BACKGROUND: Vitamin E occurs naturally in the diet. It has several biological activities, including functioning as an antioxidant to scavenge toxic free radicals. Evidence that free radicals may contribute to the pathological processes behind cognitive impairment has led to interest in the use of vitamin E supplements to treat mild cognitive impairment (MCI) and Alzheimer's disease (AD). This is an update of a Cochrane Review first published in 2000, and previously updated in 2006 and 2012.
OBJECTIVES: To assess the efficacy of vitamin E in the treatment of MCI and dementia due to AD.
SEARCH METHODS: We searched the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (ALOIS), the Cochrane Library, MEDLINE, Embase, PsycINFO, CINAHL, LILACS as well as many trials databases and grey literature sources on 22 April 2016 using the terms: "Vitamin E", vitamin-E, alpha-tocopherol.
SELECTION CRITERIA: We included all double-blind, randomised trials in which treatment with any dose of vitamin E was compared with placebo in people with AD or MCI.
DATA COLLECTION AND ANALYSIS: We used standard methodological procedures according to the Cochrane Handbook for Systematic Reviews of Interventions. We rated the quality of the evidence using the GRADE approach. Where appropriate we attempted to contact authors to obtain missing information.
MAIN RESULTS: Four trials met the inclusion criteria, but we could only extract outcome data in accordance with our protocol from two trials, one in an AD population (n = 304) and one in an MCI population (n = 516). Both trials had an overall low to unclear risk of bias. It was not possible to pool data across studies owing to a lack of comparable outcome measures.In people with AD, we found no evidence of any clinically important effect of vitamin E on cognition, measured with change from baseline in the Alzheimer's Disease Assessment Scale - Cognitive subscale (ADAS-Cog) over six to 48 months (mean difference (MD) -1.81, 95% confidence interval (CI) -3.75 to 0.13, P = 0.07, 1 study, n = 272; moderate quality evidence). There was no evidence of a difference between vitamin E and placebo groups in the risk of experiencing at least one serious adverse event over six to 48 months (risk ratio (RR) 0.86, 95% CI 0.71 to 1.05, P = 0.13, 1 study, n = 304; moderate quality evidence), or in the risk of death (RR 0.84, 95% CI 0.52 to 1.34, P = 0.46, 1 study, n = 304; moderate quality evidence). People with AD receiving vitamin E showed less functional decline on the Alzheimer's Disease Cooperative Study/Activities of Daily Living Inventory than people receiving placebo at six to 48 months (mean difference (MD) 3.15, 95% CI 0.07 to 6.23, P = 0.04, 1 study, n = 280; moderate quality evidence). There was no evidence of any clinically important effect on neuropsychiatric symptoms measured with the Neuropsychiatric Inventory (MD -1.47, 95% CI -4.26 to 1.32, P = 0.30, 1 study, n = 280; moderate quality evidence).We found no evidence that vitamin E affected the probability of progression from MCI to probable dementia due to AD over 36 months (RR 1.03, 95% CI 0.79 to 1.35, P = 0.81, 1 study, n = 516; moderate quality evidence). Five deaths occurred in each of the vitamin E and placebo groups over the 36 months (RR 1.01, 95% CI 0.30 to 3.44, P = 0.99, 1 study, n = 516; moderate quality evidence). We were unable to extract data in accordance with the review protocol for other outcomes. However, the study authors found no evidence that vitamin E differed from placebo in its effect on cognitive function, global severity or activities of daily living . There was also no evidence of a difference between groups in the more commonly reported adverse events.
AUTHORS' CONCLUSIONS: We found no evidence that the alpha-tocopherol form of vitamin E given to people with MCI prevents progression to dementia, or that it improves cognitive function in people with MCI or dementia due to AD. However, there is moderate quality evidence from a single study that it may slow functional decline in AD. Vitamin E was not associated with an increased risk of serious adverse events or mortality in the trials in this review. These conclusions have changed since the previous update, however they are still based on small numbers of trials and participants and further research is quite likely to affect the results.
BACKGROUND: This is an update of our previous 2013 review. Several recent trials and systematic reviews of the impact of exercise on people with dementia are reporting promising findings.
