Testing the Benefits of Cognitive Training vs. Cognitive Stimulation in Mild Alzheimer's Disease: A Randomised Controlled Trial

The efficacy of cognitive stimulation, cognitive training, and cognitive rehabilitation for people living with dementia: a systematic review and meta-analysis

Cognition-oriented treatments (COTs) are a group of non-pharmacological treatments aimed at maintaining or improving cognitive functioning. Specific recommendations on the use of these interventions in people living with dementia (PLwD) are included in the Italian Guideline on the Diagnosis and Treatment of Dementia and Mild Cognitive Impairment, developed by the Italian National Institute of Health. This systematic review and meta-analysis, based on the GRADE methodology, is part of the guideline. Considered outcomes included the cognitive functions, quality of life, and functional abilities of PLwD, taking into account disease severity, modality and system of delivery, and form of the intervention. The effectiveness of these interventions on caregivers' outcomes was also assessed. Both group and individual cognitive stimulation were reported as effective in supporting cognitive functions in PLwD at any degree of severity. Individual cognitive training and group cognitive training were reported as effective in improving global cognitive functions in people with mild dementia. Cognitive rehabilitation appeared to be effective only in improving the functional abilities of people with mild dementia. Cognitive rehabilitation appeared to be the most effective in improving caregivers' outcomes, with results suggesting a reduction in care burden. The observed differences in the effectiveness of these interventions in people with different disease severity can be explained by the intrinsic characteristics of each intervention. Despite the large number of available studies, a high clinical, statistical, and methodological heterogeneity was observed. More methodologically rigorous studies are needed to clarify the effectiveness of each protocol and modality of intervention.

Effects of home-based interventions on cognitive performance in patients with dementia: A systematic review and meta-analysis

BACKGROUND

With increasing age, dementia is a common disease in the elderly population，especially Alzheimer's disease. Owing to the nature of the disease, the function of patients deteriorates, which places a heavy burden on the country and family. Home-based training programs have been shown to improve cognitive function in patients with dementia.

OBJECTIVE

To examine the effects and methods of home-based interventions on the cognitive performance of patients with dementia.

METHODS

This systematic review and meta-analysis was conducted on the basis of the PRISMA statement. This protocol was registered in advance at PROSPERO (CRD42021277269). Six English electronic databases, including PubMed, EMBASE, the Cochrane Library, Web of Science, SCOPUS, and OTseeker, were searched and updated to January 31, 2024. Two researchers independently completed the literature retrieval and data extraction. RevMan 5.3 software was used to analyze the data. The standardized mean difference and the 95% confidence interval were used for statistical analysis. Subgroup analyses were performed by assessment tools, intervention duration and intervention methods.

RESULTS

Twenty randomized controlled trials with 3543 participants were included in the qualitative synthesis, and 17 studies were included in the meta-analysis. Compared with the control intervention, the home-based intervention significantly improved cognitive performance (SMD = 0.45; 95% CI = [0.17, 0.74]; p = 0.002).

CONCLUSIONS

Moderate to high evidence shows that home-based interventions significantly improve the cognitive performance of patients with dementia, especially their comprehensive cognitive function.

Cognition-oriented treatments and physical exercise on cognitive function in Huntington's disease: a systematic review

Cognitive impairment is prevalent in Huntington's disease (HD), with no treatments currently available. While cognition-oriented treatments and physical exercise have shown efficacy in improving cognition in other populations, they have not been systematically reviewed in HD. This systematic review aims to examine the effects of cognitive and exercise interventions on cognition in HD, along with effects on psychosocial function, functional independence, and neuroimaging outcomes. Seventeen studies (three cognitive, seven exercise, seven combining cognitive and physical exercise) were included. While there was generally low certainty of evidence, interventions that included cognitive training appeared to have larger effect sizes on cognition, while physical exercise (alone or combined with cognitive rehabilitation or stimulation) showed negligible effect sizes. On the other hand, combined interventions had larger effects on psychosocial function. Finally, effects on functional independence appeared negligible following exercise and combined interventions, and effects on neuroimaging outcomes were inconclusive. Larger studies should seek to confirm the benefits of cognitive and physical interventions, and further explore changes in functional independence and neural outcomes.

