Alzheimer's disease research in the context of the national plan to address Alzheimer's disease

Introduction to the Special Issue: Toward a Lifespan Prevention Science - A Focus on Middle and Late Adulthood

The interdisciplinary field of prevention science was founded on the premise of a lifespan developmental model. Prevention scientists have developed a strong set of tools and intervention technologies for understanding and potentially modifying risk and protective factors through early adulthood. However, there is a demographic imperative to apply prevention science principles to health issues in middle and late adulthood. The articles in this special issue utilize a variety of methods to investigate important scientific questions about how theories, methodologies, and interventions applied in the science of prevention can be usefully integrated into the study of health and wellness in middle and late adulthood. More specifically, contributions (1) highlight current empirical research that draws on lifespan developmental science to address the unique prevention and intervention needs in middle and late adulthood, (2) illustrate the opportunities and challenges of a lifespan approach to prevention science with special attention to middle and late adulthood, and (3) identify additional areas that prevention science can contribute to advancements in middle and late adulthood. These articles provide a glimpse into the challenges and opportunities at the intersection of prevention science and gerontology. As a field, we have much room to grow in leveraging innovative tools, approaches, and efforts to best support older adults' physical, mental, and social health, particularly for diverse and under-served populations.

A qualitative analysis of communication workflows between adult day service centers and primary care providers

OBJECTIVES

Our study documented communication workflows across adult day care centers (ADCs) and primary care providers (PCPs) around complex needs of persons living with dementia (PLWD). We also identified barriers and facilitators to productive communication in clinical decision support and clinical information systems.

MATERIALS AND METHODS

We conducted 6 focus groups with ADC staff (N = 33) and individual semistructured interviews with PCPs (N = 22) in California. The eHealth Enhanced Chronic Care Model was used to frame the directed qualitative content analysis.

RESULTS

Our results captured cumbersome and ineffective workflows currently used to exchange information across PCPs and ADCs. Stakeholders characterized current communication as (1) infrequent, (2) delayed, (3) incomplete, (4) unreliable, (5) irrelevant, and (6) generic. Conversely, communication that was bidirectional, relevant, succinct, and interdisciplinary was needed to elevate the standard of care for PLWD.

DISCUSSION AND CONCLUSION

ADCs possess a wealth of information that can support clinical decision-making across community-based providers involved in the care of PLWD, especially PCPs. However, effective information exchange is mired by complicated workflows that rely on antiquated technologies (eg, facsimile) and standard templates. Current information exchange largely focuses on satisfying regulatory guidelines rather than supporting clinical decision-making. Integrating community-based services into the health care continuum is a necessary step in elevating the standard of care for PLWD. In the absence of interoperable electronic health records, which may not be financially viable for ADCs, other options, such as mobile health, should be explored to facilitate productive information exchange of personalized relevant information.

The neuroprotective effects of alpha-lipoic acid on an experimental model of Alzheimer's disease in PC12 cells

With the growth of the aging population, the prevalence of Alzheimer's disease (AD) has increased and influenced the work and daily life of AD patients, imposing a heavy burden on society and the patients' families. AD is a progressive disease with a long duration, and the pathogenesis is very complicated. Here, we found that alpha-lipoic acid (LA), an endogenous, naturally synthesized compound, could attenuate amyloid beta fragment (Aβ_25-35 )-induced PC12 cell toxicity. Aβ_25-35 treatment largely decreased the viability of PC12 cells, increased reactive oxygen species (ROS) levels, and increased the percentage of apoptotic cells, which were accompanied by changes in the expression of the apoptosis-related genes. Further, the Wnt pathway was inactivated, and the expression of Wnt pathway-related proteins such as Frizzled2, GSK3β, and phosphorylated GSK3β were dysregulated after Aβ_25-35 treatment. LA efficiently attenuated Aβ_25-35 -induced PC12 cell apoptosis and downregulated the phosphorylation-mediated degradation of β-catenin as well as GSK3β. Our results demonstrate that LA rescues Aβ_25-35 -induced neurocytotoxicity through the Wnt-β-catenin pathway.

Transport of Alzheimer's associated amyloid-β catalyzed by P-glycoprotein

P-glycoprotein (P-gp) is a critical membrane transporter in the blood brain barrier (BBB) and is implicated in Alzheimer’s disease (AD). However, previous studies on the ability of P-gp to directly transport the Alzheimer’s associated amyloid-β (Aβ) protein have produced contradictory results. Here we use molecular dynamics (MD) simulations, transport substrate accumulation studies in cell culture, and biochemical activity assays to show that P-gp actively transports Aβ. We observed transport of Aβ40 and Aβ42 monomers by P-gp in explicit MD simulations of a putative catalytic cycle. In in vitro assays with P-gp overexpressing cells, we observed enhanced accumulation of fluorescently labeled Aβ42 in the presence of Tariquidar, a potent P-gp inhibitor. We also showed that Aβ42 stimulated the ATP hydrolysis activity of isolated P-gp in nanodiscs. Our findings expand the substrate profile of P-gp, and suggest that P-gp may contribute to the onset and progression of AD.

