Clinical trial design issues in mild to moderate Alzheimer disease

Advances in Alzheimer's Therapy: Exploring Neuropathological Mechanisms to Revolutionize the Future Therapeutic Landscape

Alzheimer's disease (AD) is still an excessively complicated neurological disorder that impacts millions of individuals globally. The ideal defensive feature of the central nervous system (CNS) is the intimate junction of endothelial cells, which functions as a biological barrier to safely control molecular transport throughout the brain. The blood-brain barrier (BBB) comprises tightly locked astrocyte cell junctions on CNS blood capillaries. This biological barrier shields the brain from hazardous toxins by preventing the entry of polar medications, cells, and ions. However, it is very challenging to provide any treatment to the brain for neurodegenerative illnesses like Alzheimer's. Different causative mechanisms, such as amyloid-β (Aβ) plaques, tubulin-associated unit (Tau) tangles, and neuroinflammation, cause neuronal dysfunction, leading to dementia and memory loss in the subject. Several treatments are approved for AD therapy, whereas most only help treat related symptoms. Disappointingly, current remedies have not been able to control the progression of AD due to associated side effects. Specific pathogenic mechanisms are involved in the initiation and development of this disease. Therefore, the expected survival of a patient with AD is limited and is approximately ten years. Hence, the pathogenic mechanism behind AD progression must be understood to better comprehend and improve the overall survival rate. This review highlighted the recent insights into AD pathogenesis, molecular mechanisms, advancements in theragnostic techniques, the existing updates of clinical trials, and emerging innovations for AD medicinal development. That has helped researchers develop other strategies to address the shortcomings of traditional medications.

Mini-mental status examination phenotyping for Alzheimer's disease patients using both structured and narrative electronic health record features

OBJECTIVE

This study aims to automate the prediction of Mini-Mental State Examination (MMSE) scores, a widely adopted standard for cognitive assessment in patients with Alzheimer's disease, using natural language processing (NLP) and machine learning (ML) on structured and unstructured EHR data.

MATERIALS AND METHODS

We extracted demographic data, diagnoses, medications, and unstructured clinical visit notes from the EHRs. We used Latent Dirichlet Allocation (LDA) for topic modeling and Term-Frequency Inverse Document Frequency (TF-IDF) for n-grams. In addition, we extracted meta-features such as age, ethnicity, and race. Model training and evaluation employed eXtreme Gradient Boosting (XGBoost), Stochastic Gradient Descent Regressor (SGDRegressor), and Multi-Layer Perceptron (MLP).

RESULTS

We analyzed 1654 clinical visit notes collected between September 2019 and June 2023 for 1000 Alzheimer's disease patients. The average MMSE score was 20, with patients averaging 76.4 years old, 54.7% female, and 54.7% identifying as White. The best-performing model (ie, lowest root mean squared error (RMSE)) is MLP, which achieved an RMSE of 5.53 on the validation set using n-grams, indicating superior prediction performance over other models and feature sets. The RMSE on the test set was 5.85.

DISCUSSION

This study developed a ML method to predict MMSE scores from unstructured clinical notes, demonstrating the feasibility of utilizing NLP to support cognitive assessment. Future work should focus on refining the model and evaluating its clinical relevance across diverse settings.

CONCLUSION

We contributed a model for automating MMSE estimation using EHR features, potentially transforming cognitive assessment for Alzheimer's patients and paving the way for more informed clinical decisions and cohort identification.

Sociotechnical feasibility of natural language processing-driven tools in clinical trial eligibility prescreening for Alzheimer's disease and related dementias

BACKGROUND

Alzheimer's disease and related dementias (ADRD) affect over 55 million globally. Current clinical trials suffer from low recruitment rates, a challenge potentially addressable via natural language processing (NLP) technologies for researchers to effectively identify eligible clinical trial participants.

OBJECTIVE

This study investigates the sociotechnical feasibility of NLP-driven tools for ADRD research prescreening and analyzes the tools' cognitive complexity's effect on usability to identify cognitive support strategies.

