Abstract
Background
Cognitive impairments, particularly memory problems, are a defining feature of the early stages of Alzheimer’s disease (AD) and vascular dementia. Cognitive training and cognitive rehabilitation are specific interventional approaches designed to address difficulties with memory and other aspects of cognitive functioning. The present review is an update of previous versions of this review.
Objectives
The main aim of the current review was to evaluate the effectiveness and impact of cognitive training and cognitive rehabilitation for people with mild Alzheimer’s disease or vascular dementia in relation to important cognitive and non-cognitive outcomes for the person with dementia and the primary caregiver in the short, medium and long term.
Search methods
The CDCIG Specialized Register, ALOIS, which contains records from MEDLINE, EMBASE, CINAHL, PsycINFO, LILACS and many other clinical trial databases and grey literature sources, was most recently searched on 2 November 2012.
Selection criteria
Randomised controlled trials (RCTs), published in English, comparing cognitive rehabilitation or cognitive training interventions with control conditions, and reporting relevant outcomes for the person with dementia and/or the family caregiver, were considered for inclusion.
Data collection and analysis
Eleven RCTs reporting cognitive training interventions were included in the review. A large number of measures were used in the different studies, and meta-analysis could be conducted for 11 of the primary and secondary outcomes of interest. Several outcomes were not measured in any of the studies. The unit of analysis in the meta-analysis was the change from baseline score. Overall estimates of treatment effect were calculated using a fixed-effect model, and statistical heterogeneity was measured using a standard Chi2 statistic. One RCT of cognitive rehabilitation was identified, allowing examination of effect sizes, but no meta-analysis could be conducted.
Main results
Cognitive training was not associated with positive or negative effects in relation to any reported outcomes. The overall quality of the trials was low to moderate. The single RCT of cognitive rehabilitation found promising results in relation to a number of participant and caregiver outcomes, and was generally of high quality.
Authors’ conclusions
Available evidence regarding cognitive training remains limited, and the quality of the evidence needs to improve. However, there is still no indication of any significant benefit derived from cognitive training. Trial reports indicate that some gains resulting from intervention may not be captured adequately by available standardised outcome measures. The results of the single RCT of cognitive rehabilitation show promise but are preliminary in nature. Further, well-designed studies of cognitive training and cognitive rehabilitation are required to obtain more definitive evidence. Researchers should describe and classify their interventions appropriately using available terminology.
Plain language summary
Cognitive training and cognitive rehabilitation for mild to moderate Alzheimer’s disease and vascular dementia
Dementia due to Alzheimer’s and vascular disease is an enormous public health problem. Currently, an estimated 36 million people worldwide live with dementia, and this number is expected to increase to more than 115 million by the year 2050. Effective interventions to reduce the burden of disease are urgently needed. Cognitive training and cognitive rehabilitation are non-pharmacological methods that aim to help people with early-stage dementia make the most of their memory and cognitive functioning despite the difficulties they are experiencing. Cognitive training focuses on guided practice on a set of tasks that reflect particular cognitive functions, such as memory, attention or problem-solving. Cognitive rehabilitation focuses on identifying and addressing individual needs and goals, which may require strategies for taking in new information or compensatory methods such as using memory aids.
This review included 11 trials of cognitive training and a single trial of cognitive rehabilitation. We found no evidence for the efficacy of cognitive training in improving cognitive functioning, mood or activities of daily living in people with mild to moderate Alzheimer’s disease or vascular dementia; however the quality of the studies was generally not high. The single trial of cognitive rehabilitation provided preliminary indications of the potential benefits of individual cognitive rehabilitation in improving activities of daily living in people with mild Alzheimer’s disease. More high-quality trials of both cognitive training and cognitive rehabilitation are needed to establish their efficacy for people with early-stage dementia.
