Anti-Aβ agents for mild to moderate Alzheimer's disease: systematic review and meta-analysis

Non-coding RNAs involved in the molecular pathology of Alzheimer's disease: a systematic review

Alzheimer's disease (AD) is the leading cause of dementia globally, having a pathophysiology that is complex and multifactorial. Recent findings highlight the significant role of non-coding RNAs (ncRNAs), specifically microRNAs (miRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and piwi-interacting RNAs (piRNAs) in the molecular mechanisms underlying AD. These ncRNAs are involved in critical biological processes such as cell proliferation, apoptosis, oxidative stress, amyloid-beta aggregation, tau phosphorylation, neuroinflammation, and autophagy, which are pivotal in AD development and progression. This systematic review aims to consolidate current scientific knowledge on the role of ncRNAs in AD, making it the first to encompass the four types of ncRNAs associated with the disease. Our comprehensive search and analysis reveal that ncRNAs not only play crucial roles in the pathogenesis of AD but also hold potential as biomarkers for its early detection and as novel therapeutic targets. Specifically, the findings underscore the significance of miRNAs in regulating genes involved in key AD pathways such as activin receptor signaling pathway, actomyosin contractile ring organization, and advanced glycation endproducts-receptor advanced glycation endproducts (AGE-RAGE) signaling pathway. This review also highlights the potential of ncRNAs in unveiling novel diagnostic and therapeutic strategies, emphasizing the need for further research to validate their clinical utility. Our systematic exploration provides a foundation for future bioinformatic analyses and the development of ncRNA-based precision medicine approaches for AD, offering new insights into the disease's molecular pathology and paving the way for innovative treatment strategies.

Systematic review registration

PROSPERO, https://www.crd.york.ac.uk/prospero/, CRD42022355307.

Astrocyte-derived lactoferrin reduces β-amyloid burden by promoting the interaction between p38 kinase and PP2A phosphatase in male APP/PS1 transgenic mice

BACKGROUND AND PURPOSE

Overexpression of astrocytic lactoferrin (Lf) was observed in the brain of Alzheimer's disease (AD) patients, whereas the role of astrocytic Lf in AD progression remains unexplored. In this study, we aimed to evaluate the effects of astrocytic Lf on AD progression.

EXPERIMENTAL APPROACH

Male APP/PS1 mice with astrocytes overexpressing human Lf were developed to evaluate the effects of astrocytic Lf on AD progression. N2a-sw cells also were employed to further uncover the mechanism of astrocytic Lf on β-amyloid (Aβ) production.

KEY RESULTS

Astrocytic Lf overexpression increased protein phosphatase 2A (PP2A) activity and reduced amyloid precursor protein (APP) phosphorylation, Aβ burden and tau hyperphosphorylation in APP/PS1 mice. Mechanistically, astrocytic Lf overexpression promoted the uptake of astrocytic Lf into neurons in APP/PS1 mice, and conditional medium from astrocytes overexpressing Lf inhibited p-APP (Thr668) expression in N2a-sw cells. Furthermore, recombinant human Lf (hLf) significantly enhanced PP2A activity and inhibited p-APP expression, whereas inhibition of p38 or PP2A activities abrogated the hLf-induced p-APP down-regulation in N2a-sw cells. Additionally, hLf promoted the interaction of p38 and PP2A via p38 activation, thereby enhancing PP2A activity, and low-density lipoprotein receptor-related protein 1 (LRP1) knockdown significantly reversed the hLf-induced p38 activation and p-APP down-regulation.

CONCLUSIONS AND IMPLICATIONS

Our data suggested that astrocytic Lf promoted neuronal p38 activation, via targeting to LRP1, subsequently promoting p38 binding to PP2A to enhance PP2A enzyme activity, which finally inhibited Aβ production via APP dephosphorylation. In conclusion, promoting astrocytic Lf expression may be a potential strategy against AD.

LINKED ARTICLES

This article is part of a themed issue From Alzheimer's Disease to Vascular Dementia: Different Roads Leading to Cognitive Decline. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.6/issuetoc.

Safety Analysis of Bapineuzumab in the Treatment of Mild to Moderate Alzheimer's Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Alzheimer's disease affects millions of people worldwide, and very few drugs are available for its treatment. Monoclonal antibodies have shown promising effects in the treatment of various types of diseases. Bapineuzumab is one of the humanized monoclonal antibodies, which have shown promising effects in AD patients. Bapineuzumab has shown efficacy in the treatment of mild to moderate Alzheimer's disease. However, its safety is still unclear.

OBJECTIVE

Thus, the main objective of the current study is to find out the exact safety profile of bapineuzumab in the treatment of mild to moderate Alzheimer's disease.

METHODS

We performed a web-based literature search of PubMed and clinical trial websites using the relevant keywords. Data were extracted from eligible records, and the risk ratio (RR) was calculated with a 95% confidence interval (CI). All the analyses were performed using Review Manager software (version 5.3 for windows). Heterogeneity was measured by Chi-square and I-square tests.

