Dementia screening, biomarkers and protein misfolding: Implications for public health and diagnosis

The long term effects of uncoupling interventions as a therapy for dementia in humans

In this paper we use simulation methods to study a hypothetical uncoupling agent as a therapy for dementia. We simulate the proliferation of mitochondrial deletion mutants amongst a population of wild-type in human neurons. Mitochondria play a key role in ATP generation. Clonal expansion can lead to the wild-type being overwhelmed by deletions such that a diminished population can no longer fulfil a cell's energy requirement, eventually leading to its demise. The intention of uncoupling is to reduce the formation of deletion mutants by reducing mutation rate. However, a consequence of uncoupling is that the energy production efficacy is also reduced which in turn increases wild-type copy number in order to compensate for the energy deficit. The results of this paper showed that uncoupling reduced the severity of dementia, however, there was some increase in cognitive dysfunction pre-onset of dementia. The effectiveness of uncoupling was dependent upon the timing of intervention relative to the onset of dementia and would necessitate predicting its onset many years in advance.

Using a patient-reported outcome to improve detection of cognitive impairment and dementia: The patient version of the Quick Dementia Rating System (QDRS)

INTRODUCTION

Community detection of mild cognitive impairment (MCI) and Alzheimer's disease and related disorders (ADRD) is a challenge. While Gold Standard assessments are commonly used in research centers, these methods are time consuming, require extensive training, and are not practical in most clinical settings or in community-based research projects. Many of these methods require an informant (e.g., spouse, adult child) to provide ratings of the patients' cognitive and functional abilities. A patient-reported outcome that captures the presence of cognitive impairment and corresponds to Gold Standard assessments could improve case ascertainment, clinical care, and recruitment into clinical research. We tested the patient version of the Quick Dementia Rating System (QDRS) as a patient-reported outcome to detect MCI and ADRD.

METHODS

The patient QDRS was validated in a sample of 261 consecutive patient-caregiver dyads compared with the informant version of the QDRS, the Clinical Dementia Rating (CDR), neuropsychological tests, and Gold Standard measures of function, behavior, and mood. Psychometric properties including item variability, floor and ceiling effects, construct, concurrent, and known-groups validity, and internal consistency were determined.

RESULTS

The patient QDRS strongly correlated with Gold Standard measures of cognition, function, mood, behavior, and global staging methods (p-values < .001) and had strong psychometric properties with excellent data quality and internal consistency (Cronbach alpha = 0.923, 95%CI:0.91-0.94). The patient QDRS had excellent agreement with the informant QDRS, the CDR and its sum of boxes (Intraclass Correlation Coefficients: 9.781-0.876). Receiver operator characteristic curves showed excellent discrimination between normal controls from CDR 0.5 (AUC:0.820;95% CI: 0.74-0.90) and for normal controls from any cognitive impairment (AUC:0.885;95% CI: 0.83-0.94).

DISCUSSION

The patient QDRS validly and reliably differentiates individuals with and without cognitive impairment and can be completed by patients through all stages of dementia. The patient QDRS is highly correlated with Gold Standard measures of cognitive, function, behavior, and global staging. The patient QDRS provides a rapid method to screen patients for MCI and ADRD in clinical practice, determine study eligibility, improve case ascertainment in community studies.

What older adults do with the results of dementia screening programs

Introduction

Alzheimer’s disease and related dementias (ADRD) and mild cognitive impairment (MCI) are often under-recognized in the community. MCI/ADRD screening could offer benefits such as early treatment, research participation, lifestyle modification, and advanced care planning. To date, there are no clear guidelines regarding the benefits vs. harms of dementia screening or whether a dementia screening program could be successful.

Methods

A community-based study was conducted to evaluate an MCI/ADRD screening program and determine what older adults would do with the information. Measures of cognition, physical health, functionality, and mood were collected. Participants met with a health professional, were given screening results with recommendations, and then contacted 60 days later to determine what was done with the results. Logistic regression models were used to build predictive models.