METHODS

A randomized experiment was conducted with 60 clinical research staff using three prescreening tools (Criteria2Query, Informatics for Integrating Biology and the Bedside [i2b2], and Leaf). Cognitive task analysis was employed to analyze the usability of each tool using the Health Information Technology Usability Evaluation Scale. Data analysis involved calculating descriptive statistics, interrater agreement via intraclass correlation coefficient, cognitive complexity, and Generalized Estimating Equations models.

RESULTS

Leaf scored highest for usability followed by Criteria2Query and i2b2. Cognitive complexity was found to be affected by age, computer literacy, and number of criteria, but was not significantly associated with usability.

DISCUSSION

Adopting NLP for ADRD prescreening demands careful task delegation, comprehensive training, precise translation of eligibility criteria, and increased research accessibility. The study highlights the relevance of these factors in enhancing NLP-driven tools' usability and efficacy in clinical research prescreening.

CONCLUSION

User-modifiable NLP-driven prescreening tools were favorably received, with system type, evaluation sequence, and user's computer literacy influencing usability more than cognitive complexity. The study emphasizes NLP's potential in improving recruitment for clinical trials, endorsing a mixed-methods approach for future system evaluation and enhancements.

Linking the Clinical Dementia Rating Scale-Sum of Boxes, the Clinician's Interview-Based Impression Plus Caregiver Input, and the Clinical Global Impression Scale: Evidence based on Individual Participant Data from Five Randomized Clinical Trials of Donepezil

BACKGROUND

In patients with Alzheimer's disease, global assessment scales, such as the Clinical Dementia Rating-Sum of Boxes (CDR-SB), the Clinician's Interview-Based Impression Plus Caregiver Input (CIBI plus), and the Clinical Global Impression (CGI) are commonly used.

OBJECTIVE

To clinically understand and interpret the associations between these scales, we examined the linkages for the total and change scores of CDR-SB, CIBI plus, and CGI.

METHODS

Individual participant data (N = 2,198) from five pivotal randomized placebo-controlled trials of donepezil were included. Data were collected at baseline and scheduled visits for up to 6 months. Spearman's correlation coefficients ρ were examined between corresponding total and change scores of simultaneous CDR-SB, CIBI plus, and CGI ratings. To link between the simultaneous ratings, equipercentile linking was used.

RESULTS

We found strong evidence that the Spearman's correlation coefficients between the CDR-SB and CGI, and CDR-SB and CIBI plus total scores were at least adequately correlated (ρ= 0.50 to 0.71, with p < 0.01). The correlation coefficients between the change scores of CDR-SB and CGI were deemed adequate for weeks 6 to 24 (ρ= 0.44 to 0.65); the remaining correlations were smaller in magnitude (ρ= 0.09 to 0.35). Overall, the linkages were in-line with expectations, e.g., CDR-SB range score of 3-4 (= very mild dementia) was linked to a CGI score of 3 (= mildly ill), and an increase of CDR-SB of 1 was linked to a change of 5 (= minimal worsening) in both CGI and CIBI plus.

CONCLUSION

The study findings can be useful for clinicians wishing to compare scores of different scales across patients. They can also help researchers understand results of studies using different scales and can facilitate meta-analyses, to increase statistical power.

Linking the Mini-Mental State Examination, the Alzheimer's Disease Assessment Scale-Cognitive Subscale and the Severe Impairment Battery: evidence from individual participant data from five randomised clinical trials of donepezil

BACKGROUND

The Mini-Mental State Examination (MMSE), the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) and the Severe Impairment Battery (SIB) are widely used rating scales to assess cognition in Alzheimer's disease.

OBJECTIVE

To understand the correspondence between these rating scales, we aimed to examine the linkage of MMSE with the ADAS-Cog and SIB total and change scores.

METHODS

We used individual-level data on participants with Alzheimer's disease (n=2925) from five pivotal clinical trials of donepezil. Data were collected at baseline and scheduled visits for up to 6 months. We used equipercentile linking to identify the correspondence between simultaneous measurements of MMSE with ADAS-Cog, and SIB total and change ratings.

