Alzheimer's Disease: Past, Present, and Future

Periventricular and deep abnormal white matter differ in associations with cognitive performance at midlife

Objective: Abnormal white matter (AWM) on magnetic resonance imaging is associated with cognitive performance in older adults. We explored cognitive associations with AWM during late-midlife. Method: Participants were community-dwelling men (n = 242; M = 61.90 years; range = 56-66). Linear-mixed effects regression models examined associations of total, periventricular, and deep AWM with cognitive performance, controlling for multiple comparisons. Models considering specific cognitive domains controlled for current general cognitive ability (GCA). We hypothesized that total AWM would be associated with worse processing speed, executive function, and current GCA; deep AWM would correlate with GCA and periventricular AWM would relate to specific cognitive abilities. We also assessed the potential influence of cognitive reserve by examining a moderation effect of early life (mean age of 20) cognition. Results: Greater total and deep AWM were associated with poorer current GCA. Periventricular AWM was associated with worse executive function, working memory, and episodic memory. When periventricular and deep AWM were modeled simultaneously, both retained their respective significant associations with cognitive performance. Cognitive reserve did not moderate associations. Conclusions: Our findings suggest that AWM contributes to poorer cognitive function in late-midlife. Examining only total AWM may obscure the potential differential impact of regional AWM. Separating total AWM into subtypes while controlling for current GCA revealed a dissociation in relationships with cognitive performance; deep AWM was associated with nonspecific cognitive ability whereas periventricular AWM was associated with specific frontal-related abilities and memory. Management of vascular or other risk factors that may increase the risk of AWM should begin during or before early late-midlife. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Baicalein inhibits heparin-induced Tau aggregation by initializing non-toxic Tau oligomer formation

Background

Amyloid aggregate deposition is the key feature of Alzheimer’s disease. The proteinaceous aggregates found in the afflicted brain are the intra-neuronal neurofibrillary tangles formed by the microtubule-associated protein Tau and extracellular deposits, senile plaques, of amyloid beta (Aβ) peptide proteolytically derived from the amyloid precursor protein. Accumulation of these aggregates has manifestations in the later stages of the disease, such as memory loss and cognitive inabilities originating from the neuronal dysfunction, neurodegeneration, and brain atrophy. Treatment of this disease at the late stages is difficult, and many clinical trials have failed. Hence, the goal is to find means capable of preventing the aggregation of these intrinsically disordered proteins by inhibiting the early stages of their pathological transformations. Polyphenols are known to be neuroprotective agents with the noticeable potential against many neurodegenerative diseases, such as Alzheimer’s, Parkinson’s, and Prion diseases.

Methods

We analyzed the capability of Baicalein to inhibit aggregation of human Tau protein by a multifactorial analysis that included several biophysical and biochemical techniques.

Results

The potency of Baicalein, a polyphenol from the Scutellaria baicalensis Georgi, against in vitro Tau aggregation and PHF dissolution has been screened and validated. ThS fluorescence assay revealed the potent inhibitory activity of Baicalein, whereas ANS revealed its mechanism of Tau inhibition viz. by oligomer capture and dissociation. In addition, Baicalein dissolved the preformed mature fibrils of Tau thereby possessing a dual target action. Tau oligomers formed by Baicalein were non-toxic to neuronal cells, highlighting its role as a potent molecule to be screened against AD.

Conclusion

In conclusion, Baicalein inhibits aggregation of hTau40 by enhancing the formation of SDS-stable oligomers and preventing fibril formation. Baicalein-induced oligomers do not affect the viability of the neuroblastoma cells. Therefore, Baicalein can be considered as a lead molecule against Tau pathology in AD.

CD33 rs3865444 as a risk factor for Parkinson's disease

BACKGROUND

Alzheimer's (AD) and Parkinson's diseases (PD) share a few elements of their clinical, pathological and genetic backgrounds. The CD33 rs3865444 has emerged as a strong genetic locus associated with AD through genome-wide association study (GWAS). However, little is known for its role in PD.

OBJECTIVE

To assess the role of CD33 rs3865444 on PD risk.

METHODS

We genotyped 358 patients with PD and 358 healthy controls for theCD33 rs3865444. Odds ratios (ORs) with the respective 95% confidence intervals (CIs)], were calculated with the SNPStats software, assuming five genetic models (co-dominant, dominant, recessive, over-dominant and log-additive), with the G allele as the reference allele.

RESULTS

The CD33 rs3865444 was associated with decreased PD risk in the dominant [GG vs GT + TT; OR (95% CI) = 0.61 (0.45-0.82), p = 0.001], the over-dominant [GG + TT vs GT; OR (95% CI) = 0.65 (0.48-0.89), p = 0.0061], log-additive [OR (95% CI) = 0.67 (0.52-0.86), p = 0.0014], and co-dominant [with overall p = 0.0043, and OR (95% CI) = 0.62 (0.45-0.84) for the TG genotype compared to the GG], modes of inheritance.

CONCLUSIONS

The CD33 rs3865444 is associated with decreased PD risk, and larger studies investigating the role of CD33 rs3865444 on PD are needed.

Partner-Specific Communication Deficits in Individuals With Alzheimer's Disease

Purpose Speakers adjust referential expressions to the listeners' knowledge while communicating, a phenomenon called "audience design." While individuals with Alzheimer's disease (AD) show difficulties in discourse production, it is unclear whether they exhibit preserved partner-specific audience design. The current study examined if individuals with AD demonstrate partner-specific audience design skills. Method Ten adults with mild-to-moderate AD and 12 healthy older adults performed a referential communication task with two experimenters (E1 and E2). At first, E1 and participants completed an image-sorting task, allowing them to establish shared labels. Then, during testing, both experimenters were present in the room, and participants described images to either E1 or E2 (randomly alternating). Analyses focused on the number of words participants used to describe each image and whether they reused shared labels. Results During testing, participants in both groups produced shorter descriptions when describing familiar images versus new images, demonstrating their ability to learn novel knowledge. When they described familiar images, healthy older adults modified their expressions depending on the current partner's knowledge, producing shorter expressions and more established labels for the knowledgeable partner (E1) versus the naïve partner (E2), but individuals with AD were less likely to do so. Conclusions The current study revealed that both individuals with AD and the control participants were able to acquire novel knowledge, but individuals with AD tended not to flexibly adjust expressions depending on the partner's knowledge state. Conversational inefficiency and difficulties observed in AD may, in part, stem from disrupted audience design skills.

Potential of Naturally Derived Alkaloids as Multi-Targeted Therapeutic Agents for Neurodegenerative Diseases

Alkaloids are a class of secondary metabolites that can be derived from plants, fungi and marine sponges. They are widely known as a continuous source of medicine for the management of chronic disease including cancer, diabetes and neurodegenerative diseases. For example, galanthamine and huperzine A are alkaloid derivatives currently being used for the symptomatic management of neurodegenerative disease. The etiology of neurodegenerative diseases is polygenic and multifactorial including but not limited to inflammation, oxidative stress and protein aggregation. Therefore, natural-product-based alkaloids with polypharmacology modulation properties are potentially useful for further drug development or, to a lesser extent, as nutraceuticals to manage neurodegeneration. This review aims to discuss and summarise recent developments in relation to naturally derived alkaloids for neurodegenerative diseases.

