Hampel et al. review the role of the cholinergic system in cognition and how cholinergic deficits in Alzheimer's disease interact with other aspects of disease pathophysiology. They document the ...benefits of cholinergic therapies at various stages of disease, and argue that the weight of the evidence confirms their continued value.
Abstract
Cholinergic synapses are ubiquitous in the human central nervous system. Their high density in the thalamus, striatum, limbic system, and neocortex suggest that cholinergic transmission is likely to be critically important for memory, learning, attention and other higher brain functions. Several lines of research suggest additional roles for cholinergic systems in overall brain homeostasis and plasticity. As such, the brain's cholinergic system occupies a central role in ongoing research related to normal cognition and age-related cognitive decline, including dementias such as Alzheimer's disease. The cholinergic hypothesis of Alzheimer's disease centres on the progressive loss of limbic and neocortical cholinergic innervation. Neurofibrillary degeneration in the basal forebrain is believed to be the primary cause for the dysfunction and death of forebrain cholinergic neurons, giving rise to a widespread presynaptic cholinergic denervation. Cholinesterase inhibitors increase the availability of acetylcholine at synapses in the brain and are one of the few drug therapies that have been proven clinically useful in the treatment of Alzheimer's disease dementia, thus validating the cholinergic system as an important therapeutic target in the disease. This review includes an overview of the role of the cholinergic system in cognition and an updated understanding of how cholinergic deficits in Alzheimer's disease interact with other aspects of disease pathophysiology, including plaques composed of amyloid-β proteins. This review also documents the benefits of cholinergic therapies at various stages of Alzheimer's disease and during long-term follow-up as visualized in novel imaging studies. The weight of the evidence supports the continued value of cholinergic drugs as a standard, cornerstone pharmacological approach in Alzheimer's disease, particularly as we look ahead to future combination therapies that address symptoms as well as disease progression.
Abstract Introduction The Dominantly Inherited Alzheimer Network Trials Unit (DIAN-TU) trial is an adaptive platform trial testing multiple drugs to slow or prevent the progression of Alzheimer's ...disease in autosomal dominant Alzheimer's disease (ADAD) families. With completion of enrollment of the first two drug arms, the DIAN-TU now plans to add new drugs to the platform, designated as the Next Generation (NexGen) prevention trial. Methods In collaboration with ADAD families, philanthropic organizations, academic leaders, the DIAN-TU Pharma Consortium, the National Institutes of Health, and regulatory colleagues, the DIAN-TU developed innovative clinical study designs for the DIAN-TU NexGen prevention trial. Results Our expanded trial toolbox consists of a disease progression model for ADAD, primary end point DIAN-TU cognitive performance composite, biomarker development, self-administered cognitive assessments, adaptive dose adjustments, and blinded data collection through the last participant completion. Conclusion These steps represent elements to improve efficacy of the adaptive platform trial and a continued effort to optimize prevention and treatment trials in ADAD.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In two phase 3 placebo-controlled, randomized trials in 1012 and 1040 patients with mild-to-moderate Alzheimer's disease, solanezumab, a humanized monoclonal antibody that preferentially binds ...soluble forms of amyloid, did not improve cognition or functional status.
Alzheimer's disease is associated with the accumulation of aggregated amyloid-beta (Aβ) peptide in the cerebral cortex and hippocampus. One approach to reducing brain amyloid involves increasing the clearance of Aβ by means of prolonged treatment with monoclonal antibodies directed against this peptide. In preclinical studies, a murine antibody that targeted the central domain of Aβ and was selective for soluble forms slowed Aβ deposition in a transgenic mouse model
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; in another transgenic murine model, Aβ–antibody complexes were present in the cerebrospinal fluid (CSF) and plasma, and behavioral deficits were reversed without a decrease in amyloid plaques, as assessed by . . .