Metabolic syndrome exacerbates amyloid pathology in a comorbid Alzheimer's mouse model

Alzheimer's disease (AD) often coexists with other aging-associated diseases including obesity, diabetes, hypertension, and cardiovascular diseases. The early stage of these comorbidities is known as metabolic syndrome (MetS) which is highly prevalent in mid-life. An important cause of MetS is the deficiency of SIRT3, a mitochondrial deacetylase which enhances the functions of critical mitochondrial proteins, including metabolic enzymes, by deacetylation. Deletion of Sirt3 gene has been reported to result in the acceleration of MetS. In a recently published study, we demonstrated in the brain of Sirt3^-/- mice, downregulation of metabolic enzymes, insulin resistance and elevation of inflammatory markers including microglial proliferation. These findings suggested a novel pathway that could link SIRT3 deficiency to neuroinflammation, an important cause of Alzheimer's pathogenesis. Therefore, we hypothesized that MetS and amyloid pathology may interact through converging pathways of insulin resistance and neuroinflammation in comorbid AD. To investigate these interactions, we crossed Sirt3^-/- mice with APP/PS1 mice and successfully generated APP/PS1/Sirt3^-/- mice with amyloid pathology and MetS. In these comorbid AD mice, we observed exacerbation of insulin resistance, glucose intolerance, amyloid plaque deposition, markers of neuroinflammation, including elevated expression of IL-1β, TNF-α and Cox-2 at 8 months of age. There was also increased microglial proliferation and activation. Our observations suggest a novel mechanism by which MetS may interact with amyloid pathology during the cellular phase of AD. Therapeutic targeting of SIRT3 in AD with comorbidities may produce beneficial effects.

Reframing Alzheimer's Disease: Guided by a New Research Framework, the Field is Poised For Greater Precision and Promising Horizons

This in-depth article on the sixth leading cause of death in the U.S. reports on the optimism of cutting-edge leaders in Alzheimer's disease research. The author examines key considerations such as the status of biomarker tests, and the search for new biomarkers; securing an accurate definition of the disease; risk factors; clinical trials and non-pharmacological studies.

Detecting Non-cognitive Features of Prodromal Neurodegenerative Diseases

BACKGROUND

Prodromal Neurodegenerative Disease (ND) due to tauopathies such as Alzheimer's Disease (AD) and Synucleinopathies (SN) such as Parkinson's Disease (PD) and Dementia with Lewy Bodies (DLB) present subtly. Although ND are considered cognitive disorders, in fact ND present with behavioral and even medical symptomatology years to decades prior to the onset of cognitive changes. Recognizing prodromal ND syndromes is a public health priority because ND is common, disabling and expensive. Diagnosing prodromal ND in real world clinical settings is challenging because ND of the same pathology can present with different symptoms in different people. Individual variability in nature and variability in nurture across the life course influence how ND pathology manifests clinically. The objective of this study was to describe how non-cognitive symptoms from behavioral, medical, neurological and psychiatric domains cluster in prodromal and early stages of ND.

METHODS

This was an observational study of patients receiving routine clinical care for memory disorders. All patients receiving a standardized evaluation including complete neurological history and examination and standardized brief neuropsychological testing. A Principal Component Analysis (PCA) considering emotion, motor, sensory and sleep factors was performed on the entire sample of patients in order to identify co-occurring symptom clusters. All patients received a consensus diagnosis adjudicated by at least two dementia experts. Patients were grouped into Cognitively Normal, Detectable Cognitive Impairment, and Mild Cognitive Impairment categories due to AD and/or PD/LBD or NOS pathology. Symptom cluster scores were compared between clinical diagnostic groups.

RESULTS

In this study 165 patients completed baseline neuropsychological testing and reported subjective measures of non-cognitive symptoms. Four syndrome specific symptom factors emerged and eight non-specific symptom factors. Symptoms of personality changes, paranoia, hallucinations, cravings, agitation, and changes in appetite grouped together into a cluster consistent with an "SN Non-motor Phenotype". Appetite, walking, balance, hearing, increased falls, and dandruff grouped together into a cluster consistent with an "SN Motor Phenotype". The Prodromal AD phenotype included symptoms of anxiety, irritability, apathy, sleep disturbance and social isolation. The fourth factor included symptoms of increased sweating, twitching, and tremor grouped into a cluster consistent with an Autonomic phenotype.

