Safety and efficacy of galantamine in subjects with mild cognitive impairment

Biological Factors Contributing to the Response to Cognitive Training in Mild Cognitive Impairment

In mild cognitive impairment (MCI), small benefits from cognitive training were observed for memory functions but there appears to be great variability in the response to treatment. Our study aimed to improve the characterization and selection of those participants who will benefit from cognitive intervention. We evaluated the predictive value of disease-specific biological factors for the outcome after cognitive training in MCI (n = 25) and also considered motivation of the participants. We compared the results of the cognitive intervention group with two independent control groups of MCI patients (local memory clinic, n = 20; ADNI cohort, n = 302). The primary outcome measure was episodic memory as measured by verbal delayed recall of a 10-word list. Episodic memory remained stable after treatment and slightly increased 6 months after the intervention. In contrast, in MCI patients who did not receive an intervention, episodic memory significantly decreased during the same time interval. A larger left entorhinal cortex predicted more improvement in episodic memory after treatment and so did higher levels of motivation. Adding disease-specific biological factors significantly improved the prediction of training-related change compared to a model based simply on age and baseline performance. Bootstrapping with resampling (n = 1000) verified the stability of our finding. Cognitive training might be particularly helpful in individuals with a bigger left entorhinal cortex as individuals who did not benefit from intervention showed 17% less volume in this area. When extended to alternative treatment options, stratification based on disease-specific biological factors is a useful step towards individualized medicine.

Cognition comes of age: comments on the new FDA draft guidance for early Alzheimer's disease

Background

The FDA have recently published draft guidance for the development of treatments for early Alzheimer’s disease. Key features of this guidance are the advocacy of sensitive cognitive measures and a taxonomy of disease severity. Whilst desirable patterns of cognitive-functional improvement are included, specific measures, and the magnitude of required effects, are not described.

Main section

We describe key elements of the guidance content, especially with regard targeting key cognitive domains and the means by which they might be efficiently indexed in the disease stages included in the guidance. We discuss also the opportunities to assess cognitive performance in ‘Stage 2’ and ‘Stage 3’ patients, as well as the possibilities for effectively assessing function in the latter category. In this section we review candidate cognitive assessments that we judge are capable of delivering on the guidance specification for sensitive neuropsychological measures. This includes detailed consideration of the ADCS-PACC and Catch-Cog initiatives. With respect to the magnitude of effects, we propose that standardised effect sizes of 0.3 represent a reasonable level of efficacy based on the observation that already marketed drugs on average deliver this level of improvement.

Conclusions

We propose the use of cognitive measures in stage 2 patients to index the cognitive skills known to be compromised early in the Alzheimer’s disease process. We recommend extending the traditional interest in episodic memory to include sensitive, reliable and valid measures of attention, working memory and aspects of executive function. We propose a focus on these additional cognitive abilities based on evidence that performance on tests of these domains is moderately well related to functional skills.

Exploring the effects of galantamine paired with meditation and dream reliving on recalled dreams: Toward an integrated protocol for lucid dream induction and nightmare resolution

An experimental home study examined the impact of a pre-sleep protocol for enhancing self-awareness, lucidity, and responsiveness in dreams. It included ingesting the cholinesterase inhibitor galantamine--which is widely reported to increase the frequency of lucid dreaming--prior to engaging in middle-of-the-night meditation and the imaginary reliving of a distressing dream while exercising new responses. Thirty-five participants completed an eight-night study, which included pre- and post-baseline nights and six conditions: waking for 40 min before returning to bed, called Wake-Back-to-Bed (WBTB); Wake-Back-to-Bed plus placebo (WBTB + P); Wake-Back-to-Bed plus galantamine (WBTB + G); meditation and dream reliving (MDR); meditation and dream reliving plus placebo (MDR + P); and meditation and dream reliving plus galantamine (MDR + G). The outcome measures included lucidity, reflectiveness, interactive behavior, role change, constructive action, and fear and threat, as measured by the participants' self-ratings. The results support the use of this protocol in further studies of lucid dream induction and nightmare/trauma resolution.

Memantine improves semantic memory in patients with amnestic mild cognitive impairment: A single-photon emission computed tomography study

Objective This study was performed to assess the efficacy of memantine in patients with amnestic mild cognitive impairment (aMCI). Methods Thirty healthy controls and 45 patients diagnosed with aMCI based on the Petersen criteria were classified into 3 groups. Group 1 comprised patients who received a single memantine dose following examination (n = 25), Group 2 comprised patients who did not receive memantine treatment following examination (n = 20), and Group 3 comprised healthy age-matched volunteers (n = 30). Neuropsychological testing was performed, and the response to memantine was examined at baseline and at 12, 24, and 48 weeks. Single-photon emission computed tomography was performed at baseline and at 48 weeks in patients who received memantine treatment. Results Memantine treatment significantly improved the symptoms of aMCI according to the Wechsler Adult Intelligence Scale-Revised vocabulary subtest, backward digit span, and Blessed Dementia Rating Scale, all of which were recorded for the duration of the study. Conclusion These data indicate that patients with aMCI receiving memantine develop an improved semantic memory compared with no treatment. Further studies including larger patient cohorts are necessary to validate these findings.

Cognitive Training Using a Novel Memory Game on an iPad in Patients with Amnestic Mild Cognitive Impairment (aMCI)

Background

Cognitive training is effective in patients with mild cognitive impairment but does not typically address the motivational deficits associated with older populations with memory difficulties.

Methods

We conducted a randomized controlled trial of cognitive training using a novel memory game on an iPad in 42 patients with a diagnosis of amnestic mild cognitive impairment assigned to either the cognitive training (n=21; 8 hours of gameplay over 4 weeks) or control (n=21; clinic visits as usual) groups.

Results

Significant time-by-pattern-by-group interactions were found for cognitive performance in terms of the number of errors made and trials needed on the Cambridge Neuropsychological Test Automated Battery Paired Associates Learning task (P=.044; P=.027). Significant time-by-group interactions were also found for the Cambridge Neuropsychological Test Automated Battery Paired Associates Learning first trial memory score (P=.002), Mini-Mental State Examination (P=.036), the Brief Visuospatial Memory Test (P=.032), and the Apathy Evaluation Scale (P=.026). Within-group comparisons revealed highly specific effects of cognitive training on episodic memory. The cognitive training group maintained high levels of enjoyment and motivation to continue after each hour of gameplay, with self-confidence and self-rated memory ability improving over time.

Conclusions

Episodic memory robustly improved in the cognitive training group. "Gamified" cognitive training may also enhance visuospatial abilities in patients with amnestic mild cognitive impairment. Gamification maximizes engagement with cognitive training by increasing motivation and could complement pharmacological treatments for amnestic mild cognitive impairment and mild Alzheimer's disease. Larger, more controlled trials are needed to replicate and extend these findings.

Towards the concept of disease-modifier in post-stroke or vascular cognitive impairment: a consensus report

BACKGROUND

Vascular cognitive impairment (VCI) is a complex spectrum encompassing post-stroke cognitive impairment (PSCI) and small vessel disease-related cognitive impairment. Despite the growing health, social, and economic burden of VCI, to date, no specific treatment is available, prompting the introduction of the concept of a disease modifier.