RESULTS

Non-significant association of bapineuzumab with serious treatment-emergent adverse events [RR: 1.11 (0.92, 1.35)], headache [RR: 1.03 (0.81, 1.32)], delirium [RR: 2.21 (0.36, 13.53)], vomiting [RR: 0.92 (0.55, 1.55)], hypertension [RR: 0.49 (0.12, 2.12)], convulsions [RR:2.23 (0.42, 11.71)], falls [RR: 0.98 (0.80, 1.21)], fatal AEs [RR: 1.18 (0.59, 2.39)], and neoplasms [RR:1.81 (0.07, 49.52)] was reported; however, a significant association was found with vasogenic edema [RR: 22.58 (3.48, 146.44)].

CONCLUSION

Based on available evidence, bapineuzumab is found to be safe in the treatment of AD patients. However, vasogenic edema should be considered.

Current Anti-Amyloid-β Therapy for Alzheimer's Disease Treatment: From Clinical Research to Nanomedicine

Recent successive approval of anti-amyloid-β (Aβ) monoclonal antibodies as disease-modifying therapies against Alzheimer's disease (AD) has raised great confidence in the development of anti-AD therapies; however, the current therapies still face the dilemma of significant adverse reactions and limited effects. In this review, we summarized the therapeutic characteristics of the approved anti-Aβ immunotherapies and dialectically analyzed the gains and losses from clinical trials. The review further proposed the reasonable selection of animal models in preclinical studies from the perspective of different animal models of Aβ deposition and deals in-depth with the recent advances of exploring preclinical nanomedical application in Aβ targeted therapy, aiming to provide a reliable systematic summary for the development of novel anti-Aβ therapies. Collectively, this review comprehensively dissects the pioneering work of Aβ-targeted therapies and proposed perspective insight into AD-modified therapies.

Immunotherapies Targeting Amyloid and Tau Protein in Alzheimer's Disease: Should We Move Away from Diseases and Focus on Biological Targets? A Systematic Review and Expert Opinion

INTRODUCTION

Alzheimer's disease (AD) is the most common cause of dementia worldwide, making it a major public health issue. Anti-amyloid and anti-tau antibodies are the most advanced therapeutic approach at present. Three drugs (lecanemab, donanemab and aducanumab) are on track to be marketed in the coming months. In this systematic review, we review all Phase 2 and Phase 3 clinical trials conducted in this indication and the particularities of the molecules tested.

METHODS

The PubMed and ClinicalTrials.gov databases were searched through February 2023 for Phase 2 and 3 clinical trials involving passive anti-amyloid or anti-tau immunotherapies with published results. This review has been compiled in compliance with the PRISMA checklists.

RESULTS

Of the 165 studies found and after eliminating duplicates, 40 studies had their results published on PubMed and/or ClinicalTrials.gov. Eight anti-amyloid molecules and four anti-tau molecules were the subject of Phase 2 studies, seven anti-amyloids were the subject of Phase 3 trials, and two molecules were granted early marketing approval by the US Food and Drug Administration (FDA). The results were compiled in summary tables showing the primary endpoints used, results, age of the study population and specific adverse events for these molecules.

DISCUSSION

Passive immunotherapy in AD is largely dominated by anti-amyloid antibodies, which are more numerous and more advanced in the pipeline. Lecanemab, donanemab and aducanumab are distinguished by their relative efficacy in terms of cognitive and functional evaluation but also by a decrease in amyloid and tau proteins in the brain. These three molecules have in common that they bind to N-terminal ends of amyloid fibrils and plaques. The findings of their studies raise the question of which criteria to apply when choosing which patient will receive them when marketed, such as the apoliprotein E gene's fourth allele (APOE4) genetic status of patients. The large number of negative studies may also raise the question of the criteria for defining the disease and the possible interest in redefining it on biological grounds to offer a more personalized medicine to patients suffering from neurodegenerative diseases.

The efficacy and safety of anti-Aβ agents for delaying cognitive decline in Alzheimer's disease: a meta-analysis

Background

This meta-analysis evaluates the efficacy and safety of amyloid-β (Aβ) targeted therapies for delaying cognitive deterioration in Alzheimer's disease (AD).

Methods

PubMed, EMBASE, the Cochrane Library, and ClinicalTrials.gov were systematically searched to identify relevant studies published before January 18, 2023.

Results

We pooled 33,689 participants from 42 studies. The meta-analysis showed no difference between anti-Aβ drugs and placebo in the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), and anti-Aβ drugs were associated with a high risk of adverse events [ADAS-Cog: MDs = -0.08 (-0.32 to 0.15), p = 0.4785; AEs: RR = 1.07 (1.02 to 1.11), p = 0.0014]. Monoclonal antibodies outperformed the placebo in delaying cognitive deterioration as measured by ADAS-Cog, Clinical Dementia Rating-Sum of Boxes (CDR-SB), Mini-Mental State Examination (MMSE) and Alzheimer's Disease Cooperative Study-Activities of Daily Living (ADCS-ADL), without increasing the risk of adverse events [ADAS-Cog: MDs = -0.55 (-0.89 to 0.21), p = 0.001; CDR-SB: MDs = -0.19 (-0.29 to -0.10), p < 0.0001; MMSE: MDs = 0.19 (0.00 to 0.39), p = 0.05; ADCS-ADL: MDs = 1.26 (0.84 to 1.68), p < 0.00001]. Intravenous immunoglobulin and γ-secretase modulators (GSM) increased cognitive decline in CDR-SB [MDs = 0.45 (0.17 to 0.74), p = 0.002], but had acceptable safety profiles in AD patients. γ-secretase inhibitors (GSI) increased cognitive decline in ADAS-Cog, and also in MMSE and ADCS-ADL. BACE-1 inhibitors aggravated cognitive deterioration in the outcome of the Neuropsychiatric Inventory (NPI). GSI and BACE-1 inhibitors caused safety concerns. No evidence indicates active Aβ immunotherapy, MPAC, or tramiprosate have effects on cognitive function and tramiprosate is associated with serious adverse events.