Calcium Signaling and Mitochondrial Function in Presenilin 2 Knock-Out Mice: Looking for Any Loss-of-Function Phenotype Related to Alzheimer's Disease

Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder in which learning, memory and cognitive functions decline progressively. Familial forms of AD (FAD) are caused by mutations in amyloid precursor protein (APP), presenilin 1 (PSEN1) and presenilin 2 (PSEN2) genes. Presenilin 1 (PS1) and its homologue, presenilin 2 (PS2), represent, alternatively, the catalytic core of the γ-secretase complex that, by cleaving APP, produces neurotoxic amyloid beta (Aβ) peptides responsible for one of the histopathological hallmarks in AD brains, the amyloid plaques. Recently, PSEN1 FAD mutations have been associated with a loss-of-function phenotype. To investigate whether this finding can also be extended to PSEN2 FAD mutations, we studied two processes known to be modulated by PS2 and altered by FAD mutations: Ca2+ signaling and mitochondrial function. By exploiting neurons derived from a PSEN2 knock-out (PS2-/-) mouse model, we found that, upon IP3-generating stimulation, cytosolic Ca2+ handling is not altered, compared to wild-type cells, while mitochondrial Ca2+ uptake is strongly compromised. Accordingly, PS2-/- neurons show a marked reduction in endoplasmic reticulum-mitochondria apposition and a slight alteration in mitochondrial respiration, whereas mitochondrial membrane potential, and organelle morphology and number appear unchanged. Thus, although some alterations in mitochondrial function appear to be shared between PS2-/- and FAD-PS2-expressing neurons, the mechanisms leading to these defects are quite distinct between the two models. Taken together, our data appear to be difficult to reconcile with the proposal that FAD-PS2 mutants are loss-of-function, whereas the concept that PS2 plays a key role in sustaining mitochondrial function is here confirmed.

Syringin Prevents Aβ25-35-Induced Neurotoxicity in SK-N-SH and SK-N-BE Cells by Modulating miR-124-3p/BID Pathway

Alzheimer's disease (AD) is a neurodegenerative disorder disease, disturbing people's normal life. Syringin was mentioned to antagonize Amyloid-β (Aβ)-induced neurotoxicity. However, the action mechanism is still not fully elucidated. This study aimed to explore a molecular mechanism of syringin in defending Aβ-induced neurotoxicity. SK-N-SH and SK-N-BE cells were treated with amyloid β-protein fragment 25-35 (Aβ_25-35) to induce cell neurotoxicity. The injury effects were distinguished by assessing cell viability and cell apoptosis using cell counting kit-8 (CCK-8) assay and flow cytometry assay, respectively. The expression of Cleaved-caspase3 (Cleaved-casp3), B cell lymphoma/leukemia-2 (Bcl-2), Bcl-2 associated X protein (Bax) and BH3 interacting domain death agonist (BID) at the protein level was determined by western blot. The expression of miR-124-3p and BID was detected using quantitative real-time polymerase chain reaction (qRT-PCR). The interaction between miR-124-3p and BID was predicted by the online database starBase and confirmed by dual-luciferase reporter assay plus RNA pull-down assay. Aβ_25-35 treatment inhibited cell viability and induced cell apoptosis, while the addition of syringin recovered cell viability and suppressed cell apoptosis. MiR-124-3p was significantly downregulated in Aβ_25-35-treated SK-N-SH and SK-N-BE cells, and BID was upregulated. Nevertheless, the addition of syringin reversed their expression. BID was a target of miR-124-3p, and its downregulation partly prevented Aβ_25-35-induced injuries. Syringin protected against Aβ_25-35-induced neurotoxicity by enhancing miR-124-3p expression and weakening BID expression, and syringin strengthened the expression of miR-124-3p to diminish BID level. Syringin ameliorated Aβ_25-35-induced neurotoxicity in SK-N-SH and SK-N-BE cells by regulating miR-124-3p/BID pathway, which could be a novel theoretical basis for syringin to treat AD.

Potential Impacts of Extreme Heat and Bushfires on Dementia

Australia often experiences natural disasters and extreme weather conditions such as: flooding, sandstorms, heatwaves, and bushfires (also known as wildfires or forest fires). The proportion of the Australian population aged 65 years and over is increasing, alongside the severity and frequency of extreme weather conditions and natural disasters. Extreme heat can affect the entire population but particularly at the extremes of life, and patients with morbidities. Frequently identified as a vulnerable demographic in natural disasters, there is limited research on older adults and their capacity to deal with extreme heat and bushfires. There is a considerable amount of literature that suggests a significant association between mental disorders such as dementia, and increased vulnerability to extreme heat. The prevalence rate for dementia is estimated at 30%by age 85 years, but there has been limited research on the effects extreme heat and bushfires have on individuals living with dementia. This review explores the differential diagnosis of dementia, the Australian climate, and the potential impact Australia's extreme heat and bushfires have on individuals from vulnerable communities including low socioeconomic status Indigenous and Non-Indigenous populations living with dementia, in both metropolitan and rural communities. Furthermore, we investigate possible prevention strategies and provide suggestions for future research on the topic of Australian bushfires and heatwaves and their impact on people living with dementia. This paper includes recommendations to ensure rural communities have access to appropriate support services, medical treatment, awareness, and information surrounding dementia.

Neuroprotective Effects of 2-Substituted 1, 3-Selenazole Amide Derivatives on Amyloid-Beta-Induced Toxicity in a Transgenic Caenorhabditis Elegans Model of Alzheimer's Disease

Alzheimer's disease is an age-related neurodegenerative disease, associated with the presence of extracellular amyloid-β (Aβ) plaques and neurofibrillary tangles. Although the pathogenesis of AD remains unclear, the characteristic feature of AD was reported to be the buildup of Aβ plaques. In this study, we extensively investigated the neuroprotective effects of 2-substituted 1,3-selenazole amide derivatives (CHF11) on Aβ1-42 transgenic Caenorhabditis elegans CL4176. Results showed that worms fed with CHF11 exhibited remarkably reduced paralysis, decreased levels of toxic Aβ oligomers and Aβ plaque deposition, as well as less ROS production in comparison with the untreated worms. The effective concentrations of CHF11 were arranged in the descending order of 100 µM > 10 µM > 1 µM. Real-time PCR analysis showed that there was no significant difference in Aβ expression between CHF11-administered group and the blank control group, suggesting that CHF11-induced reduction in toxic protein deposition may be regulated at the post-transcriptional level. In the meantime, the gene expressions of hsf-1 and its downstream target hsp-12.6 were significantly increased, indicating that CHF11 against Aβ toxicity may involve in HSF-1 signaling pathway in worms. In conclusion, CHF11 exhibits a significant protective effect against β-amyloid-induced toxicity in CL4176 by reducing β-amyloid aggregation and ROS production, which may involve in HSF-1 and downstream target HSP-12.6 pathway.

Platycodin D Inhibits β-Amyloid-Induced Inflammation and Oxidative Stress in BV-2 Cells Via Suppressing TLR4/NF-κB Signaling Pathway and Activating Nrf2/HO-1 Signaling Pathway

Alzheimer's disease (AD) is a common neurodegenerative disease associated with deposition of β-amyloid peptide (Aβ). Platycodin D (PLD), a triterpenesaponin, may possess neuro-protective effect. In the current study, we aimed to explore the effects of PLD on Aβ-induced inflammation and oxidative stress in microglial BV-2 cells. Our study showed that PLD treatment improved cell viability in Aβ-induced BV-2 cells. PLD attenuated Aβ-induced inflammation with deceased production of TNF-α, IL-1β and IL-6 in Aβ-induced BV-2 cells. PLD also mitigated the oxidative stress in Aβ-induced BV-2 cells, as evidenced by deceased production of ROS and MDA, and increased SOD activity. Furthermore, the increased expression levels of TLR4 and p-p65 and decreased IκBα expression in the Aβ-stimulated BV-2 cells were attenuated by PLD treatment. Overexpression of TLR4 reversed the anti-inflammatory effect of PLD in Aβ-stimulated BV-2 cells. In addition, PLD treatment enhanced the Aβ-stimulated increase in the expression levels of Nrf2, HO-1, and NQO1 in BV-2 cells. Knockdown of Nrf2 abrogated the anti-oxidative effect of PLD in Aβ-stimulated BV-2 cells. In conclusion, these findings indicated that PLD protected BV-2 cells from Aβ-induced oxidative stress and inflammation via regulating the TLR4/NF-κB and Nrf2/HO-1 signaling pathways. Thus, PLD may be a potential candidate for the treatment of AD.