Abstract In order to assist physicians in the effective pharmacologic management of this challenging population, evidence-based pharmacologic treatment algorithms for the different stages of ...Alzheimer’s disease have been developed. Evidence-based guidelines outlining pharmacotherapeutic strategies can be systematically implemented to optimize outcomes for patients in different stages of Alzheimer’s disease. The first step toward the best possible long-term management is early diagnosis of Alzheimer’s disease, thereby facilitating early initiation of cholinesterase inhibitor treatment, which may stabilize/reduce the rate of symptomatic cognitive and functional decline. Cholinesterase inhibitor therapy with rivastigmine, donepezil, or galantamine is endorsed as standard first-line therapy in patients with mild-to-moderate Alzheimer’s disease. The N-methyl-D-aspartate receptor-antagonist, memantine, may be used as monotherapy or in combination with a cholinesterase inhibitor for patients with moderate Alzheimer’s disease, and as monotherapy for patients with severe Alzheimer’s disease. During treatment, cognitive and functional status should be monitored over 6-month intervals, and pharmacologic therapy should ideally be continued until there are no meaningful social interactions and quality of life has irreversibly deteriorated.
In this placebo-controlled trial, the γ-secretase inhibitor semagacestat did not improve cognitive status in patients with Alzheimer's disease and was associated with more adverse events than ...placebo, including skin cancers and infections.
Alzheimer's disease begins decades before the appearance of clinical symptoms, with the deposition of aggregated amyloid-beta (Aβ) peptide plaques in the cortex and hippocampus. This protein is cleaved from the amyloid precursor protein (APP) by the sequential action of β- and γ-secretases, producing fragments that include Aβ1-40 and Aβ1-42. Since the accumulation of aggregated Aβ is associated with disease progression, both β-secretase and γ-secretase represent potential therapeutic targets. Multiple small molecules can inhibit γ-secretase in vitro,
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but Notch and other transmembrane proteins are also substrates for γ-secretase,
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and studies have raised concern that the inhibition of γ-secretase could . . .
•Tau deposition is associated with white-matter (WM) degeneration along connecting tracts.•Tau-related WM degeneration demonstrates distinct spatial pattern, similar to Braak staging.•WM degeneration ...is characterized by increased mean diffusivity and decreased axon density.•WM plays an important role in the deposition of tau pathology.
Progressive accumulation of tau neurofibrillary tangles in the brain is a defining pathologic feature of Alzheimer's disease (AD). Tau pathology exhibits a predictable spatiotemporal spreading pattern, but the underlying mechanisms of this spread are poorly understood. Although AD is conventionally considered a disease of the gray matter, it is also associated with pronounced and progressive deterioration of the white matter (WM). A link between abnormal tau and WM degeneration is suggested by findings from both animal and postmortem studies, but few studies demonstrated their interplay in vivo. Recent advances in diffusion magnetic resonance imaging and the availability of tau positron emission tomography (PET) have made it possible to evaluate the association of tau and WM degeneration (tau-WM) in vivo. In this study, we explored the spatial pattern of tau-WM associations across the whole brain to evaluate the hypothesis that tau deposition is associated with WM microstructural alterations not only in isolated tracts, but in continuous structural connections in a stereotypic pattern. Sixty-two participants, including 22 cognitively normal subjects, 22 individuals with subjective cognitive decline, and 18 with mild cognitive impairment were included in the study. WM characteristics were inferred by classic diffusion tensor imaging (DTI) and a complementary diffusion compartment model – neurite orientation dispersion and density imaging (NODDI) that provides a proxy for axonal density. A data-driven iterative searching (DDIS) approach, coupled with whole-brain graph theory analyses, was developed to continuously track tau-WM association patterns. Without applying prior knowledge of the tau spread, we observed a distinct spatial pattern that resembled the typical propagation of tau pathology in AD. Such association pattern was not observed between diffusion and amyloid-β PET signal. Tau-related WM degeneration is characterized by an increase in the mean diffusivity (with a dominant change in the radial direction) and a decrease in the intra-axonal volume fraction. These findings suggest that cortical tau deposition (as measured in tau PET) is associated with a lower axonal packing density and greater diffusion freedom. In conclusion, our in vivo findings using a data-driven method on cross-sectional data underline the important role of WM alterations in the AD pathological cascade with an association pattern similar to the postmortem Braak staging of AD. Future studies will focus on longitudinal analyses to provide in vivo evidence of tau pathology spreads along neuroanatomically connected brain areas.