Cognitive intervention was reported to be the most promising one that can preserve cognitive function and help to maintain quality of life and independence well into old age. However there is not a comprehensive literature on the effects of cognitive intervention on cognition in generally healthy elderly persons to find when is the optimal stage.
Searches
We will conduct a systematic literature search of the major English and Chinese healthcare databases as indicated below: English databases including PubMed/MEDLINE, EMBASE, Web of science, OVID, PsycINFO, CINAHL, LILACS and ALOIS (www.medicine.ox.ac.uk/alois), the Cochrane Dementia and Cognitive Improvement Group Specialized Register; Chinese databases including Chinese Biomedical Database (CBM), China National Knowledge Infrastructure/Chinese Academic Journals full-text Database (CNKI), VIP (a full-text database of Chinese journals) and Wanfang Data. To get comprehensive literature collection, we will also search the reference lists in those published articles. All the published papers written in English and Chinese before the search day meet the search strategy will be collected for further review.
Types of study to be included
This review will focus on randomized controlled trials (RCTs) for which adequate information was provided or could be obtained from the researchers. The studies included must have been published, written in English or Chinese, and presented in a peer-reviewed journal article.
Condition or domain being studied
Nowadays there is no cure for the major aging related disease such as stroke, Alzheimer's disease (AD) and Parkinson’s disease (PD). Moreover, compliance to drug treatments is limited by possible adverse effects. Besides, nearly all the patients relied on long-term rehabilitation, which would cost major part of the social and public health sources with the cost of care in many developed countries already outstripping those associated with cardiovascular disease and cancer combined. It’s estimated that if onset of AD is delayed by 5 years, the overall prevalence rate would reduce by 50%, and by 10 years would reduce by 75% [3], profoundly reducing caregiver burden and institutional care and enhancing quality of life. Thus, the most promising avenues of intervention now lie in prevention. As cognitive deterioration is a core symptom of many neuropsychiatric disorders and target of increasing significance for novel treatment strategies, thus, the worldwide expanding aging population leads to an urgent need for development of strategies for interventions in a normal aging population to delay onset and slow progression from healthy elderly to mild cognitive impairment (MCI) and from MCI to AD. Among which, cognitive intervention was reported to be the most promising one that can preserve cognitive function and help to maintain quality of life and independence well into old age.
References
[1]. Hohmann C, Neumann-Haefelin T, Klotz JM, Freidank A, Radziwill R. Drug-related problems in patients with ischemic stroke in hospital. Int J Clin Pharm.
[2]. Wimo A, Winblad B, Jonsson L. The worldwide societal costs of dementia: Estimates for 2009. Alzheimers Dement. 6: 98-103.
[3]. Thal LJ, Carta A, Doody R, et al. Prevention protocols for Alzheimer disease. Position paper from the International Working Group on Harmonization of Dementia Drug Guidelines. Alzheimer Dis Assoc Disord. 1997 11 Suppl 3: 46-49.
Participants/ population
To be included in the present review, the mean age of participants (both male and female) have to be community dwelling healthy elderly, on average, at least 50 years of age at the time of training. Participants will be excluded if they were diagnosed with mild cognitive impairment, Alzheimer’s disease or some other neurodegenerative disease.
Intervention(s), exposure(s)
Studies will only be included in the review if the interventions they adopted meet the following criteria: (1) they recorded participants’ performance at least at two time points (before and after the training); (2) any setting (group and individual) of cognitive intervention; (3) with any type of control group (wait-list control or active control); (4)duration of intervention was up to at least one month, with at least a baseline and a post-intervention assessment reported. There will be no restrictions on the number of treatment sessions, although this was noted.
Comparator(s)/ control
any type of control group (wait-list control or active control) will be included.
Outcome(s)
Primary outcomes
The changes relevant to general enhancement of cognitive functioning, or increased or maintained particular cognitive functions will be considered as primary outcome measures. Any measures of cognitive functioning, improvement, sustainability and transfer of training effects will be compared before and after cognitive intervention.
Secondary outcomes
Outcome variables such as well-being, quality of life, mental health, caregiver burden and everyday functioning will be considered as secondary outcome measures. Short term (immediately after the intervention completed), medium term (follow-up one month to one year after the intervention completed) and long term (follow-up more than one year after the intervention completed) outcomes will be considered.
Risk of bias (quality) assessment
All the selected RCTs are described in tabular form, permitting an evaluation of their methodological quality. Studies are assessed against a checklist of quality requirements described in the Cochrane Reviewers’ Handbook (see risk of bias tables).Grading of recommendation, assessment, development, and evaluation (GRADE) method was used to core the literature, transform it into level of evidence and develop these evidence-based recommendations. This grading scheme classifies recommendations as either strong recommendations or weak suggestions. The quality of evidence was further classified as high (grade A), moderate (grade B), or low (grade C) according to the study design, consistency of results and directness of the evidence. Only trials with a grade A or B ranking were included in the review.
Strategy for data synthesis
Data from the RCTs selected for inclusion was extracted, recorded and entered into RevMan 5.1 software. The summary statistics required for each trial and each outcome for continuous data are the mean change from baseline, the standard deviation of the mean change, and the number of patients for each treatment group at each assessment. Where changes from baseline were not reported, the mean, standard deviation and the number of people in each treatment group
We pooled studies with sufficient data, judged to be clinically homogeneous, using RevMan 5.1 software. The meta-analyses included the combination of data from trials that may not use the same rating scale to assess an outcome. Therefore, the measure of the treatment difference for any outcome used was the weighted mean difference when the pooled trials used the same rating scale or test and the standardised mean difference (the absolute mean difference divided by the standard deviation) when they used different rating scales or tests. The meta-analyses presented overall estimates of the treatment difference from a fixed-effect model and a test for heterogeneity was performed using a standard Chi-squared statistic. Where there was evidence of heterogeneity of the treatment effect between trials then a random-effects model was utilised (which results in broader confidence intervals than for those of a fixed-effect model). The review authors discussed and reached consensus on the interpretation of the statistical analyses, seeking specialist statistical advice from CDCIG as required. The review authors discussed and reached consensus on the presentation of the findings in the background to the review.
Analysis of subgroups or subsets
We will analyze the subgroup as indicated below:
1. different kind of cognitive interventions;
2. the mean age of the participants;
2. short term (immediately after the intervention completed), medium term (follow-up one month to one year after the intervention completed) and long term (follow-up more than one year after the intervention completed) outcomes will be considered.
Dissemination plans
To extract all the relevant data: 1 week;
To analyse the data: 2 weeks;
To complete the remaining part of the manuscript and submit it: 3 weeks.
Contact details for further information
Chunbo Li
600 South Wan Ping Road, Shanghai, 200030
chunbo_li@163.com
Organisational affiliation of the review
Department of Biological Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China
www.smhc.org.cn
Review team
Ms Hongmei Liu, Department of Biological Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China Ms Juanjuan Ren, Department of Biological Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China Ms Ting Li, Department of Biological Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China Dr Chunbo Li, Department of Biological Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China
Formal screening of search results against eligibility criteria
Data extraction
Risk of bias (quality) assessment
Data analysis
Prospective meta-analysis
PROSPERO This information has been provided by the named contact for this review. CRD has accepted this information in good faith and registered the review in PROSPERO. CRD bears no responsibility or liability for the content of this registration record, any associated files or external websites.
