Computerized Cognitive Training Enhances Episodic Memory by Down-Modulating Posterior Cingulate-Precuneus Connectivity in Older Persons With Mild Cognitive Impairment: A Randomized Controlled Trial

Effects of virtual reality-based interventions on cognitive function, emotional state, and quality of life in patients with mild cognitive impairment: a meta-analysis

Objectives

This meta-analysis aims to systematically evaluate the effects of virtual reality (VR)-based interventions on cognitive function, emotional state, and quality of life in patients with mild cognitive impairment (MCI).

Methods

A comprehensive literature search was conducted using five databases from their inception to June 2024. The inclusion criteria focused on randomized controlled trials (RCTs) that examined VR-based interventions in adults aged 60 or older diagnosed with MCI. The primary outcome was cognitive function, while secondary outcomes included emotional state, quality of life, and dynamic balance. To investigate potential sources of heterogeneity, subgroup analyses and meta-regression were conducted. Subgroup analyses were stratified by VR parameters (immersion level, duration, session, and frequency) and demographic factors (geographic region, education level, and male proportion). Publication bias was assessed using funnel plots and Egger's regression test. A "trim and fill" method was employed to adjust for any detected publication bias. The certainty of the evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework with the GRADEpro GDT software.

Results

A total of 30 RCTs involving 1,365 participants from 9 countries across 4 continents were included. The meta-analysis revealed that VR-based interventions significantly improved global cognition, as assessed by the Montreal Cognitive Assessment (MoCA; SMD = 0.82, 95% CI: 0.27 to 1.38, p = 0.003, GRADE: moderate) and the Mini-Mental State Examination (MMSE; SMD = 0.83, 95% CI: 0.40 to 1.26, p = 0.0001, GRADE: low). Additionally, VR interventions enhanced attention, as measured by the Digit Span Backward (DSB; SMD = 0.61, 95% CI: 0.21 to 1.02, p = 0.003, GRADE: low) and Digit Span Forward (DSF; SMD = 0.89, 95% CI: 0.34 to 1.45, p = 0.002, GRADE: low). Improvements were also observed in quality of life, as indicated by scores on the Instrumental Activities of Daily Living (IADL; SMD = 0.22, 95% CI: 0.00 to 0.45, p = 0.049, GRADE: moderate). However, no significant effects were found for executive function, memory, verbal fluency, visual abilities, emotional status, or dynamic balance (p > 0.05). Subgroup analysis revealed that VR interventions were more effective when using semi-immersive VR, with session durations of ≤60 min and a frequency of more than twice per week. Participants from Asia and Europe demonstrated better outcomes, and a lower proportion of male participants (≤ 40%) was also associated with improvements in targeted cognitive domains.

Conclusion

The findings indicate that VR interventions can significantly improve global cognition, attention, and quality of life in individuals with MCI. Subgroup analyses further revealed that optimal cognitive outcomes were associated with semi-immersive VR, session durations of ≤60 min, intervention frequencies exceeding twice per week, studies conducted in Asia and Europe, and participant groups with a male proportion of ≤40%. Moreover, the study provides valuable insights into secondary outcomes, suggesting that VR interventions may positively impact emotional state and dynamic balance when appropriately tailored to factors such as immersion level, duration, frequency, and other relevant parameters.

Differential effects of 2 and 4 weeks repetitive transcranial magnetic stimulation inducing neuroplasticity on cognitive improvement