CONSENSUS AND SUGGESTIONS

Within this clinical spectrum, VCI and PSCI remain advancing conditions as neurodegenerative diseases with progression of both vascular and degenerative lesions accounting for cognitive decline. Disease-modifying strategies should integrate both pharmacological and non-pharmacological multimodal approaches, with pleiotropic effects targeting (1) endothelial and brain-blood barrier dysfunction; (2) neuronal death and axonal loss; (3) cerebral plasticity and compensatory mechanisms; and (4) degenerative-related protein misfolding. Moreover, pharmacological and non-pharmacological treatment in PSCI or VCI requires valid study designs clearly stating the definition of basic methodological issues, such as the instruments that should be used to measure eventual changes, the biomarker-based stratification of participants to be investigated, and statistical tests, as well as the inclusion and exclusion criteria that should be applied.

CONCLUSION

A consensus emerged to propose the development of a disease-modifying strategy in VCI and PSCI based on pleiotropic pharmacological and non-pharmacological approaches.

Efficacy and Safety of an Herbal Therapy in Patients with Amnestic Mild Cognitive Impairment: A 24-Week Randomized Phase III Trial

OBJECTIVE

In the 24-week randomized, double-blind, double-placebo, parallel-controlled trial, we aimed to test the effects of herbal therapy with amnestic mild cognitive impairment (aMCI).

METHODS

A total of 324 patients with aMCI entered a 2-week placebo run-in period followed by 24 weeks' treatment of either (a) herbal capsule (5 shenwu capsules/administration, 3 times/day) and placebo identical to donepezil tablets (n = 216) or (b) donepezil (5 mg/day) and placebo identical to herbal capsule (n = 108).

RESULTS

Herbal therapy showed a significant improvement on the primary efficacy measure, measured by Alzheimer Disease Assessment Scale-cognitive subscale (ADAS-cog), and showed a mean decrease from baseline of 4.23 points at the endpoint, without a significant difference from the donepezil group. Secondary efficacy measurement of the Logical Memory II Delayed Story Recall subtest (DSR) showed modest improvement in those taking herbal capsule compared to baseline, and there was no significant difference from donepezil group. The frequency of adverse events was much less in the herbal therapy group than the donepezil.

CONCLUSION

Herbal therapy demonstrated a significant improvement in cognition and memory, which were similar to the donepezil in patients with aMCI. Herbal therapy was safe and well tolerated.

TRIAL REGISTRATION

This study is registered with clinicaltrials.gov NCT01451749.

Randomized controlled trials in mild cognitive impairment: Sources of variability

OBJECTIVE

To examine the variability in performance among placebo groups in randomized controlled trials for mild cognitive impairment (MCI).

METHODS

Placebo group data were obtained from 2 National Institute on Aging (NIA) MCI randomized controlled trials, the Alzheimer's Disease Cooperative Study (ADCS) MCI trial and the Alzheimer's Disease Neuroimaging Initiative (ADNI), which is a simulated clinical trial, in addition to industry-sponsored clinical trials involving rivastigmine, galantamine, rofecoxib, and donepezil. The data were collated for common measurement instruments. The performance of the placebo participants from these studies was tracked on the Alzheimer's Disease Assessment Scale-cognitive subscale, Mini-Mental State Examination, and Clinical Dementia Rating-sum of boxes, and for progression on these measures to prespecified clinical study endpoints. APOE status, where available, was also analyzed for its effects.

RESULTS

The progression to clinical endpoints varied a great deal among the trials. The expected performances were seen for the participants in the 2 NIA trials, ADCS and ADNI, with generally worsening of performance over time; however, the industry-sponsored trials largely showed stable or improved performance in their placebo participants. APOE4 carrier status influenced results in an expected fashion on the study outcomes, including rates of progression and cognitive subscales.

CONCLUSIONS

In spite of apparently similar criteria for MCI being adopted by the 7 studies, the implementation of the criteria varied a great deal. Several explanations including instruments used to characterize participants and variability among study populations contributed to the findings.

From mild cognitive impairment to subjective cognitive decline: conceptual and methodological evolution

Identification of subjects at the early stages of Alzheimer's disease (AD) is fundamental for drug development and possible intervention or prevention of cognitive decline. The concept of mild cognitive impairment (MCI) evolved during the past two decades to define subjects at the transitional stage between normal aging and dementia. Evidence from cross-sectional and longitudinal studies has shown that MCI is associated with an increased risk of positive AD biomarkers and an increased annual conversion rate of 5%-17% to AD. The presence of AD biomarkers in subjects with MCI was associated with an even higher risk of progression to dementia. However, earlier clinical trials for pharmacotherapy in subjects with MCI were disappointing. To extend the spectrum of AD to an earlier stage before MCI, subjective cognitive decline (SCD) was introduced and was defined as self-reported cognitive decline before the deficits could be detected by cognitive tests. Subjects with SCD have an increased risk of underlying AD pathology. However, SCD can also develop secondary to other heterogeneous etiologies, including other neurodegenerative and psychiatric diseases, personality traits, physical conditions, and medication use. Several clinical and biomarker features were proposed to predict risk of conversion to AD in subjects with SCD. Further longitudinal studies are needed to support the validity of these high-risk features.

Prevention Trials in Alzheimer's Disease: Current Status and Future Perspectives

Alzheimer's disease (AD) is the most common form of dementia in the elderly. Over the past 20 years, both pharmacological and lifestyle interventions have been studied for AD prevention, but the overall results have been disappointing. The majority of disappointing results have raised questions and great challenges for the future of AD prevention trials. Ongoing advances in the knowledge of pathogenesis, in the identification of novel targets, in improved outcome measures, and in identification and validation of biomarkers may lead to effective strategies for AD prevention. In this paper, we review the selection of participants and interventions, trial design, outcome assessments, and promising biomarkers in prevention trials, and summarize the lessons learned from completed trials and perspectives from ongoing trials in AD prevention. Selection of optimal participants and interventions, coupled with more refined outcomes and more efficient trial design, may have the capacity to deliver a new era of preventive discovery in this challenging area.

Clinical Predictors for Mild Cognitive Impairment Progression in a Korean Cohort

Background and Purpose

Patients with mild cognitive impairment (MCI) and their caregivers are concerned with the likelihood and time course of progression to dementia. This study was performed to identify the clinical predictors of the MCI progression in a Korean registry, and investigated the effects of medications without evidence, frequently prescribed in clinical practice.

Methods

Using a Korean cohort that included older adults with MCI who completed at least one follow-up visit, clinical characteristics and total medical expenses including prescribed medications were compared between two groups: progressed to dementia or not. Cox proportional hazards regression analysis was conducted.

Results

During the mean 1.42±0.72 years, 215 (27.63%) of 778 participants progressed to dementia. The best predictors were age [hazard ratio (HR), 1.036; 95% confidence interval (CI), 1.006–1.067; p=0.018], apolipoprotein ε4 allele (HR, 2.247; 95% CI, 1.512–3.337; p<0.001), Clinical Dementia Rating scale-sum of boxes scores (HR, 1.367; 95% CI, 1.143–1.636; p=0.001), Instrumental Activities of Daily Living scores (HR, 1.035; 95% CI, 1.003–1.067; p=0.029), and lower Mini-Mental State Examination scores (HR, 0.892; 95% CI, 0.839–0.949; p<0.001). Total medical expenses were not different.

Conclusions

Our data are in accordance with previous reports about clinical predictors for the progression from MCI to dementia. Total medical expenses were not different between groups with and without progression.

Combined treatment with memantine/es-citalopram for older depressed patients with cognitive impairment: a pilot study

OBJECTIVE

The objective of the study is to assess combined antidepressant and memantine treatment in older patients presenting with depression and cognitive impairment.