Conclusion

Current evidence does not show that anti-Aβ drugs have an effect on cognitive performance in AD patients. However, monoclonal antibodies can delay cognitive decline in AD. Development of other types of anti-Aβ drugs should be cautious.

Systematic Review Registration

PROSPERO (https://www.crd.york.ac.uk/prospero/), identifier CRD42023391596.

Amyloid and tau pathology are associated with cerebral blood flow in a mixed sample of nondemented older adults with and without vascular risk factors for Alzheimer's disease

Identification of biomarkers for the early stages of Alzheimer's disease (AD) is an imperative step in developing effective treatments. Cerebral blood flow (CBF) is a potential early biomarker for AD; generally, older adults with AD have decreased CBF compared to normally aging peers. CBF deviates as the disease process and symptoms progress. However, further characterization of the relationships between CBF and AD risk factors and pathologies is still needed. We assessed the relationships between CBF quantified by arterial spin-labeled magnetic resonance imaging, hypertension, APOEε4, and tau and amyloid positron emission tomography in 77 older adults: cognitively normal, subjective cognitive decline, and mild cognitive impairment. Tau and amyloid aggregation were related to altered CBF, and some of these relationships were dependent on hypertension or APOEε4 status. Our findings suggest a complex relationship between risk factors, AD pathologies, and CBF that warrants future studies of CBF as a potential early biomarker for AD.

Repetitive transcranial magnetic stimulation may be superior to drug therapy in the treatment of Alzheimer's disease: A systematic review and Bayesian network meta-analysis

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive brain stimulation therapy that is primarily used to treat a variety of neuropsychiatric conditions. Recently, previous research reports stated that rTMS have the characteristics of neurorestorative in Alzheimer's disease (AD). However, the relevant clinical research evidence has not been fully summarized.

METHODS

This article performed a network meta-analysis of individual participant data from eligible studies searched in PubMed, Embase, and the Cochrane Library from inception to March 31, 2022. The drug treatments involved were acetylcholinesterase inhibitors (AChEIs), N-methyl-d-aspartate (NMDA), anti-amyloid-beta (Aβ), and some new targeted therapeutic drugs.

RESULTS

A total of 15, 548 individuals with AD disease in 57 randomized clinical trials (RCTs) were included in this meta-analysis. The results indicated that the patients who received rTMS treatment (standard mean difference [SMD]: 0.65; 95% confidence interval [CI]: 0.22-1.07) had a better MMSE score than placebo. Treatment outcome analysis showed that, compared with multiple pharmacological interventions, rTMS acquired the greatest probability rank with the best cognitive improvement in MMSE score [the surface under the cumulative ranking curve (SUCRA) 93.3%] and ADAS-cog score (SUCRA 86.7%). At the same time, rTMS treatment had the lowest rank in the adverse events (SUCRA 24.1%) except for the placebo group (SUCRA 19.1%).

CONCLUSION

Compared with the current clinical drug treatment, rTMS demonstrated better cognitive function improvement and fewer adverse events in AD patients. Therefore, rTMS shows broad prospects in the treatment of Alzheimer's disease, and it is worth being widely popularized in clinic.

Fatigue in Alzheimer's disease: biological basis and clinical management-a narrative review

BACKGROUND

Fatigue is a common symptom in neurodegenerative diseases and is associated with decreased cognitive performances. A full knowledge of the causes and physiopathological pathways leading to fatigue in Alzheimer's disease could help treating this symptom and obtain positive effects on cognitive functions.

OBJECTIVES

To provide an overview of the clinical conditions and the biological mechanisms leading to fatigue in Alzheimer's disease patients. To review the recent advances on fatigue management and describe the landscape of future possibilities.

METHODS

We performed a narrative review including all type of studies (e.g. cross-sectional and longitudinal analysis, reviews, clinical trials).