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract Background: Currently approved Alzheimer's disease (AD) treatments have been reported to provide symptomatic benefit, without proven impact on clinical progression. We hypothesized that the ...loss of initial therapeutic benefit over time may be mitigated by higher doses of a cholinesterase inhibitor. Objective: The aim of this study was to determine the effectiveness and tolerability of increasing donepezil from 10 to 23 mg/d in patients with moderate to severe AD. Methods: This randomized, double-blind study was conducted at 219 sites in Asia, Europe, Australia, North America, South Africa, and South America from June 6, 2007, to March 27, 2009. Patients aged 45 to 90 years with probable AD, Mini-Mental State Examination score 0 to 20 (moderate to severe impairment), and who were receiving donepezil 10 mg once daily for ≥12 weeks before the start of the study were eligible. Patients (n = 1467) were randomly assigned to receive high-dose donepezil (23 mg once daily) or standard-dose donepezil (10 mg once daily) for 24 weeks. Coprimary effectiveness measures were changes in cognition and global functioning, as assessed using least squares mean changes from baseline (LSM SE A) scores (last observation carried forward) on the Severe Impairment Battery (SIB; cognition) and the Clinician's Interview-Based Impression of Change Plus Caregiver Input scale (CIBIC+; global function rating) overall change score (mean SD) at week 24. Treatmentemergent adverse events (TEAEs) were assessed using spontaneous patient/caregiver reporting and open-ended questioning; clinical laboratory testing (hematology, biochemistry, and urinalysis panels analyzed by a central laboratory); 12-lead ECG; and physical and neurologic examinations, including vital sign measurements. Results: The effectiveness analyses included 1371 patients (mean age, 73.8 years; 62.8% female; 73.5% white; weight range, 34.0–138.7 kg). A total of 296 of 981 patients (30.2%) withdrew from the donepezil 23-mg/d group; 87 of 486 patients (17.9%) withdrew from the donepezil 10-mg/d group. At study end (week 24), the LSM (SE) Δ in SIB score was significantly greater with donepezil 23 mg/d than with donepezil 10 mg/d (+2.6 0.58 vs +0.4 0.66, respectively; difference, 2.2; P < 0.001). The between-treatment difference in CIBIC+ score was nonsignificant (4.23 1.07 vs 4.29 1.07). In post hoc analysis, LSM Δ in SIB score and CIBIC+ treatment effect at end point were greater with donepezil 23 mg/d than 10 mg/d in patients with more advanced AD compared with less impaired patients (SIB, +1.6 0.78 vs −1.5 0.88, respectively P < 0.001; CIBIC+, 4.31 1.09 vs 4.42 1.10 P = 0.028). TEAEs were reported in 710 of 963 patients (73.7%) who received donepezil 23 mg/d and in 300 of 471 patients (63.7%) who received donepezil 10 mg/d. With donepezil 23 mg/d, mild, moderate, and severe TEAEs were reported in 297 (30.8%), 332 (34.5%), and 81 (8.4%) patients, respectively; with donepezil 10 mg/d, these proportions were 147 (31.2%), 119 (25.3%), and 34 (7.2%). The 3 most common severe AEs reported with the 23-mg/d dose were nausea (9 patients 0.9% vs 1 0.2% with the 10-mg/d dose), dizziness (7 0.7% vs 1 0.2%), and vomiting (6 0.6% vs 0). The most commonly reported TEAEs considered probably related to treatment with the 23-mg/d dose were nausea (59 patients 6.1% vs 9 1.9% with the 10-mg/d dose), vomiting (48 5.0% vs 4 0.8%), and diarrhea (31 3.2% vs 7 1.5%).Thirteen deaths were reported during the study or within 30 days of study discontinuation (23 mg/d, 8 patients 0.8%; 10 mg/d, 5 patients 1.1%); all were considered unrelated to the study medication. Conclusions: In this study in patients with moderate to severe AD, donepezil 23 mg/d was associated with greater benefits in cognition compared with donepezil 10 mg/d. The between-treatment difference in global functioning was not significant in the overall population. Patients with more advanced AD appeared to benefit from donepezil 23 mg/d on the assessment of global functioning, but this observation requires additional studies for confirmation. ClinicalTrials.gov identifier: NCT00478205.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Bryostatin-activated PKC epsilon pre-clinically induces synaptogenesis, anti-apoptosis, anti-amyloid-β oligomers, and anti-hyperphosphorylated tau.