Results

Participants (n = 288) had a mean age of 71.5±8.3y, mean education of 13.3±4.8y, and were 70% female, 67% White, 26% African American, and 48% Hispanic. After 60 days, 75% of participants were re-contacted; 54% shared results with family, 33% shared results with health care providers (HCPs), and 52% initiated behavioral change. Among participants sharing results with HCPs, 51% reported HCPs did not follow-up on the results, and 18% that HCPs did not show any interest in the screening visit or its results. Predictors of sharing results with HCPs were elevated hemoglobin A1C (OR = 1.85;95%CI:1.19–2.88), uncontrolled hypertension (OR = 2.73;95%CI:1.09–6.83), and mobility issues (OR = 2.43;95%CI: 1.93–5.54). Participant behavioral changes included lifestyle modification (58%), social engagement (10%), cognitive stimulation (5%), and advanced care planning (4%). The most significant predictors of sharing with family were better overall mental health (OR = 0.19; 95%CI: 0.06–0.59) and better physical function (OR = 0.38; 95%CI: 0.17–0.81).

Discussion

MCI/ADRD screening was well-received by a diverse community sample. Participants showed interest in sharing the results with their family and HCPs and many attempted behavioral change. While HCPs did not always act on screening results, 25% ordered further testing and evaluation. Efforts need to be directed toward (1) increasing self-efficacy of older adults to discuss screening results with their HCPs, and (2) educating HCPs on the value of early detection of MCI/ADRD. Community dementia screening programs can increase MCI/ADRD detection and improve patient-centered outcomes and medical decision-making.

Using Informant and Performance Screening Methods to Detect Mild Cognitive Impairment and Dementia

Purpose of Review

Dementia detection in the community is challenging. The purpose of this paper is to review methods of dementia screening and provide a useable algorithm for screening for dementia a variety of clinical settings.

Recent Findings

In recent years, a number of brief performance and informant-based assessments have been developed and validated in research, clinical, and community samples. These assessments are now complemented by patient self-reports that afford the ability to detect subjective cognitive impairment.

Summary

An optimal approach to dementia screening is to combine performance, informant, and self-reports, many of which can be completed in the waiting room or by non-physician staff prior to the start of the office visit. This diverse information may help inform the provider as to the presence or absence of a cognitive disorder, assist in staging the extent of the disorder, and help to develop a differential diagnosis and management plan.

Service use, advance planning and lifestyle changes following cognitive screening in primary healthcare in Singapore

BACKGROUND

Despite recent interest in community-based screening programs to detect undiagnosed cognitive disorder, little is known about whether screening leads to further diagnostic evaluation, or the effects of such programs in terms of actual changes in patient or caregiver behavior. This study followed up informants of older adults (i.e. caregivers of patients who completed informant-based screening regarding the patient) following participation in a study screening for undiagnosed memory problems, to explore uptake of further diagnostic evaluation or treatment, advance planning or preparations, lifestyle changes, medication adherence, and use of support services.

METHODS

A total of 140 informants of older adult patients were surveyed four to fifteen months following participation in a cognitive screening study. The informants were interviewed with a study-specific survey about cognitive assessment, advance planning, lifestyle changes, and use of support services and general medication adherence.

RESULTS

A minority of patients and informants had engaged in advance planning or made relevant lifestyle changes following cognitive screening. Those assessed as being at higher risk of memory problems were more likely to have attended a full diagnostic evaluation, engaged in support services and experienced medication adherence difficulties.

CONCLUSION

Only a small proportion of patients participating in cognitive screening subsequently engaged in diagnostic evaluation, advance planning, or lifestyle changes. However, those with higher risk of cognitive impairment were generally more likely to take some action following cognitive screening. Those at higher risk were also more vulnerable due to greater difficulties with medication adherence.

