Amyloid Cascade Hypothesis for the Treatment of Alzheimer's Disease: Progress and Challenges

Impact of Helicobacter pylori eradication on age-specific risk of incident dementia in patients with peptic ulcer disease: a nationwide population-based cohort study

The impact of peptic ulcer disease (PUD) and Helicobacter pylori (H. pylori) eradication therapy on dementia risk in high H. pylori prevalence populations remains uncertain. This study investigates the relationship between PUD, H. pylori eradication, and dementia risk, including Alzheimer's disease (AD), in an elderly South Korean cohort, considering age and eradication timing. Data from the Korean National Health Insurance Service (2002-2015) for individuals aged 55-79 were analyzed. Participants were divided based on PUD and H. pylori therapy status. Propensity score matching was used to evaluate dementia incidence and hazard ratios over 5 and 10 years, alongside the timing of eradication therapy. PUD is linked to higher dementia risk at 5 and 10 years, more for overall dementia than AD, with eradication status not significantly altering the risk. Age-specific analysis showed increased AD risk in the 60s and 70s age groups. Late eradication therapy is correlated with a higher dementia risk. PUD is a risk factor for dementia in elderly South Koreans, particularly with delayed H. pylori therapy. The findings emphasize timely H. pylori management and its potential role in neurodegenerative disease prevention.

Loss of Direct Vascular Contact to Astrocytes in the Hippocampus as an Initial Event in Alzheimer's Disease. Evidence from Patients, In Vivo and In Vitro Experimental Models

Alzheimer's disease (AD) is characterized by the accumulation of aggregated amyloid peptides in the brain parenchyma and within the walls of cerebral vessels. The hippocampus-a complex brain structure with a pivotal role in learning and memory-is implicated in this disease. However, there is limited data on vascular changes during AD pathological degeneration in this susceptible structure, which has distinctive vascular traits. Our aim was to evaluate vascular alterations in the hippocampus of AD patients and PDAPP-J20 mice-a model of AD-and to determine the impact of Aβ40 and Aβ42 on endothelial cell activation. We found a loss of physical astrocyte-endothelium interaction in the hippocampus of individuals with AD as compared to non-AD donors, along with reduced vascular density. Astrocyte-endothelial interactions and levels of the tight junction protein occludin were altered early in PDAPP-J20 mice, preceding any signs of morphological changes or disruption of the blood-brain barrier in these mice. At later stages, PDAPP-J20 mice exhibited decreased vascular density in the hippocampus and leakage of fluorescent tracers, indicating dysfunction of the vasculature and the BBB. In vitro studies showed that soluble Aβ40 exposure in human brain microvascular endothelial cells (HBMEC) was sufficient to induce NFκB translocation to the nucleus, which may be linked with an observed reduction in occludin levels. The inhibition of the membrane receptor for advanced glycation end products (RAGE) prevented these changes in HBMEC. Additional results suggest that Aβ42 indirectly affects the endothelium by inducing astrocytic factors. Furthermore, our results from human and mouse brain samples provide evidence for the crucial involvement of the hippocampal vasculature in Alzheimer's disease.

Essential New Complexity-Based Themes for Patient-Centered Diagnosis and Treatment of Dementia and Predementia in Older People: Multimorbidity and Multilevel Phenomenology

Dementia is a highly prevalent condition with devastating clinical and socioeconomic sequela. It is expected to triple in prevalence by 2050. No treatment is currently known to be effective. Symptomatic late-onset dementia and predementia (SLODP) affects 95% of patients with the syndrome. In contrast to trials of pharmacological prevention, no treatment is suggested to remediate or cure these symptomatic patients. SLODP but not young onset dementia is intensely associated with multimorbidity (MUM), including brain-perturbating conditions (BPCs). Recent studies showed that MUM/BPCs have a major role in the pathogenesis of SLODP. Fortunately, most MUM/BPCs are medically treatable, and thus, their treatment may modify and improve SLODP, relieving suffering and reducing its clinical and socioeconomic threats. Regrettably, the complex system features of SLODP impede the diagnosis and treatment of the potentially remediable conditions (PRCs) associated with them, mainly due to failure of pattern recognition and a flawed diagnostic workup. We suggest incorporating two SLODP-specific conceptual themes into the diagnostic workup: MUM/BPC and multilevel phenomenological themes. By doing so, we were able to improve the diagnostic accuracy of SLODP components and optimize detecting and favorably treating PRCs. These revolutionary concepts and their implications for remediability and other parameters are discussed in the paper.