Effectiveness of non-pharmacological therapies on cognitive function in patients with dementia-A network meta-analysis of randomized controlled trials

Objective

Non-pharmacological therapies (NPTs) have received increasing attention from researchers as a category of treatment to improve cognitive impairment in patients with dementia because of their fewer side effects. In this study, photobiomodulation (PBM), enriched environment (EE), exercise therapy (ET), computerized cognitive training (CCT), and cognitive stimulation therapy (CST) were selected to compare the effects of NPTs that improve dementia by quantifying information from randomized controlled trials (RCTs).

Methods

We did a systematic review and network meta-analysis. We searched PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), China National Knowledge Infrastructure Database, Wan Fang Database, Chinese Biomedical Literature Database, Web of Science, and VIP Database from the time of database creation to 1 August 2022. Two investigators independently screened the literature, extracted information, and assessed the RCTs' quality with the Cochrane Collaboration Network Risk of Bias 2.0. Network meta-analysis was performed using R language (X64 version 4.1.3) and STATA 17.0.

Results

We identified 1,268 citations and of these included 38 trials comprising 3,412 participants. For improving dementia, the results of the network meta-analysis showed that compared with the control group (CON), PBM (SMD = 0.90, 95% CI: 0.43-1.37), EE (SMD = 0.71, 95% CI: 0.02-1.41), ET (SMD = 0.42, 95% CI: 0.16-0.68), and CST (SMD = 0.36, 95% CI: 0.11-0.62) were significantly different (P < 0.05); There was no significant difference in CCT (SMD = 0.41, 95% CI: -0.07-0.88) (P > 0.05). The ranked results showed that PBM has more potential to be the best intervention (P = 0.90). In addition, there was a significant difference between PBM and CST in improving cognitive function (SMD = 0.54, 95% CI: 0.00; 1.08, P < 0.05).

Conclusion

In this study, NPTs have excellent potential to improve cognition in people with dementia, and PBM may have more significant benefits in improving cognition than the other four NPTs.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42022363746.

Cognitive stimulation to improve cognitive functioning in people with dementia

BACKGROUND

Cognitive stimulation (CS) is an intervention for people with dementia offering a range of enjoyable activities providing general stimulation for thinking, concentration and memory, usually in a social setting, such as a small group. CS is distinguished from other approaches such as cognitive training and cognitive rehabilitation by its broad focus and social elements, aiming to improve domains such as quality of life (QoL) and mood as well as cognitive function. Recommended in various guidelines and widely implemented internationally, questions remain regarding different modes of delivery and the clinical significance of any benefits. A systematic review of CS is important to clarify its effectiveness and place practice recommendations on a sound evidence base. This review was last updated in 2012.

OBJECTIVES

To evaluate the evidence for the effectiveness of CS for people with dementia, including any negative effects, on cognition and other relevant outcomes, accounting where possible for differences in its implementation.

SEARCH METHODS

We identified trials from a search of the Cochrane Dementia and Cognitive Improvement Group Specialized Register, last searched on 3 March 2022. We used the search terms: cognitive stimulation, reality orientation, memory therapy, memory groups, memory support, memory stimulation, global stimulation, cognitive psychostimulation. We performed supplementary searches in a number of major healthcare databases and trial registers to ensure the search was up-to-date and comprehensive.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) of CS for dementia published in peer review journals in the English language incorporating a measure of cognitive change.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. As CS is a psychosocial intervention, we did not expect those receiving or delivering CS to be blinded to the nature of the intervention. Where necessary, we contacted study authors requesting data not provided in the papers. Where appropriate, we undertook subgroup analysis by modality (individual versus group), number of sessions and frequency, setting (community versus care home), type of control condition and dementia severity. We used GRADE methods to assess the overall quality of evidence for each outcome.