FINDINGS

Spearman's correlation coefficients were of strong magnitude between the MMSE total score and the ADAS-Cog (rs from -0.82 to -0.87; p<0.05) and SIB total scores (rs from 0.70 to 0.75; p<0.05). Weaker correlations between the change scores were observed between the MMSE change score and the ADAS-Cog (week 1: r=-0.11, p=0.18; rs thereafter: -0.28 to -0.45; p<0.05) and SIB change scores (rs from 0.31 to 0.44; p<0.05). Linking suggested that the MMSE total scores were sensitive to moderate and severe cognitive impairment levels. Despite weak to moderate correlations for the change scores, moderate change levels linked well, indicating ceiling and floor effects.

CONCLUSIONS

The current results can be used in meta-analyses, data harmonisation and may contribute to increasing statistical power when pooling data from multiple sources.

CLINICAL IMPLICATIONS

The current study results help clinicians to understand these cognitive rating scale scores.

The Influence of Baseline Alzheimer's Disease Severity on Cognitive Decline and CSF Biomarkers in the NILVAD Trial

We examined the effects of a dihydropyridine calcium channel blocker nilvadipine with anti-inflammatory properties on cognition and cerebrospinal fluid (CSF) biomarkers by baseline Alzheimer's disease (AD) severity. Exploratory analyses were performed on the dataset (n = 497) of a phase III randomized placebo-controlled trial to examine the response to nilvadipine in AD subjects stratified by baseline AD severity into very mild (MMSE ≥ 25), mild (MMSE 20-24) and moderate AD (MMSE < 20). The outcome measures included total and subscale scores of the Alzheimer's Disease Assessment Scale Cognitive 12 (ADAS-Cog 12), the Clinical Dementia Rating Scale sum of boxes (CDR-sb) and the AD composite score (ADCOMS). Cerebrospinal fluid biomarkers Aβ38, Aβ40, Aβ42, neurofilament light chain (NFL), neurogranin, YKL-40, total tau and P181 tau (ptau) were measured in a subset of samples (n = 55). Regression analyses were adjusted for confounders to specifically examine the influence of nilvadipine and baseline AD severity on cognitive outcomes over 78-weeks. Compared to their respective placebo-controls, nilvadipine-treated, very mild AD subjects showed less decline, whereas moderate AD subjects showed a greater cognitive decline on the ADAS-Cog 12 test and the ADCOMS. A lower decline was observed after nilvadipine treatment for a composite memory trait in very mild AD subjects and a composite language trait in mild AD subjects. Cerebrospinal fluid Aβ42/Aβ40 ratios were increased in mild AD and decreased in moderate AD patients treated with nilvadipine, compared to their respective controls. Among moderate AD subjects, levels of ptau, total tau, neurogranin and YKL-40 increased in subjects treated with nilvadipine compared to placebo. These studies suggest that baseline AD severity influenced the treatment outcome in the NILVAD trial and that future clinical trials of nilvadipine should be restricted to mild and very mild AD patients.

Trial Registration: NCT02017340 Registered 20 December 2013, https://clinicaltrials.gov/ct2/show/NCT02017340

EUDRACT Reference Number 2012-002764-27 Registered 04 February 2013, https://www.clinicaltrialsregister.eu/ctr-search/search?query=2012-002764-27

Short-Term Response to Cholinesterase Inhibitors in Alzheimer's Disease Delays Time to Nursing Home Placement

Background:

A varying response to cholinesterase inhibitor (ChEI) treatment has been report-ed among patients with Alzheimer’s disease (AD). Whether the individual-specific response directly af-fects time to nursing home placement (NHP) was not investigated.

Objective:

We examined the relationship between the 6-month response to ChEI and institutionalization.

Methods:

In a prospective, observational, multicenter study, 881 outpatients with a clinical AD diagnosis and a Mini-Mental State Examination score of 10-26 at the start of ChEI therapy (baseline) were included. The participants were evaluated using cognitive, global, and activities of daily living (ADL) scales at base-line and semiannually over 3 years. The date of NHP was recorded.

Results:

During the study, 213 patients (24%) were admitted to nursing homes. The mean ± standard de-viation time from baseline (AD diagnosis) to NHP was 20.8 ± 9.3 months. After 6 months of ChEI treat-ment, the improved/unchanged individuals had longer time to NHP than those who worsened. The pro-longed time to NHP was 3 months for cognitive response (P=0.022), 4 months for global response (P=0.004), 6 months for basic ADL response (P<0.001), and 8 months for response in all three scales (P<0.001). No differences were detected between the improved and unchanged groups in any scales.

