Overview of therapeutic targets in management of dementia

Therapeutic potential of plant-derived natural compounds in Alzheimer's disease: Targeting microglia-mediated neuroinflammation

Microglia are resident immune cells of the central nervous system (CNS) with roles in sensing, housekeeping, and defense. Exploring the role of microglia in the occurrence and development of Alzheimer's disease (AD) and the possible therapeutic mechanism of plant-derived natural compounds (PDNCs) that regulate microglia-associated neuroinflammation may potentially help in elucidating the pathogenesis of AD and provide novel insights for its treatment. This review explores the role of abnormal microglial activation and its dominant neuroinflammatory response, as well as the activation of their target receptors and signaling pathways in AD pathogenesis. Additionally, we report an update on the potential pharmacological mechanisms of multiple PDNCs in modulating microglia-associated neuroinflammation in AD treatment. Dysregulated activation of microglial receptors and their downstream pathways impaired immune homeostasis in animal models of AD. Multiple signaling pathways, such as mitogen-activated protein kinase (MAPK), nuclear factor kappa light chain enhancer of activated B cells (NF-κB), and Toll-like receptors, play important roles in microglial activation and can exacerbate microglia-mediated neuroinflammation. PDNCs, such as magnolol, stigmasterol, matrine, naringenin, naringin, and resveratrol, can delay the progression of AD by inhibiting the proinflammatory receptors of microglia, activating its anti-inflammatory receptors, regulating the receptors related to β-amyloid (Aβ) clearance, reversing immune dysregulation, and maintaining the immune homeostasis of microglial downstream pathways. This review summarizes the mechanisms by which microglia cause chronic inflammation in AD and evaluates the beneficial effects of PDNCs on immune regulation in AD by regulating microglial receptors and their downstream pathways.

Recent advances in Alzheimer's disease: Mechanisms, clinical trials and new drug development strategies

Alzheimer's disease (AD) stands as the predominant form of dementia, presenting significant and escalating global challenges. Its etiology is intricate and diverse, stemming from a combination of factors such as aging, genetics, and environment. Our current understanding of AD pathologies involves various hypotheses, such as the cholinergic, amyloid, tau protein, inflammatory, oxidative stress, metal ion, glutamate excitotoxicity, microbiota-gut-brain axis, and abnormal autophagy. Nonetheless, unraveling the interplay among these pathological aspects and pinpointing the primary initiators of AD require further elucidation and validation. In the past decades, most clinical drugs have been discontinued due to limited effectiveness or adverse effects. Presently, available drugs primarily offer symptomatic relief and often accompanied by undesirable side effects. However, recent approvals of aducanumab (1) and lecanemab (2) by the Food and Drug Administration (FDA) present the potential in disrease-modifying effects. Nevertheless, the long-term efficacy and safety of these drugs need further validation. Consequently, the quest for safer and more effective AD drugs persists as a formidable and pressing task. This review discusses the current understanding of AD pathogenesis, advances in diagnostic biomarkers, the latest updates of clinical trials, and emerging technologies for AD drug development. We highlight recent progress in the discovery of selective inhibitors, dual-target inhibitors, allosteric modulators, covalent inhibitors, proteolysis-targeting chimeras (PROTACs), and protein-protein interaction (PPI) modulators. Our goal is to provide insights into the prospective development and clinical application of novel AD drugs.

Systemic inflammation in Aβ1-40-induced Alzheimer's disease model: New translational opportunities

Alzheimer disease (AD) is the most frequent cause of dementia, and the most common neurodegenerative disease, which is characterized by memory impairment, neuronal death, and synaptic loss in the hippocampus. Sporadic late-onset AD, which accounts for over 95 % of disease cases, is a multifactorial pathology with complex etiology and pathogenesis. Nowadays, neuroinflammation is considered the third most important component of AD pathogenesis in addition to amyloid peptide generation and deposition. Neuroinflammation is associated with the impairment of blood-brain barrier and leakage of inflammatory mediators into the periphery with developing systemic inflammatory responses. Systemic inflammation is currently considered one of the therapeutic targets for AD treatment, that necessitates in-depth study of this phenomenon in appropriate non-transgenic animal models. This study was aimed to explore systemic inflammatory manifestations in rats with Aβ1-40-induced AD. The impairment of spatial memory and cognitive flexibility in Aβ1-40-lesioned rats was accompanied by pronounced systemic inflammation, which was confirmed by commonly accepted biomarkers: increased hematological indices of systemic inflammation (NLR, dNLR, LMR, PLR and SII), signs of anemia of inflammation or chronic diseases, and pro-inflammatory polarized activation of circulating phagocytes. In addition, markers of systemic inflammation strongly correlated with disorders of remote cognitive flexibility in Aβ1-40-lesioned rats. These results indicate, that Aβ1-40-induced AD model permits the investigation of specific element of the disease - systemic inflammation in addition to well reproduced neuroinflammation and impairment of spatial memory and cognitive flexibility. It increases translational value of this well-known model.