Cholinergic neurodegeneration in Alzheimer disease mouse models

Cholinergic signaling is critical for cognitive function. The basal forebrain is the major cholinergic output of the central nervous system. Degeneration of basal forebrain cholinergic neurons is a hallmark of Alzheimer's disease (AD). Mouse models are invaluable tools in disease research and have been used to study AD for over 25 years. However, animal models of AD vary greatly with respect to the degree of cholinergic degeneration observed. The following review will outline the most influential animal models of AD with an emphasis on the basal forebrain cholinergic system.

Miro (Mitochondrial Rho GTPase), a key player of mitochondrial axonal transport and mitochondrial dynamics in neurodegenerative diseases

Miro (mitochondrial Rho GTPases) a mitochondrial outer membrane protein, plays a vital role in the microtubule-based mitochondrial axonal transport, mitochondrial dynamics (fusion and fission) and Mito-Ca2+ homeostasis. It forms a major protein complex with Milton (an adaptor protein), kinesin and dynein (motor proteins), and facilitates bidirectional mitochondrial axonal transport such as anterograde and retrograde transport. By forming this protein complex, Miro facilitates the mitochondrial axonal transport and fulfills the neuronal energy demand, maintain the mitochondrial homeostasis and neuronal survival. It has been demonstrated that altered mitochondrial biogenesis, improper mitochondrial axonal transport, and mitochondrial dynamics are the early pathologies associated with most of the neurodegenerative diseases (NDs). Being the sole mitochondrial outer membrane protein associated with mitochondrial axonal transport-related processes, Miro proteins can be one of the key players in various NDs such as Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD). Thus, in the current review, we have discussed the evolutionarily conserved Miro proteins and its role in the pathogenesis of the various NDs. From this, we indicated that Miro proteins may act as a potential target for a novel therapeutic intervention for the treatment of various NDs.

Ontology-based Precision Vaccinology for Deep Mechanism Understanding and Precision Vaccine Development

Vaccination is one of the most important innovations in human history. It has also become a hot research area in a new application - the development of new vaccines against non-infectious diseases such as cancers. However, effective and safe vaccines still do not exist for many diseases, and where vaccines exist, their protective immune mechanisms are often unclear. Although licensed vaccines are generally safe, various adverse events, and sometimes severe adverse events, still exist for a small population. Precision medicine tailors medical intervention to the personal characteristics of individual patients or sub-populations of individuals with similar immunity-related characteristics. Precision vaccinology is a new strategy that applies precision medicine to the development, administration, and post-administration analysis of vaccines. Several conditions contribute to make this the right time to embark on the development of precision vaccinology. First, the increased level of research in vaccinology has generated voluminous "big data" repositories of vaccinology data. Secondly, new technologies such as multi-omics and immunoinformatics bring new methods for investigating vaccines and immunology. Finally, the advent of AI and machine learning software now makes possible the marriage of Big Data to the development of new vaccines in ways not possible before. However, something is missing in this marriage, and that is a common language that facilitates the correlation, analysis, and reporting nomenclature for the field of vaccinology. Solving this bioinformatics problem is the domain of applied biomedical ontology. Ontology in the informatics field is human- and machine-interpretable representation of entities and the relations among entities in a specific domain. The Vaccine Ontology (VO) and Ontology of Vaccine Adverse Events (OVAE) have been developed to support the standard representation of vaccines, vaccine components, vaccinations, host responses, and vaccine adverse events. Many other biomedical ontologies have also been developed and can be applied in vaccine research. Here, we review the current status of precision vaccinology and how ontological development will enhance this field, and propose an ontology-based precision vaccinology strategy to support precision vaccine research and development.

Emotion recognition of morphed facial expressions in presymptomatic and symptomatic frontotemporal dementia, and Alzheimer's dementia

BACKGROUND

The emotion recognition task (ERT) was developed to overcome shortcomings of static emotion recognition paradigms, by identifying more subtle deficits in emotion recognition across different intensity levels. In this study, we used the ERT to investigate emotion recognition deficits across the frontotemporal (FTD) and Alzheimer's Dementia (AD) spectrum.

METHODS

With the ERT, we assessed the recognition of facial emotional expressions (anger-disgust-fear-happiness-sadness-surprise) across four intensities (40-60-80-100%) in patients with behavioural variant FTD (bvFTD; n = 32), and AD (n = 32), presymptomatic FTD mutation carriers (n = 47) and controls (n = 49). We examined group differences using multilevel linear regression with age, sex and education level as covariates, and performed post hoc analyses on presymptomatic (MAPT, GRN and C9orf72) mutation carriers. Classification abilities were investigated by means of logistic regression.

RESULTS

Lowest ERT total scores were found in patients with bvFTD and AD, whereas equal highest performance was found in presymptomatic mutation carriers and controls. For all emotions, significantly lower subscores were found in patients with bvFTD than in presymptomatic mutation carriers and in controls (highest p value = 0.025). Patients with bvFTD performed lower than patients with AD on anger (p = 0.005) and a trend towards significance was found for a lower performance on happiness (p = 0.065). Task performance increased with higher emotional intensity, and classification was better at the lowest than at the highest intensity. C9orf72 mutation carriers performed worse on recognizing anger at the lowest intensity than GRN mutation carriers (p = 0.047) and controls (p = 0.038). The ERT differentiated between patients with bvFTD and controls, and between patients with AD and controls (both p < 0.001).

DISCUSSION

Our results demonstrate emotion recognition deficits in both bvFTD and AD, and suggest the presence of subtle emotion recognition changes in presymptomatic C9orf72-FTD. This highlights the importance of incorporating emotion recognition paradigms into standard neuropsychological assessment for early differential diagnosis, and as clinical endpoints in upcoming therapeutic trials.

Particulate Matter Exposure Exacerbates Amyloid-β Plaque Deposition and Gliosis in APP/PS1 Mice

BACKGROUND

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) plaques, neuroinflammation, and neuronal death. There are several well-established genetic and environmental factors hypothesized to contribute to AD progression including air pollution. However, the molecular mechanisms by which air pollution exacerbates AD are unclear.

OBJECTIVE

This study explored the effects of particulate matter exposure on AD-related brain changes using the APP/PS1 transgenic model of disease.

METHODS

Male C57BL/6;C3H wild type and APP/PS1 mice were exposed to either filtered air (FA) or particulate matter sized under 2.5μm (PM2.5) for 6 h/day, 5 days/week for 3 months and brains were collected. Immunohistochemistry for Aβ, GFAP, Iba1, and CD68 and western blot analysis for PS1, BACE, APP, GFAP, and Iba1 were performed. Aβ ELISAs and cytokine arrays were performed on frozen hippocampal and cortical lysates, respectively.

RESULTS

The Aβ plaque load was significantly increased in the hippocampus of PM2.5-exposed APP/PS1 mice compared to their respective FA controls. Additionally, in the PM2.5-exposed APP/PS1 group, increased astrocytosis and microgliosis were observed as indicated by elevated GFAP, Iba1, and CD68 immunoreactivities. PM2.5 exposure also led to an elevation in the levels of PS1 and BACE in APP/PS1 mice. The cytokines TNF-α, IL-6, IL-1β, IFN-γ, and MIP-3α were also elevated in the cortices of PM2.5-exposed APP/PS1 mice compared to FA controls.

CONCLUSION

Our data suggest that chronic particulate matter exposure exacerbates AD by increasing Aβ plaque load, gliosis, and the brain inflammatory status.