Conclusion:

Patients who exhibit a positive short-term response to ChEI can expect to stay in their own home for 3-8 months longer. These findings underline the importance of a comprehensive clinical exami-nation including various assessment scales to evaluate treatment response and provide a more accurate prognosis.

The conceptual relevance of assessment measures in patients with mild/mild-moderate Alzheimer's disease

Introduction

This study aims to evaluate the conceptual relevance of four measures of disease activity in patients with mild/mild-moderate Alzheimer's disease (AD): (1) the Alzheimer's Disease Assessment Scale–Cognitive Subscale; (2) the Alzheimer's Disease Cooperative Study–Activities of Daily Living Inventory; (3) the Neuropsychiatry Inventory; and (4) the Dependence Scale.

Methods

A conceptual model depicting patient experience of mild AD was developed via literature review; concepts were compared with the items of the four measures. Relevance of the concepts included in the four measures was evaluated by patients with mild AD in a survey and follow-up interviews.

Results

The four measures assessed few of the symptoms/impacts of mild AD identified within the literature. Measured items addressing emotional impacts were deemed most relevant by participants but were included in the measures only superficially.

Discussion

The four assessment measures do not appear to capture the concepts most relevant to/important to patients with mild/mild-moderate AD.

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Many impacts associated with mild Alzheimer's disease were reported by patients.

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The included outcome measures assessed did not provide high conceptual coverage.

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These four measures appeared more suitable for more severe Alzheimer's disease.

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Completion of patient reported outcomes should be possible in this patient population.

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These may be currently used in addition to clinician- and observer-reported outcomes.

The importance of endpoint selection: How effective does a drug need to be for success in a clinical trial of a possible Alzheimer's disease treatment?

To date, Alzheimer’s disease (AD) clinical trials have been largely unsuccessful. Failures have been attributed to a number of factors including ineffective drugs, inadequate targets, and poor trial design, of which the choice of endpoint is crucial. Using data from the Alzheimer’s Disease Neuroimaging Initiative, we have calculated the minimum detectable effect size (MDES) in change from baseline of a range of measures over time, and in different diagnostic groups along the AD development trajectory. The Functional Activities Questionnaire score had the smallest MDES for a single endpoint where an effect of 27% could be detected within 3 years in participants with Late Mild Cognitive Impairment (LMCI) at baseline, closely followed by the Clinical Dementia Rating Sum of Boxes (CDRSB) score at 28% after 2 years in the same group. Composite measures were even more successful than single endpoints with an MDES of 21% in 3 years. Using alternative cognitive, imaging, functional, or composite endpoints, and recruiting patients that have LMCI could improve the success rate of AD clinical trials.

Epidemiology of Dementia: The Burden on Society, the Challenges for Research

Dementia is among the leading causes of death and disability. Due to the ageing population, its prevalence is expected to nearly triple worldwide by 2050, urging the development of preventive and curative interventions. Various modifiable risk factors have been identified in community-based cohort studies, but insight into the underlying pathophysiological mechanisms is lacking. Clinical trials have thus far failed in the development of disease-modifying therapy in patients with dementia, thereby triggering a shift of focus toward the presymptomatic phase of disease. The extensive preclinical disease course of Alzheimer's disease warrants reliable, easily obtainable biomarkers to aid in timely application of preventive strategies, selecting participants for neuroprotective trials, and disease monitoring in trials and clinical practice. Biomarker and drug discovery may yield the fruits from technology-driven developments in the field of genomics, epigenetics, metabolomics, and brain imaging. In that context, bridging the gap between translational and population research may well prove a giant leap toward development of successful preventive and curative interventions against dementia.

Study partners should be required in preclinical Alzheimer's disease trials

Background

In an effort to intervene earlier in Alzheimer’s disease (AD), clinical trials are testing promising candidate therapies in preclinical disease. Preclinical AD trial participants are cognitively normal, functionally independent, and autonomous decision-makers. Yet, like AD dementia trials, preclinical trials require dual enrollment of a participant and a knowledgeable informant, or study partner.