OBJECTIVES: Primary objectiveDo exercise programs for older people with dementia improve their cognition, activities of daily living (ADLs), neuropsychiatric symptoms, depression, and mortality? Secondary objectivesDo exercise programs for older people with dementia have an indirect impact on family caregivers' burden, quality of life, and mortality?Do exercise programs for older people with dementia reduce the use of healthcare services (e.g. visits to the emergency department) by participants and their family caregivers?
SEARCH METHODS: We identified trials for inclusion in the review by searching ALOIS (www.medicine.ox.ac.uk/alois), the Cochrane Dementia and Cognitive Improvement Group's Specialised Register, on 4 September 2011, on 13 August 2012, and again on 3 October 2013.
SELECTION CRITERIA: In this review, we included randomized controlled trials in which older people, diagnosed with dementia, were allocated either to exercise programs or to control groups (usual care or social contact/activities) with the aim of improving cognition, ADLs, neuropsychiatric symptoms, depression, and mortality. Secondary outcomes related to the family caregiver(s) and included caregiver burden, quality of life, mortality, and use of healthcare services.
DATA COLLECTION AND ANALYSIS: Independently, at least two authors assessed the retrieved articles for inclusion, assessed methodological quality, and extracted data. We analysed data for summary effects. We calculated mean differences or standardized mean difference (SMD) for continuous data, and synthesized data for each outcome using a fixed-effect model, unless there was substantial heterogeneity between studies, when we used a random-effects model. We planned to explore heterogeneity in relation to severity and type of dementia, and type, frequency, and duration of exercise program. We also evaluated adverse events.
MAIN RESULTS: Seventeen trials with 1067 participants met the inclusion criteria. However, the required data from three included trials and some of the data from a fourth trial were not published and not made available. The included trials were highly heterogeneous in terms of subtype and severity of participants' dementia, and type, duration, and frequency of exercise. Only two trials included participants living at home.Our meta-analysis revealed that there was no clear evidence of benefit from exercise on cognitive functioning. The estimated standardized mean difference between exercise and control groups was 0.43 (95% CI -0.05 to 0.92, P value 0.08; 9 studies, 409 participants). There was very substantial heterogeneity in this analysis (I² value 80%), most of which we were unable to explain, and we rated the quality of this evidence as very low. We found a benefit of exercise programs on the ability of people with dementia to perform ADLs in six trials with 289 participants. The estimated standardized mean difference between exercise and control groups was 0.68 (95% CI 0.08 to 1.27, P value 0.02). However, again we observed considerable unexplained heterogeneity (I² value 77%) in this meta-analysis, and we rated the quality of this evidence as very low. This means that there is a need for caution in interpreting these findings.In further analyses, in one trial we found that the burden experienced by informal caregivers providing care in the home may be reduced when they supervise the participation of the family member with dementia in an exercise program. The mean difference between exercise and control groups was -15.30 (95% CI -24.73 to -5.87; 1 trial, 40 participants; P value 0.001). There was no apparent risk of bias in this study. In addition, there was no clear evidence of benefit from exercise on neuropsychiatric symptoms (MD -0.60, 95% CI -4.22 to 3.02; 1 trial, 110 participants; P value .0.75), or depression (SMD 0.14, 95% CI -0.07 to 0.36; 5 trials, 341 participants; P value 0.16). We could not examine the remaining outcomes, quality of life, mortality, and healthcare costs, as either the appropriate data were not reported, or we did not retrieve trials that examined these outcomes.
AUTHORS' CONCLUSIONS: There is promising evidence that exercise programs may improve the ability to perform ADLs in people with dementia, although some caution is advised in interpreting these findings. The review revealed no evidence of benefit from exercise on cognition, neuropsychiatric symptoms, or depression. There was little or no evidence regarding the remaining outcomes of interest (i.e., mortality, caregiver burden, caregiver quality of life, caregiver mortality, and use of healthcare services).
BACKGROUND: Caring for someone with dementia can be emotionally and physically demanding. Respite care is any intervention designed to give rest or relief to caregivers. It is not clear what positive and negative effects such care may have on them, or on people with dementia.
OBJECTIVES: To assess the benefits and harms of respite care for people with dementia and their caregivers, in particular the effect of respite care on rates of institutionalisation.