METHODS

Thirty-five depressed patients with cognitive impairment participated in this open-label pilot study. We evaluated whether, over a 48-week period, combined antidepressant (primarily es-citalopram) and memantine treatment was effective in the treatment of cognitive impairment and depression. Neuropsychological testing was performed, and antidepressant response monitored at baseline and at the 12, 24, and 48-week time points.

RESULTS

Treatment with escitalopram (mean daily dose 18.62 mg, SD 5.15) and memantine (mean daily dose 13.62 mg, SD 6.67) was associated with improvement in Hamilton Depression Rating Scale scores over the 48-week study period. Patients demonstrated significant improvement in the primary outcome of cognitive performance (Selective Reminding Test total immediate recall; SRT-IR) over the 48-week treatment period (p = 0.0147). Significant improvement was also observed in measures of naming and verbal fluency but not in the other cognitive domains. One of the 35 patients (2.9%) converted to Alzheimer's disease over the 48-week treatment period. In the amnestic mild cognitive impairment subsample (n = 22), the conversion rate was 4.5%, a rate lower than in other reports of patients with DEP-CI.

CONCLUSIONS

In this open-label trial, combined antidepressant and memantine treatment in patients with DEP-CI was associated with improved cognition and a low rate of conversion to dementia compared with published studies in patients with DEP-CI. Although limited by the open-label study design that incorporates practice effects that can improve cognitive test performance, the findings suggest the need for a larger randomized placebo-controlled trial.

Patient-Centred Care of Older Adults With Cardiovascular Disease and Multiple Chronic Conditions

Multimorbidity, defined as the presence of 2 or more chronic conditions, is common among older adults with cardiovascular disease. These individuals are at increased risk for poor health outcomes and account for a large proportion of health care utilization. Clinicians are challenged with the heterogeneity of this population, the complexity of the treatment regimen, limited high-quality evidence, and fragmented health care systems. Each treatment recommended by a clinical practice guideline for a single cardiovascular disease might be rational, but the combination of all evidence-based recommendations can be impractical or even harmful to individuals with multimorbidity. These challenges can be overcome with a patient-centred approach that incorporates the individual's preferences, relevant evidence, the overall and condition-specific prognosis, clinical feasibility of treatments, and interactions with other treatments and coexisting chronic conditions. The ultimate goal is to maximize benefits and minimize harms by optimizing adherence to the most essential treatments, while acknowledging trade-offs between treatments for different health conditions. It might be necessary to discontinue therapies that are not essential or potentially harmful to decrease the risk of drug-drug and drug-disease interactions from polypharmacy. A decision to initiate, withhold, or stop a treatment should be on the basis of the time horizon to benefits vs the individual's prognosis. In this review, we illustrate how cardiologists and general practitioners can adopt a patient-centred approach to focus on the aspects of cardiovascular and noncardiovascular health that have the greatest effect on functioning and quality of life in older adults with cardiovascular disease and multimorbidity.

Mild Cognitive Impairment

PURPOSE OF REVIEW

As individuals age, the quality of cognitive function becomes an increasingly important topic. The concept of mild cognitive impairment (MCI) has evolved over the past 2 decades to represent a state of cognitive function between that seen in normal aging and dementia. As such, it is important for health care providers to be aware of the condition and place it in the appropriate clinical context.

RECENT FINDINGS

Numerous international population-based studies have been conducted to document the frequency of MCI, estimating its prevalence to be between 15% and 20% in persons 60 years and older, making it a common condition encountered by clinicians. The annual rate in which MCI progresses to dementia varies between 8% and 15% per year, implying that it is an important condition to identify and treat. In those MCI cases destined to develop Alzheimer disease, biomarkers are emerging to help identify etiology and predict progression. However, not all MCI is due to Alzheimer disease, and identifying subtypes is important for possible treatment and counseling. If treatable causes are identified, the person with MCI might improve.

SUMMARY

MCI is an important clinical entity to identify, and while uncertainties persist, clinicians need to be aware of its diagnostic features to enable them to counsel patients. MCI remains an active area of research as numerous randomized controlled trials are being conducted to develop effective treatments.

Alzheimer's Disease Assessment Scale-Cognitive subscale variants in mild cognitive impairment and mild Alzheimer's disease: change over time and the effect of enrichment strategies

Background

Development of new treatments for Alzheimer’s disease (AD) has broadened into early interventions in individuals with modest cognitive impairment and a slow decline. The 11-item version of the Alzheimer’s Disease Assessment Scale–Cognitive subscale (ADAS-Cog) was originally developed to measure cognition in patients with mild to moderate AD. Attempts to improve its properties for early AD by removing items prone to ceiling and/or by adding cognitive measures known to be impaired early have yielded a number of ADAS-Cog variants. Using Alzheimer’s Disease Neuroimaging Initiative data, we compared the performance of the 3-, 5-, 11- and 13-item ADAS-Cog variants in subjects with early AD. Given the interest in enrichment strategies, we also examined this aspect with a focus on cerebrospinal fluid (CSF) markers.

Methods

Subjects with mild cognitive impairment (MCI) and mild AD with available ADAS-Cog 13 and CSF data were analysed. The decline over time was defined by change from baseline. Direct cross-comparison of the ADAS-Cog variants was performed using the signal-to-noise ratio (SNR), with higher values reflecting increased sensitivity to detect change over time.

Results

The decline over time on any of the ADAS-Cog variants was minimal in subjects with MCI. Approximately half of subjects with MCI fulfilled enrichment criteria for positive AD pathology. The impact of enrichment was detectable but subtle in MCI. The annual decline in mild AD was more pronounced but still modest. More than 90 % of subjects with mild AD had positive AD pathology. SNRs were low in MCI but greater in mild AD. The numerically largest SNRs were seen for the ADAS-Cog 5 in MCI and for both the 5- and 13-item ADAS-Cog variants in mild AD, although associated confidence intervals were large.

Conclusions

The possible value of ADAS-Cog expansion or reduction is less than compelling, particularly in MCI. In mild AD, adding items known to be impaired at early stages seems to provide more benefit than removing items on which subjects score close to ceiling.

Electronic supplementary material

The online version of this article (doi:10.1186/s13195-016-0170-5) contains supplementary material, which is available to authorized users.

The effect of Sailuotong (SLT) on neurocognitive and cardiovascular function in healthy adults: a randomised, double-blind, placebo controlled crossover pilot trial

Background

Sailuotong (SLT) is a standardised herbal medicine formula consisting of Panax ginseng, Ginkgo biloba, and Crocus sativus, and has been designed to enhance cognitive and cardiovascular function.

Methods

Using a randomised, double-blind, placebo controlled crossover design, this pilot study assessed the effect of treatment for 1 week with SLT and placebo (1 week washout period) on neurocognitive and cardiovascular function in healthy adults. Sixteen adults completed a computerised neuropsychological test battery (Compass), and had their electroencephalographic (EEG) activity and cardiovascular system function assessed. Primary outcome measures were cognitive test scores and oddball task event-related potential (ERP) component amplitudes. Secondary outcome measures were resting EEG spectral band amplitudes, and cardiovascular parameters.

Results

Treatment with SLT, compared to placebo, resulted in small improvements in working memory, a slight increase in auditory target (cf. nontarget) P3a amplitude, and a decrease in auditory N1 target (cf. nontarget) amplitude. There was no effect of SLT on EEG amplitude in delta, theta, alpha, or beta bands in both eyes open and eyes closed resting conditions, or on aortic and peripheral pulse pressure, and resting heartrate.