BackgroundRepetitive transcranial magnetic stimulation (rTMS) is an efficient intervention for alleviating cognitive symptoms in Alzheimer's disease (AD), but the optimal treatment duration for high efficacy remains unclear.ObjectiveThis study investigates the effects of 2-week and 4-week rTMS on neural network plasticity and cognitive improvement, aiming to identify the optimal treatment duration for cognitive impairment.MethodsrTMS was administered to cognitively impaired patients over 2-week and 4-week periods, exploring its effects on cognitive improvement and induced neural circuits. The study also examines the predictive value of these neural circuits for individual treatment responses.ResultsThe 4-week rTMS treatment significantly outperformed the 2-week course in improving cognitive function. Neural activity analysis identified the precuneus as a key region for episodic memory. Changes in brain regions, particularly within the default mode network (DMN), visual network (VN), and motor network (MN), were associated with cognitive improvements. Baseline functional connectivity in these regions predicted changes in general cognition (r = 0.724, p < 0.001) and episodic memory (r = 0.447, p = 0.022) after rTMS.ConclusionsExtended rTMS treatment enhances cognitive performance in cognitive impairment patients, with the 4-week course showing superior effects. Reduced connectivity in the DMN following rTMS was linked to cognitive improvements. The neural network baseline can predict patients' treatment responses.

Decreases in frequency-dependent intrinsic activity of the default mode network are associated with depression and cognition in patients with postacute sequelae of SARS-CoV-2 infection

A significant proportion of patients who have recovered from COVID-19 suffer from persistent symptoms, referred to as "post-acute sequelae of SARS-CoV-2 infection (PASC)". Abnormal brain intrinsic activity has been observed in PASC patients, but the patterns of frequency-dependent intrinsic activity in the PASC and non-PASC (recovered COVID-19 patients without persistent symptoms) groups and their association with neuropsychiatric sequelae remain unclear in PASC. Twenty-nine PASC patients, 27 non-PASC subjects, and 31 healthy controls (HCs) were recruited. The voxel-level fractional amplitude of low-frequency fluctuation (fALFF) was calculated in different frequency bands (typical frequency band: 0.01-0.10 Hz; slow 5: 0.01-0.023 Hz; slow 4: 0.023-0.073 Hz) to assess regional intrinsic activity patterns within different groups. Correlation analyses were performed to explore the associations between frequency-dependent alterations and clinical variables. Significant frequency-dependent alterations in intrinsic activity patterns were observed in both the PASC and non-PASC groups, primarily involving regions of the default mode network (DMN). The decreased fALFF values of the DMN in different frequency bands were associated with different symptoms in PASC. For example, decreased fALFF in the left precuneus in the typical frequency band was related to general attention impairment in PASC, whereas decreased fALFF in the left superior frontal gyrus appeared in non-PASC. The fALFF alterations in the left precuneus/posterior cingulate gyrus in the slow 5 band were also related to cognitive performance in PASC. Additionally, in the slow 4 band, decreased fALFF in the right angular gyrus was associated with depressive symptoms in the PASC. Our results may provide insights into the potential neural mechanisms underlying symptoms in PASC patients.

Subgroups of cognitive impairments in schizophrenia characterized by executive function and their morphological features: a latent profile analysis study

BACKGROUND

The heterogeneity of cognitive impairments in schizophrenia has been widely observed. However, reliable cognitive boundaries to differentiate the subgroups remain elusive. The key challenge for cognitive subtyping is applying an integrated and standardized cognitive assessment and understanding the subgroup-specific neurobiological mechanisms. The present study endeavors to explore cognitive subgroups and identify their morphological features.

METHODS

A total of 920 schizophrenia patients and 169 healthy controls were recruited. MATRICS Consensus Cognitive Battery was applied to assess cognitive performance and recognize cognitive subgroups through latent profile and latent transition analysis. Cortical thickness and gray matter volume were employed for the morphological features across subgroups.

RESULTS

Four reproducible cognitive subgroups were identified, including multidomain-intact, executive-preserved, executive-deteriorated, and multidomain-deteriorated subgroup. After 12 weeks of follow-up, the cognitive characteristics of three out of the four subgroups kept stability, except for multidomain-deteriorated subgroup in which 48.8% of patients with improved cognition transited into the executive-deteriorated subgroup. Across subgroups, significant gradient features of brain structure were exhibited in fronto-temporal regions, hippocampus, and insula. Compared to healthy controls, multidomain-intact subgroup showed the most intact cognition and morphology, and multidomain-deteriorated subgroup with youngest age showed morphological decline in extensive regions. The remaining two subgroups showed intermediate cognitive performance, but could be distinguished by executive function and morphological differences in posterior cingulate cortex.