Adverse event profile of memantine and donepezil combination therapy: a real-world pharmacovigilance analysis based on FDA adverse event reporting system (FAERS) data from 2004 to 2023

Background

Donepezil in combination with memantine is a widely used clinical therapy for moderate to severe dementia. However, real-world population data on the long-term safety of donepezil in combination with memantine are incomplete and variable. Therefore, the aim of this study was to analyze the adverse events (AEs) of donepezil in combination with memantine according to US Food and Drug Administration Adverse Event Reporting System (FAERS) data to provide evidence for the safety monitoring of this therapy.

Methods

We retrospectively analyzed reports of AEs associated with the combination of donepezil and memantine from 2004 to 2023 extracted from the FAERS database. Whether there was a significant association between donepezil and memantine combination therapy and AEs was assessed using four disproportionality analysis methods, namely, the reporting odds ratio, proportional reporting ratio, Bayesian confidence propagation neural network, and multi-item gamma Poisson shrinker methods. To further investigate potential safety issues, we also analyzed differences and similarities in the time of onset and incidence of AEs stratified by sex and differences and similarities in the incidence of AEs stratified by age.

Results

Of the 2,400 adverse drug reaction (ADR) reports in which the combination of donepezil and memantine was the primary suspected drug, most of the affected patients were female (54.96%) and older than 65 years of age (79.08%). We identified 22 different system organ classes covering 100 AEs, including some common AEs such as dizziness and electrocardiogram PR prolongation; fall, pleurothotonus and myoclonus were AEs that were not listed on the drug label. Moreover, we obtained 88 reports of AEs in men and 100 reports of AEs in women; somnolence was a common AE in both men and women and was more common in women, whereas pleurothotonus was a more common AE in men. In addition, we analyzed 12 AEs in patients younger than 18 years, 16 in patients between 18 and 65 years, and 113 in patients older than 65 years. The three age groups had distinctive AEs, but lethargy was the common AE among all age groups. Finally, the median time to AE onset was 19 days in all cases. In both men and women, most AEs occurred within a month of starting donepezil plus memantine, but some continued after a year of treatment.

Conclusion

Our study identified potential and new AEs of donepezil in combination with memantine; some of these AEs were the same as in the specification, and some of the AE signals were not shown in the specification. In addition, there were sex and age differences in some of the AEs. Therefore, our findings may provide valuable insights for further studies on the safety of donepezil and memantine combination therapy, which are expected to contribute to the safe use of this therapy in clinical practice.

The Neurosurgical Research Progress of 98 Low and Lower Middle-Income Countries from 1928 to 2024

OBJECTIVE

The aim of the present study was to analyze the trends of neurosurgical research in low and lower middle-income countries (LLMICs).

METHODS

The data was retrieved from Scopus database and 82 neurosurgical journals were analyzed.

RESULTS

Initially the global research scholarly output (n = 195,658) was explored and later papers originating solely from LLMICs, without international collaboration with advance countries (n = 8408) were analyzed. The per decade number of publications (from 1920 to May 2024), top ten authors, universities, countries and sources of all (global) countries, and 98 LLMICs is provided. Eighty countries have published less than 50 papers. Even more striking, 68, 55, 38, and 36 LLMICs countries have produced less than 20, 10, 5, and 3 papers, respectively. The keywords analysis was performed to present the main focus of 8408 publications. The top 1000 most cited documents were also identified, and later relevant scientometrics details were provided. The top countries dynamic and most prolific authors (on the basis of number of publications, total citations, h-index, g-index, and m-index) in the top 1000 cited documents (from LLMICs) are highlighted.

CONCLUSIONS

The findings suggest that neurosurgical research in LLMICs is low, which could be attributed to several factors including limited funding, inadequate infrastructure, and insufficient training opportunities.