Conclusions

Findings suggest that SLT has the potential to improve working memory performance in healthy adults; a larger sample size is needed to confirm this.

Trial registration

Australia New Zealand Clinical Trials Registry Trial Registration Id: ACTRN12610000947000.

Drug and Exercise Treatment of Alzheimer Disease and Mild Cognitive Impairment: A Systematic Review and Meta-Analysis of Effects on Cognition in Randomized Controlled Trials

OBJECTIVE

Demographic changes are increasing the pressure to improve therapeutic strategies against cognitive decline in Alzheimer disease (AD) and mild cognitive impairment (MCI). Besides drug treatment, physical activity seems to be a promising intervention target as epidemiological and clinical studies suggest beneficial effects of exercise training on cognition. Using comparable inclusion and exclusion criteria, we analyzed the efficacy of drug therapy (cholinesterase inhibitors, memantine, and Ginkgo biloba) and exercise interventions for improving cognition in AD and MCI populations.

METHODS

We searched The Cochrane Library, EBSCO, OVID, Web of Science, and U.S Food and Drug Administration data from inception through October 30, 2013. Randomized controlled trials in which at least one treatment arm consisted of an exercise or a pharmacological intervention for AD or MCI patients, and which had either a non-exposed control condition or a control condition that received another intervention. Treatment discontinuation rates and Standardized Mean Change score using Raw score standardization (SMCR) of cognitive performance were calculated.

RESULTS

Discontinuation rates varied substantially and ranged between 0% and 49% with a median of 18%. Significantly increased discontinuation rates were found for galantamine and rivastigmine as compared to placebo in AD studies. Drug treatments resulted in a small pooled effect on cognition (SMCR: 0.23, 95% CI: 0.20 to 0.25) in AD studies (N = 45, 18,434 patients) and no effect in any of the MCI studies (N = 5, 3,693 patients; SMCR: 0.03, 95% CI: 0.00 to 0.005). Exercise interventions had a moderate to strong pooled effect size (SMCR: 0.83, 95% CI: 0.59 to 1.07) in AD studies (N = 4, 119 patients), and a small effect size (SMCR: 0.20, 95% CI: 0.11 to 0.28) in MCI (N = 6, 443 patients).

CONCLUSIONS

Drug treatments have a small but significant impact on cognitive functioning in AD and exercise has the potential to improve cognition in AD and MCI. Head-to-head trials with sufficient statistical power are necessary to directly compare efficacy, safety, and acceptability. Combining these two approaches might further increase the efficacy of each individual intervention.

IDENTIFIER

PROSPERO (2013:CRD42013003910).

Treatment for mild cognitive impairment: a systematic review and meta-analysis

BACKGROUND

The effectiveness of treatments for mild cognitive impairment is uncertain. The aim of this review was to evaluate the effectiveness and harms of treatment for mild cognitive impairment in adults 65 years of age and older.

METHODS

We searched MEDLINE, Embase and Cochrane Central (December 2012-December 2014); citations from 2 systematic reviews were considered for inclusion. We included randomized controlled trials involving community-dwelling adults aged 65 years and older with a diagnosis of mild cognitive impairment. Studies reporting on cognition, function, behaviour, global status, mortality and adverse events for treatment with pharmacologic and nonpharmacologic interventions were included.

RESULTS

Seventeen studies were included. Cholinesterase inhibitor studies evaluating cognition (Alzheimer's Disease Assessment Scale, cognition subscale) showed no difference between intervention and control groups (mean difference [MD] -0.33, 95% CI -0.73 to 0.06]; one behavioural study showed no significant effect on cognition (Alzheimer's Disease Assessment Scale, cognition subscale) for the intervention group when compared to controls (MD -0.60, (95% CI -1.44 to 0.24), and one study on vitamin E showed no difference between intervention and control groups (MD 0.85, 95% CI -0.32 to 2.02). With the Mini-Mental State Examination, cholinesterase inhibitors showed no difference between intervention and control groups (MD 0.17, 95% CI -0.13 to 0.47); behavioural studies showed a significant difference favouring intervention (MD 1.01, 95% CI 0.25 to 1.77), and studies of dietary supplements and/or vitamins showed no difference between intervention and control groups (MD 0.20, 95% CI -0.04 to 0.43). Pharmacologic studies showed no difference in serious adverse events (risk ratio 0.98, 95% CI 0.86 to 1.10). No serious adverse events were reported for nonpharmacologic interventions.

INTERPRETATION

Treatment of mild cognitive impairment with cholinesterase inhibitors showed no benefit when compared with a control group. A small cognitive benefit was observed using behavioural therapies when compared with the control group. However, the clinical significance of this small benefit remains uncertain. The current evidence does not support the use of cholinesterase inhibitors for treating mild cognitive impairment, and future high-quality research using a standardized approach is needed to affirm the finding of a small benefit on cognition that was observed for behavioural interventions.

REGISTRATION

PROSPERO no. CRD42014015431.

Prevention of sporadic Alzheimer's disease: lessons learned from clinical trials and future directions

Interventions that have even quite modest effects at the individual level could drastically reduce the future burden of dementia associated with Alzheimer's disease at the population level. In the past three decades, both pharmacological and lifestyle interventions have been studied for the prevention of cognitive decline or dementia in randomised controlled trials of individuals mostly aged older than 50-55 years with or without risk factors for Alzheimer's disease. Several trials testing the effects of physical activity, cognitive training, or antihypertensive interventions showed some evidence of efficacy on a primary cognitive endpoint. However, most of these trials had short follow-up periods, and further evidence is needed to confirm effectiveness and establish the optimum design or dose of interventions and ideal target populations. Important innovations in ongoing trials include the development of multidomain interventions, and the use of biomarker or genetic inclusion criteria. Challenges include the use of adaptive trial designs, the development of standardised, sensitive outcome measures, and the need for interventions that can be implemented in resource-poor settings.

Prevention studies in Alzheimer's disease: progress towards the development of new therapeutics

Alzheimer's disease (AD) is the most common form of dementia and is a major cause of disability and dependency amongst older people. AD drugs approved so far are symptomatic treatments and are not thought to affect the underlying disease process. Trials conducted with agents aiming to slow or stop disease progression in patients with AD have all failed, perhaps because they were tested too late in the disease process. Therefore, there has been a move towards prevention of AD. This paper presents an overview of trials testing pharmacological interventions for sporadic AD prevention. Those tested to date were initially developed for the treatment of AD or for the treatment of other conditions, rather than being specifically developed for AD prevention. Associated issues, such as evidence of 'proof-of-concept,' doses and safety, are discussed. A major shift has taken place in the methodology of AD prevention trials since the results of the first trials were published in the 1990s. New directions that are currently being considered in ongoing or future prevention trials are discussed, in terms of endpoints, target populations, and study design. The use of AD-specific drugs to prevent AD in high-risk individuals is currently limited by a lack of validated predictive and surrogate markers. Population approaches, such as lifestyle changes, are an alternative strategy that could be of public health interest, but may provide only limited benefits for individuals. The best chance of preventing AD may come from a combination of individual and population prevention approaches.