RESULTS

We found very few studies considering the symptom fatigue in Alzheimer's disease patients. Populations, designs, and objectives varied across studies rendering comparability across studies difficult to perform. Results from cross-sectional and longitudinal analysis suggest that the amyloid cascade may be involved in the pathogenesis of fatigue and that fatigue may be a prodromal manifestation of Alzheimer's disease. Fatigue and neurodegeneration of Alzheimer's disease could share common brain signatures (i.e. hippocampal atrophy and periventricular leukoaraiosis). Some mechanisms of aging (i.e. inflammation, mitochondrial dysfunction, telomere shortening) may be proposed to play a common underlying role in Alzheimer's disease neurodegeneration and muscle fatigability. Considering treatments, donepezil has been found to reduce cognitive fatigue in a 6-week randomized controlled study. Fatigue is frequently reported as an adverse event in patients treated by anti-amyloid agents in clinical trials.

CONCLUSION

The literature is actually inconclusive about the main causes of fatigue in Alzheimer's disease individuals and its potential treatments. Further research is needed to disentangle the role of several components such as comorbidities, depressive symptoms, iatrogenic factors, physical decline and neurodegeneration itself. Given the clinical relevance of this symptom, it seems to be important to systematically assess fatigue by validated tools in Alzheimer's disease clinical trials.

Effects of three kinds of anti-amyloid-β drugs on clinical, biomarker, neuroimaging outcomes and safety indexes: A systematic review and meta-analysis of phase II/III clinical trials in Alzheimer's disease

OBJECTIVE

To investigate the effects of the three kinds of anti-amyloid-β (Aβ) drugs on cognitive and other functions, fluid and neuroimaging biomarkers, and safety on patients with Alzheimer's disease (AD), and rank the three kinds of anti-Aβ drugs.

METHODS

We searched Medline, Embase, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and AlzForum from inception to January 21, 2023 to include randomized controlled clinical trials. Random effects meta-analyses were performed.

RESULTS

Forty-one clinical trials (20929 participants, 9167 male) were included. Anti-Aβ drugs had significant but relatively low efficacy in preventing cognitive decline (ADAS-Cog SMD -0.07, 95% CI: -0.10 to -0.03, p < 0.001; CDR-SOB -0.05, -0.09 to -0.01, p = 0.017). Instrumental variable meta-analysis and trial sequential analysis confirmed the reliability of the pooled estimation. Beneficial effects were also observed by assessing other cognitive and activity of daily living scales and biomarkers, with acceptable safety of anti-Aβ drugs. Meta-regression demonstrated significant association between higher baseline mini-mental statement examination scores (MMSE) and better cognitive protective effects on cognitive function (ADAS-Cog β: -0.02, -0.05 to 0.00, p = 0.017) and clearance of pathological productions of anti-Aβ drugs. Network meta-analysis ranked the passive immunotherapy drugs to have the best cognitive efficacy, followed by active immunotherapy and small molecule drugs.

CONCLUSION

Anti-Aβ drugs have relatively low efficacy in preventing cognitive decline, and they reduce pathological productions with acceptable safety. Patients with higher baseline MMSE scores benefit more from anti-Aβ drugs. Passive immunotherapy anti-Aβ drugs show relatively better efficacy than active immunotherapy and small molecule anti-Aβ drugs.

The role of microbiome-host interactions in the development of Alzheimer´s disease

Alzheimer`s disease (AD) is the most prevalent cause of dementia. It is often assumed that AD is caused by an aggregation of extracellular beta-amyloid and intracellular tau-protein, supported by a recent study showing reduced brain amyloid levels and reduced cognitive decline under treatment with a beta-amyloid-binding antibody. Confirmation of the importance of amyloid as a therapeutic target notwithstanding, the underlying causes of beta-amyloid aggregation in the human brain, however, remain to be elucidated. Multiple lines of evidence point towards an important role of infectious agents and/or inflammatory conditions in the etiology of AD. Various microorganisms have been detected in the cerebrospinal fluid and brains of AD-patients and have thus been hypothesized to be linked to the development of AD, including Porphyromonas gingivalis (PG) and Spirochaetes. Intriguingly, these microorganisms are also found in the oral cavity under normal physiological conditions, which is often affected by multiple pathologies like caries or tooth loss in AD patients. Oral cavity pathologies are mostly accompanied by a compositional shift in the community of oral microbiota, mainly affecting commensal microorganisms and referred to as 'dysbiosis'. Oral dysbiosis seems to be at least partly mediated by key pathogens such as PG, and it is associated with a pro-inflammatory state that promotes the destruction of connective tissue in the mouth, possibly enabling the translocation of pathogenic microbiota from the oral cavity to the nervous system. It has therefore been hypothesized that dysbiosis of the oral microbiome may contribute to the development of AD. In this review, we discuss the infectious hypothesis of AD in the light of the oral microbiome and microbiome-host interactions, which may contribute to or even cause the development of AD. We discuss technical challenges relating to the detection of microorganisms in relevant body fluids and approaches for avoiding false-positives, and introduce the antibacterial protein lactoferrin as a potential link between the dysbiotic microbiome and the host inflammatory reaction.

Safety and efficacy of lecanemab for Alzheimer's disease: a systematic review and meta-analysis of randomized clinical trials

Objective

We performed a systematic review and meta-analysis of the cognitive effectiveness and safety of lecanemab on subjects with Alzheimer's disease (AD).