MAIN RESULTS

We included 37 RCTs (with 2766 participants), 26 published since the previous update. Most evaluated CS groups; eight examined individual CS. Participants' median age was 79.7 years. Sixteen studies included participants resident in care homes or hospitals. Study quality showed indications of improvement since the previous review, with few areas of high risk of bias. Assessors were clearly blinded to treatment allocation in most studies (81%) and most studies (81%) reported use of a treatment manual by those delivering the intervention. However, in a substantial number of studies (59%), we could not find details on all aspects of the randomisation procedures, leading us to rate the risk of selection bias as unclear. We entered data in the meta-analyses from 36 studies (2704 participants; CS: 1432, controls: 1272). The primary analysis was on changes evident immediately following the treatment period (median length 10 weeks; range 4 to 52 weeks). Only eight studies provided data allowing evaluation of whether effects were subsequently maintained (four at 6- to 12-week follow-up; four at 8- to 12-month follow-up). No negative effects were reported. Overall, we found moderate-quality evidence for a small benefit in cognition associated with CS (standardised mean difference (SMD) 0.40, 95% CI 0.25 to 0.55). In the 25 studies, with 1893 participants, reporting the widely used MMSE (Mini-Mental State Examination) test for cognitive function in dementia, there was moderate-quality evidence of a clinically important difference of 1.99 points between CS and controls (95% CI: 1.24, 2.74). In secondary analyses, with smaller total sample sizes, again examining the difference between CS and controls on changes immediately following the intervention period, we found moderate-quality evidence of a slight improvement in self-reported QoL (18 studies, 1584 participants; SMD: 0.25 [95% CI: 0.07, 0.42]) as well as in QoL ratings made by proxies (staff or caregivers). We found high-quality evidence for clinically relevant improvements in staff/interviewer ratings of communication and social interaction (5 studies, 702 participants; SMD: 0.53 [95% CI: 0.36, 0.70]) and for slight benefits in instrumental Activities of Daily Living, self-reported depressed mood, staff/interviewer-rated anxiety and general behaviour rating scales. We found moderate-quality evidence for slight improvements in behaviour that challenges and in basic Activities of Daily Living and low-quality evidence for a slight improvement in staff/interviewer-rated depressed mood. A few studies reported a range of outcomes for family caregivers. We found moderate-quality evidence that overall CS made little or no difference to caregivers' mood or anxiety. We found a high level of inconsistency between studies in relation to both cognitive outcomes and QoL. In exploratory subgroup analyses, we did not identify an effect of modality (group versus individual) or, for group studies, of setting (community versus care home), total number of group sessions or type of control condition (treatment-as-usual versus active controls). However, we did find improvements in cognition were larger where group sessions were more frequent (twice weekly or more versus once weekly) and where average severity of dementia among participants at the start of the intervention was 'mild' rather than 'moderate'. Imbalance in numbers of studies and participants between subgroups and residual inconsistency requires these exploratory findings to be interpreted cautiously.

AUTHORS' CONCLUSIONS

In this updated review, now with a much more extensive evidence base, we have again identified small, short-term cognitive benefits for people with mild to moderate dementia participating in CS programmes. From a smaller number of studies, we have also found clinically relevant improvements in communication and social interaction and slight benefits in a range of outcomes including QoL, mood and behaviour that challenges. There are relatively few studies of individual CS, and further research is needed to delineate the effectiveness of different delivery methods (including digital and remote, individual and group) and of multi-component programmes. We have identified that the frequency of group sessions and level of dementia severity may influence the outcomes of CS, and these aspects should be studied further. There remains an evidence gap in relation to the potential benefits of longer-term CS programmes and their clinical significance.

Phytochemical Compounds and Nanoparticles as Phytochemical Delivery Systems for Alzheimer's Disease Management

Alzheimer's disease remains one of the most widespread neurodegenerative reasons for dementia worldwide and is associated with considerable mortality and morbidity. Therefore, it has been considered a priority for research. Indeed, several risk factors are involved in the complexity of the therapeutic ways of this pathology, including age, traumatic brain injury, genetics, exposure to aluminum, infections, diabetes, vascular diseases, hypertension, dyslipidemia, and obesity. The pathophysiology of Alzheimer's disease is mostly associated with hyperphosphorylated protein in the neuronal cytoplasm and extracellular plaques of the insoluble β-amyloid peptide. Therefore, the management of this pathology needs the screening of drugs targeting different pathological levels, such as acetylcholinesterase (AchE), amyloid β formation, and lipoxygenase inhibitors. Among the pharmacological strategies used for the management of Alzheimer's disease, natural drugs are considered a promising therapeutic strategy. Indeed, bioactive compounds isolated from different natural sources exhibit important anti-Alzheimer effects by their effectiveness in promoting neuroplasticity and protecting against neurodegeneration as well as neuroinflammation and oxidative stress in the brain. These effects involve different sub-cellular, cellular, and/or molecular mechanisms, such as the inhibition of acetylcholinesterase (AchE), the modulation of signaling pathways, and the inhibition of oxidative stress. Moreover, some nanoparticles were recently used as phytochemical delivery systems to improve the effects of phytochemical compounds against Alzheimer's disease. Therefore, the present work aims to provide a comprehensive overview of the key advances concerning nano-drug delivery applications of phytochemicals for Alzheimer's disease management.