Mild cognitive impairment: diagnosis, longitudinal course, and emerging treatments

Mild cognitive impairment (MCI) is widely regarded as the intermediate stage of cognitive impairment between the changes seen in normal cognitive aging and those associated with dementia. Elderly patients with MCI constitute a high-risk population for developing dementia, in particular Alzheimer's disease (AD). Although the core clinical criteria for MCI have remained largely unchanged, the operational definition of MCI has undergone several revisions over the course of the last decade and remains an evolving diagnosis. Prognostic implications of this diagnosis are becoming clearer with regard to the risk of progressive cognitive deterioration. Although patients with MCI may represent an optimal target population for pharmacological and non-pharmacological interventions, results from clinical trials have been mixed and an effective treatment remains elusive. This article provides a brief overview of the evolution of the concept of MCI and reviews current diagnostic criteria, the longitudinal course of the disorder, and current and emerging treatments for MCI.

The effect of galantamine on brain atrophy rate in subjects with mild cognitive impairment is modified by apolipoprotein E genotype: post-hoc analysis of data from a randomized controlled trial

INTRODUCTION

The aim of this investigation was to assess the effect of galantamine, an acetylcholinesterase inhibitor and allosteric modulator of nicotinic receptors, on brain atrophy in individuals with mild cognitive impairment (MCI), and to assess effect modification by apolipoprotein E (APOE) genotype.

METHODS

We used data from the Galantamine-International-11 (Gal-Int-11) trial, a 24-month, randomized, double blind, placebo-controlled, flexible-dose (16 to 24 mg daily) study in patients with MCI. Brain magnetic resonance imaging (MRI), including a 3-dimensional T1-weighted gradient echo volumetric sequence, was performed at screening and at 24 months. We recorded whole brain and hippocampal volumes, and calculated annual atrophy rates. Linear regression analysis was used to calculate adjusted mean differences in the rate of whole brain and hippocampal atrophy, between MCI patients treated with galantamine and with placebo. Additionally, we performed stratified analyses according to APOE genotype.

RESULTS

Data from 364 MCI patients with 24-month MRI data (galantamine, n = 176; placebo, n = 188) were included in the volumetric analysis. Subjects treated with galantamine demonstrated a lower rate of whole brain atrophy compared to those treated with placebo (adjusted mean difference 0.18% per year (95% confidence interval (CI) 0.04; 0.30)). Stratified analyses according to APOE genotype, showed that this effect was confined to patients who carried an APOE ϵ4 allele (adjusted mean difference 0.28% per year (95% CI 0.07; 0.50)). Rates of hippocampal atrophy did not differ significantly between study groups.

CONCLUSIONS

Patients with MCI who were treated with galantamine demonstrated a lower rate of whole brain atrophy, but not of hippocampal atrophy, over a 24-month treatment period, compared to those treated with placebo. This protective effect of galantamine on whole brain atrophy rate in MCI was only present in APOE ϵ4 carriers.

Mild Cognitive Impairment: A Brief Review and Suggested Clinical Algorithm

Mild cognitive impairment (MCI) is a dynamic state between normal cognition and dementia, where interventions can be taken to stop or delay the progression to dementia. It is broadly of 2 types-amnestic, where memory loss is the chief concern and nonamnestic, where it is not. One variant of nonamnestic, dysexecutive, being more prevalent is sometimes known as a separate subtype by itself. Diagnosis of MCI is mostly clinical and is aided by various scales and neuropsychological testing. Functional imaging studies help in early detection and is superior to biomarkers or structural magnetic resonance imaging. Although there is no evidence supporting any pharmacological intervention, cognitive rehabilitation, memory training, and caregiver support play a strong role in limiting and sometimes reversing the ongoing cognitive decline. As the spectrum of MCI is heterogeneous, making the right diagnosis can be a challenging; hence, we need a systematic yet cost-effective algorithm for the timely management of MCI.

Mild cognitive impairment. Part 2: Biological markers for diagnosis and prediction of dementia in Alzheimer's disease

OBJECTIVE

To present a critical review of publications reporting on the rationale and clinical implications of the use of biomarkers for the early diagnosis of Alzheimer's disease (AD).

METHODS

We conducted a systematic search of the PubMed and Web of Science electronic databases, limited to articles published in English between 1999 and 2012, and based on the following terms: mild cognitive impairment, Alzheimer's disease OR dementia, biomarkers. We retrieved 1,130 articles, of which 175 were reviews. Overall, 955 original articles were eligible.

RESULTS

The following points were considered relevant for the present review: a) rationale for biomarkers research in AD and mild cognitive impairment (MCI); b) usefulness of distinct biomarkers for the diagnosis and prediction of AD; c) the role of multimodality biomarkers for the diagnosis and prediction of AD; d) the role of biomarkers in clinical trials of patients with AD and MCI; and e) current limitations to the widespread use of biomarkers in research and clinical settings.

CONCLUSION

Different biomarkers are useful for the early diagnosis and prediction of AD in at-risk subjects. Nonetheless, important methodological limitations need to be overcome for widespread use of biomarkers in research and clinical settings.

Mild cognitive impairment: a concept in evolution

The construct of mild cognitive impairment (MCI) has evolved over the past 10 years since the publication of the new MCI definition at the Key Symposium in 2003, but the core criteria have remained unchanged. The construct has been extensively used worldwide, both in clinical and in research settings, to define the grey area between intact cognitive functioning and clinical dementia. A rich set of data regarding occurrence, risk factors and progression of MCI has been generated. Discrepancies between studies can be mostly explained by differences in the operationalization of the criteria, differences in the setting where the criteria have been applied, selection of subjects and length of follow-up in longitudinal studies. Major controversial issues that remain to be further explored are algorithmic versus clinical classification, reliability of clinical judgment, temporal changes in cognitive performances and predictivity of putative biomarkers. Some suggestions to further develop the MCI construct include the tailoring of the clinical criteria to specific populations and to specific contexts. The addition of biomarkers to the clinical phenotypes is promising but requires deeper investigation. Translation of findings from the specialty clinic to the population setting, although challenging, will enhance uniformity of outcomes. More longitudinal population-based studies on cognitive ageing and MCI need to be performed to clarify all these issues.

Clinical trials and late-stage drug development for Alzheimer's disease: an appraisal from 1984 to 2014

The modern era of drug development for Alzheimer's disease began with the proposal of the cholinergic hypothesis of memory impairment and the 1984 research criteria for Alzheimer's disease. Since then, despite the evaluation of numerous potential treatments in clinical trials, only four cholinesterase inhibitors and memantine have shown sufficient safety and efficacy to allow marketing approval at an international level. Although this is probably because the other drugs tested were ineffective, inadequate clinical development methods have also been blamed for the failures. Here, we review the development of treatments for Alzheimer's disease during the past 30 years, considering the drugs, potential targets, late-stage clinical trials, development methods, emerging use of biomarkers and evolution of regulatory considerations in order to summarize advances and anticipate future developments. We have considered late-stage Alzheimer's disease drug development from 1984 to 2013, including individual clinical trials, systematic and qualitative reviews, meta-analyses, methods, commentaries, position papers and guidelines. We then review the evolution of drugs in late clinical development, methods, biomarkers and regulatory issues. Although a range of small molecules and biological products against many targets have been investigated in clinical trials, the predominant drug targets have been the cholinergic system and the amyloid cascade. Trial methods have evolved incrementally: inclusion criteria have largely remained focused on mild-to-moderate Alzheimer's disease criteria, recently extending to early or prodromal Alzheimer disease or 'mild cognitive impairment due to Alzheimer's disease', for drugs considered to be disease modifying. The duration of trials has remained at 6-12 months for drugs intended to improve symptoms; 18- to 24-month trials have been established for drugs expected to attenuate clinical course. Cognitive performance, activities of daily living, global change and severity ratings have persisted as the primary clinically relevant outcomes. Regulatory guidance and oversight have evolved to allow for enrichment of early-stage Alzheimer's disease trial samples using biomarkers and phase-specific outcomes. In conclusion, validated drug targets for Alzheimer's disease remain to be developed. Only drugs that affect an aspect of cholinergic function have shown consistent, but modest, clinical effects in late-phase trials. There is opportunity for substantial improvements in drug discovery and clinical development methods.