Cornus officinalis Sieb. Et Zucc. attenuates Aβ25-35-induced mitochondrial damage and neuroinflammation in mice by modulating the ERK pathway

BACKGROUND

Cornus officinalis Sieb. Et Zucc. has the efficacy of tonifying the marrow and filling up the essence, breaking up the accumulation and opening up the orifices. Our research team found that CoS extracts were protective against Aβ25-35-induced memory impairment in mice. However, the pharmacodynamic components and mechanisms by which CoS improves AD have yet to be thoroughly explored and investigated.

PURPOSE

This study focused on exploring the bioactive components and pharmacodynamic mechanisms of CoS aqueous extract underlying mitochondrial damage and neuroinflammation to improve Aβ25-35-induced AD.

METHODS

AD mouse models were generated using Aβ25-35 brain injections. Different doses of CoS aqueous extract were orally administered to mice for 28 days. The cognitive function, neuronal and synaptic damage, mitochondrial damage (mitochondrial length, mitochondrial fusion fission-related protein expression), neuroglial activation, and immune inflammatory factor and ERK pathway-related protein levels of mice were assessed. The CoS aqueous extracts components were identified using UPLC-TQ/MS and screened for cellular activity. Midivi-1 (Drp1 inhibitor) or PD98059 (ERK inhibitor) was added to Aβ25-35-exposed PC12 cells to assess whether CoS and its active compounds mMorB and CorE regulate mitochondrial fission through ERK/Drp1. PC12-N9 cells were cocultured to investigate whether mMorB and CorE could regulate mitochondrial division through the ERK pathway to modulate neuroinflammation.

RESULTS

CoS improved exploration and memory in AD mice, reduced synaptic and mitochondrial damage in their hippocampus, and modulated disturbed mitochondrial dynamics. Moreover, CoS inhibited ERK pathway signaling and attenuated abnormal activation of glial cells and secondary immune inflammatory responses. Additionally, in vitro experiments revealed that CoS and its compounds 7β-O-methylmorroniside (mMorB) and Cornusdiridoid E (CorE) ameliorated mitochondrial injury caused by Aβ25-35 in PC12 cells through inhibition of the ERK/Drp1 pathway. Meanwhile, mMorB and CorE ameliorated cellular inflammation by inhibiting the Ras/ERK/CREB signaling pathway.

CONCLUSION

CoS aqueous extract ameliorates behavioral deficits and brain damage in Aβ25-35-induced AD mice by modulating the ERK pathway to attenuate mitochondrial damage and neuroinflammation, and the compounds mMorB and CorE are the therapeutically active ingredients.

Design, synthesis, and evaluation of 2,2'-bipyridyl derivatives as bifunctional agents against Alzheimer's disease

Alzheimer's disease (AD) is a complex multifactorial neurodegenerative disease. Metal ion dyshomeostasis and Aβ aggregation have been proposed to contribute to AD progression. Metal ions can bind to Aβ and promote Aβ aggregation, and ultimately lead to neuronal death. Bifunctional (metal chelation and Aβ interaction) compounds are showing promise against AD. In this work, eleven new 3,3'-diamino-2,2'-bipyridine derivatives 4a-4k were synthesized, and evaluated as bifunctional agents for AD treatment. In vitro Aβ aggregation inhibition assay confirmed that most of the synthesized compounds exhibited significant self-induced Aβ1-42 aggregation inhibition. Among them, compound 4d displayed the best inhibitory potency of self-induced Aβ1-42 aggregation with IC50 value of 9.4 µM, and it could selectively chelate with Cu2+ and exhibited 66.2% inhibition of Cu2+-induced Aβ1-42 aggregation. Meanwhile, compound 4d showed strong neuroprotective activity against Aβ1-42 and Cu2+-treated Aβ1-42 induced cell damage. Moreover, compound 4d in high dose significantly reversed Aβ-induced memory impairment in mice.