SEARCH METHODS: The trials were identified from a search of ALOIS, the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group, using the terms respite* OR daycare OR caregiver* relief. ALOIS contains up-to-date records from all major healthcare databases and many ongoing trial databases.
SELECTION CRITERIA: Randomised controlled trials comparing respite care with a control intervention for people with dementia.
DATA COLLECTION AND ANALYSIS: Two review authors carried out study selection independently and reached a consensus through discussion. Data were extracted by a single review author. The review authors contacted all investigators for methodological details not reported in the text and for additional data for three studies included in the previous version of the review.
MAIN RESULTS: Four trials are now included in the review, with 753 participants. They were different in many ways including the intervention, duration, outcomes and control group so pooling of data was not possible. Overall, the quality of the evidence was rated as very low. Re-analysis of outcomes using data from the published studies found no significant effects of respite care compared to no respite care on any caregiver variable. When respite care was compared to polarity therapy a significant effect was found in favour of polarity therapy for caregiver perceived stress (n = 38, MD 5.80, 95% CI 1.43 to 10.17), but not for other measures of psychological health and other caregiver outcomes. No studies reported evaluable data on outcomes related to the people with dementia.
AUTHORS' CONCLUSIONS: Current evidence does not demonstrate any benefits or adverse effects from the use of respite care for people with dementia or their caregivers. These results should be treated with caution, however, as they may reflect the lack of high quality research in this area rather than an actual lack of benefit. Given the frequency with which respite care is advocated and provided, well-designed trials are needed in this area.
BACKGROUND: The use of statin therapy in established Alzheimer's disease (AD) or vascular dementia (VaD) is a relatively unexplored area. In AD, β-amyloid protein (Aβ) is deposited in the form of extracellular plaques and previous studies have determined Aβ generation is cholesterol dependent. Hypercholesterolaemia has also been implicated in the pathogenesis of VaD. Due to the role of statins in cholesterol reduction, it is biologically plausible they may be efficacious in the treatment of AD and VaD.
OBJECTIVES: To assess the clinical efficacy and safety of statins in the treatment of AD and VaD. To evaluate if the efficacy of statins in the treatment of AD and VaD depends on cholesterol level, ApoE genotype or cognitive level.
SEARCH METHODS: We searched ALOIS, the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group, The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL and LILACS, as well as many trials registries and grey literature sources (20 January 2014).
SELECTION CRITERIA: Double-blind, randomised controlled trials of statins given for at least six months in people with a diagnosis of dementia.
DATA COLLECTION AND ANALYSIS: Two independent authors extracted and assessed data against the inclusion criteria. We pooled data where appropriate and entered them into a meta-analysis. We used standard methodological procedures expected by The Cochrane Collaboration.
MAIN RESULTS: We identified four studies (1154 participants, age range 50 to 90 years). All participants had a diagnosis of probable or possible AD according to standard criteria and most participants were established on a cholinesterase inhibitor. The primary outcome in all studies was change in Alzheimer's Disease Assessment Scale - cognitive subscale (ADAS-Cog) from baseline. When we pooled data, there was no significant benefit from statin (mean difference -0.26, 95% confidence interval (CI) -1.05 to 0.52, P value = 0.51). All studies provided change in Mini Mental State Examination (MMSE) from baseline. There was no significant benefit from statins in MMSE when we pooled the data (mean difference -0.32, 95% CI -0.71 to 0.06, P value = 0.10). Three studies reported treatment-related adverse effects. When we pooled data, there was no significant difference between statins and placebo (odds ratio 1.09, 95% CI 0.58 to 2.06, P value = 0.78). There was no significant difference in behaviour, global function or activities of daily living in the statin and placebo groups. We assessed risk of bias as low for all studies. We found no studies assessing role of statins in treatment of VaD.
AUTHORS' CONCLUSIONS: Analyses from the studies available, including two large randomised controlled trials, indicate that statins have no benefit on the primary outcome measures of ADAS-Cog or MMSE.
OBJECTIVES: Meta-analysis studies of specific types of support groups are limited. We conducted a review and assessment of the effectiveness of support groups for caregivers of demented patients, and examined the impact of support group characteristics.
METHODS: A search of multiple, electronic databases including the Cochrane Library, Medline, PUBMED, and others was conducted; studies published between 1998 and 2009 were collected. Thirty quantitative journal articles that were true and quasi-experimental controlled trials on support groups for non-professional caregivers, including mutual support, psychoeducational, and educational groups were analyzed. Outcome indicators were psychological well-being, depression, burden, and social outcomes.