Imaging Transcriptomics in Neurodegenerative Diseases

Imaging transcriptomics investigates the relationship between neuroanatomical/neuroimaging features and gene expression. The spatial and temporal distribution of the expressed genes and their pattern of spreading over time can contribute to elucidating cellular and molecular processes involved in neurodegeneration. In this study, we review recent findings regarding the correlation between neuroimaging and expression data in neurodegenerative diseases with a focus on Alzheimer's disease and Parkinson's disease. An association between gene expression data and different neuroimaging neurodegeneration features, such as R2 relaxation time and volumetric cortical atrophy, was established. Several positive and negative expression correlations were identified, and they confirmed the focal nature of neurodegeneration. Positively correlated genes were associated with cell motility, immune system activity, neuroinflammation, and microglia. Data from connectome studies support the hypothesis of selective network vulnerability and a temporal spreading pattern in neurodegenerative pathologies. Genes related to cellular mobility and transport are overexpressed in the neuroimaging-defined delineated areas of degeneration. In addition, expression enrichment of genes involved in immunological processes in vulnerable regions-such as the Toll-like receptor, a receptor involved in innate immunity-plays a major role in neuroinflammation in neurodegenerative diseases. However, substantial limitations must be overcome in future studies: the lack of high-quality resolution expression data, the lack of standardized study protocols, and insufficient sensitive early stage neuroimaging markers of degeneration. Identifying neuroimaging and expression prodromal biomarkers and investigating their causal relation in the preclinical disease stage may enable early targeted therapy before the onset of irreversible brain changes.

Alzheimer's Disease: An Overview of Major Hypotheses and Therapeutic Options in Nanotechnology

Alzheimer's disease (AD), a progressively fatal neurodegenerative disorder, is the most prominent form of dementia found today. Patients suffering from Alzheimer's begin to show the signs and symptoms, like decline in memory and cognition, long after the cellular damage has been initiated in their brain. There are several hypothesis for the neurodegeneration process; however, the lack of availability of in vivo models makes the recapitulation of AD in humans impossible. Moreover, the drugs currently available in the market serve to alleviate the symptoms and there is no cure for the disease. There have been two major hurdles in the process of finding the same-the inefficiency in cracking the complexity of the disease pathogenesis and the inefficiency in delivery of drugs targeted for AD. This review discusses the different drugs that have been designed over the recent years and the drug delivery options in the field of nanotechnology that have been found most feasible in surpassing the blood-brain barrier (BBB) and reaching the brain.

Alexithymia in Alzheimer's Disease

Alexithymia is widely recognized as the inability to identify and express emotions. It is a construct which consists of four cognitive traits such as difficulty in identifying feelings, describing feelings to others, externally oriented thinking, and limited imaginative capacity. Several studies have linked alexithymia to cognitive functioning, observing greater alexithymia scores associated with poorer cognitive abilities. Despite Alzheimer's disease (AD) being a neurodegenerative pathology characterized by cognitive troubles from the early stages, associated to behavioral and emotional disturbances, very few investigations have studied the alexithymia in AD. These studies have shown that alexithymia scores-assessed with Toronto Alexithymia Scale (TAS)-were greater in AD patients than healthy participants. The objective of the study was to investigate if the alexithymia was present in patients with mild AD. We hypothesized that the AD group would show more alexithymia features than the control group. We evaluated 54 subjects, including 27 patients diagnosed with mild AD and 27 normal healthy controls, using the Shalling Sifneos Psychosomatic Scale (SSPS-R) and a neuropsychological test battery. Using non-parametric statistical analyses-Wilcoxon and Mann-Whitney U tests-we observed that the SSPS-R scores were similar in the AD and control groups. All participants showed SSPS-R scores below to 10 points, which means no-alexithymia. We did not find significant correlations between SSPS-R scores and cognitive variables in both groups (p > 0.22), but we observed a negative association between name abilities and alexithymia, but it does not reach to significance (p = 0.07). However, a significant correlation between SSPS-R score and mood state, assessed using Zerssen Rating Scale, was found in both groups (p = 0.01). Because we did not find a significant difference in the alexithymia assessment between both subject groups, pot hoc analyses were computed for each item of the SSPS-R. We made comparisons of alexithymic responses percentages in each SSPS-R item between AD and control groups, using Fisher's test. We observed that AD patients produced more alexithymic responses in some items of SSPS-R test than the control group, particularly about difficulties to find the words to describe feelings, as well as difficulties of imagination capacity and externally oriented thinking. The present results do not confirm our hypothesis and they do not support the results of previous studies revealing great alexithymia in AD.

Pursuing the Complexity of Alzheimer's Disease: Discovery of Fluoren-9-Amines as Selective Butyrylcholinesterase Inhibitors and N-Methyl-d-Aspartate Receptor Antagonists

Alzheimer’s disease (AD) is a complex disorder with unknown etiology. Currently, only symptomatic therapy of AD is available, comprising cholinesterase inhibitors and N-methyl-d-aspartate (NMDA) receptor antagonists. Drugs targeting only one pathological condition have generated only limited efficacy. Thus, combining two or more therapeutic interventions into one molecule is believed to provide higher benefit for the treatment of AD. In the presented study, we designed, synthesized, and biologically evaluated 15 novel fluoren-9-amine derivatives. The in silico prediction suggested both the oral availability and permeation through the blood–brain barrier (BBB). An initial assessment of the biological profile included determination of the cholinesterase inhibition and NMDA receptor antagonism at the GluN1/GluN2A and GluN1/GluN2B subunits, along with a low cytotoxicity profile in the CHO-K1 cell line. Interestingly, compounds revealed a selective butyrylcholinesterase (BChE) inhibition pattern with antagonistic activity on the NMDARs. Their interaction with butyrylcholinesterase was elucidated by studying enzyme kinetics for compound 3c in tandem with the in silico docking simulation. The docking study showed the interaction of the tricyclic core of new derivatives with Trp82 within the anionic site of the enzyme in a similar way as the template drug tacrine. From the kinetic analysis, it is apparent that 3c is a competitive inhibitor of BChE.

Synthesis and pharmacological effects of novel benzenesulfonamides carrying benzamide moiety as carbonic anhydrase and acetylcholinesterase inhibitors

N -(1-(4-Methoxyphenyl)-3-oxo-3-((4-( N -(substituted)sulfamoyl)phenyl)amino)prop-1-en-1-yl)benzamides 3a – g were designed since sulfonamide and benzamide pharmacophores draw great attention in novel drug design due to their wide range of bioactivities including acetylcholinesterase (AChE) and human carbonic anhydrase I and II (hCA I and hCA II) inhibitory potencies. Structure elucidation of the compounds was carried out by 1H NMR, 13C NMR, and HRMS spectra. In vitro enzyme assays showed that the compounds had significant inhibitory potential against hCA I, hCA II, and AChE enzymes at nanomolar levels. Ki values were in the range of 4.07 ± 0.38 – 29.70 ± 3.18 nM for hCA I and 10.68 ± 0.98 – 37.16 ± 7.55 nM for hCA II while Ki values for AChE were in the range of 8.91 ± 1.65 – 34.02 ± 5.90 nM. The most potent inhibitors 3g (Ki = 4.07 ± 0.38 nM, hCA I), 3c (Ki = 10.68 ± 0.98 nM, hCA II ) , and 3f (Ki = 8.91 ± 1.65 nM, AChE) can be considered as lead compounds of this study with their promising bioactivity results. Secondary sulfonamides showed promising enzyme inhibitory effects on AChE while primary sulfonamide derivative was generally effective on hCA I and hCA II isoenzymes.

Exposure to Traffic-Generated Pollutants Exacerbates the Expression of Factors Associated with the Pathophysiology of Alzheimer’s Disease in Aged C57BL/6 Wild-Type Mice

Background: Multiple studies report a strong correlation between traffic-generated air pollution-exposure and detrimental outcomes in the central nervous system (CNS), including Alzheimer’s disease (AD). Incidence of AD is rapidly increasing and, worldwide, many live in regions where pollutants exceed regulatory standards. Thus, it is imperative to identify environmental pollutants that contribute to AD, and the mechanisms involved. Objective: We investigated the effects of mixed gasoline and diesel engine emissions (MVE) on the expression of factors involved in progression of AD in the hippocampus and cerebrum in a young versus aged mouse model. Methods: Young (2 months old) and aged (18 months old) male C57BL/6 mice were exposed to either MVE (300μg/m3 PM) or filtered air (FA) for 6 h/d, 7 d/wk, for 50 d. Immunofluorescence and RT-qPCR were used to quantify oxidative stress (8-OHdG) and expression of amyloid-β protein precursor (AβPP), β secretase (BACE1), amyloid-β (Aβ), aryl hydrocarbon receptor (AhR), cytochrome P450 (CYP) 1B1, angiotensin-converting enzyme (ACE1), and angiotensin II type 1 (AT1) receptor in the cerebrum and hippocampus, in addition to cerebral microvascular tight junction (TJ) protein expression. Results: We observed age-related increases in oxidative stress, AhR, CYP1B1, Aβ, BACE1, and AT1 receptor in the CA1 region of the hippocampus, and elevation of cerebral AβPP, AhR, and CYP1B1 mRNA, associated with decreased cerebral microvascular TJ protein claudin-5. MVE-exposure resulted in further promotion of oxidative stress, and significant increases in AhR, CYP1B1, BACE1, ACE1, and Aβ, compared to the young and aged FA-exposed mice. Conclusion: Such findings suggest that MVE-exposure exacerbates the expression of factors in the CNS associated with AD pathogenesis in aged populations.