Passive Anti-Amyloid Beta Immunotherapies in Alzheimer's Disease: From Mechanisms to Therapeutic Impact

Alzheimer's disease, the most common type of dementia worldwide, lacks effective disease-modifying therapies despite significant research efforts. Passive anti-amyloid immunotherapies represent a promising avenue for Alzheimer's disease treatment by targeting the amyloid-beta peptide, a key pathological hallmark of the disease. This approach utilizes monoclonal antibodies designed to specifically bind amyloid beta, facilitating its clearance from the brain. This review offers an original and critical analysis of anti-amyloid immunotherapies by exploring several aspects. Firstly, the mechanisms of action of these therapies are reviewed, focusing on their ability to promote Aβ degradation and enhance its efflux from the central nervous system. Subsequently, the extensive history of clinical trials involving anti-amyloid antibodies is presented, from initial efforts using first-generation molecules leading to mixed results to recent clinically approved drugs. Along with undeniable progress, the authors also highlight the pitfalls of this approach to offer a balanced perspective on this topic. Finally, based on its potential and limitations, the future directions of this promising therapeutic strategy for Alzheimer's disease are emphasized.

Proteomics revealed an association between ribosome-associated proteins and amyloid beta deposition in Alzheimer's disease

Most scholars believe that amyloid-beta (Aβ) has the potential to induce apoptosis, stimulate an inflammatory cascade, promote oxidative stress and exacerbate the pathological progression of Alzheimer's disease (AD). Therefore, it is crucial to investigate the deposition of Aβ in AD. At approximately 6 months of age, APP/PS1 double transgenic mice gradually exhibit the development of plaques, as well as spatial and learning impairment. Notably, the hippocampus is specifically affected in the course of AD. Herein, 6-month-old APP/PS1 double transgenic mice were utilized, and the differentially expressed (DE) proteins in the hippocampus were identified and analyzed using 4D label-free quantitative proteomics technology and parallel reaction monitoring (PRM). Compared to wild-type mice, 29 proteins were upregulated and 25 proteins were downregulated in the AD group. Gene Ontology (GO) enrichment analysis of biological processes (BP) indicated that the DE proteins were mainly involved in 'ribosomal large subunit biogenesis'. Molecular function (MF) analysis results were primarily associated with '5.8S rRNA binding' and 'structural constituent of ribosome'. In terms of cellular components (CC), the DE proteins were mainly found in 'polysomal ribosome', 'cytosolic large ribosomal subunit', 'cytosolic ribosome', and 'large ribosomal subunit', among others. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that the results were mainly enriched in the 'Ribosome signaling pathway'. The key target proteins identified were ribosomal protein (Rp)l18, Rpl17, Rpl19, Rpl24, Rpl35, and Rpl6. The PRM verification results were consistent with the findings of the 4D label-free quantitative proteomics analysis. Overall, these findings suggest that Rpl18, Rpl17, Rpl19, Rpl24, Rpl35, and Rpl6 may have potential therapeutic value for the treatment of AD by targeting Aβ.

Effect of berberine on cognitive function and β-amyloid precursor protein in Alzheimer's disease models: a systematic review and meta-analysis

Introduction: Berberine is an isoquinoline alkaloid extracted from Berberis vulgaris, which possesses a variety of pharmacological activities. Alzheimer's disease (AD) is a complex disease with multiple pathologic factors, with cognitive decline being the main manifestation of AD. The neuroprotective effects of berberine in animal models of Alzheimer's disease (AD) have been widely reported, exhibiting protective effects against risk factors associated with AD. In this study, we summarize and evaluate the effects of berberine on cognitive function and β-amyloid precursor protein in animal models of AD. Material and methods: Eligible studies were retrieved from PubMed, MEDLINE, EMBASE, Web of Science, and Cochrane Library databases up to 1 June 2023. Risk of bias was assessed by the Systematic Review Center for Laboratory Animal Experiments (SYRCLE). Statistical analyses were performed using STATA 14.0 and Review Manger 5.4 software to calculate weighted standardized mean difference (SMD) and 95% confidence intervals (CI), Morris water maze (MWM) test and β-amyloid precursor protein as outcome measures. Heterogeneity was tested using the I2 test. Sensitivity analysis and publication bias were also assessed. Results: 19 studies involving 360 animals met the inclusion criteria, and the results of the meta-analysis showed that berberine decreased escape latency (SMD = -2.19, 95% CI: (-2.50, -1.88), p < 0.00001), increased the number of platform crossings (SMD = 4.27, 95% CI (3.38, 5.17), p < 0.00001), time in the target quadrant (SMD = 5.92, 95% CI (4.43, 7.41), p < 0.00001) and APP expression (SMD = 0.73, 95% CI: (0.25, 1.21), p = 0.003). Conclusion: Berberine can regulate APP expression and improve cognitive function in animal models of AD, and the mechanism may be related to the involvement of berberine in APP processing and influence the expression of its related factors. Systematic review registration: PROSPERO, CRD42023437445.