Prevention of Alzheimer's Disease: Lessons Learned and Applied

Alzheimer's disease (AD) affects more than 5 million Americans, with substantial consequences for individuals with AD, families, and society in terms of morbidity, mortality, and healthcare costs. With disease-modifying treatment trials unsuccessful at the present time and only medications to treat symptoms available, an emerging approach is prevention. Advances in diagnostic criteria, biomarker development, and greater understanding of the biophysiological basis of AD make these initiatives feasible. Ongoing pharmacological trials using anti-amyloid therapies are underway in sporadic and genetic forms of AD, although a large number of modifiable risk factors for AD have been identified in observational studies, many of which do not appear to exert effects through amyloid or tau. This suggests that prevention studies focusing on risk reduction and lifestyle modification may offer additional benefits. Rather than relying solely on large-sample, long-duration, randomized clinical trial designs, a precision medicine approach using N-of-1 trials may provide more-rapid information on whether personalized prevention plans can improve person-centered outcomes. Because there appear to be multiple pathways to developing AD, there may also be multiple ways to prevent or delay the onset of AD. Even if these precision approaches alone are not successful in preventing AD, they may greatly improve the likelihood of amyloid- or tau-specific therapies to reach their endpoints by reducing comorbidities. Keeping this in mind, dementia may be a disorder that develops over a lifetime, with individualized ways to build a better brain as we age.

Minocycline attenuates post-operative cognitive impairment in aged mice by inhibiting microglia activation

Although it is known that isoflurane exposure or surgery leads to post‐operative cognitive dysfunction in aged rodents, there are few clinical interventions and treatments available to prevent this disorder. Minocycline (MINO) produces neuroprotection from several neurodegenerative diseases and various experimental animal models. Therefore, we set out to investigate the effects of MINO pre‐treatment on isoflurane or surgery induced cognitive impairment in aged mice by assessing the hippocampal‐dependent spatial memory performance using the Morris water maze task. Hippocampal tissues were isolated from mice and evaluated by Western blot analysis, immunofluorescence procedures and protein array system. Our results elucidate that MINO down‐regulated the isoflurane‐induced and surgery‐induced enhancement in the protein levels of pro‐inflammatory cytokine tumour necrosis factor alpha, interleukin (IL)‐1β, interferon‐γ and microglia marker Iba‐1, and up‐regulated protein levels of the anti‐inflammatory cytokine IL‐4 and IL‐10. These findings suggest that pre‐treatment with MINO attenuated isoflurane or surgery induced cognitive impairment by inhibiting the overactivation of microglia in aged mice.

Alzheimer's as a Systems-Level Disease Involving the Interplay of Multiple Cellular Networks

Alzheimer's disease (AD), and many neurodegenerative disorders, are multifactorial in nature. They involve a combination of genomic, epigenomic, interactomic and environmental factors. Progress is being made, and these complex diseases are beginning to be understood as having their origin in altered states of biological networks at the cellular level. In the case of AD, genomic susceptibility and mechanisms leading to (or accompanying) the impairment of the central Amyloid Precursor Protein (APP) processing and tau networks are widely accepted as major contributors to the diseased state. The derangement of these networks may result in both the gain and loss of functions, increased generation of toxic species (e.g., toxic soluble oligomers and aggregates) and imbalances, whose effects can propagate to supra-cellular levels. Although well sustained by empirical data and widely accepted, this global perspective often overlooks the essential roles played by the main counteracting homeostatic networks (e.g., protein quality control/proteostasis, unfolded protein response, protein folding chaperone networks, disaggregases, ER-associated degradation/ubiquitin proteasome system, endolysosomal network, autophagy, and other stress-protective and clearance networks), whose relevance to AD is just beginning to be fully realized. In this chapter, an integrative perspective is presented. Alzheimer's disease is characterized to be a result of: (a) intrinsic genomic/epigenomic susceptibility and, (b) a continued dynamic interplay between the deranged networks and the central homeostatic networks of nerve cells. This interplay of networks will underlie both the onset and rate of progression of the disease in each individual. Integrative Systems Biology approaches are required to effect its elucidation. Comprehensive Systems Biology experiments at different 'omics levels in simple model organisms, engineered to recapitulate the basic features of AD may illuminate the onset and sequence of events underlying AD. Indeed, studies of models of AD in simple organisms, differentiated cells in culture and rodents are beginning to offer hope that the onset and progression of AD, if detected at an early stage, may be stopped, delayed, or even reversed, by activating or modulating networks involved in proteostasis and the clearance of toxic species. In practice, the incorporation of next-generation neuroimaging, high-throughput and computational approaches are opening the way towards early diagnosis well before irreversible cell death. Thus, the presence or co-occurrence of: (a) accumulation of toxic Aβ oligomers and tau species; (b) altered splicing and transcriptome patterns; (c) impaired redox, proteostatic, and metabolic networks together with, (d) compromised homeostatic capacities may constitute relevant 'AD hallmarks at the cellular level' towards reliable and early diagnosis. From here, preventive lifestyle changes and tailored therapies may be investigated, such as combined strategies aimed at both lowering the production of toxic species and potentiating homeostatic responses, in order to prevent or delay the onset, and arrest, alleviate, or even reverse the progression of the disease.