Cognition in MCI and Alzheimer's disease: baseline data from a longitudinal study of the NTB

Baseline data are summarized from a study examining the psychometric properties of the Neuropsychological Test Battery (NTB) and its subtests, and correlating the NTB with other cognitive and functional assessments. A multicenter, longitudinal, non-interventional study included mild to moderate Alzheimer's disease (AD, n = 196), mild cognitive impairment (MCI, n = 70), or normal cognition participants (NC, n = 75). The NTB, other cognitive assessment tools, functional/behavioral questionnaires, and health outcome assessments were administered. At baseline composite NTB, NTB memory, and NTB executive function z-scores were significantly lower for participants with AD compared with MCI, and for participants with MCI compared with NC. The composite NTB z-score had high test-retest reliability between screening and baseline. The results of this study suggest that NTB exhibits good reliability in patients with mild to moderate AD and MCI.

Effects of galantamine in a 2-year, randomized, placebo-controlled study in Alzheimer's disease

BACKGROUND

Currently available treatments for Alzheimer's disease (AD) can produce mild improvements in cognitive function, behavior, and activities of daily living in patients, but their influence on long-term survival is not well established. This study was designed to assess patient survival and drug efficacy following a 2-year galantamine treatment in patients with mild to moderately severe AD.

METHODS

In this multicenter, double-blind study, patients were randomized 1:1 to receive galantamine or placebo. One primary end point was safety; mortality was assessed. An independent Data Safety Monitoring Board monitored mortality for the total deaths reaching prespecified numbers, using a time-to-event method and a Cox-regression model. The primary efficacy end point was cognitive change from baseline to month 24, as measured by the Mini-Mental State Examination (MMSE) score, analyzed using intent-to-treat analysis with the 'last observation carried forward' approach, in an analysis of covariance model.

RESULTS

In all, 1,024 galantamine- and 1,021 placebo-treated patients received study drug, with mean age ~73 years, and mean (standard deviation [SD]) baseline MMSE score of 19 (4.08). A total of 32% of patients (661/2,045) completed the study, 27% (554/2,045) withdrew, and 41% (830/2,045) did not complete the study and were discontinued due to a Data Safety Monitoring Board-recommended early study termination. The mortality rate was significantly lower in the galantamine group versus placebo (hazard ratio [HR] =0.58; 95% confidence interval [CI]: 0.37; 0.89) (P=0.011). Cognitive impairment, based on the mean (SD) change in MMSE scores from baseline to month 24, significantly worsened in the placebo (-2.14 [4.34]) compared with the galantamine group (-1.41 [4.05]) (P<0.001). Functional impairment, based on mean (SD) change in the Disability Assessment in Dementia score (secondary end point), at month 24 significantly worsened in the placebo (-10.81 [18.27]) versus the galantamine group (-8.16 [17.25]) (P=0.002). Incidences of treatment-emergent adverse events were 54.0% for the galantamine and 48.6% for the placebo group.

CONCLUSION

Long-term treatment with galantamine significantly reduced mortality and the decline in cognition and daily living activities, in mild to moderate AD patients.

IDENTIFICATION

This study is registered at ClinicalTrials.gov (NCT00679627).

Effect of cholinergic signaling on neuronal cell bioenergetics

Alzheimer's disease (AD) patients have reduced brain acetylcholine and reversing this deficit yields clinical benefits. In this study we explored how increased cholinergic tone impacts cell bioenergetics, which are also perturbed in AD. We treated SH-SY5Y neuroblastoma cells with carbachol, a cholinergic agonist, and tested for bioenergetic flux and bioenergetic infrastructure changes. Carbachol rapidly increased both oxidative phosphorylation and glycolysis fluxes. ATP levels rose slightly, as did cell energy demand, and AMPK phosphorylation occurred. At least some of these effects depended on muscarinic receptor activation, ER calcium release, and ER calcium re-uptake. Our data show that increasing cholinergic signaling enhances cell bioenergetics, and reveal mechanisms that mediate this effect. Phenomena we observed could potentially explain why cholinesterase inhibitor therapy increases AD brain glucose utilization and N-acetyl aspartate levels. The question of whether cholinesterase inhibitors have a disease modifying effect in AD has long been debated; our data suggest a theoretical mechanism through which such an effect could potentially arise.

Mild cognitive impairment

PURPOSE OF REVIEW

The term mild cognitive impairment (MCI) is used to describe older subjects with demonstrable cognitive impairment who have not crossed the threshold for dementia. Because patients with MCI have an increased risk of developing dementia, especially Alzheimer disease (AD), there is significant interest in the clinical characterization of these subjects and in understanding the pathophysiology of the transition from MCI to AD.

RECENT FINDINGS

The MCI syndrome, as an expression of an incipient disorder that may lead to dementia, is extremely heterogeneous and may coexist with systemic, neurologic, or psychiatric disorders that can cause cognitive deficits. Recent clinical criteria were designed to take into account the different forms of clinical presentation of the syndrome, and introduced the possible contribution of biomarkers to the clinical diagnosis. Bedside diagnosis of MCI can be difficult, since patients who report having cognitive problems may have normal scores in global cognitive scales or in brief neuropsychological instruments.

SUMMARY

This article presents the evolution of the clinical concept of MCI, the operationalization of its current definitions, the development of biomarkers that can help to identify an underlying neurodegenerative process as the etiology of the syndrome, and its proposed treatments.

Efficacy and safety of cognitive enhancers for patients with mild cognitive impairment: a systematic review and meta-analysis

BACKGROUND

Cognitive enhancers, including cholinesterase inhibitors and memantine, are used to treat dementia, but their effectiveness for mild cognitive impairment is unclear. We conducted a systematic review to examine the efficacy and safety of cognitive enhancers for mild cognitive impairment.

METHODS

Our eligibility criteria were studies of the effects of donepezil, rivastigmine, galantamine or memantine on mild cognitive impairment reporting cognition, function, behaviour, global status, and mortality or harms. We identified relevant material by searching electronic databases (e.g., MEDLINE, Embase), the references of included studies, trial registries and conference proceedings, and by contacting experts. Two reviewers independently screened the results of the literature search, abstracted data and appraised risk of bias using the Cochrane risk-of-bias tool.

RESULTS

We screened 15,554 titles and abstracts and 1384 full-text articles. Eight randomized clinical trials and 3 companion reports met our inclusion criteria. We found no significant effects of cognitive enhancers on cognition (Mini-Mental State Examination: 3 randomized clinical trials [RCTs], mean difference [MD] 0.14, 95% confidence interval [CI] -0.22 to 0.50; Alzheimer's Disease Assessment Scale - cognition subscale: 3 RCTs, standardized MD -0.07, 95% CI-0.16 to 0.01]) or function (Alzheimer's Disease Cooperative Study activities of daily living inventory: 2 RCTs, MD 0.30, 95% CI -0.26 to 0.86). Cognitive enhancers were associated with higher risks of nausea, diarrhea and vomiting than placebo.