Biomarkers associated with the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is a progressive degenerative neurological illness with insidious onset. Due to the complexity of the pathogenesis of AD and different pathological changes, the clinical phenotypes of dementia are diverse, and these pathological changes also interact with each other. Therefore, it is of great significance to search for biomarkers that can diagnose these pathological changes to improve the ability to monitor the course of disease and treat the disease. The pathological mechanism hypothesis with high recognition of AD mainly includes the accumulation of β-amyloid (Aβ) around neurons and hyperphosphorylation of tau protein, which results in the development of neuronal fiber tangles (NFTs) and mitochondrial dysfunction. AD is an irreversible disease; currently, there is no clinical cure or delay in the disease process of drugs, and there is a lack of effective early clinical diagnosis methods. AD patients, often in the dementia stages and moderate cognitive impairment, will seek medical treatment. Biomarkers can help diagnose the presence or absence of specific diseases and their pathological processes, so early screening and diagnosis are crucial for the prevention and therapy of AD in clinical practice. β-amyloid deposition (A), tau pathology (T), and neurodegeneration/neuronal damage (N), also known as the AT (N) biomarkers system, are widely validated core humoral markers for the diagnosis of AD. In this paper, the pathogenesis of AD related to AT (N) and the current research status of cerebrospinal fluid (CSF) and blood related biomarkers were reviewed. At the same time, the limitations of humoral markers in the diagnosis of AD were also discussed, and the future development of humoral markers for AD was prospected. In addition, the contents related to mitochondrial dysfunction, prion virology and intestinal microbiome related to AD are also described, so as to understand the pathogenesis of AD in many aspects and dimensions, so as to evaluate the pathological changes related to AD more comprehensively and accurately.

Predicting cognitive dysfunction and regional hubs using Braak staging amyloid-beta biomarkers and machine learning

Mild cognitive impairment (MCI) is a transitional stage between normal aging and early Alzheimer's disease (AD). The presence of extracellular amyloid-beta (Aβ) in Braak regions suggests a connection with cognitive dysfunction in MCI/AD. Investigating the multivariate predictive relationships between regional Aβ biomarkers and cognitive function can aid in the early detection and prevention of AD. We introduced machine learning approaches to estimate cognitive dysfunction from regional Aβ biomarkers and identify the Aβ-related dominant brain regions involved with cognitive impairment. We employed Aβ biomarkers and cognitive measurements from the same individuals to train support vector regression (SVR) and artificial neural network (ANN) models and predict cognitive performance solely based on Aβ biomarkers on the test set. To identify Aβ-related dominant brain regions involved in cognitive prediction, we built the local interpretable model-agnostic explanations (LIME) model. We found elevated Aβ in MCI compared to controls and a stronger correlation between Aβ and cognition, particularly in Braak stages III-IV and V-VII (p < 0.05) biomarkers. Both SVR and ANN, especially ANN, showed strong predictive relationships between regional Aβ biomarkers and cognitive impairment (p < 0.05). LIME integrated with ANN showed that the parahippocampal gyrus, inferior temporal gyrus, and hippocampus were the most decisive Braak regions for predicting cognitive decline. Consistent with previous findings, this new approach suggests relationships between Aβ biomarkers and cognitive impairment. The proposed analytical framework can estimate cognitive impairment from Braak staging Aβ biomarkers and delineate the dominant brain regions collectively involved in AD pathophysiology.

A novel transgenic mouse line with hippocampus-dominant and inducible expression of truncated human tau

BACKGROUND

Intraneuronal accumulation of hyperphosphorylated tau is a defining hallmark of Alzheimer's disease (AD). However, mouse models imitating AD-exclusive neuronal tau pathologies are lacking.

METHODS

We generated a new tet-on transgenic mouse model expressing truncated human tau N1-368 (termed hTau368), a tau fragment increased in the brains of AD patients and aged mouse brains. Doxycycline (dox) was administered in drinking water to induce hTau368 expression. Immunostaining and Western blotting were performed to measure the tau level. RNA sequencing was performed to evaluate gene expression, and several behavioral tests were conducted to evaluate mouse cognitive functions, emotion and locomotion.