The Effect of Multimodal Non-pharmacological Interventions on Cognitive Function Improvement for People With Dementia: A Systematic Review

Introduction

Dementia is a progressive brain degeneration characterized by a progressive deterioration in cognition and independent living capacity. Since dementia is a complex syndrome, multimodal non-pharmacological interventions (MNPIs) are highly recommended. Currently, there is less available evidence to describe the content, length, and frequency of multimodal interventions for cognitive function improvement for people with dementia (PWD).

Method

A comprehensive search was performed in PubMed, EMBASE, CINAHL, Web of Science, and Medline international databases. The quality appraisal of the studies was done by the Cochrane risk of bias assessment tools.

Results

A total of 19 controlled trial studies were included. Most of the included studies reported that MNPIs resulted in improvement, stability, or attenuation of decline in cognitive function of PWD. The reported effectiveness of MNPIs on cognitive function ranged from medium (0.29 Cohen's d) to large (2.02 Cohen's d) effect sizes. The median duration of intervention was 12 weeks for a 1-h session.

Conclusion

This systematic review showed that MNPIs might improve people's cognitive functions for PWD. Physical exercise, music, and cognitive interventions were used in the content of multimodal interventions in a majority of the studies. Therefore, high-quality randomized controlled trial (RCT) studies with repeated-measured design on the combined effect of physical exercise, music, and cognitive intervention on cognitive function for PWD are recommended.

Systematic Review Registration

http://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42020222065.

Cognitive Stimulation in Moderate Alzheimer's Disease

Cognitive stimulation is one of the non-pharmacological therapies recommended for dementia intervention. The present study evaluated the efficacy of an intervention based on cognitive stimulation in people with moderate Alzheimer's disease. Fifty-nine subjects with moderate dementia were randomly assigned to the stimulation group (N = 36) and the control group (N = 35). The treatment group received 16 intervention sessions cognitive tasks. All participants were evaluated with a battery of neuropsychological tests at three time points (pre, post, and follow-up). The treatment group showed significant increases in the three domains studied (memory, attention, and executive functions), although some of these effects were not maintained at follow-up. The control group progressively worsened. Cognitive stimulation was found to be an effective intervention for people with moderate Alzheimer's disease because it helped to maintain memory function, executive functions, and attention. However, the effects were minimized at the 3-month follow-up.

Prospective Memory Training in Older Adults: A Systematic Review and Meta-Analysis

Prospective memory (PM), which enables one to remember to carry out delayed intentions, is crucial for everyday functioning. PM commonly deteriorates upon cognitive decline in older adults, but several studies have shown that PM in older adults can be improved by training. The current study aimed to summarise this evidence by conducting a qualitative systematic analysis and quantitative meta-analysis of the effects of PM training in older adults, for which systematic searches were conducted across seven databases (Cochrane Library, Embase, PubMed, PsycInfo, Web of Science, CINAHL and Scopus). Forty-eight studies were included in the qualitative analysis, and 43% of the assessed PM training interventions showed positive gains in enhancing PM. However, the methodological quality varied across the studies, with 41% of the non-randomised control trials (non-RCTs) rated as having either serious or critical risk of bias. Therefore, only 29 RCTs were included in the subsequent quantitative meta-analysis. We found a significant and moderate immediate efficacy (Hedges' g = 0.54) of PM training in enhancing PM performance in older adults, but no significant long-term efficacy (Hedges' g = 0.21). Two subgroup analyses also revealed a robust training efficacy across the study population (i.e., healthy and clinical population) and the number of training sessions (i.e., single session and programme-based). Overall, this study provided positive evidence to support PM training in older adults. Further studies are warranted to explore the mechanisms by which PM training exerts its effects, and better-quality RCTs are needed to provide more robust evidence supporting our findings.