THE QUICK DEMENTIA RATING SYSTEM (QDRS): A RAPID DEMENTIA STAGING TOOL

INTRODUCTION

Test the validity and reliability of the Quick Dementia Rating System (QDRS), a rapid dementia staging tool.

METHODS

The QDRS was tested in 267 patient-caregiver dyads compared with Clinical Dementia Ratings (CDR), neuropsychological testing, and gold standard measures of function, mood, and behavior. Psychometric properties including, item variability, floor and ceiling effects, concurrent and construct validity, and internal consistency were determined. The QDRS was used to derive an independent CDR and sum of boxes. Interscale reliability between QDRS and CDR was tested using intraclass correlation coefficients (ICC). Area under the receiver operator characteristic curves (AUC) tested discrimination properties of QDRS across CDR stages.

RESULTS

QDRS scores increased with higher CDR staging and poorer neuropsychological performance (p's <.001). The QDRS demonstrated low floor and ceiling effects; excellent known-groups validity across CDR stages (p's<.001); construct validity against cognitive, behavioral, and functional measures (p-value's:0.004 to <0.001); and reliability (Cronbach α: 0.86-0.93). The QDRS demonstrated differential scores across different dementia etiologies. The AUC for the QDRS was 0.911 (95%CI 0.86-0.96) and for the CDR-SB was 0.996 (95% CI: 0.99-1.0) demonstrating comparable ability to discriminate normal controls from dementia. The QDRS-generated CDR demonstrated excellent correspondence with the CDR (ICC=0.90) and sum-of-boxes (ICC=0.92).

DISCUSSION

The QDRS validly and reliably differentiates individuals with and without dementia and accurately stages dementia without extensive training or clinician input, and is highly correlated with our gold standard measures. The QDRS provides a rapid method to determine study eligibility; stage patients in clinical practice; and improve case ascertainment in population studies.

Comparison of 2 informant questionnaire screening tools for dementia and mild cognitive impairment: AD8 and IQCODE

BACKGROUND

Dementia and mild cognitive impairment (MCI) are underrecognized in community settings. This may be due in part to the lack of brief dementia screening tools available to clinicians. We compared 2 brief, informant-based screening tests: the AD8 and the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) in a community-based neurology practice in the midwestern United States.

METHODS

We examined 186 consecutive patients (44 controls, 13 with MCI, and 129 with dementia). Receiver operator characteristic curves were used to examine the ability of AD8 and IQCODE to discriminate between controls and MCI or dementia. Sensitivity, specificity, predictive values, and likelihood ratios were reported.

RESULTS

AD8 differentiated healthy controls from MCI (P<0.001) or dementia (P<0.001), and MCI from dementia (P=0.008). The IQCODE differentiated controls and MCI from dementia (both P<0.001), and between controls and MCI (P=0.002). Both AD8 (AUC=0.953; 95% confidence interval, 0.92-0.99) and IQCODE (AUC=0.930, 95% confidence interval, 0.88-0.97) provided discrimination between controls and patients with dementia; however, the AD8 had superior sensitivity detecting dementia (99.2%) and MCI (100%) compared with the IQCODE (79.1% for dementia, 46.1% for MCI) with nonoverlapping confidence intervals. Using published cut-offs (AD8≥2, IQCODE≥3.4), only 1 case of dementia was missed with the AD8, whereas the IQCODE failed to detect dementia in 27 individuals. The AD8 detected MCI in all 13 individuals, whereas the IQCODE misclassified 7 individuals.