RESULTS

Dox treatment for 1-2 months at a young age induced overt and reversible human tau accumulation in the brains of hTau368 transgenic mice, predominantly in the hippocampus. Meanwhile, the transgenic mice exhibited AD-like high level of tau phosphorylation, glial activation, loss of mature neurons, impaired hippocampal neurogenesis, synaptic degeneration and cognitive deficits.

CONCLUSIONS

This study developed a well-characterized and easy-to-use tool for the investigations and drug development for AD and other tauopathies.

Acoustic stimulation during sleep improves cognition and ameliorates Alzheimer's disease pathology in APP/PS1 mice

Nonpharmacological therapies for Alzheimer's disease (AD) have become a popular research topic, and acoustic stimulation during sleep is one such promising strategy for the clinical treatment of AD. Some animal experiments have illustrated that acoustic stimulation at a specific frequency can ameliorate AD-related pathology or improve cognition in mice, but these studies did not explore the effective time window of auditory stimulation. Here, we explored the effects of acoustic stimulation during wakefulness and acoustic stimulation during sleep on cognition and AD-related pathology in APP/PS1 mice and the underlying mechanisms. In this study, forty APP/PS1 mice were equally divided into the following 4 groups and treated for 28 days: the chronic sleep deprivation (CSD) group (exposed to sleep deprivation from zeitgeber time [ZT] 0 to ZT 12 each day), the normal sleep and stress exposure (NSS) group (exposed to a stressor from ZT 0 to ZT 12 each day), the acoustic stimulation during wakefulness (ASW) group (exposed to sleep deprivation and 40 Hz acoustic stimulation from ZT 0 to ZT 12 each day) and the acoustic stimulation during sleep (ASS) group (exposed to sleep deprivation from ZT 0 to ZT 12 and 40 Hz acoustic stimulation from ZT 12 to ZT 24 each day). After the intervention, cognition was assessed by behavioural experiments. The amyloid-β burden was analysed by Western blotting, immunofluorescence and enzyme-linked immunosorbent assay. Tau pathology was assessed by Western blotting. Mitochondrial function was evaluated by transmission electron microscopy, Western blotting and fluorescence intensity measurement. We found that the NSS and ASS groups had better cognitive functions than the CSD and ASW groups. The Aβ burden and tau phosphorylation were lower in the NSS and ASS groups than in the CSD and ASW groups. Mitochondrial function was better in the NSS and ASS groups than in the CSD and ASW groups. However, the differences in these parameters between the NSS and ASS groups and between the CSD and ASW groups were not significant. Our findings suggest that acoustic stimulation at a specific frequency during sleep, but not during wakefulness, reduces the amyloid-β burden by inhibiting amyloid beta precursor protein-binding protein 2, hinders tau phosphorylation by blocking glycogen synthase kinase 3 beta, and restores mitochondrial function by elevating mitophagy and promoting mitochondrial biogenesis.

The Impact of Hydroxytyrosol on the Metallomic-Profile in an Animal Model of Alzheimer's Disease

It is undeniable that as people get older, they become progressively more susceptible to neurodegenerative illnesses such as Alzheimer's disease (AD). Memory loss is a prominent symptom of this condition and can be exacerbated by uneven levels of certain metals. This study used inductively coupled plasma mass spectrometry (ICP-MS) to examine the levels of metals in the blood plasma, frontal cortex, and hippocampus of Wistar rats with AD induced by streptozotocin (STZ). It also tested the effects of the antioxidant hydroxytyrosol (HT) on metal levels. The Barnes maze behavior test was used, and the STZ group showed less certainty and greater distance when exploring the Barnes maze than the control group. The results also indicated that the control group and the STZ + HT group exhibited enhanced learning curves during the Barnes maze training as compared to the STZ group. The ICP-MS analysis showed that the STZ group had lower levels of cobalt in their blood plasma than the control group, while the calcium levels in the frontal cortex of the STZ + HT group were higher than in the control group. The most important finding was that copper levels in the frontal cortex from STZ-treated animals were higher than in the control group, and that the STZ + HT group returned to equivalent levels to the control group. The antioxidant HT can restore copper levels to their basal physiological state. This finding may help explain HT's potential beneficial effect in AD-patients.