Cognitive and Behavioral Profiles of Left and Right Semantic Dementia: Differential Diagnosis with Behavioral Variant Frontotemporal Dementia and Alzheimer's Disease

BACKGROUND

Semantic dementia (SD) is a subtype of frontotemporal dementia (FTD) characterized by semantic memory loss and preserved abilities of other cognitive functions. The clinical manifestations of SD require a differential diagnosis with Alzheimer's disease (AD), especially those with early onset, and behavioral variant FTD (bvFTD).

OBJECTIVE

The present study aimed to compare cognitive performances and neuropsychiatric symptoms in a population of AD, bvFTD, and left and right SD defined with the support of molecular imaging (amyloid and 2-[18F] fluoro-2-deoxy-D-glucose positron emission tomography) and assessed the accuracy of different neuropsychological markers in distinguishing these neurodegenerative diseases.

METHODS

Eighty-seven participants (32 AD, 20 bvFTD, and 35 SD (17 Left-SD and 18 Right-SD) completed a comprehensive neuropsychological battery that included memory, language, attention and executive functions, visuospatial function, visuoconstructional skills, and tasks designed specifically to evaluate prosopagnosia and facial emotions recognition. The Neuropsychiatric Inventory was administered to assess neuropsychiatric symptoms.

RESULTS

An episodic memory test that included semantic cues, a visuospatial test (both impaired in AD), a naming test and a prosopagnosia task (both impaired in SD) were the four most valuable cognitive metrics for the differential diagnosis between groups. Several behavioral abnormalities were differentially present, of which aggression, self-care (both more frequent in bvFTD), and eating habits, specifically overeating and altered dietary preference (more frequent in SD), were the most valuable in group discrimination.

CONCLUSION

Our study highlights the value of a comprehensive neuropsychological and neuropsychiatric evaluation for the differential diagnosis between FTD syndromes and AD.

Neuropsychological presentation of colpocephaly and porencephaly with symptom onset in adulthood

Colpocephaly is a form of congenital ventriculomegaly while porencephaly describes any full-thickness defect within the brain which usually presents as a cystic structure. Postulated aetologies include intrauterine/perinatal injuries, genetic disorders, and morphogenesis error. Colopocephaly and porencephaly is typically diagnosed in infancy while diagnosis in adulthood is exceptionally rare. We report a case of co-existence of colpocephaly with porencephaly diagnosed incidentally in a 54-year-old male presenting with subtle cognitive and neurologic abnormalities. Neuropsychological assessment revealed weaknesses in executive functions, processing speed, and language.To our knowledge, this is the only reported case of dual incidental findings of porencephaly and colpocephaly in an adult.

Biosensing based on field-effect transistors (FET): Recent progress and challenges

The use of field-Effect-Transistor (FET) type biosensing arrangements has been highlighted by researchers in the field of early biomarker detection and drug screening. Their non-metalized gate dielectrics that are exposed to an electrolyte solution cover the semiconductor material and actively transduce the biological changes on the surface. The efficiency of these novel devices in detecting different biomolecular analytes in a real-time, highly precise, specific, and label-free manner has been validated by numerous research studies. Considerable progress has been attained in designing FET devices, especially for biomedical diagnosis and cell-based assays in the past few decades. The exceptional electronic properties, compactness, and scalability of these novel tools are very desirable for designing rapid, label-free, and mass detection of biomolecules. With the incorporation of nanotechnology, the performance of biosensors based on FET boosts significantly, particularly, employment of nanomaterials such as graphene, metal nanoparticles, single and multi-walled carbon nanotubes, nanorods, and nanowires. Besides, their commercial availability, and high-quality production on a large-scale, turn them to be one of the most preferred sensing and screening platforms. This review presents the basic structural setup and working principle of different types of FET devices. We also focused on the latest progression regarding the use of FET biosensors for the recognition of viruses such as, recently emerged COVID-19, Influenza, Hepatitis B Virus, protein biomarkers, nucleic acids, bacteria, cells, and various ions. Additionally, an outline of the development of FET sensors for investigations related to drug development and the cellular investigation is also presented. Some technical strategies for enhancing the sensitivity and selectivity of detection in these devices are addressed as well. However, there are still certain challenges which are remained unaddressed concerning the performance and clinical use of transistor-based point-of-care (POC) instruments; accordingly, expectations about their future improvement for biosensing and cellular studies are argued at the end of this review.

An Overview of Astrocyte Responses in Genetically Induced Alzheimer's Disease Mouse Models

Alzheimer's disease (AD) is the most common form of dementia. Despite many years of intense research, there is currently still no effective treatment. Multiple cell types contribute to disease pathogenesis, with an increasing body of data pointing to the active participation of astrocytes. Astrocytes play a pivotal role in the physiology and metabolic functions of neurons and other cells in the central nervous system. Because of their interactions with other cell types, astrocyte functions must be understood in their biologic context, thus many studies have used mouse models, of which there are over 190 available for AD research. However, none appear able to fully recapitulate the many functional changes in astrocytes reported in human AD brains. Our review summarizes the observations of astrocyte biology noted in mouse models of familial and sporadic AD. The limitations of AD mouse models will be discussed and current attempts to overcome these disadvantages will be described. With increasing understanding of the non-neuronal contributions to disease, the development of new methods and models will provide further insights and address important questions regarding the roles of astrocytes and other non-neuronal cells in AD pathophysiology. The next decade will prove to be full of exciting opportunities to address this devastating disease.

Polymorphism rs11867353 of Tyrosine Kinase Non-Receptor 1 (TNK1) Gene Is a Novel Genetic Marker for Alzheimer's Disease

Several single-nucleotide polymorphisms (SNPs) and rare variants of non-receptor tyrosine kinase 1 gene (TNK1) have been associated with Alzheimer's disease (AD). To date, none of the associations have proven to be of practical importance in predicting the risk of AD either because the evidence is not conclusive, or the risk alleles occur at very low frequency. In the present study, we are evaluating the associations between rs11867353 polymorphism of TNK1 gene and both AD and mild cognitive impairment (MCI) in a group of 1656 persons. While the association with AD was found to be highly statistically significant (p < 0.0001 for the risk genotype CC), no statistically significant association with MCI could be established. Possible explanation of the apparent discrepancy could be rapid progression of MCI to AD in persons with the CC genotype. Additional findings of the study are statistically significant associations of rs11867353 polymorphism with body mass index, body weight, and body height. The patients with AD and CC genotype had significantly lower values of body mass index and body weight compared with patients with other genotypes. The main outcome of the study is the finding of a previously never described association between the rs11867353 polymorphism of the TNK1 gene and AD. The rs11867353 polymorphism has a potential to become a significant genetic marker when predicting the risk of AD.