CONCLUSIONS

Our study provides novel insights into the heterogeneity of cognitive impairments in schizophrenia and the morphological features from cross-sectional and longitudinal levels, which could advance our understanding of complex cognition-morphology relationships and guide personalized interventions.

The cognitive effect of non-invasive brain stimulation combined with cognitive training in Alzheimer's disease and mild cognitive impairment: a systematic review and meta-analysis

BACKGROUND

Non-invasive brain stimulation (NIBS) combined with cognitive training (CT) may have shown some prospects on improving cognitive function in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI). However, data from clinical trials or meta-analysis involving NIBS combined with CT have shown controversial results. The aim of this systematic review and meta-analysis was to evaluate short-term and long-term effects of NIBS combined with CT on improving global cognition and other specific cognitive domains in patients with AD and MCI.

METHODS

This systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Five electronic databases including PubMed, Web of Science, EBSCO, Cochrane Library and Embase were searched up from inception to 20 November 2023. The PEDro scale and the Cochrane's risk of bias assessment were used to evaluate risk of bias and methodological quality of included studies. All statistical analyses were conducted with Review Manager 5.3.

RESULTS

We included 15 studies with 685 patients. The PEDro scale was used to assess methodological quality with a mean score of 7.9. The results of meta-analysis showed that NIBS combined with CT was effective on improving global cognition in AD and MCI (SMD = 0.52, 95% CI (0.18, 0.87), p = 0.003), especially for patients accepting repetitive transcranial magnetic stimulation (rTMS) combined with CT (SMD = 0.46, 95% CI (0.14, 0.78), p = 0.005). AD could achieve global cognition improvement from NIBS combined with CT group (SMD = 0.77, 95% CI (0.19, 1.35), p = 0.01). Transcranial direct current stimulation (tDCS) combined with CT could improve language function in AD and MCI (SMD = 0.29, 95% CI (0.03, 0.55), p = 0.03). At evaluation follow-up, rTMS combined with CT exhibited larger therapeutic responses to AD and MCI in global cognition (SMD = 0.55, 95% CI (0.09, 1.02), p = 0.02). AD could achieve global cognition (SMD = 0.40, 95% CI (0.03, 0.77), p = 0.03) and attention/working memory (SMD = 0.72, 95% CI (0.23, 1.20), p = 0.004) improvement after evaluation follow-up from NIBS combined with CT group.

CONCLUSIONS

Overall, NIBS combined with CT, particularly rTMS combined with CT, has both short-term and follow-up effects on improving global cognition, mainly in patients with AD. tDCS combined with CT has advantages on improving language function in AD and MCI. Future more studies need evaluate cognitive effects of NIBS combined with CT on other specific cognitive domain in patients with cognitive deterioration.

Network meta-analysis of the effects of different cognitive trainings on the cognitive function of patients with mild cognitive impairment

OBJECTIVE

Examining the relationship between the responses of a number of different cognitive trainings on cognitive functioning in middle-aged and elderly patients with mild cognitive impairment.

METHODS

Randomized controlled experimental studies published publicly from the time of inception to October 30, 2023 were searched through Web of Science, PubMed, Embase, and Cochrane library databases. Traditional and network meta-analyses were performed using Stata 17.0 software.