Nucleoside analogues: N-glycosylation methodologies, synthesis of antiviral and antitumor drugs and potential against drug-resistant bacteria and Alzheimer's disease

Nucleosides have gained significant attention since the discovery of the structure of DNA. Nucleoside analogues may be synthesized through multiple synthetic pathways, however the N-glycosylation of a nucleobase is the most common method. Amongst the different classical N-glycosylation methodologies, the Vorbrüggen glycosylation is the most popular method. This review focuses on the synthesis and therapeutic applications of several FDA approved nucleoside analogues as antiviral and anticancer agents. Moreover, this review also focuses on the potential of these compounds as new antibacterial and anti-Alzheimer's disease agents, offering an overview of the most recent research in these fields.

The Sigma Enigma: A Narrative Review of Sigma Receptors

The sigma-1 and sigma-2 receptors were first discovered in the 1960s and were thought to be a form of opioid receptors initially. Over time, more was gradually learned about these receptors, which are actually protein chaperones, and many of their unique or unusual properties can contribute to a range of important new therapeutic applications. These sigma receptors translocate in the body and regulate calcium homeostasis and mitochondrial bioenergetics and they also have neuroprotective effects. The ligands to which these sigma receptors respond are several and dissimilar, including neurosteroids, neuroleptics, and cocaine. There is controversy as to their endogenous ligands. Sigma receptors are also involved in the complex processes of cholesterol homeostasis and protein folding. While previous work on this topic has been limited, research has been conducted in multiple disease states, such as addiction, aging. Alzheimer's disease, cancer, psychiatric disorders, pain and neuropathic pain, Parkinson's disease, and others. There is currently increasing interest in sigma-1 and sigma-2 receptors as they provide potential therapeutic targets for many disease indications.

The Nerve Growth Factor Receptor (NGFR/p75NTR): A Major Player in Alzheimer's Disease

Alzheimer's disease (AD) represents the most prevalent type of dementia in elderly people, primarily characterized by brain accumulation of beta-amyloid (Aβ) peptides, derived from Amyloid Precursor Protein (APP), in the extracellular space (amyloid plaques) and intracellular deposits of the hyperphosphorylated form of the protein tau (p-tau; tangles or neurofibrillary aggregates). The Nerve growth factor receptor (NGFR/p75^NTR) represents a low-affinity receptor for all known mammalians neurotrophins (i.e., proNGF, NGF, BDNF, NT-3 e NT-4/5) and it is involved in pathways that determine both survival and death of neurons. Interestingly, also Aβ peptides can blind to NGFR/p75^NTR making it the "ideal" candidate in mediating Aβ-induced neuropathology. In addition to pathogenesis and neuropathology, several data indicated that NGFR/p75^NTR could play a key role in AD also from a genetic perspective. Other studies suggested that NGFR/p75^NTR could represent a good diagnostic tool, as well as a promising therapeutic target for AD. Here, we comprehensively summarize and review the current experimental evidence on this topic.

A coarse-grained molecular dynamics investigation on spontaneous binding of Aβ1-40 fibrils with cholesterol-mixed DPPC bilayers

Alzheimer's disease is the most common form of dementia. Its aetiology is characterized by the misfolding and aggregation of amyloid-β (Aβ) peptides into β-sheet-rich Aβ oligomers/fibrils. Although multiple experimental studies have suggested that Aβ oligomers/fibrils interact with the cell membranes and perturb their structures and dynamics, the molecular mechanism of this interaction is still not fully understood. In the present work, we have performed a total of 120 μs-long simulations to investigate the interaction between trimeric or hexameric Aβ_1-40 fibrils with either a 100% DPPC bilayer, a 70% DPPC-30% cholesterol bilayer or a 50% DPPC-50% cholesterol bilayer. Our simulation data capture the spontaneous binding of the aqueous Aβ_1-40 fibrils with the membranes and show that the central hydrophobic amino acid cluster, the lysine residue adjacent to it and the C-terminal hydrophobic residues are all involved in the process. Moreover, our data show that while the Aβ_1-40 fibril does not bind to the 100% DPPC bilayer, its binding affinity for the membrane increases with the amount of cholesterol. Overall, our data suggest that two clusters of hydrophobic residues and one lysine help Aβ_1-40 fibrils establish stable interactions with a cholesterol-rich DPPC bilayer. These residues are likely to represent potential target regions for the design of inhibitors, thus opening new avenues in structure-based drug design against Aβ oligomer/fibril-membrane interaction.