Electroacupuncture at GV24 and bilateral GB13 improves cognitive ability via influences the levels of Aβ, p-tau (s396) and p-tau (s404) in the hippocampus of Alzheimer's disease model rats

Acupuncture is widely used to treat various neurodegenerative diseases and can effectively improve cognitive and memory states in Alzheimer's disease. However, its mechanism is unclear. We speculated that the effect of acupuncture on cognitive function may be associated with reductions in the levels of Aβ and phosphorylated tau in the brain. In this experiment, 60 male Sprague-Dawley rats were randomly divided into control, model, electroacupuncture and nonacupoint groups. We perform electroacupuncture at Shenting (GV24) and bilateral Benshen (GB13) acupoints once a day for 4 weeks in electroacupuncture group (with 1 day of rest after every 6 days of treatment). The electroacupuncture group showed a better performance in cognitive-related behavior tests and significantly lowers the levels of Aβ, p-tau (s396) and p-tau (s404) in the hippocampus. These results may suggest that electroacupuncture at the GV24 and bilateral GB13 acupoints might improve cognitive functions in Alzheimer's disease by decreasing the levels of Aβ, p-tau (s396) and p-tau (s404) in the brain as these proteins are the main causes of neurological damage and cognitive dysfunction during the pathogenesis underlying Alzheimer's disease.

Multi-target approach for Alzheimer's disease treatment: computational biomolecular modeling of cholinesterase enzymes with a novel 4-N-phenylaminoquinoline derivative reveal promising potentials

The identification of dual inhibitors targeting the active sites of the cholinesterase enzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), have lately surfaced as a multi-approach towards Alzheimer treatment. More recently, a novel series of 4-N-phenylaminoquinolines was synthesized and evaluated against AChE and BuChE in which one of the compounds displayed appreciable inhibition compared to the standard compound, galantamine. To provide a clearer picture of the inhibition mechanism of this potent compound at the molecular level, computational biomolecular modeling was carried out. The investigation was initiated with the exploration of the chemical properties of the identified compound 11 b and reference drug, galantamine. Density functional theory (DFT) calculations reveal some conceptual parameters that provide information on the stability and reactivity of the compounds as potential inhibitors. To unveil the binding mechanism, energetics and enzyme-ligand interactions, molecular dynamics (MD) simulations of six different systems were executed over a period. Calculated binding free energy values are in the same order with experimental IC₅₀ data. Identification of the main residues driving optimum binding of the active compound 11 b to the binding region of both AChE and BuChE showed Trp81 and Trp110 as the most important, respectively. It was proposed that the studied compound could serve as a dual inhibitor for AChE and BuChE, therefore, would potentially be a promising moiety in a multi-target approach for the treatment of Alzheimer's disorder.Communicated by Ramaswamy H. Sarma.

The Golgi Apparatus May Be a Potential Therapeutic Target for Apoptosis-Related Neurological Diseases

Increasing evidence shows that, in addition to the classical function of protein processing and transport, the Golgi apparatus (GA) is also involved in apoptosis, one of the most common forms of cell death. The structure and the function of the GA is damaged during apoptosis. However, the specific effect of the GA on the apoptosis process is unclear; it may be involved in initiating or promoting apoptosis, or it may inhibit apoptosis. Golgi-related apoptosis is associated with a variety of neurological diseases including glioma, Alzheimer’s disease (AD), Parkinson’s disease (PD), and ischemic stroke. This review summarizes the changes and the possible mechanisms of Golgi structure and function during apoptosis. In addition, we also explore the possible mechanisms by which the GA regulates apoptosis and summarize the potential relationship between the Golgi and certain neurological diseases from the perspective of apoptosis. Elucidation of the interaction between the GA and apoptosis broadens our understanding of the pathological mechanisms of neurological diseases and provides new research directions for the treatment of these diseases. Therefore, we propose that the GA may be a potential therapeutic target for apoptosis-related neurological diseases.

A Glimmer of Hope: Maintain Mitochondrial Homeostasis to Mitigate Alzheimer's Disease

Mitochondria are classically known to be cellular energy producers. Given the high-energy demanding nature of neurons in the brain, it is essential that the mitochondrial pool remains healthy and provides a continuous and efficient supply of energy. However, mitochondrial dysfunction is inevitable in aging and neurodegenerative diseases. In Alzheimer’s disease (AD), neurons experience unbalanced homeostasis like damaged mitochondrial biogenesis and defective mitophagy, with the latter promoting the disease-defining amyloid β (Aβ) and p-Tau pathologies impaired mitophagy contributes to inflammation and the aggregation of Aβ and p-Tau-containing neurotoxic proteins. Interventions that restore defective mitophagy may, therefore, alleviate AD symptoms, pointing out the possibility of a novel therapy. This review aims to illustrate mitochondrial biology with a focus on mitophagy and propose strategies to treat AD while maintaining mitochondrial homeostasis.

Anti-Amnesic and Neuroprotective Effects of Fluoroethylnormemantine in a Pharmacological Mouse Model of Alzheimer's Disease

BACKGROUND

Current therapies in Alzheimer's disease (AD), including Memantine, have proven to be only symptomatic but not curative or disease modifying. Fluoroethylnormemantine (FENM) is a structural analogue of Memantine, functionalized with a fluorine group that allowed its use as a positron emission tomography tracer. We here analyzed FENM neuroprotective potential in a pharmacological model of AD compared with Memantine.

METHODS

Swiss mice were treated intracerebroventricularly with aggregated Aβ 25-35 peptide and examined after 1 week in a battery of memory tests (spontaneous alternation, passive avoidance, object recognition, place learning in the water-maze, topographic memory in the Hamlet). Toxicity induced in the mouse hippocampus or cortex was analyzed biochemically or morphologically.

RESULTS

Both Memantine and FENM showed symptomatic anti-amnesic effects in Aβ 25-35-treated mice. Interestingly, FENM was not amnesic when tested alone at 10 mg/kg, contrarily to Memantine. Drugs injected once per day prevented Aβ 25-35-induced memory deficits, oxidative stress (lipid peroxidation, cytochrome c release), inflammation (interleukin-6, tumor necrosis factor-α increases; glial fibrillary acidic protein and Iba1 immunoreactivity in the hippocampus and cortex), and apoptosis and cell loss (Bcl-2-associated X/B-cell lymphoma 2 ratio; cell loss in the hippocampus CA1 area). However, FENM effects were more robust than observed with Memantine, with significant attenuations vs the Aβ 25-35-treated group.

CONCLUSIONS

FENM therefore appeared as a potent neuroprotective drug in an AD model, with a superior efficacy compared with Memantine and an absence of direct amnesic effect at higher doses. These results open the possibility to use the compound at more relevant dosages than those actually proposed in Memantine treatment for AD.

Dysfunctional proteins in neuropsychiatric disorders: From neurodegeneration to autism spectrum disorders

Despite fundamental differences in disease course and outcomes, neurodevelopmental (autism spectrum disorders - ASD) and neurodegenerative disorders (Alzheimer's disease - AD and Parkinson's disease - PD) present surprising, common traits in their molecular pathomechanisms. Uncontrolled oligomerization and aggregation of amyloid β (Aβ), microtubule-associated protein (MAP) tau, or α-synuclein (α-syn) contribute to synaptic impairment and the ensuing neuronal death in both AD and PD. Likewise, the pathogenesis of ASD may be attributed, at least in part, to synaptic dysfunction; attention has also been recently paid to irregularities in the metabolism and function of the Aβ precursor protein (APP), tau, or α-syn. Commonly affected elements include signaling pathways that regulate cellular metabolism and survival such as insulin/insulin-like growth factor (IGF) - PI3 kinase - Akt - mammalian target of rapamycin (mTOR), and a number of key synaptic proteins critically involved in neuronal communication. Understanding how these shared pathomechanism elements operate in different conditions may help identify common targets and therapeutic approaches.