INTERPRETATION

Cognitive enhancers did not improve cognition or function among patients with mild cognitive impairment and were associated with a greater risk of gastrointestinal harms. Our findings do not support the use of cognitive enhancers for mild cognitive impairment.

Treatment for mild cognitive impairment: systematic review

BACKGROUND

More people are presenting with mild cognitive impairment (MCI), frequently a precursor to dementia, but we do not know how to reduce deterioration.

AIMS

To systematically review randomised controlled trials (RCTs) evaluating the effects of any intervention for MCI on cognitive, neuropsychiatric, functional, global outcomes, life quality or incident dementia.

METHOD

We reviewed 41 studies fitting predetermined criteria, assessed validity using a checklist, calculated standardised outcomes and prioritised primary outcome findings in placebo-controlled studies.

RESULTS

The strongest evidence was that cholinesterase inhibitors did not reduce incident dementia. Cognition improved in single trials of: a heterogeneous psychological group intervention over 6 months; piribedil, a dopamine agonist over 3 months; and donepezil over 48 weeks. Nicotine improved attention over 6 months. There was equivocal evidence that Huannao Yicong improved cognition and social functioning.

CONCLUSIONS

There was no replicated evidence that any intervention was effective. Cholinesterase inhibitors and rofecoxib are ineffective in preventing dementia. Further good-quality RCTs are needed and preliminary evidence suggests these should include trials of psychological group interventions and piribedil.

How can we improve transfer of outcomes from randomized clinical trials to clinical practice with disease-modifying drugs in Alzheimer's disease?

BACKGROUND

Randomized clinical trials (RCTs) for putative disease-modifying drugs in Alzheimer's disease (AD) are using cognitive outcomes, such as the Alzheimer's Disease Assessment Scale--cognitive subscale, activities of daily living scales, such as the Alzheimer's Disease Cooperative Study Activities of Daily Living, and time from mild cognitive impairment to AD dementia.

OBJECTIVE

It was the aim of this study to build clinically relevant outcomes for future use in clinical practice into RCT designs and help third-party payers to measure benefit.

METHODS

We used a literature review for analysis.

RESULTS

The Clinical Dementia Rating Scale Sum of Boxes (CDR-SB) appears to be the most reliable primary outcome for RCT at different stages of AD, with the Relevant Outcome Scale for Alzheimer's Disease (ROSA) as a suitable alternative. The importance of current AD biomarkers vis-à- vis determination of efficacy of disease-modifying drugs has yet to be established; however, it is likely that at least one amyloid-specific test will be required prior to treatment with a drug acting predominantly on β-amyloid (Aβ42). Furthermore, serial MRI may be required to monitor adverse side effects associated with such drugs.

CONCLUSIONS

Global clinical scales such as CDR-SB and ROSA should be considered for use with treatments aiming at slowing disease progression.

The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS): Utility in detection and characterization of mild cognitive impairment due to Alzheimer's disease

Current diagnostic criteria for mild cognitive impairment (MCI) due to Alzheimer's disease (AD) require standardized tests that are capable of measuring a range of neurocognitive abilities in healthy elderly individuals and sensitive to detect change over time. There currently is no clearly-established "gold standard" for this purpose. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) is a widely used neuropsychological test battery for the clinical diagnosis/tracking of dementia also recently incorporated into clinical trials of new investigational medications for AD treatment. The RBANS has a number of design features that suggest possible utility in diagnosis/tracking of MCI. Eighty-one patients with MCI completed the RBANS and their scores were compared with 81 demographically matched healthy controls. RBANS Total Scale scores in both groups were normally distributed, demonstrating no floor/ceiling effects. The MCI group was most impaired on the Delayed Memory Index (DMI). Receiver operating characteristic analyses reflected good discrimination, with an area under the curve of 0.88 for the Total Scale score and 0.90 for the DMI score. The profile of performance for the MCI group was similar to that previously reported for mild AD patients. The RBANS may be a suitable neurocognitive battery for the detection and tracking of MCI presumed to be due to AD.

Subjective cognitive impairment: Towards early identification of Alzheimer disease

INTRODUCTION

Neurodegeneration in Alzheimer disease (AD) begins decades before dementia and patients with mild cognitive impairment (MCI) already demonstrate significant lesion loads. Lack of information about the early pathophysiology in AD complicates the search for therapeutic strategies.Subjective cognitive impairment is the description given to subjects who have memory-related complaints without pathological results on neuropsychological tests. There is no consensus regarding this heterogeneous syndrome, but at least some of these patients may represent the earliest stage in AD.

METHOD

We reviewed available literature in order to summarise current knowledge on subjective cognitive impairment.

RESULTS

Although they may not present detectable signs of disease, SCI patients as a group score lower on neuropsychological tests than the general population does, and they also have a higher incidence of future cognitive decline. Depression and psychiatric co-morbidity play a role but cannot account for all cognitive complaints. Magnetic resonance imaging studies in these patients reveal a pattern of hippocampal atrophy similar to that of amnestic mild cognitive impairment and functional MRI shows increased activation during cognitive tasks which might indicate compensation for loss of function. Prevalence of an AD-like pattern of beta-amyloid (Aβ42) and tau proteins in cerebrospinal fluid is higher in SCI patients than in the general population.

CONCLUSIONS

Memory complaints are relevant symptoms and may predict AD. Interpatient variability and methodological differences between clinical studies make it difficult to assign a definition to this syndrome. In the future, having a standard definition and longitudinal studies with sufficient follow-up times and an emphasis on quantifiable variables may clarify aspects of early AD.

Diagnosing Mild Cognitive Impairment (MCI) in clinical trials: a systematic review

OBJECTIVE

To describe how criteria for amnestic Mild Cognitive Impairment (aMCI) have been operationalised in randomised controlled clinical trials (RCTs).

DESIGN

Systematic review.

INFORMATION SOURCES

EMBASE, PubMed and PSYCHInfo were searched from their inception to February 2012. Electronic clinical trial registries were also searched (February 2012).

STUDY SELECTION

RCTs were included where participant selection was made using Petersen et al-defined aMCI. There was no restriction on intervention type or the outcome tested.

DATA EXTRACTION

For each trial, we extracted information on study design, demographics, exclusion criteria and the operationalisation strategy for the five aMCI diagnostic criteria including: (1) memory complaint, (2) normal general cognitive function, (3) memory impairment, (4) no functional impairment and (5) no dementia.

RESULTS

223 articles and 278 registered trials were reviewed, of which 22 met inclusion criteria. Various methods were applied for operationalising aMCI criteria resulting in variability in participant selection. Memory complaint and assessment of general cognitive function were the most consistently measured criteria. There was large heterogeneity in the neuropsychological methods used to determine memory impairment. It was not possible to assess the impact of these differences on case selection accuracy for dementia prediction. Further limitations include selective and unclear reporting of how each of the criteria was measured.

CONCLUSIONS

The results highlight the urgent need for a standardised approach to map aMCI. Lack of uniformity in clinical diagnosis, however, is not exclusively a problem for MCI but also for other clinical states such as dementia including Alzheimer's disease, Lewy Body, frontotemporal or vascular dementia. Defining a uniform approach to MCI classification, or indeed for any classification concept within the field of dementia, should be a priority if further trials are to be undertaken in the older aged population based on these concepts.