Main text

The requirement of dyadic enrollment is a barrier to recruitment and may present unique ethical challenges. Despite these limitations, the requirement should continue. Study partners may be essential to ensure participant safety and wellbeing, including overcoming distress related to biomarker disclosure and minimizing risk for catastrophic reactions and suicide. The requirement may maximize participant retention and ensure data integrity, including that study partners are the source of data that will ultimately instruct whether a new treatment has a clinical benefit and meaningful impact on the population health burden associated with AD. Finally, study partners are needed to ensure the scientific and clinical value of trials.

Conclusions

Preclinical AD will represent a new model of care, in which persons with no symptoms are informed of probable cognitive decline and eventual dementia. The rationale for early diagnosis in symptomatic AD is equally applicable in preclinical AD—to minimize risk, maximize quality of life, and ensure optimal planning and communication. Family members and other sources of support will likely be essential to the goals of this new model of care for preclinical AD patients and trials must instruct this clinical practice.

Study partners perform essential tasks in dementia research and can experience burdens and benefits in this role

Most studies that enroll individuals with dementia require a study partner for each participant. Study partners-usually family members-perform several key roles: accompanying the participant to visits, providing information about the participant, and assisting with procedures such as taking medication. Little is known, however, about their experiences when performing these roles. Dementia researchers and institutional review boards need to know these experiences because the study partner role is one key factor in a study's success. This prospective qualitative study, using up to three semi-structured interviews with 62 study partners involved in a range of dementia studies, documented their subjective experiences. Content analysis demonstrates that study partners perform a range of tasks-often within the context of being a caregiver-that enable cognitively impaired individuals to participate in dementia research. These tasks present study partners with unique burdens and benefits, some of which dementia researchers and institutional review boards can address.

Global Trends in Alzheimer Disease Clinical Development: Increasing the Probability of Success

PURPOSE

Alzheimer disease (AD) is a growing global health and economic issue as elderly populations increase dramatically across the world. Despite the many clinical trials conducted, currently no approved disease-modifying treatment exists. In this commentary, the present status of AD drug development and the grounds for collaborations between government, academia, and industry to accelerate the development of disease-modifying AD therapies are discussed.

METHODS

Official government documents, literature, and news releases were surveyed by MEDLINE and website research.

FINDINGS

Currently approved anti-AD drugs provide only short-lived symptomatic improvements, which have no effect on the underlying pathogenic mechanisms or progression of the disease. The failure to approve a disease-modifying drug for AD may be because the progression of AD in the patient populations enrolled in clinical studies was too advanced for drugs to demonstrate cognitive and functional improvements. The US Food and Drug Administration and the European Medicines Agency recently published draft guidance for industry which discusses approaches for conducting clinical studies with patients in early AD stages. For successful clinical trials in early-stage AD, however, it will be necessary to identify biomarkers highly correlated with the clinical onset and the longitudinal progress of AD. In addition, because of the high cost and length of clinical AD studies, support in the form of global initiatives and collaborations between government, industry, and academia is needed.

IMPLICATIONS

In response to this situation, national guidance and international collaborations have been established. Global initiatives are focusing on 2025 as a goal to provide new treatment options, and early signs of success in biomarker and drug development are already emerging.

Effect of sample size re-estimation in adaptive clinical trials for Alzheimer's disease and mild cognitive impairment

Introduction

The sample size re-estimation (SSR) adaptive design allows interim analyses and resultant modifications of the ongoing trial to preserve or increase power. We investigated the applicability of SSR in Alzheimer's disease (AD) trials using a meta-database of clinical studies.

Methods

Based on six studies, we simulated clinical trials using Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-Cog) as primary outcome. A single SSR based on effect sizes or based on variances was conducted at 6 months and 12 months. Resultant power improvement and sample size adjustments were evaluated.

Results

SSR resulted in highly variable outcomes for both sample size increases and power improvement. The gain in power after SSR varies by initial sample sizes, trial durations, and effect sizes.

Conclusions

SSR adaptive designs can be effective for trials in AD and mild cognitive impairment with small or medium initial sample sizes. However, SSR in larger trials (>200 subjects per arm) generates no major advantages over the typical randomized trials.