CONCLUSIONS

Both the AD8 and IQCODE were able to detect dementia in a community setting. The AD8, however, was more successful than IQCODE in detecting MCI. If simple and efficient screening for early cognitive impairment is the goal, particularly in the early stages (e.g., for prevention trials or public screening), the combination of an informant interview (the AD8) and a brief performance measure could be considered as they meet the basic requirements of the Personalized Prevention Plan for Medicare beneficiaries.

Utility of AD8 for cognitive impairment in a Chinese physical examination population: a preliminary study

Objective. To investigate the utility of AD8 for cognitive impairment in a Chinese physical examination population. Methods. Military cadres who took routine physical examination in Chinese PLA General Hospital from Jan 1, 2013, to Dec 31, 2013, were subjected to AD8 scale. Individual information such as age, gender, and education was also collected. All data were analyzed by SPSS 19.0. Results. 1544 subjects were enrolled in this study with mean age 75.4 ± 10.6 years. The subjects who scored 0 to 8 of AD8 scale were 1015, 269, 120, 60, 30, 14, 19, 8, and 9, respectively. Corresponding proportions were 65.7%, 17.4%, 7.8%, 3.9%, 2.0%, 0.9%, 1.2%, 0.5%, and 0.6%, respectively. The endorsement prevalence of 8 questions was 5.6%, 9.2%, 6.6%, 9.2%, 4.8%, 4.5%, 8.9%, and 24.1%, respectively. The endorsement prevalence of question 8 was significantly higher than others (P < 0.05). 260 subjects were scored equal to or greater than 2. The abnormal rate was 16.9%. All the participants were stratified into 9 groups by age; the prevalence of dementia was highly correlated with age (P < 0.01). Conclusion. AD8 scale is a convenient and effective tool for cognitive screening in routine physical examination population.

Current guidelines for dementia screening: shortcomings and recommended changes

The availability of various guidelines regarding the diagnosis of Alzheimer's disease (AD) leaves most primary care providers with the task of having to decide which guidelines to follow. This review will help them navigate these different guidelines and understand how they differ from previous guidelines. Challenges related to the use of these guidelines are discussed, including biomarker testing, the lack of recognition in the community of what constitutes memory impairment and how to best screen for it, and recommendations for easy and early detection and diagnosis in the clinical settings are made. Adoption of biomarkers in clinical practice will give primary care providers the means to establish with certainty the underlying pathology responsible for the observed clinical symptoms and increase their ability to establish the presence of AD pathology before symptoms occur and, therefore, potentially help prevent or slow down the progression to AD.

New pharmacological strategies for treatment of Alzheimer's disease: focus on disease modifying drugs

Current approved drug treatments for Alzheimer disease (AD) include cholinesterase inhibitors (donepezil, rivastigmine, galantamine) and the NMDA receptor antagonist memantine. These drugs provide symptomatic relief but poorly affect the progression of the disease. Drug discovery has been directed, in the last 10 years, to develop 'disease modifying drugs' hopefully able to counteract the progression of AD. Because in a chronic, slow progressing pathological process, such as AD, an early start of treatment enhances the chance of success, it is crucial to have biomarkers for early detection of AD-related brain dysfunction, usable before clinical onset. Reliable early biomarkers need therefore to be prospectively tested for predictive accuracy, with specific cut off values validated in clinical practice. Disease modifying drugs developed so far include drugs to reduce β amyloid (Aβ) production, drugs to prevent Aβ aggregation, drugs to promote Aβ clearance, drugs targeting tau phosphorylation and assembly and other approaches. Unfortunately none of these drugs has demonstrated efficacy in phase 3 studies. The failure of clinical trials with disease modifying drugs raises a number of questions, spanning from methodological flaws to fundamental understanding of AD pathophysiology and biology. Recently, new diagnostic criteria applicable to presymptomatic stages of AD have been published. These new criteria may impact on drug development, such that future trials on disease modifying drugs will include populations susceptible to AD, before clinical onset. Specific problems with completed trials and hopes with ongoing trials are discussed in this review.

Z-formamidoximes in molecular folding and macrocycles

The formamidoxime configurational Z isomer coupled with the pyridylbiscarboxamide conformational codon were used to fold planar, curved structures. When embedded into macrocycles, this folded motif promotes dimerization through π-π stacking and hydrogen-bonding and the formation of tubules akin to molecular channels in the solid state.