To investigate bryostatin safety, tolerability, and ...efficacy to improve cognition in advanced Alzheimer's disease (AD) patients.
A double-blind, randomized, placebo-controlled Phase II, 12-week trial of i.v. bryostatin for 150 advanced AD patients (55-85) with MMSE-2 of 4-15, randomized 1:1:1 into 20 μg and 40 μg bryostatin, and placebo arms. The Full Analysis Set (FAS) and the Completer Analysis Set (CAS) were pre-specified alternative assessments (1-sided, p < 0.1 for primary efficacy, and 2-sided, p < 0.05 for pre-specified and post hoc exploratory analyses).
The safety profile was similar for 20 μg treatment and placebo patients. The 40 μg patients showed safety and drop-out issues, but no efficacy. Primary improvement of Severe Impairment Battery (SIB) scores at 13 weeks was not significant (p = 0.134) in the FAS, although in the CAS, the SIB comparison favored 20 μg bryostatin compared to placebo patients (p < 0.07). Secondary analyses at weeks 5 and 15 (i.e., 30 days post-final dosing) also favored 20 μg bryostatin compared to placebo patients. A pre-specified ANCOVA for baseline memantine blocking bryostatin and positive post-hoc trend analyses were statistically significant (2-sided, p < 0.05).
Although the primary endpoint was not significant in the FAS, primary and secondary analyses in the CAS, and pre-specified and post-hoc exploratory analyses did favor bryostatin 20 μg compared to the placebo cohort. These promising Phase II results support further trials of 20 μg bryostatin- without memantine- to treat AD.
Abstract We evaluated the most current evidence regarding the benefits and harms of atypical antipsychotics in adults with dementia. In June 2016, following a protocol developed a priori , we ...systematically searched several databases for published and unpublished data from randomized controlled trials (RCT), observational studies, and meta-analyses; conducted direct meta-analyses using a random effects model; and graded the quality of evidence according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group. One high-quality meta-analysis and published and unpublished data from 8 RCTs and 12 large observational studies met inclusion criteria. When compared with placebo, aripiprazole, risperidone, and olanzapine but not quetiapine result in modest (standardized mean difference <0.5 standard deviations) improvement in neuropsychiatric symptoms. Aripiprazole, risperidone, quetiapine, and olanzapine are associated with increased odds of acute myocardial infraction, and risperidone and olanzapine are associated with increased odds of hip fracture. Observational studies suggest no differences in all-cause mortality between atypical antipsychotics. Observational studies suggest that atypical antipsychotics are associated with lower risk of all-cause mortality and extrapyramidal symptoms but higher risk of stroke when compared with conventional antipsychotics. To manage agitation in adults with progressive dementia, clinicians may recommend atypical antipsychotics with continuous monitoring of behavioral symptoms, informing patients and their families or caregivers of the significant risk of adverse effects and baseline risk of acute myocardial infraction and bone fractures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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