Sensitivity to change and prediction of global change for the Alzheimer's Questionnaire

INTRODUCTION

Longitudinal assessment of cognitive decline in amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD) often involves the use of both informant-based and objective cognitive assessments. As efforts have focused on identifying individuals in pre-clinical stages, instruments that are sensitive to subtle cognitive changes are needed. The Alzheimer's Questionnaire (AQ) has demonstrated high sensitivity and specificity in identifying aMCI and AD; however its ability to measure longitudinal change has not been assessed. The aims of this study are to assess the sensitivity to change of the AQ and to determine whether the AQ predicts change in global cognition and function in cognitively normal (CN), aMCI, and AD subjects.

METHODS

Data from 202 individuals participating in a brain and body donation program were utilized for this study (101 CN, 62 aMCI, 39 AD). AD and aMCI individuals were matched on age, education, and gender to CN individuals. Sensitivity to change of the AQ was assessed in addition to the AQ's ability to predict change in global cognition and function. The Mini Mental State Exam (MMSE) and Functional Activities Questionnaire (FAQ) were used as gold standard comparisons of cognition and function. Sample size calculations for a 25% treatment effect were also carried out for all three groups.

RESULTS

The AQ demonstrated small sensitivity to change in the aMCI and CN groups (d = 0.33, d = 0.23, respectively) and moderate sensitivity to change in the AD group (d = 0.43). The AQ was associated with increases in the Clinical Dementia Rating Global Score (OR = 1.20 (1.09, 1.32), P <0.001). Sample size calculations found that the AQ would require substantially fewer subjects than the MMSE given a 25% treatment effect.

CONCLUSIONS

Although the AQ demonstrated small sensitivity to change in aMCI and CN individuals in terms of effect size, the AQ may be superior to objective cognitive tests in terms of required sample size for a clinical trial. As clinicians and researchers continue to identify and treat individuals in earlier stages of AD, there is a need for instruments that are sensitive to cognitive changes in these earlier stages.

Optimization of touchscreen-based behavioral paradigms in mice: implications for building a battery of tasks taxing learning and memory functions

Although many clinical pathological states are now detectable using imaging and biochemical analyses, neuropsychological tests are often considered as valuable complementary approaches to confirm diagnosis, especially for disorders like Alzheimer’s or Parkinson’s disease, and schizophrenia. The touchscreen-based automated test battery, which was introduced two decades ago in humans to assess cognitive functions, has recently been successfully back-translated in monkeys and rodents. We focused on optimizing the protocol of three distinct behavioral paradigms in mice: two variants of the Paired Associates Learning (PAL) and the Visuo-Motor Conditional Learning (VMCL) tasks. Acquisition of these tasks was assessed in naive versus pre-trained mice. In naive mice, we managed to define testing conditions allowing significant improvements of learning performances over time in the three aforementioned tasks. In pre-trained mice, we observed differential acquisition rates after specific task combinations. Particularly, we identified that animals previously trained in the VMCL paradigm subsequently poorly learned the sPAL rule. Together with previous findings, these data confirm the feasibility of using such behavioral assays to evaluate the power of different models of cognitive dysfunction in mice. They also highlight the risk of interactions between tasks when rodents are run through a battery of different cognitive touchscreen paradigms.

Add-on prolonged-release melatonin for cognitive function and sleep in mild to moderate Alzheimer's disease: a 6-month, randomized, placebo-controlled, multicenter trial

Purpose

A link between poor sleep quality and Alzheimer’s disease (AD) has recently been suggested. Since endogenous melatonin levels are already reduced at preclinical AD stages, it is important to ask whether replenishing the missing hormone would be beneficial in AD and whether any such effects would be related to the presence of sleep disorder in patients.