Methods

We screened the literature published before February 2023 in PubMed, Embase, Web of Science, and Cochrane that were searched for randomized controlled trials testing lecanemab for the treatment of cognitive decline in patients with MCI or AD. Outcomes measured were CDR Sum of Boxes (CDR-SB), Alzheimer's Disease Composite Score (ADCOMS), AD Assessment Scale-Cognitive Subscale (ADAS-Cog), Clinical Dementia Rating (CDR), amyloid PET Standardized Uptake Volume Ratio (SUVr), amyloid burden on PET, and risks for adverse events.

Results

A total of four randomized controlled trials were included, involving 3,108 AD patients (1,695 lecanemab groups and 1,413 placebo groups) to synthesize evidence. Baseline characteristics of the two groups were similar in all outcomes except that ApoE 4 status and higher MMSE score were observed in the lecanemab group. It is reported that lecanemab was beneficial to stabilize or slow down the decrease in CDR-SB (WMD: -0.45; 95% CI: -0.64, -0.25; p < 0.00001), ADCOMS (WMD: -0.05; 95% CI: -0.07, -0.03; p < 0.00001), ADAS-cog (WMD: -1.11; 95% CI: -1.64, -0.57; p < 0.0001), amyloid PET SUVr (WMD: -0.15; 95% CI: -0.48, 0.19; p = 0.38), amyloid burden on PET (WMD:-35.44; 95% CI: -65.22,-5.67; p = 0.02), adverse events (subjects with any TEAE) (OR: 0.73; 95% CI: 0.25, 2.15; p = 0.57), ARIA-E (OR:8.95; 95% CI: 5.36, 14.95; p < 0.00001), and ARIA-H (OR:2.00; 95% CI: 1.53, 2.62; p < 0.00001) in early AD patients.

Conclusion

Our analysis found that lecanemab showed significant positive statistical efficacy with respect to cognition, function, and behavior in patients with early AD though the actual clinical significance is yet to be established.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/#recordDetails, identifier: CRD42023393393.

Signal and Noise: Proton Pump Inhibitors and the Risk of Dementia?

The association between proton pump inhibitor (PPI) use and dementia remains controversial. This cohort study re-examines this issue, addressing shortcomings identified in previous publications using a population-based and a high-dimension propensity-score matched cohort to follow patients for up to 22 years. Cox regression models using baseline characteristics, a lag period, and time-varying variables were used to examine the risk of dementia by cumulative PPI exposure. High-dose PPI users (> 180 days of use) had significantly higher risk of dementia in crude Cox models. After adjustment for medical diagnoses and prescription drug use, these associations disappeared. Among high-dose users starting PPI therapy between 46 and 55 years old, the unadjusted hazard ratio (HR) was 1.55 (95% confidence interval (CI) 1.14, 2.10); the adjusted hazard ratio (aHR) was 1.10 (95% CI 0.80, 1.51). For high-dose users starting therapy between 56 and 65 years, HR = 1.22 (95% CI1.03, 1.44); aHR = 0.99 (95% CI 0.83, 1.17). High-dose users between the ages of 66 and 75 years had no association with the risk of dementia. The use of lag models or time-varying parameters similarly found some association with dementia in crude, but not multivariable Cox models. Although high-dose PPI users were more likely to develop dementia, they were more likely to be diagnosed with dementia risk factors, such as diabetes and cardiovascular disease, which are risk factors for dementia. Controlling for these conditions using multivariable models or a propensity-score matched cohort eliminated this association.

Electroacupuncture ameliorates cerebrovascular impairment in Alzheimer's disease mice via melatonin signaling

AIMS

Cerebrovascular impairment contributes to the pathogenesis of Alzheimer's disease (AD). However, it still lacks effective intervention in clinical practice. Here, we investigated the efficacy of electroacupuncture (EA) in cerebrovascular repair in 3xTg-AD mice and its mechanism.

METHODS

3xTg-AD mice were employed to evaluate the protective effect of EA at ST36 acupoint (EAST36). Behavioral tests were performed to assess neurological disorders. Laser speckle contrast imaging, immunostaining, and Western blot were applied to determine EAST36-boosted cerebrovascular repair. The mechanism was explored in 3xTg mice and endothelial cell cultures by melatonin signaling modulation.

RESULTS

EAST36 at 20/100 Hz effectively alleviated the olfactory impairment and anxiety behavior and boosted cerebrovascular repair in AD mice. EAST36 attenuated cerebral microvascular degeneration in AD mice by modulating endothelial cell viability and injury. Consequently, the Aβ deposits and neural damage in AD mice were reversed after EAST36. Mechanistically, we revealed that EAST36 restored melatonin levels in AD mice. Melatonin supplement mimicked the EAST36 effect on cerebrovascular protection in AD mice and endothelial cell cultures. Importantly, blockage of melatonin signaling by antagonist blunted EAST36-induced cerebrovascular recovery and subsequent neurological improvement.

CONCLUSIONS

These findings provided strong evidence to support EAST36 as a potential nonpharmacological therapy against cerebrovascular impairment in AD. Further study is necessary to better understand how EAST36 treatment drives melatonin signaling.