Network Pharmacology Analysis and Molecular Characterization of the Herbal Medicine Formulation Qi-Fu-Yin for the Inhibition of the Neuroinflammatory Biomarker iNOS in Microglial BV-2 Cells: Implication for the Treatment of Alzheimer's Disease

Aberrant microglial activation drives neuroinflammation and neurodegeneration in Alzheimer's disease (AD). The present study is aimed at investigating whether the herbal formula Qi-Fu-Yin (QFY) could inhibit the inflammatory activation of cultured BV-2 microglia. A network pharmacology approach was employed to predict the active compounds of QFY, protein targets, and affected pathways. The representative pathways and molecular functions of the targets were analyzed by Gene Ontology (GO) and pathway enrichment. A total of 145 active compounds were selected from seven herbal ingredients of QFY. Targets (e.g., MAPT, APP, ACHE, iNOS, and COX-2) were predicted for the selected active compounds based on the relevance to AD and inflammation. As a validation, fractions were sequentially prepared by aqueous extraction, ethanolic precipitation, and HPLC separation, and assayed for downregulating two key proinflammatory biomarkers iNOS and COX-2 in lipopolysaccharide- (LPS-) challenged BV-2 cells by the Western blotting technique. Moreover, the compounds of QFY in 90% ethanol downregulated iNOS in BV-2 cells but showed no activity against COX-2 induction. Among the herbal ingredients of QFY, Angelicae Sinensis Radix and Ginseng Radix et Rhizoma contributed to the selective inhibition of iNOS induction. Furthermore, chemical analysis identified ginsenosides, especially Rg3, as antineuroinflammatory compounds. The herbal formula QFY may ameliorate neuroinflammation via downregulating iNOS in microglia.

Chronic Traumatic Encephalopathy: A Comparison with Alzheimer's Disease and Frontotemporal Dementia

The clinical diagnosis of chronic traumatic encephalopathy (CTE) is challenging due to heterogeneous clinical presentations and overlap with other neurodegenerative dementias. Depending on the clinical presentation, the differential diagnosis of CTE includes Alzheimer's disease (AD), behavioral variant frontotemporal dementia (bvFTD), Parkinson's disease, amyotrophic lateral sclerosis, primary mood disorders, posttraumatic stress disorder, and psychotic disorders. The aim of this article is to compare the clinical aspects, genetics, fluid biomarkers, imaging, treatment, and pathology of CTE to those of AD and bvFTD. A detailed clinical evaluation, neurocognitive assessment, and structural brain imaging can inform the differential diagnosis, while molecular biomarkers can help exclude underlying AD pathology. Prospective studies that include clinicopathological correlations are needed to establish tools that can more accurately determine the cause of neuropsychiatric decline in patients at risk for CTE.

Mitochondrial Dysfunction and Alzheimer's Disease: Role of Microglia

In 1907, Alois Alzheimer observed, as he quoted, development of "numerous fibers" and "adipose saccules" in the brain of his diseased patient Auguste Deter. The neurodegenerative disease became known as Alzheimer's disease (AD) and is the most common cause of dementia worldwide. AD normally develops with aging and is mostly initiated because of the imbalance between the formation and clearance of amyloid-β (Aβ). Formation of neurofibrillary tangles (NFTs) of hyperphosphorylated tau is another hallmark of AD. Neuroinflammation plays a significant role in the development and pathology of AD. This chapter explores the role of mitochondrial dysfunction in microglia in case of AD. Mitochondrial oxidative stress in microglia has been linked to the development of AD. Elevated generation of reactive oxygen species (ROS) and loss of mitochondrial membrane potential through various mechanisms have been observed in AD. Aβ interacts with microglial receptors, such as triggering receptor expressed in myeloid cells 2 (TREM2), activating downstream pathways causing mitochondrial damage and aggravating inflammation and cytotoxicity. Fibrillar Aβ activates nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in microglia leading to elevated induction of mitochondrial ROS which further causes neurotoxicity. Elevated ROS in microglia causes activation of inflammatory and cell death pathways. Production of ATP, regulation of mitochondrial health, autophagy, and mitophagy in microglia play significant roles in the AD pathology. Understanding microglial physiology and mitochondrial dysfunction will enable better therapeutic interventions.

Metformin Improves Learning and Memory in the SAMP8 Mouse Model of Alzheimer's Disease

Metformin is used for the treatment of insulin resistant diabetes. Diabetics are at an increased risk of developing dementia. Recent epidemiological studies suggest that metformin treatment prevents cognitive decline in diabetics. A pilot clinical study found cognitive improvement with metformin in patients with mild cognitive impairment (MCI). Preclinical studies suggest metformin reduces Alzheimer-like pathology in mouse models of Alzheimer's disease (AD). In the current study, we used 11-month-old SAMP8 mice. Mice were given daily injections of metformin at 20 mg/kg/sc or 200 mg/kg/sc for eight weeks. After four weeks, mice were tested in T-maze footshock avoidance, object recognition, and Barnes maze. At the end of the study, brain tissue was collected for analysis of PKC (PKCζ, PKCι, PKCα, PKCγ, PKCɛ), GSK-3β, pGSK-3βser9, pGSK-3βtyr216, pTau404, and APP. Metformin improved both acquisition and retention in SAMP8 mice in T-maze footshock avoidance, retention in novel object recognition, and acquisition in the Barnes maze. Biochemical analysis indicated that metformin increased both atypical and conventional forms of PKC; PKCζ, and PKCα at 20 mg/kg. Metformin significantly increased pGSK-3βser9 at 200 mg/kg, and decreased Aβ at 20 mg/kg and pTau404 and APPc99 at both 20 mg/kg and 200 mg/kg. There were no differences in blood glucose levels between the aged vehicle and metformin treated mice. Metformin improved learning and memory in the SAMP8 mouse model of spontaneous onset AD. Biochemical analysis indicates that metformin improved memory by decreasing APPc99 and pTau. The current study lends support to the therapeutic potential of metformin for AD.

From monomer to fibril: Abeta-amyloid binding to Aducanumab antibody studied by molecular dynamics simulation

Alzheimer's disease is one of the most common causes of dementia. It is believed that the aggregation of short Aβ-peptides to form oligomeric and protofibrillar amyloid assemblies plays a central role for disease-relevant neurotoxicity. In recent years, passive immunotherapy has been introduced as a potential treatment strategy with anti-amyloid antibodies binding to Aβ-amyloids and inducing their subsequent degradation by the immune system. Although so far mostly unsuccessful in clinical studies, the high-dosed application of the monoclonal antibody Aducanumab has shown therapeutic potential that might be attributed to its much greater affinity to Aβ-aggregates vs monomeric Aβ-peptides. In order to better understand how Aducanumab interacts with aggregated Aβ-forms compared to monomers, we have generated structural model complexes based on the known structure of Aducanumab in complex with an Aβ_2 - 7 -eptitope. Structural models of Aducanumab bound to full-sequence Aβ_1 - 40 -monomers, oligomers, protofilaments and mature fibrils were generated and investigated using extensive molecular dynamics simulations to characterize the flexibility and possible additional interactions. Indeed, an aggregate-specific N-terminal binding motif was found in case of Aducanumab binding to oligomers, protofilaments and fibrils that is located next to but not overlapping with the epitope binding site found in the crystal structure with Aβ_2 - 7 . Analysis of binding energetics indicates that this motif binds weaker than the epitope but likely contributes to Aducanumab's preference for aggregated Aβ-species. The predicted aggregate-specific binding motif could potentially serve as a basis to reengineer Aducanumab for further enhanced preference to bind Aβ-aggregates vs monomers.

Early diagnosis and treatment of Alzheimer's disease: new definitions and challenges

The prevalence of Alzheimer's disease (AD), a progressive neurodegenerative disorder, is expected to more than double by 2050. Studies on the pathophysiology of AD have been changing our understanding of this disorder and setting a new scenario for drug development and other therapies. Concepts like the "amyloid cascade" and the "continuum of AD," discussed in this article, are now well established. From updated classifications and recommendations to advances in biomarkers of AD, we aim to critically assess the literature on AD, addressing new definitions and challenges that emerged from recent studies on the subject. Updates on the status of major clinical trials are also given, and future perspectives are discussed.

