Nevertheless, after one-year follow up after last training, training effects were not significant. The study provided new evidence of beneficial effect of multi-model cognitive training.

Effective multicomponent interventions in comparison to active control and no interventions on physical capacity, cognitive function and instrumental activities of daily living in elderly people with and without mild impaired cognition - A systematic review and network meta-analysis

Multicomponent interventions (MCT) combine physical exercises and cognitive training and seem to be most effective in improving cognition in elderly people. However, literature is inconclusive if MCTs are superior to active comparison interventions, if delivery modes matter, and if people can transfer achieved effects to instrumental activities of daily living (IADL). This network meta-analysis aimed to a) identify MCTs that were effective on physical capacity and/or cognitive function and able to transfer these effects into IADL in elderly people with normal cognition (NC) and mild cognitive impairment (MCI); b) provide a rating on the best interventions per outcome; c) evaluate MCTs' mode of delivery. Eligible studies were randomized controlled trials comparing MCTs to active comparison or no treatments. Six studies in participants with MCI (n = 1088) and eleven studies in participants with NC (n = 670) were included. Five effective MCTs that were superior to physical exercises or cognitive training alone in improving physical capacity and/or cognitive function were detected, however none of these MCTs improved IADL. In people with NC MCTs performed separately or simultaneously were effective. However, in people with MCI MCTs performed separately were more effective. A framework needs to be developed to better understand the mediating effects of physical capacity and cognitive function on IADL and to design MCTs that effectively improve IADL.

Non-physical approaches to counteract age-related functional deterioration: Applications for rehabilitation and neural mechanisms

Normal and pathological ageing are associated with several motor impairments that reduce quality of life and represent a general challenge for public healthcare systems. Consequently, over the past decades, many scientists and physiotherapists dedicated their research to the development and improvement of safe and costless methods to counteract the progressive decline of motor functions with age. The urgency of finding new and easy to implement methods is even more paramount in case of acute pathologies (e.g. stroke or hip surgery). The frailty of older population makes it difficult or even impossible to use traditional physical therapy at an early stage after the occurrence of a pathology. To that purpose, non-physical approaches such as cognitive training (e.g. memory, attention training) and mental techniques (e.g. motor imagery) have grown in popularity for the elderly. Such methods, involving individual and/or group exercises, have shown particular effects on increasing or maintaining cognitive functions, as well as physical performances. Improving the motor function (especially in older age) requires an improvement of motor execution, i.e. the pathway from the brain motor areas to the muscle but also higher cognitive control. The present work reviews different non-physical interventions that can be used as a complementary approach by asymptomatic or frail older adults, and the effects thereof on functional performance. The use of cognitive training or motor imagery protocols is recommended when physical practice is limited or not possible. Finally, insights into the underlying neurophysiological mechanisms are proposed.

Exercise for Cognitive Symptoms in Depression: A Systematic Review of Interventional Studies

OBJECTIVE

To explore the effect of exercise on cognition in depression as well as the impact of potential moderators and intervention type.

METHOD

Controlled and uncontrolled interventional studies that described an exercise intervention and cognitive outcomes in participants with major depressive disorder (MDD) were included following a search of Pubmed, Ovid Medline, PsycInfo and Embase from inception to January 2017. Meta-analyses were conducted to calculate Hedges' g using a random-effects model. Meta-regression explored the relationships among age, baseline cognition, frequency and duration of exercise, and cognitive outcomes. Subgroup analyses were also conducted according to type and intensity of exercise interventions.

RESULTS

Of 12 controlled studies and 3 uncontrolled studies that met inclusion criteria, 9 (642 patients) were included in the meta-analysis. No significant effect of exercise was found on global cognition (Hedges' g = 0.08, P = 0.33, I2 = 0%) or on individual cognitive domains. Meta-regression analyses failed to find significant relationships among participant age, baseline cognition, number of exercise sessions per wk, duration of exercise per wk, total duration of exercise during the intervention, or improvement in global cognition. Interventions combining physical with cognitive activity significantly improved global cognition ( P = 0.048), whereas low-intensity interventions were also positive ( P = 0.048).

CONCLUSIONS

No impact of physical exercise was found on cognition in MDD overall. However, we found that interventions combining physical and cognitive activities had a positive impact, and that lower-intensity interventions, where adherence was improved, also impacted positively. There remains a lack of high-quality data in this population.

The Efficacy of Cognitive Intervention in Mild Cognitive Impairment (MCI): a Meta-Analysis of Outcomes on Neuropsychological Measures

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; I² = 72.978%; τ² = 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; I² = 5.612; τ² = 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.