Patients and methods

The effects of add-on prolonged-release melatonin (PRM) (2 mg) to standard therapy on cognitive functioning and sleep were investigated in 80 patients (men [50.7%], women [49.3%], average age 75.3 years [range, 52–85 years]) diagnosed with mild to moderate AD, with and without insomnia comorbidity, and receiving standard therapy (acetylcholinesterase inhibitors with or without memantine). In this randomized, double-blind, parallel-group study, patients were treated for 2 weeks with placebo and then randomized (1:1) to receive 2 mg of PRM or placebo nightly for 24 weeks, followed by 2 weeks placebo. The AD Assessment Scale–Cognition (ADAS-Cog), Instrumental Activities of Daily Living (IADL), Mini–Mental State Examination (MMSE), sleep, as assessed by the Pittsburgh Sleep Quality Index (PSQI) and a daily sleep diary, and safety parameters were measured.

Results

Patients treated with PRM (24 weeks) had significantly better cognitive performance than those treated with placebo, as measured by the IADL (P=0.004) and MMSE (P=0.044). Mean ADAS-Cog did not differ between the groups. Sleep efficiency, as measured by the PSQI, component 4, was also better with PRM (P=0.017). In the comorbid insomnia (PSQI ≥6) subgroup, PRM treatment resulted in significant and clinically meaningful effects versus the placebo, in mean IADL (P=0.032), MMSE score (+1.5 versus −3 points) (P=0.0177), and sleep efficiency (P=0.04). Median ADAS-Cog values (−3.5 versus +3 points) (P=0.045) were significantly better with PRM. Differences were more significant at longer treatment duration. PRM was well tolerated, with an adverse event profile similar to that of placebo.

Conclusion

Add-on PRM has positive effects on cognitive functioning and sleep maintenance in AD patients compared with placebo, particularly in those with insomnia comorbidity. The results suggest a possible causal link between poor sleep and cognitive decline.

A systematic review of biomarkers for disease progression in Alzheimer's disease

Background

Using surrogate biomarkers for disease progression as endpoints in neuroprotective clinical trials may help differentiate symptomatic effects of potential neuroprotective agents from true slowing of the neurodegenerative process. A systematic review was undertaken to determine what biomarkers for disease progression in Alzheimer's disease exist and how well they perform.

Methods

MEDLINE and Embase (1950–2011) were searched using five search strategies. Abstracts were assessed to identify papers meriting review in full. Studies of participants with probable Alzheimer's disease diagnosed by formal criteria were included. We made no restriction on age, disease duration, or drug treatment. We only included studies with a longitudinal design, in which the putative biomarker and clinical measure were both measured at least twice, as this is the only appropriate study design to use when developing a disease progression biomarker. We included studies which attempted to draw associations between the changes over time in the biomarker used to investigate disease progression and a clinical measure of disease progression.

Results

Fifty-nine studies were finally included. The commonest biomarker modality examined was brain MRI (17/59, 29% of included studies). Median follow-up in included studies was only 1.0 (IQR 0.8–1.7) year and most studies only measured the putative biomarker and clinical measure twice. Included studies were generally of poor quality with small numbers of participants (median 31 (IQR 17 to 64)), applied excessively restrictive study entry criteria, had flawed methodologies and conducted overly simplistic statistical analyses without adjusting for confounding factors.

Conclusions

We found insufficient evidence to recommend the use of any biomarker as an outcome measure for disease progression in Alzheimer's disease trials. However, further investigation into the efficacy of using MRI measurements of ventricular volume and whole brain volume appeared to be merited. A provisional ‘roadmap’ to improve the quality of future disease progression biomarker studies is presented.

Differences in rate of functional decline across three dementia types

BACKGROUND

The purpose of this study was to estimate differences in rates of functional decline in Alzheimer's disease (AD), dementia with Lewy bodies (DLB), and vascular dementia (VaD) and whether differences vary by age or sex.

METHODS

Data came from 32 U.S. Alzheimer's Disease Centers. The cohort of participants (n = 5848) were ≥60 years of age and had clinical dementia with a primary etiologic diagnosis of probable AD, DLB, or probable VaD; a Clinical Dementia Rating-Sum of Boxes score <16; and a duration of symptoms ≤10 years. Dementia diagnoses were assigned using standard criteria. Annual mean rate of change of the Functional Activities Questionnaire (FAQ) score was modeled using multiple linear regression with generalized estimating equations adjusted for demographics, comorbidities, years since onset, and cognitive status (mean follow-up = 2.0 years).