Pharmacotherapy of Alzheimer's disease: an overview of systematic reviews

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disease and the most common cause of dementia. In this umbrella systematic review (SR), we summarized the efficacy of different pharmacological interventions in improving cognitive function in patients with AD.

METHODS

A systematic search was performed through the PubMed, Scopus, Embase, and Cochrane databases for SRs of studies assessing the efficacy of pharmacological interventions versus placebo in improving cognitive function in AD or mild cognitive impairment due to AD. The risk of bias (RoB) was assessed using the Risk of Bias in SRs (ROBIS) tool.

RESULTS

Out of 1748 articles found through the database survey, 33 SR articles were included. These studies assessed effects of immunotherapy, cholinesterase inhibitors (ChEIs), memantine, statins, lithium, nonsteroidal anti-inflammatory drugs (NSAIDs), antidiabetic agents, Cerebrolysin, RAS-targeting antihypertensive drugs (ARBs and ACEIs), psychostimulants, glycogen synthase kinase 3 (GSK-3) inhibitors, melatonin, and herbal medications on cognitive function in AD patients. There was no notable overall RoB in 18 studies (54.5%), the RoB in 14 studies (42.4%) was high, and in one study (3.0%) it was unclear.

CONCLUSIONS

The use of ChEIs, including rivastigmine, galantamine, and donepezil, as well as memantine has demonstrated a positive impact on improving cognitive outcomes of AD patients, but no considerable effects were found for immunotherapies. Melatonin, statins, antihypertensive drugs, antidiabetic agents, Cerebrolysin, psychostimulants, and some herbal drugs such as Danggui-Shaoyao-San and Ginkgo biloba seem to be effective in improving cognitive function of AD patients, but the evidence in this regard is limited.

Effects of different kinds of anti-Alzheimer's disease drugs on cognitive improvement: protocol for a systematic review and network meta-analysis of phase III clinical trials

BACKGROUND

Alzheimer's disease is a neurodegenerative disease characterized by progressive cognitive decline and dysfunction of independent living ability, with huge economic and healthy burden worldwide. However, there is still a lack of effective long-term drugs to improve cognitive function and reduce or halt disease progression. Phase III clinical trials of anti-AD drugs based on different hypotheses were in the pipeline, and this protocol for a systematic review and meta-analysis aims to determine what is the most effective direction for the development of drugs on cognitive improvement.

METHODS/DESIGN

We will search the following literature databases for eligible studies from inception to December 2021: Ovid MEDLINE, Ovid Embase, PubMed MEDLINE, and Cochrane Central Register of Controlled Trials. Google Scholar, ClinicalTrials.gov registration platform, and the AlzForum website will also be searched for additional studies. Studies will be included irrespective of publication status or language. Phase III clinical trials reporting on the effect of anti-AD drugs on participants with AD will be included. Two independent reviewers will screen the hit articles and identify phase III clinical trials, extract data, and assess the quality of each study individually. The Cochrane Risk of Bias tool 2 (RoB 2) will be used to assess the risk of bias. For each kind of drugs based on the corresponding hypothesis, we will compare the study design and demographic features of the clinical trials and include appropriate studies in the network meta-analysis. The primary outcomes will be the indicators of cognitive improvement. The secondary outcomes will be activities of daily living, neuroimaging changes, biomarkers, and safety. Through network meta-analysis, we will suggest the hypothesis that most likely to improve cognitive function and provide the ranks of all kinds of drugs. We will give recommendation grade of each comparison using the Confidence In Network Meta-Analysis (CINeMa) tool.

DISCUSSION

This study will provide helpful evidence for further drug development and clinical practice for treating Alzheimer's disease.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021251507.

Pantao Pill Improves the Learning and Memory Abilities of APP/PS1 Mice by Multiple Mechanisms

Background: To explore the effect and mechanisms of Pantao Pill (PTP) on cognitive impairment. Methods: Network pharmacology was performed to analyze the mechanism of PTP treating cognitive impairment. The targets of PTP and cognitive impairment were predicted and used to construct protein-protein interaction (PPI) networks. The intersection network was selected, and the core network was obtained through topological analysis. Enrichment analysis was conducted to obtain the GOBP terms and KEGG pathways. We then performed experiments to validate the results of the network pharmacology by using an APP/PS1 transgenic mouse model. The APP/PS1 mice were divided into four groups: the model group, the high-dose PTP (3.6 g/kg·d) group, the low-dose PTP (1.8 g/kg·d) group, and the positive control group (donepezil hydrochloride, 2 mg/kg·d). Wild-type (WT) C57 mice served as a normal control group. PTP and donepezil were administered by gavage for 8 weeks. Results: Network pharmacology showed that PTP might improve cognitive impairment by regulating autophagy, apoptosis, and oxidative stress. For the Morris water maze test, a significant difference was shown in the total swimming distance among groups (p < 0.05) in the positioning navigation experiment, and with training time extension, the swimming speed increased (p < 0.01). In the space probe test, PTP administration significantly reduced the swimming path length and the escape latency of APP/PS1 mice (p < 0.05 or p < 0.01), whereas it had no effect on the swimming speed (p > 0.05). PTP (3.6 g/kg/d) rescued the reduction of norepinephrine and acetylcholine levels (p < 0.05), and increased the acetylcholinesterase concentration (p < 0.05) in the brain tissue. PTP (1.8 g/kg/d) increased the norepinephrine level (p < 0.01). PTP rescued the activity reduction of superoxide dismutase in the brain tissue (p < 0.01) and the neuron cell pyknosis in the hippocampal CA region (p < 0.05). PTP reduced ATG12 and PS1 expression (p < 0.05 or p < 0.01), and increased Bcl-2 expression in the brain tissue (p < 0.05). Conclusion: PTP can significantly improve the learning and memory abilities of APP/PS1 mice, and the mechanism may be related to the increase of neurotransmitter acetylcholine and norepinephrine levels, the reduction of the excessive autophagic activation, and the suppression of oxidative stress and excessive apoptotic activity.