CONCLUSION

Non-cognitive features can be reliably measured by self-report in busy clinical settings. Such measurement can be useful in distinguishing patients with different etiologies of ND. Better characterization of unique, prodromal, non-cognitive ND trajectories could improve public health efforts to modify the course of ND for all patients at risk.

Glutaminyl cyclase inhibitor contributes to the regulation of HSP70, HSP90, actin, and ribosome on gene and protein levels in vitro

Because of the crucial roles of upregulated glutaminyl cyclase (QC) in the initiation and development of Alzheimer's disease (AD), QC inhibitors are supposed as disease-modifying agents for the treatment of AD. And reported compounds encourage this hypothesis greatly based on the remarkable anti-AD effects in vivo. To illustrate the mechanism in detail, the actions of a selected QC inhibitor (23) were assessed firstly in a cell system here. It was demonstrated that QC activities and the generation of pyroglutamate-modified β-amyloids in PC12 cells were both inhibited obviously after the treatment of 23. A total of 13 and 15 genes were up- and downregulated significantly in treated cells by RNA-sequencing analysis. Quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay, WB, and immunofluorescence analysis supported the effects of 23 on the transcriptome of PC12 cells consequently. The expressions of chaperones, heat shock proteins (HSP) 70, and 90, were upreglutated, while gene expression of actin and the level of encoded protein were reduced significantly in PC12 cells with the treatment. Furthermore, the regulations of ribosome were observed after the treatment. These results indicate the potency of 23 to improve the translation, expression and folding regulation of proteins and affect the multivalent cross-linking of cytoskeletal protein and other proteins subsequently in the cell system and might contribute to the understanding of the mechanism of QC inhibitor as potential anti-AD agents.

Synthesis and Evaluation of Diphenyl Conjugated Imidazole Derivatives as Potential Glutaminyl Cyclase Inhibitors for Treatment of Alzheimer's Disease

High expression of glutaminyl cyclase (QC) contributes to the initiation of Alzheimer's disease (AD) by catalyzing the generation of neurotoxic pyroglutamate (pE)-modified β-amyloid (Aβ) peptides. Preventing the generation of pE-Aβs by QC inhibition has been suggested as a novel approach to a disease-modifying therapy for AD. In this work, a series of diphenyl conjugated imidazole derivatives (DPCIs) was rationally designed and synthesized. Analogues with this scaffold exhibited potent inhibitory activity against human QC (hQC) and good in vitro blood-brain barrier (BBB) permeability. Further assessments corroborated that the selected hQC inhibitor 28 inhibits the activity of hQC, dramatically reduces the generation of pE-Aβs in cultured cells and in vivo, and improves the behavior of AD mice.

Alzheimer's disease drug development pipeline: 2017

INTRODUCTION

There is an urgent need to develop new treatments for Alzheimer's disease (AD) and to understand the drug development process for new AD therapies.

METHODS

We assessed the agents in the AD pipeline as documented in clinicaltrials.gov for phase I, phase II, and phase III, accessed 1/5/2017.

RESULTS

There are 105 agents in the AD treatment development pipeline, of which 25 agents are in 29 trials in phase I, 52 agents are in 68 trials in phase II, and 28 agents are in 42 trials in phase III. Seventy percent of drugs in the AD pipeline are disease-modifying therapies (DMTs). Fourteen percent are symptomatic cognitive enhancers, and 13% are symptomatic agents addressing neuropsychiatric and behavioral changes (2% have undisclosed mechanisms). Most trials are sponsored by the biopharmaceutical industry. Trials include patients with preclinical AD (cognitively normal with biomarker evidence of AD), prodromal AD (mild cognitive symptoms and biomarker evidence of AD), and AD dementia. Biomarkers are included in many drug development programs particularly those for DMTs. Thirteen of 46 phase II DMT trials have amyloid imaging as an entry criterion, and 10 of 28 phase III trials incorporate amyloid imaging for diagnosis and entry. A large number of participants are needed for AD clinical trials; in total, 54,073 participants are required for trials spanning preclinical AD to AD dementia. When compared with the 2016 pipeline, there are eight new agents in phase I, 16 in phase II, and five in phase III.

DISCUSSION

The AD drug development pipeline has 105 agents divided among phase I, phase II, and phase III. The trials include a wide range of clinical trial populations, many mechanisms of action, and require a substantial number of clinical trial participants. Biomarkers are increasingly used in patient identification and as outcome measures, particularly in trials of DMTs.