RESULTS: Support groups showed a significant positive effect on caregivers' psychological well-being (Hedge's g = -0.44, 95% CI = -0.73, -0.15), depression (Hedge's g = -0.40, 95% CI = -0.72, -0.08), burden (Hedge's g = -0.23, 95% CI = -0.33, -0.13), and social outcomes (Hedge's g = 0.40, 95% CI = 0.09, 0.71). The use of theoretical models, and length and intensity of group sessions had a significant impact on the effect sizes for psychological well-being and depression. Ratio of female participation (for psychological well-being and depression) and average age (social outcomes) were significant predictor variables.
CONCLUSIONS: Support groups benefit caregivers and findings of this meta-analysis serve as immediate guidance for group facilitators. Future research should include additional outcome variables with our defined factors on effectiveness collected as demographic characteristic data for comparison. A more comprehensive understanding of the effectiveness of support groups is indicated to enhance outcomes for caregivers and patients.
The increasing worldwide prevalence of dementia is a major public health concern. Findings from some epidemiological studies suggest that diet and nutrition may be important modifiable risk factors for development of dementia. In order to evaluate the strength of the available evidence of an association of dietary factors with dementia including Alzheimer's disease (AD), we systematically searched relevant publication databases and hand-searched bibliographies up to end July 2007. We included prospective cohort studies which evaluated the association of nutrient levels with the risk of developing dementia and randomized intervention studies examining the treatment effect of nutrient supplementation on cognitive function. One hundred and sixty studies, comprising ninety one prospective cohort studies and sixty nine intervention studies, met the pre-specified inclusion criteria. Of these, thirty-three studies (19 cohort and 14 randomized controlled trials) investigated the effects of folate, B-vitamins, and levels of homocysteine (a biomarker modifiable through B-vitamin supplementation) or fish/fatty acids and are the focus of the present report. Some observational cohort studies indicated that higher dietary intake or elevated serum levels of folate and fish/fatty acids and low serum levels of homocysteine were associated with a reduced risk of incident AD and dementia, while other studies reported no association. The results of intervention studies examining the effects of folic acid or fatty acid supplementation on cognitive function are inconsistent. In summary, the available evidence is insufficient to draw definitive conclusions on the association of B vitamins and fatty acids with cognitive decline or dementia, and further long-term trials are required.
BACKGROUND: The clock drawing test (CDT) is a common and widely used cognitive screening instrument for the diagnosis of dementia. However, it has remained unclear whether it is a suitable method to identify mild cognitive impairment (MCI). The aim of this paper is to review systematically the studies concerning the utility of the CDT in diagnosing MCI.
METHOD: A systematic literature search was conducted. All studies dealing with utility of CDT in diagnosing MCI regardless of the applied CDT scoring system and MCI concept were selected.
RESULTS: Nine relevant studies were identified. The majority of the studies compared average CDT scores of cognitively healthy and mildly impaired subjects, and four of them identified significant mean differences. If reported, sensitivity and specificity have been mostly unsatisfactory.
CONCLUSION: CDT should not be used for MCI-screening.
The growing number of dementia patients leads to both policy, economic and health organization constraints. Many healthcare systems have developed case management programs in order to optimize dementia patients and caregivers care and services delivery. Nevertheless, to what extend case management programs can lead to an improvement of care and expenditures savings is not known. Thus, the objective of this paper was to analyse the efficacy of case management programs on health care cost, institutionalization and hospitalization. A systematic review of randomized controlled trials was therefore conducted of the databases MEDLINE and SCOPUS up to September 2009. Included were English language randomized controlled trials of case management for community dwelling dementia patients and their caregivers evaluating costs, institutionalization and hospitalization. An evaluation of the methodological quality was performed. Thirteen relevant studies concerning 12 trials were identified and included. None of the 7 low quality studies reported positive impact of case management on the outcomes of interest. Among the 6 good quality studies, 4 reported positive impact on institutionalization delay, institutionalization length or nursing home admission rate. In none of the good quality studies was evidence found for savings in health care expenditures or reduction in hospitalization recourse. The weak convincing evidences from randomized trials do not allow any conclusion about the efficacy of case management for dementia patient and caregivers on costs and resource utilization. Further research should focus on determining subgroups of caregivers who could benefit the most from case management.