A Systematic Review of Prospective Memory Interventions Across Stages of Dementia-Related Disorders

BACKGROUND

There is a critical need to develop effective interventions for cognitive impairments associated with dementia-related disorders (i.e., Alzheimer's disease, frontotemporal dementia, mild cognitive impairment). Prospective memory (PM), or the ability to create and carry out future intentions, is one cognitive domain that is impaired in individuals with dementia-related disorders. Effective treatment of PM could significantly improve daily functioning, level of independence, and quality of life.

OBJECTIVE

To date, there have been a number of studies investigating potential interventions, but these interventions have not been comprehensively reviewed and compared across the stages of dementia-related disorders, as is the aim of the current review.

METHODS

This review examined 21 studies on the success of intervention strategies for prospective memory in patients with dementia-related disorders.

RESULTS

All the studies demonstrated positive effects of intervention on PM abilities, but there are questions concerning ecological validity, length of positive effects on PM, and a lack of diversity of interventions across the different stages of dementia-related disorders.

CONCLUSION

Future research should address these issues by incorporating daily functioning activities and caregiver support into the intervention process, as well as investigating these interventions at more severe stages of dementia-related disorders.

Outcomes tested in non-pharmacological interventions in mild cognitive impairment and mild dementia: a scoping review

OBJECTIVES

Non-pharmacological treatments are an important aspect of dementia care. A wide range of interventions have been trialled for mild dementia and mild cognitive impairment (MCI). However, the variety of outcome measures used in these trials makes it difficult to make meaningful comparisons. The objective of this study is to map trends in which outcome measures are used in trials of non-pharmacological treatments in MCI and mild dementia.

DESIGN

Scoping review.

DATA SOURCES

EMBASE, PsychINFO, Medline and the Cochrane Register of Controlled Trials were searched from inception until February 2018. An additional search was conducted in April 2019 ELIGIBILITY: We included randomised controlled trials (RCTs) testing non-pharmacological interventions for people diagnosed with MCI or mild dementia. Studies were restricted to full RCTs; observational, feasibility and pilot studies were not included.

CHARTING METHODS

All outcome measures used by included studies were extracted and grouped thematically. Trends in the types of outcome measures used were explored by type of intervention, country and year of publication.

RESULTS

91 studies were included in this review. We extracted 358 individual outcome measures, of which 78 (22%) were used more than once. Cognitive measures were the most frequently used, with the Mini-Mental State Examination being the most popular.

CONCLUSIONS

Our findings highlight an inconsistency in the use of outcome measures. Cognition has been prioritised over other domains, despite previous research highlighting the importance of quality of life and caregiver measures. To ensure a robust evidence base, more research is needed to highlight which outcome measures should be used over others.

PROSPERO REGISTRATION NUMBER

CRD42018102649.

Technologies for Cognitive Training and Cognitive Rehabilitation for People With Mild Cognitive Impairment and Dementia. A Systematic Review

Due to the growing number of older adults with cognitive impairment, it is essential to delay the onset and progression of cognitive decline and promote a healthy lifestyle. The rapid growth of technology has considerably advanced the field of computerized cognitive interventions. Consequently, traditional cognitive interventions are being adapted and new multimedia systems are being developed to encourage health and independent living in old age. The primary objective of this review was to identify cognitive stimulation, training and rehabilitation programs aimed at older people with mild cognitive impairment (MCI) and dementia. PsycINFO, Medline, CINAHL, Web of Science, PubMed, and CORDIS databases were searched from January 2008 to August 2018. Two researchers reviewed the potential studies individually for eligibility. Studies of computerized cognitive interventions for people with dementia and cognitive impairment were included if they clearly described objectives, users and functioning. A systematic review of the studies was carried out, providing a qualitative synthesis of the features and study characteristics of each software. Nineteen studies met the inclusion criteria, and 11 different cognitive stimulation, training, and rehabilitation programs were identified. The studies found on cognitive intervention software indicate the existence of various technological programs for people with MCI and dementia. On the overall, the programs were aimed at people with different clinical conditions, able to create specific treatments and personalized training, optimized for portable devices, and user-friendly. However, the selected programs differ from each other in terms of objectives, usage mode and characteristics, even if they were used for the same purposes. Therefore, the information obtained in the review may be relevant to distinguish between programs and select the one that best suits each user. Thus, more information about the features and context of use is needed as well as more clinical studies to be able to compare among computerized cognitive programs.