Alzheimer's disease related biomarkers in bipolar disorder - A longitudinal one-year case-control study

INTRODUCTION

Bipolar disorder (BD) is a heterogeneous mental disorder characterized by recurrent relapses of affective episodes: Subgroups of patients with BD have cognitive deficits, and an increased risk of dementia.

METHODS

This prospective, longitudinal, one-year follow-up, case-control study investigated biomarkers for AD and neurodegenerative diseases, namely: cerebrospinal fluid (CSF) amyloid beta (Aβ) isoforms and ratios (Aβ42, Aβ40, Aβ38), CSF soluble amyloid precursor protein (sAPP) α and β, CSF total (t-tau) and phosphorylated tau (p-tau), CSF neurofilament-light (NF-L), CSF neurogranin (NG), plasma-isoforms Aβ42 and Aβ40, plasma-tau, plasma-NF-L, and serum S100B, in patients with BD (N = 62, aged 18-60) and gender-and-age-matched healthy control individuals (N = 40). CSF and plasma/serum samples were collected at baseline, during and after an affective episode, if it occurred, and after a year. Data were analyzed in mixed models.

RESULTS

Levels of CSF Aβ42 decreased in patients with BD who had an episode during follow-up (BD-E) (N = 22) compared to patients without an episode (BD-NE) (N = 25) during follow-up (P = 0.002). Stable levels were seen for all other markers in BD-E compared to BD-NE during the one-year follow-up. We found no statistically significant differences between patients with BD and HC at T0 and T3 for Aβ42, Aβ40, Aβ38, Aβ42/38, Aβ42/40, sAPPα, sAPPβ, t-tau, p-tau, p-tau /t-tau, NF-L, NG in CSF and further Aβ40, Aβ42, Aβ42/40, t-tau, NF-L in plasma, S100B in serum, and APOE-status. Furthermore, all 18 biomarkers were stable in HC during the one-year follow-up from T0 to T3.

CONCLUSION

A panel of biomarkers of Alzheimer's and neurodegeneration show no differences between patients with BD and HC. There were abnormalities of amyloid production/clearance during an acute BD episode. The abnormalities mimic the pattern seen in AD namely decreasing CSF Aβ42 and may suggest an association with brain amyloidosis.

The Efficacy and Safety of Alzheimer's Disease Therapies: An Updated Umbrella Review

BACKGROUND

Evidence summaries for efficacy and safety of frequently employed treatments of Alzheimer's disease (AD) are sparse.

OBJECTIVE

We aimed to perform an updated umbrella review to identify an efficacious and safe treatment for AD patients.

METHODS

We conducted a search for meta-analyses and systematic reviews on the Embase, PubMed, The Cochrane Library, and Web of Science to address this knowledge gap. We examined the cognitive functions, behavioral symptoms, global clinical assessment, and Activities of Daily Living as efficacy endpoints, and the incidence of adverse events as safety profiles.

RESULTS

Sixteen eligible papers including 149 studies were included in the umbrella review. The results showed that AChE inhibitors (donepezil, galantamine, rivastigmine, Huperzine A), Ginkgo biloba, and cerebrolysin appear to be beneficial for cognitive, global performances, and activities of daily living in patients with AD. Furthermore, anti-Aβ agents are unlikely to have an important effect on slowing cognitive or functional impairment in mild to moderate AD.

CONCLUSION

Our study demonstrated that AChE inhibitors, Ginkgo biloba, and cerebrolysin are the optimum cognitive and activities of daily living medication for patients with AD.

Resting-state functional reorganisation in Alzheimer's disease and amnestic mild cognitive impairment: protocol for a systematic review and meta-analysis

INTRODUCTION

The incidence of Alzheimer's disease (AD) is increasing rapidly, causing a growing burden to health and economic worldwide. Several clinical trials in the past decade failed to find solutions, and there remains a lack of an effective treatment. The evidence suggests that early intervention for neurodegeneration would likely be effective in preventing cognitive decline. Cognitive decline in AD occurs continuously over a long period; however, there remains a lack of simple, rapid and accurate approach for diagnosis of amnestic mild cognitive impairment or subjective cognitive decline due to underlying Alzheimer's pathology. Resting-state functional MRI (rs-fMRI) determines the functional activities of the human brain non-invasively. The amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF) and regional homogeneity (ReHo) are rs-fMRI indicators with high repeatability. They have been studied as early diagnostic imaging markers for other diseases and may be promising markers also for AD.