Vitamin E occurs naturally in the diet. It has several biological activities, including functioning as an antioxidant to scavenge toxic free radicals. Evidence that free radicals may contribute to the pathological processes behind cognitive impairment has led to interest in the use of vitamin E supplements to treat mild cognitive impairment (MCI) and Alzheimer's disease (AD). This is an update of a Cochrane Review first published in 2000, and previously updated in 2006 and 2012.
OBJECTIVES:
To assess the efficacy of vitamin E in the treatment of MCI and dementia due to AD.
SEARCH METHODS:
We searched the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (ALOIS), the Cochrane Library, MEDLINE, Embase, PsycINFO, CINAHL, LILACS as well as many trials databases and grey literature sources on 22 April 2016 using the terms: "Vitamin E", vitamin-E, alpha-tocopherol.
SELECTION CRITERIA:
We included all double-blind, randomised trials in which treatment with any dose of vitamin E was compared with placebo in people with AD or MCI.
DATA COLLECTION AND ANALYSIS:
We used standard methodological procedures according to the Cochrane Handbook for Systematic Reviews of Interventions. We rated the quality of the evidence using the GRADE approach. Where appropriate we attempted to contact authors to obtain missing information.
MAIN RESULTS:
Four trials met the inclusion criteria, but we could only extract outcome data in accordance with our protocol from two trials, one in an AD population (n = 304) and one in an MCI population (n = 516). Both trials had an overall low to unclear risk of bias. It was not possible to pool data across studies owing to a lack of comparable outcome measures.In people with AD, we found no evidence of any clinically important effect of vitamin E on cognition, measured with change from baseline in the Alzheimer's Disease Assessment Scale - Cognitive subscale (ADAS-Cog) over six to 48 months (mean difference (MD) -1.81, 95% confidence interval (CI) -3.75 to 0.13, P = 0.07, 1 study, n = 272; moderate quality evidence). There was no evidence of a difference between vitamin E and placebo groups in the risk of experiencing at least one serious adverse event over six to 48 months (risk ratio (RR) 0.86, 95% CI 0.71 to 1.05, P = 0.13, 1 study, n = 304; moderate quality evidence), or in the risk of death (RR 0.84, 95% CI 0.52 to 1.34, P = 0.46, 1 study, n = 304; moderate quality evidence). People with AD receiving vitamin E showed less functional decline on the Alzheimer's Disease Cooperative Study/Activities of Daily Living Inventory than people receiving placebo at six to 48 months (mean difference (MD) 3.15, 95% CI 0.07 to 6.23, P = 0.04, 1 study, n = 280; moderate quality evidence). There was no evidence of any clinically important effect on neuropsychiatric symptoms measured with the Neuropsychiatric Inventory (MD -1.47, 95% CI -4.26 to 1.32, P = 0.30, 1 study, n = 280; moderate quality evidence).We found no evidence that vitamin E affected the probability of progression from MCI to probable dementia due to AD over 36 months (RR 1.03, 95% CI 0.79 to 1.35, P = 0.81, 1 study, n = 516; moderate quality evidence). Five deaths occurred in each of the vitamin E and placebo groups over the 36 months (RR 1.01, 95% CI 0.30 to 3.44, P = 0.99, 1 study, n = 516; moderate quality evidence). We were unable to extract data in accordance with the review protocol for other outcomes. However, the study authors found no evidence that vitamin E differed from placebo in its effect on cognitive function, global severity or activities of daily living . There was also no evidence of a difference between groups in the more commonly reported adverse events.
AUTHORS' CONCLUSIONS:
We found no evidence that the alpha-tocopherol form of vitamin E given to people with MCI prevents progression to dementia, or that it improves cognitive function in people with MCI or dementia due to AD. However, there is moderate quality evidence from a single study that it may slow functional decline in AD. Vitamin E was not associated with an increased risk of serious adverse events or mortality in the trials in this review. These conclusions have changed since the previous update, however they are still based on small numbers of trials and participants and further research is quite likely to affect the results.
Systematic Review Question»Systematic review of interventions