Screening for Cognitive Impairment in Older Adults: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force

IMPORTANCE

Early identification of cognitive impairment may improve patient and caregiver health outcomes.

OBJECTIVE

To systematically review the test accuracy of cognitive screening instruments and benefits and harms of interventions to treat cognitive impairment in older adults (≥65 years) to inform the US Preventive Services Task Force.

DATA SOURCES

MEDLINE, PubMed, PsycINFO, and Cochrane Central Register of Controlled Trials through January 2019, with literature surveillance through November 22, 2019.

STUDY SELECTION

Fair- to good-quality English-language studies of cognitive impairment screening instruments, and pharmacologic and nonpharmacologic treatments aimed at persons with mild cognitive impairment (MCI), mild to moderate dementia, or their caregivers.

DATA EXTRACTION AND SYNTHESIS

Independent critical appraisal and data abstraction; random-effects meta-analyses and qualitative synthesis.

MAIN OUTCOMES AND MEASURES

Sensitivity, specificity; patient, caregiver, and clinician decision-making; patient function, quality of life, and neuropsychiatric symptoms; caregiver burden and well-being.

RESULTS

The review included 287 studies with more than 280 000 older adults. One randomized clinical trial (RCT) (n = 4005) examined the direct effect of screening for cognitive impairment on patient outcomes, including potential harms, finding no significant differences in health-related quality of life at 12 months (effect size, 0.009 [95% CI, -0.063 to 0.080]). Fifty-nine studies (n = 38 531) addressed the accuracy of 49 screening instruments to detect cognitive impairment. The Mini-Mental State Examination was the most-studied instrument, with a pooled sensitivity of 0.89 (95% CI, 0.85 to 0.92) and specificity of 0.89 (95% CI, 0.85 to 0.93) to detect dementia using a cutoff of 23 or less or 24 or less (15 studies, n = 12 796). Two hundred twenty-four RCTs and 3 observational studies including more than 240 000 patients or caregivers addressed the treatment of MCI or mild to moderate dementia. None of the treatment trials were linked with a screening program; in all cases, participants were persons with known cognitive impairment. Medications approved to treat Alzheimer disease (donepezil, galantamine, rivastigmine, and memantine) improved scores on the ADAS-Cog 11 by 1 to 2.5 points over 3 months to 3 years. Psychoeducation interventions for caregivers resulted in a small benefit for caregiver burden (standardized mean difference, -0.24 [95% CI, -0.36 to -0.13) over 3 to 12 months. Intervention benefits were small and of uncertain clinical importance.

CONCLUSIONS AND RELEVANCE

Screening instruments can adequately detect cognitive impairment. There is no empirical evidence, however, that screening for cognitive impairment improves patient or caregiver outcomes or causes harm. It remains unclear whether interventions for patients or caregivers provide clinically important benefits for older adults with earlier detected cognitive impairment or their caregivers.

Psychosocial Interventions for Community-Dwelling People Following Diagnosis of Mild to Moderate Dementia: Findings of a Systematic Scoping Review

National policies and evidence reviews recommend psychosocial interventions (PIs) as an essential support, particularly in the period following dementia diagnosis. However, availability and uptake of these interventions are comparatively low. One of the reasons for this is that clinicians lack information about what might be provided and the potential benefits of different interventions. This article identifies and describes PIs for community-dwelling people following diagnosis of mild to moderate dementia and presents the available evidence to inform practice decisions. A systematic scoping review was employed to map the evidence relating to PIs for this group. This identified 63 relevant studies, testing 69 interventions, which could be grouped into 6 intervention categories: 20 cognition-oriented, 11 behavior-oriented, 11 stimulation-oriented, 13 emotion-oriented, 5 social-oriented, and 9 multimodal. There were three targets for outcome measurement of these PIs: the person with dementia, the family caregiver, and the person-caregiver dyad. Over 154 outcome measures were identified in the studies, with outcomes measured across 11 main domains. The lack of a classification framework for PIs means it is difficult to create a meaningful synthesis of the breadth of relevant evidence to guide clinical practice. Possible dimensions of a classification framework are proposed to begin to address this gap.

Cognitive training for people with mild to moderate dementia

BACKGROUND

Cognitive impairment, a defining feature of dementia, plays an important role in the compromised functional independence that characterises the condition. Cognitive training (CT) is an approach that uses guided practice on structured tasks with the direct aim of improving or maintaining cognitive abilities.