Pharmacological Treatment of Mild Cognitive Impairment as a Prodromal Syndrome of Alzheimer´s Disease

Mild cognitive impairment (MCI) is a syndrome which, depending on various neurobiological, psychological and social factors, carries a high risk of developing into dementia. As far as diagnostic uncertainty and the heterogeneous underlying pathophysiological mechanisms are concerned, only limited therapeutic options are currently available. Clinical trials involving a wide range of substances have failed to show efficacy on primary and secondary outcome parameters. Most results reflect not only a lack of effectiveness of drug therapy but also methodological constraints in true prodromal Alzheimer´s disease (AD) based on clinical criteria. Biomarkers may help to identify MCI as a prodromal phase of dementia, so it is important to use them to improve specificity of case selection in future studies. For MCI as a prodromal syndrome of AD, clinical trials with disease modifying drugs that target underlying pathological mechanisms such as amyloid-beta accumulation and neurofibrillary tangle formation may help develop effective treatment options in the future. Alternative pharmacological approaches are currently being evaluated in ongoing phase 1 and phase 2 studies. Nevertheless, a lack of approved pharmacotherapeutic options has led to specific interventions that focus on patient education and life-style related factors receiving increasing attention.

A ketone ester diet exhibits anxiolytic and cognition-sparing properties, and lessens amyloid and tau pathologies in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) involves progressive accumulation of amyloid β-peptide (Aβ) and neurofibrillary pathologies, and glucose hypometabolism in brain regions critical for memory. The 3xTgAD mouse model was used to test the hypothesis that a ketone ester-based diet can ameliorate AD pathogenesis. Beginning at a presymptomatic age, 2 groups of male 3xTgAD mice were fed a diet containing a physiological enantiomeric precursor of ketone bodies (KET) or an isocaloric carbohydrate diet. The results of behavioral tests performed at 4 and 7 months after diet initiation revealed that KET-fed mice exhibited significantly less anxiety in 2 different tests. 3xTgAD mice on the KET diet also exhibited significant, albeit relatively subtle, improvements in performance on learning and memory tests. Immunohistochemical analyses revealed that KET-fed mice exhibited decreased Aβ deposition in the subiculum, CA1 and CA3 regions of the hippocampus, and the amygdala. KET-fed mice exhibited reduced levels of hyperphosphorylated tau deposition in the same regions of the hippocampus, amygdala, and cortex. Thus, a novel ketone ester can ameliorate proteopathic and behavioral deficits in a mouse AD model.

Effects of memantine and galantamine on cognitive performance in aged rhesus macaques

Current pharmacotherapies for Alzheimer's disease (AD) are focused on improving performance of daily activities, personal care, and management of problematic behaviors. Both memantine, a noncompetitive N-methyl-D-aspartate channel blocker and galantamine, a selective acetylcholinesterase inhibitor, are currently prescribed as symptomatic therapies for AD. However, drugs that progressed directly from testing in rodent models to testing in AD patients in clinical trials failed to demonstrate consistent effects on cognitive symptoms. Considering the lack of nonhuman primate data on the effects of memantine and galantamine alone or in combination on cognitive dysfunction in aged nonhuman primates, the present study examined how closely data derived from aged nonhuman primates reflects data obtained in humans. Mild beneficial effects on aspects of cognitive performance in aged primates were found, in general agreement with the human clinical experience with these drugs but in contrast to the more positive effects reported in the rodent literature. These data suggest that the nonhuman primate might have more predictive validity for drug development in this area than comparable rodent assays.

Cholinesterase inhibitors for mild cognitive impairment

BACKGROUND

Mild cognitive impairment is hypothesised to represent a pre-clinical stage of dementia but forms a heterogeneous group with variable prognosis.

OBJECTIVES

To assess the safety and efficacy of cholinesterase inhibitors in people with mild cognitive impairment.

SEARCH METHODS

Trials were identified from the Cochrane Dementia and Cognitive Improvement Group's Specialised Register, which is frequently updated from the major healthcare databases (MEDLINE, EMBASE, CINAHL, PsycINFO and Lilacs) as well as trial registers and grey literature.

SELECTION CRITERIA

Double-blind, placebo-controlled randomised trials of any cholinesterase inhibitor in people with mild cognitive impairment.

DATA COLLECTION AND ANALYSIS

Data were extracted from the published reports of the included studies, combined by meta-analysis where appropriate, and treatment efficacy and risk of adverse events were estimated.

MAIN RESULTS

Nine studies (from eight published reports) of 5149 individuals with mild cognitive impairment (however defined) were included in the review. Limited pooling of results was possible owing to different lengths of trials. Meta-analysis of the three studies reporting conversion to dementia gives no strong evidence of a beneficial effect of cholinesterase inhibitors on the progression to dementia at one, two or three years. The risk ratio (RR) for conversion at two years was significantly different from unity (0.67; 95% confidence interval (CI) 0.55 to 0.83), but this is based on only two studies reported in the same article. There was essentially no effect of cholinesterase inhibitors on cognitive test scores.Based on the results from 4207 individuals, there were significantly more adverse events in the cholinesterase inhibitor groups (RR 1.09; 95% CI 1.02 to 1.16), but no more serious adverse events or deaths. Gastrointestinal side effects were much more common (diarrhoea: RR 2.10; 95% CI 1.30 to 3.39; nausea: RR 2.97; 95% CI 2.57 to 3.42; vomiting: RR 4.42; 95% CI 3.23 to 6.05). Cardiac problems were no more likely in either group (RR 0.71; 95% CI 0.25 to 2.02). Other side effects reported significantly more often in the cholinesterase inhibitor group were muscle spasms/leg cramps (RR 7.52; 95% CI 4.34 to 13.02), headache (RR 1.34; 95% CI 1.05 to 1.71), syncope or dizziness (RR 1.62; 95% CI 1.36 to 1.93), insomnia (RR 1.66; 95% CI 1.36 to 2.02) and abnormal dreams (RR 4.25; 95% CI 2.57 to 7.04).

AUTHORS' CONCLUSIONS

There is very little evidence that cholinesterase inhibitors affect progression to dementia or cognitive test scores in mild cognitive impairment. This weak evidence is overwhelmed by the increased risk of adverse events, particularly gastrointestinal. Cholinesterase inhibitors should not be recommended for mild cognitive impairment.

Rationale for use of the Clinical Dementia Rating Sum of Boxes as a primary outcome measure for Alzheimer's disease clinical trials

BACKGROUND

We used the database of the Alzheimer's Disease Neuroimaging Initiative (ADNI) to explore the psychometric properties of the Clinical Dementia Rating Sum of Boxes (CDR-SB) to consider its utility as an outcome measure for clinical trials in early and mild, as well as later, stages of Alzheimer's disease (AD).

METHODS

We assessed internal consistency, structural validity, convergent validity, and 2-year internal and external responsiveness of the CDR-SB using data from 382 subjects with early or mild AD at entry into the ADNI study.

RESULTS

The CDR-SB assesses both cognitive and functional domains of AD disability. Mean scores declined nearly linearly; CDR-SB cognitive and functional subsums contributed equally to total scores at both very mild (early) and mild stages of the disease.

CONCLUSIONS

The CDR-SB has psychometric properties that make it attractive as a primary outcome measure that comprehensively assesses both cognitive and functional disability in AD patients. It may prove particularly useful for studies in early, predementia stages of AD.