Global Mapping of Interventions to Improve Quality of Life of Patients with Alzheimer's Disease during 1990-2018

BACKGROUND

Alzheimer's disease (AD) with its high burden on disability is known as one of the critical public health issues worldwide. Hence, providing comprehensive care and effective symptomatic treatment are becoming a challenge for many healthcare systems. Quality of life (QOL) has been identified as an important indicator to develop holistic care for people living with AD since it reflects treatment response, the progression of AD, and activities of daily living. This study aimed to identify research trends and landscapes as well as important factors in QOL studies in the field of AD.

SUMMARY

English research was extracted from the online database Web of Science to analyze research publications' growth rate and content on AD and QOL. VOSviewer was used to visualize the correlations between terms in titles and abstracts. Research topics were created using Latent Dirichlet Allocation of abstracts' content and disciplines. Major landscapes in the QOL assessment included care and treatment for AD in epidemiological studies and clinical trials. Besides, most studies were conducted in high-income countries, such as the USA or the United Kingdom. Findings of our study also identified a lack of contextualized factors and research gaps in terms of QOL among individuals with AD. Key Messages: Further studies should be conducted taking an effort to assess QOL among demented patients as well as advancing knowledge, attitude, and practice among family caregivers.

Icaritin Improves Memory and Learning Ability by Decreasing BACE-1 Expression and the Bax/Bcl-2 Ratio in Senescence-Accelerated Mouse Prone 8 (SAMP8) Mice

Icaritin (ICT) is the main component in the traditional Chinese herb Epimedium, and it has been shown to have anti-Alzheimer's disease (AD) effects, but its neuroprotective effects and the pharmacological mechanisms are unclear. In the present study, senescence-accelerated mouse prone 8 (SAMP8) mice were randomly divided into a model group and an ICT-treated group. Learning and memory abilities were detected by the Morris water maze assay, and the expression of amyloid beta protein (Aβ) and β-site APP cleavage enzyme 1 (BACE1) was determined by Western blotting and polymerase chain reaction (PCR). Histological changes in CA1 and CA3 were detected by hematoxylin-eosin staining (H&E staining), and the immunohistochemical analysis was used to detect the expression and localization of Bax and Bcl-2. The results showed that compared with the SAMP8 mice, the ICT-treated SAMP8 mice showed improvements in spatial learning and memory retention. In addition, the number of necrotic cells and the morphological changes in CA1 and CA3 areas were significantly alleviated in the group of ICT-treated SAMP8 mice, and the expression of BACE1, Aβ_1-42 levels, and the Bax/Bcl-2 ratio in the hippocampus was obviously decreased in the ICT-treated group compared with the control group. The results demonstrated that ICT reduced BACE-1 levels, the contents of Aβ_1-42, and the Bax/Bcl-2 ratio, suggesting that ICT might have potential therapeutic benefits by delaying or modifying the progression of AD.

Amburana cearensis: Pharmacological and Neuroprotective Effects of Its Compounds

Amburana cearensis A.C. Smith is an endemic tree from Northeastern Brazil used in folk medicine as teas, decocts and syrups for the treatment of various respiratory and inflammatory diseases, since therapeutic properties have been attributed to compounds from its stem bark and seeds. Numerous pharmacological properties of semi-purified extracts and isolated compounds from A. cearensis have been described in several biological systems, ranging from antimicrobial to anti-inflammatory effects. Some of these activities are attributed to coumarins and phenolic compounds, the major compounds present in A. cearensis seed extracts. Multiple lines of research demonstrate these compounds reduce oxidative stress, inflammation and neuronal death induced by glutamate excitotoxicity, events central to most neuropathologies, including Alzheimer’s disease (AD) and Parkinson’s Disease (PD). This review focuses on the botanical aspects, folk medicine use, biological effects and pharmacological activities of A. cearensis compounds and their potential as novel non-toxic drugs for the treatment of neurodegenerative diseases.

Allosterism of Nicotinic Acetylcholine Receptors: Therapeutic Potential for Neuroinflammation Underlying Brain Trauma and Degenerative Disorders

Inflammation is a key physiological phenomenon that can be pervasive when dysregulated. Persistent chronic inflammation precedes several pathophysiological conditions forming one of the critical cellular homeostatic checkpoints. With a steady global surge in inflammatory diseases, it is imperative to delineate underlying mechanisms and design suitable drug molecules targeting the cellular partners that mediate and regulate inflammation. Nicotinic acetylcholine receptors have a confirmed role in influencing inflammatory pathways and have been a subject of scientific scrutiny underlying drug development in recent years. Drugs designed to target allosteric sites on the nicotinic acetylcholine receptors present a unique opportunity to unravel the role of the cholinergic system in regulating and restoring inflammatory homeostasis. Such a therapeutic approach holds promise in treating several inflammatory conditions and diseases with inflammation as an underlying pathology. Here, we briefly describe the potential of cholinergic allosterism and some allosteric modulators as a promising therapeutic option for the treatment of neuroinflammation.

Codonopsis pilosula polysaccharide attenuates Aβ toxicity and cognitive defects in APP/PS1 mice

Codonopsis pilosula Polysaccharides (CPPs), a traditional Chinese medicine used for thousands of years, is a potential neuroprotective polysaccharide via a relatively poorly understood mechanism. We previously reported that CPPs attenuated tau pathology in hTau transfected mice and therefore in the current work investigated the effect of CPPs on Aβ toxicity and cognitive defects in APP/PS1 mice model. It was found that one-month intragastric administration of CPPs significantly ameliorated cognitive defects in APP/PS1 mice. In addition, CPPs treatment mitigated the loss of the synaptic plasticity and increased the synaptic proteins including synaptotagmin and PSD95. The expression of Aβ42 and Aβ40 was remarkably decreased in the hippocampus of APP/PS1 mice after CPPs treatment. We also found that CPPs coincubation significantly reduced the amount of APPβ and Aβ42 expression in cells. Intriguingly, the activity of BACE1 was decreased following CPPs treatment in both the hippocampus of APP/PS1 mice and in vitro experiments. Collectively, these results indicated that CPPs attenuated Aβ pathology in APP/PS1 mice, and down-regulating BACE1 might be the underlaying mechanism which could be a therapeutic target for alleviating cognitive defects in AD pathology.

DL0410 attenuates oxidative stress and neuroinflammation via BDNF/TrkB/ERK/CREB and Nrf2/HO-1 activation

Oxidative stress and neuroinflammation have been deeply associated with Alzheimer's disease. DL0410 is a novel acetylcholinesterase inhibitor with potential anti-oxidative effects in AD-related animal models, while the specific mechanism has not been fully clarified. In this study, DL0410 was predicted to be related to the modification of cell apoptosis, oxidation-reduction process, inflammatory response and ERK1/ERK2 cascade by in silico target fishing and GO enrichment analysis. Then the possible protective effects of DL0410 were evaluated by hydrogen peroxide (H₂O₂)-induced oxidative stress model and lipopolysaccharides (LPS)-induced neuroinflammation model H₂O₂ decreased the viability of SH-SY5Y cells, induced malondialdehyde (MDA) accumulation, mitochondrial membrane potential (Δψm) loss and cell apoptosis, which could be reversed by DL0410 dose-dependently, indicating that DL0410 protected SH-SY5Y cells against H₂O₂-mediated oxidative stress. Western blot analysis showed that DL0410 increased the H₂O₂-triggered down-regulated TrkB, ERK and CREB phosphorylation and the expression of BDNF. In addition, TrkB inhibitor ANA-12, ERK inhibitor SCH772984 and CREB inhibitor 666-15 eliminated the inhibition of DL0410 on MDA accumulation and Δψm loss. Furthermore, DL0410 attenuates inflammatory responses and ROS production in LPS-treated BV2 cells, which is responsible for Nrf2 and HO-1 up-regulation. The present study demonstrates that DL0410 is a potential activator of the BDNF/TrkB/ERK/CREB and Nrf2/HO-1 pathway and may be a potential candidate for regulating oxidative stress and neuroinflammatory response in the brain. Together, the results showed that DL0410 is a promising drug candidate for treating AD and possibly other nervous system diseases associated with oxidative stress and neuroinflammation.