OBJECTIVES

• To assess effects of CT on cognitive and non-cognitive outcomes for people with mild to moderate dementia and their caregivers.• To compare effects of CT with those of other non-pharmacological interventions, including cognitive stimulation or rehabilitation, for people with mild to moderate dementia and their caregivers.• To identify and explore factors related to intervention and trial design that may be associated with the efficacy of CT for people with mild to moderate dementia and their caregivers.

SEARCH METHODS

We searched ALOIS, the Cochrane Dementia and Cognitive Improvement Group Specialised Register, on 5 July 2018. ALOIS contains records of clinical trials identified through monthly searches of several major healthcare databases and numerous trial registries and grey literature sources. In addition to this, we searched MEDLINE, Embase, PsycINFO, CINAHL, LILACS, Web of Science Core Collection, ClinicalTrials.gov, and the World Health Organization's trials portal, ICTRP, to ensure that searches were comprehensive and up-to-date.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that described interventions for people with mild to moderate dementia and compared CT versus a control or alternative intervention.

DATA COLLECTION AND ANALYSIS

We extracted relevant data from published manuscripts and through contact with trial authors if required. We assessed risk of bias using the Cochrane 'Risk of bias' tool. We divided comparison conditions into active or passive control conditions and alternative treatments. We used a large number of measures and data to evaluate 19 outcomes at end of treatment, as well as 16 outcomes at follow-up in the medium term; we pooled this information in meta-analyses. We calculated pooled estimates of treatment effect using a random-effects model, and we estimated statistical heterogeneity using a standard Chi² statistic. We graded the evidence using GradePro.

MAIN RESULTS

The 33 included trials were published between 1988 and 2018 and were conducted in 12 countries; most were unregistered, parallel-group, single-site RCTs, with samples ranging from 12 to 653 participants. Interventions were between two and 104 weeks long. We classified most experimental interventions as 'straight CT', but we classified some as 'augmented CT', and about two-thirds as multi-domain interventions. Researchers investigated 18 passive and 13 active control conditions, along with 15 alternative treatment conditions, including occupational therapy, mindfulness, reminiscence therapy, and others.The methodological quality of studies varied, but we rated nearly all studies as having high or unclear risk of selection bias due to lack of allocation concealment, and high or unclear risk of performance bias due to lack of blinding of participants and personnel.We used data from 32 studies in the meta-analysis of at least one outcome. Relative to a control condition, we found moderate-quality evidence showing a small to moderate effect of CT on our first primary outcome, composite measure of global cognition at end of treatment (standardised mean difference (SMD) 0.42, 95% confidence interval (CI) 0.23 to 0.62), and high-quality evidence showing a moderate effect on the secondary outcome of verbal semantic fluency (SMD 0.52, 95% CI 0.23 to 0.81) at end of treatment, with these gains retained in the medium term (3 to 12 months post treatment). In relation to many other outcomes, including our second primary outcome of clinical disease severity in the medium term, the quality of evidence was very low, so we were unable to determine whether CT was associated with any meaningful gains.When compared with an alternative treatment, we found that CT may have little to no effect on our first primary outcome of global cognition at end of treatment (SMD 0.21, 95% CI -0.23 to 0.64), but the quality of evidence was low. No evidence was available to assess our second primary outcome of clinical disease severity in the medium term. We found moderate-quality evidence showing that CT was associated with improved mood of the caregiver at end of treatment, but this was based on a single trial. The quality of evidence in relation to many other outcomes at end of treatment and in the medium term was too low for us to determine whether CT was associated with any gains, but we are moderately confident that CT did not lead to any gains in mood, behavioural and psychological symptoms, or capacity to perform activities of daily living.

AUTHORS' CONCLUSIONS

Relative to a control intervention, but not to a variety of alternative treatments, CT is probably associated with small to moderate positive effects on global cognition and verbal semantic fluency at end of treatment, and these benefits appear to be maintained in the medium term. Our certainty in relation to many of these findings is low or very low. Future studies should take stronger measures to mitigate well-established risks of bias, and should provide long-term follow-up to improve our understanding of the extent to which observed gains are retained. Future trials should also focus on direct comparison of CT versus alternative treatments rather than passive or active control conditions.