RESULTS

FAQ declined more slowly over time in those with VaD compared with AD (difference in mean annual rate of change: -0.91; 95% confidence interval [CI]: -1.68, -0.14). VaD participants also declined at a slower rate than DLB participants, but this difference was not statistically significant (-0.61; 95% CI: -1.45, 0.24). There was no significant difference between DLB and AD. Within each group, rate of decline was more rapid for the youngest participants.

CONCLUSIONS

In this sample, findings suggested that VaD patients declined in their functional abilities at a slower rate compared with AD patients and that there were no significant differences in rate of functional decline between patients with DLB compared with those with either AD or VaD. These results may provide guidance to clinicians about average expected rates of functional decline in three common dementia types.

Reasons that prevent the inclusion of Alzheimer's disease patients in clinical trials

AIM

To assess reasons that prevent Alzheimer's disease (AD) patients from being included in clinical trials.

METHODS

In 2009, we reviewed the Lille Memory Clinic's case database to identify patients suitable for inclusion in four AD clinical trials. An initial selection was made on the basis of four criteria: (i) a diagnosis of AD (with or without white matter lesions [WML]), (ii) age, (iii) mini mental state examination (MMSE) score and (iv) symptomatic treatment of AD (cholinesterase inhibitors/memantine). Next, data on patients fulfilling these criteria were reviewed against all the inclusion/exclusion criteria for four clinical trials performed in 2009 at the Memory Clinic. Reasons for non-inclusion were analyzed.

RESULTS

Two hundred and five patients were selected according to the four initial criteria. Reasons for subsequently not including some of patients in clinical trials were abnormalities on MRI (56.9%, 88.9% of which were WML), unauthorized medication (37.3%), the lack of a study partner/informant (37.1%), the presence of a non-authorized disease (24.4%), contraindication to MRI (9%), a change in diagnosis over time (3.9%), visual/auditory impairments (2.9%), alcohol abuse (2%) and an insufficient educational level (1%).

CONCLUSION

A high proportion of AD patients presented with vascular abnormalities on MRI. This was not unexpected, since the patients were selected from the database and, as shown in epidemiologic studies, cerebrovascular diseases are frequently associated with AD. The presence of a study partner is essential for enabling a patient to participate in clinical trials because of the need to record reliably primary and secondary outcomes.

Vision-fair neuropsychological assessment in normal aging, Parkinson's disease and Alzheimer's disease

We examined performance of healthy older and younger adults and individuals with Alzheimer's disease (AD) and Parkinson's disease (PD) on digit cancellation, a task putatively sensitive to cognitive impairment, but possibly affected by visual impairment, particularly in contrast sensitivity. Critical contrast thresholds were established to create custom stimulus arrays that were proximally matched across individuals. Age- and PD-related differences in search were fully accounted for by the sensory deficit. Increased contrast benefited AD patients, but could not override cognitive impairment. We conclude that visually fair neuropsychological testing can effectively compensate for normal age- and PD-related visual changes that affect cognitive performance.

Risk of decline in functional activities in dementia with Lewy bodies and Alzheimer disease

We examined the risk of 1-year decline in 4 everyday activities in patients with dementia with Lewy bodies (DLB), relative to patients with Alzheimer disease (AD). Data were from the National Alzheimer's Coordinating Center, gathered from 32 Alzheimer's Disease Centers. Participants (n=1880) were: aged 60+ years, demented with a primary clinical diagnosis of probable AD or DLB, and had a global Clinical Dementia Rating of 0.5 to 2. The activities were measured with the Functional Activities Questionnaire. In modified Poisson regression models adjusted for demographics, baseline activity, years from symptom onset, cognitive impairment, and comorbidities; DLB participants aged 67 to 81 years had 1.5 to 2 times increased risk of decline in performing basic kitchen tasks, engaging in games/hobbies, and paying attention/understanding, relative to AD participants of the same age (P<0.05). There was no significant difference between AD and DLB participants beyond this age range. For decline in ability to go shopping alone, there was also no significant difference between AD and DLB participants. In summary, the functional course of DLB, relative to AD, may depend on the age of the patient. These findings may provide anticipatory guidance to families and healthcare providers, which may be useful in the planning of care strategies.