RESULTS

Fifty papers on 4 types of cognitive training were included. Traditional meta-analysis showed that virtual reality training (SMD = 0.53, 95%CI: [0.36,0.70], P = 0.00), neuropsychological training (SMD = 0.44, 95%CI: [0.18,0.70], P = 0.00), cognitive strategy training (SMD = 0.26, 95%CI: [0.16,0.36], P = 0.00), and cognitive behavioral therapy (SMD = 0.25, 95%CI: [0.08,0.41], P = 0.00) all had significant improvement effects on the cognitive function of middle-aged and elderly patients with mild cognitive impairment. Network meta-analysis revealed neuropsychological training as the best cognitive training, and subgroup analysis of cognitive function subdimensions showed that neuropsychological training had the best effects on working memory, lobal cognitive function, memory, and cognitive flexibility improvement. Meanwhile, virtual reality training had the best effects on processing speed, verbal ability, overall executive function, spatial cognitive ability, and attention improvement.

CONCLUSION

Cognitive training can significantly improve the cognitive function of middle-aged and elderly patients with mild cognitive impairment, and neuropsychological training is the best intervention, most effective in interventions lasting more than 8 weeks.

Positive affect disrupts neurodegeneration effects on cognitive training plasticity in older adults

Cognitive training for older adults varies in efficacy, but it is unclear why some older adults benefit more than others. Positive affective experience (PAE), referring to high positive valence and/or stable arousal states across everyday scenarios, and associated functional networks can protect plasticity mechanisms against Alzheimer's disease neurodegeneration, which may contribute to training outcome variability. The objective of this study is to investigate whether PAE explains variability in cognitive training outcomes by disrupting the adverse effect of neurodegeneration on plasticity. The study's design is a secondary analysis of a randomized control trial of cognitive training with concurrent real or sham brain stimulation (39 older adults with mild cognitive impairment; mean age, 71). Moderation analyses, with change in episodic memory or executive function as the outcome, PAE or baseline resting-state connectivity as the moderator and baseline neurodegeneration as the predictor are the methods used in the study. The result of the study is that PAE stability and baseline default mode network (DMN) connectivity disrupted the effect of neurodegeneration on plasticity in executive function but not episodic memory. The study concludes that PAE stability and degree of DMN integrity both explained cognitive training outcome variability, by reducing the adverse effect of neurodegeneration on cognitive plasticity. We highlight the need to account for PAE, brain aging factors and their interactions with plasticity in cognitive training.

Computerized cognitive training for memory functions in mild cognitive impairment or dementia: a systematic review and meta-analysis

Dementia is a common medical condition in the ageing population, and cognitive intervention is a non-pharmacologic strategy to improve cognitive functions. This meta-analysis evaluated the benefits of computerized cognitive training (CCT) on memory functions in individuals with MCI or dementia. The study was registered prospectively with PROSPERO under CRD42022363715 and received no funding. The search was conducted on MEDLINE, Embase, and PsycINFO on Sept 19, 2022, and Google Scholar on May 9, 2023, to identify randomized controlled trials that examined the effects of CCT on memory outcomes in individuals with MCI or dementia. Mean differences and standard deviations of neuropsychological assessment scores were extracted to derive standardized mean differences. Our search identified 10,678 studies, of which 35 studies were included. Among 1489 participants with MCI, CCT showed improvements in verbal memory (SMD (95%CI) = 0.55 (0.35-0.74)), visual memory (0.36 (0.12-0.60)), and working memory (0.37 (0.10-0.64)). Supervised CCT showed improvements in verbal memory (0.72 (0.45-0.98)), visual memory (0.51 (0.22-0.79)), and working memory (0.33 (0.01-0.66)). Unsupervised CCT showed improvement in verbal memory (0.21 (0.04-0.38)) only. Among 371 participants with dementia, CCT showed improvement in verbal memory (0.64 (0.02-1.27)) only. Inconsistency due to heterogeneity (as indicated by I2 values) is observed, which reduces our confidence in MCI outcomes to a moderate level and dementia outcomes to a low level. The results suggest that CCT is efficacious on various memory domains in individuals with MCI. Although the supervised approach showed greater effects, the unsupervised approach can improve verbal memory while allowing users to receive CCT at home without engaging as many healthcare resources.

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.