METHODS AND ANALYSIS

The following electronic literature databases will be searched from inception to December 2021: Medline-Ovid, Medline-PubMed, EMBase-Ovid, Cochrane Central and ClinicalTrials.gov. Two independent reviewers will select studies with eligible criteria, extract data and assess the quality of the original studies with our quality assessment tool individually. Missing data will be requested by sending emails to the corresponding authors. Brain regions will be presented for ALFF/fALFF and ReHo by performing activation likelihood estimation with the Seed-based d Mapping-Permutation of subject images V.6.21 software. Meta-regression will be performed to determine the potential brain regions that may strongly correlate with cognitive decline progression. Subgroup analysis, funnel plot, Egger's test and sensitivity analysis will be conducted to detect and explain potential heterogeneity.

ETHICS AND DISSEMINATION

This study does not require formal ethical approval. The findings will be submitted to a peer-review journal.

PROSPERO REGISTRATION NUMBER

CRD42021229009.

Effect of antiamyloid-β drugs on Alzheimer's disease: study protocol for a systematic review and meta-analysis

INTRODUCTION

Alzheimer's disease (AD) is a neurodegenerative disease with a complex aetiology involving multiple targets and pathways. With the continuous growth of the ageing population, the burden of AD is increasing year by year. However, there has not been new drug approved for over a decade. In addition, the efficacy of memantine and cholinesterase inhibitors is not satisfactory. As amyloid-β (Aβ) is regarded as the core pathological change and the trigger mechanism of AD, anti-Aβ therapy may be an effective therapy. In recent years, a lot of clinical trials have been carried out in this field, but the results have not been well summarised and analysed.

METHODS AND ANALYSIS

In this study, we will study the effect of anti-Aβ antibodies versus placebo on the clinical efficacy, biomarkers, neuroimaging and safety in different stages of AD, as well as the factors that may affect the efficacy. Drugs that only target the existing Aβ are regarded as anti-Aβ antibodies. Following electronic databases will be searched from inception to April 2021: Medline-Ovid, EMBase-Ovid, Cochrane Central and clinical trial registration platform ClinicalTrials.gov. After identifying eligible studies through screening title, abstract and read full text of each retrieved literature, we will contact the correspondence authors for additional information and grey literatures. To get more reliable results, random effect model will be conducted for meta-analysis and analysis of subgroups or subsets. Funnel plot, Egger's test and sensitivity analysis will be conducted to explore potential heterogeneity. Meta-regression will be conducted to identify the factors that may affect clinical efficacy. Evidence quality assessment and trial sequential analysis will be conducted to assess the quality of evidence and confirm the reliability of the results in this study.

ETHICS AND DISCUSSION

This study does not require formal ethical approval. The findings will be submitted to a peer-review journal.

PROSPERO REGISTRATION NUMBER

CRD42020202370.

Repetitive Transcranial Magnetic Stimulation for Alzheimer's Disease Based on Apolipoprotein E Genotyping: Protocol for a Randomized Controlled Study

To date, there is a shortage of effective treatment strategies for Alzheimer's disease (AD), and although repetitive transcranial magnetic stimulation (rTMS) can improve AD cognitive function, there are obvious individual differences, which may be related to different apolipoprotein E (APOE) genotypes. As the risk and pathogenesis of AD varies greatly among different genotypes precise treatment strategies should be implemented depending upon genotype, which has not been proved by clinical studies. Apart from that, the published clinical studies are highly heterogeneous, and therefore, systematic and well-developed randomized controlled Trails (RCT) and demonstration of precise administration protocols are required. To verify this hypothesis, this project designed a RCT study, and randomly divided apoE4 carrier AD and non-carrier AD into high-frequency rTMS (HF-rTMS) or low-frequency rTMS (LF-rTMS) treatment groups. Specifically, 80 patients with AD, namely 48 APOE4 carriers and 32 non-APOE4 carriers will be included in the study. After that, based on different stimulation frequencies of rTMS, they will be divided into the HF-rTMS group and the LF-rTMS group, when patients with AD will be randomly assigned to different treatment groups. After AD patients are involved in the study, their memory, cognition, anxiety, depression and activities of daily living will be tested before and during 2 weeks of rTMS. Furthermore, peripheral blood will be collected before and after treatment to detect changes in pathological indexes via MSD platform (Meso Scale Discovery), while 32-channel EEG data will be also collected to detect and analyze changes in gamma oscillation. In addition, these patients will be followed up for 6 months and their neuropsychological scale was also evaluated every month. At present, our study has included 18 AD patients (10 APOE4 carriers; 8 non-carriers). Our study is still in progress. The grouping has not been unblinded. But the preliminary data demonstrated that non-carriers had better MoCA score improvement than APOE4 carriers. The results indicated that the two populations of AD patients should be treated differently. Thus, this project will provide direction for precision rTMS in AD and also promotes a shift in relevant treatment philosophy. Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [ChiCTR2100041625].