Therapeutic Potential of Intravenous Ketamine in Early-Onset Dementia: A Case Report

This case report discusses the use of intravenous (IV) ketamine as a potential therapeutic agent for early-onset dementia. A 56-year-old female with a diagnosis of early-onset dementia showed significant cognitive decline despite trying and failing several standard treatments such as memantine, donepezil, and rivastigmine. Given the promising results of ketamine in other neurological and psychiatric disorders, the patient underwent a series of IV ketamine infusions over a period of two months. Following treatment, there was a notable improvement in cognitive function, mood, and daily living activities. By the end of her treatments, the patient stated she had more mental clarity, increased focus, improved memory, and increased energy. This case highlights the potential use of ketamine as a novel treatment approach for early-onset dementia and warrants further investigation in larger clinical trials.

The potential of five c-miRNAs as serum biomarkers for Late-Onset Alzheimer's disease diagnosis: miR-10a-5p, miR-29b-2-5p, miR-125a-5p, miR-342-3p, and miR-708-5p

The nervous system is rich in miRNAs, indicating an important role of these molecules in regulating processes associated with cognition, memory, and others. Therefore, qualitative and quantitative imbalances involving such miRNAs may be involved in dementia contexts, including Late-Onset Alzheimer's Disease (LOAD). To test the viability of circulating miRNAs (c-miRNAs) as biomarkers for LOAD, we proceed accordingly to the following reasoning. The first stage was to discover and identify profile of c-miRNAs by RNA sequencing (RNA-Seq). For this purpose, blood serum samples were used from LOAD patients (n = 5) and cognitively healthy elderly control group (CTRL_CH) (n = 5), all over 70 years old. We identified seven c-miRNAs differentially expressed (p ≤ 0.05) in the serum of LOAD patients compared to CTRL_CH (miR-10a-5p; miR-29b-2-5p; miR-125a-5p; miR-342-3p, miR-708-5p, miR-380-5p and miR-340-3p). Of these, five (p ≤ 0.01) were selected for in silico analysis (miR-10a-5p; miR-29b-2-5p; miR-125a-5p; miR-342-3p, miR-708-5p), for which 44 relevant target genes were found regulated by these c-miRNAs and related to LOAD. Through the analysis of these target genes in databases, it was possible to observe that they have functions related to the development and progress of LOAD, directly or indirectly connecting the different Alzheimer's pathways. Thus, this work found five promising serum c-miRNAs as options for biomarkers contributing to LOAD diagnosis. Our study shows the complex network between these molecules and LOAD, supporting the relevance of studies using c-miRNAs in dementia contexts.

Dementia in Australia: Clinical recommendations post-diagnosis

The delivery of a dementia diagnosis, the information provided, and the practical advice and support arranged can have a long-lasting impact on patients and their families and deserves attention equal to that given to the assessment and investigation process. Patients and their families need a constructive yet sensitive conversation about the nature and cause of their difficulties, communicated in plain language, and tailored to their main concerns and needs. This conversation should lead to the provision of high-quality, easily accessible information. Following this, clinicians may wish to consider broaching the following dementia topics: (1) pharmacological and non-pharmacological interventions, (2) connection and integration with relevant organisations, (3, 4) application for formal support services and engagement with support teams, (5) safety in the home, (6, 7) financial planning, guardianship and legal matters, (8) driving eligibility, (9) support and education resources to family carers and (10) research initiatives and genetic information. Addressing these topics will contribute to improved disease management, which is likely to improve the dementia journey for the patient, their carer(s), and family.

Electroacupuncture improves cognitive function in APP/PS1 mice by inhibiting oxidative stress related hippocampal neuronal ferroptosis

BACKGROUND

Electroacupuncture, recognized as a crucial non-pharmacological therapeutic approach, has demonstrated notable efficacy in enhancing cognitive function among Alzheimer's disease (AD) patients. This study aimed to investigate the neuroprotective properties of electroacupuncture in APP/PS1 mice with AD.

METHODS

A total of thirty APP/PS1 mice were randomly assigned to three groups: the Alzheimer's disease group (AD), the electroacupuncture treatment group (EA), and the ferroptosis inhibitor deferasirox treatment group (DFX). Additionally, ten C57BL/6 mice were included as a control group (Control). In the EA group, mice underwent flat needling at Baihui and Yintang, as well as point needling at Renzhong, once daily for 15 min each time. In the DFX group, mice received intraperitoneal injections of deferasirox at a dosage of 100 mg/kg/day. Following the 28-day treatment period, behavioral evaluation, morphological observation of neurons, and detection of neuronal ferroptosis were conducted.

RESULTS

The electroacupuncture treatment demonstrated a significant improvement in spatial learning, memory ability, and neuronal damage in mice with AD. Analysis of neuronal ferroptosis markers indicated that electroacupuncture interventions reduced the elevated levels of malondialdehyde, iron, and ptgs2 expression, while also increasing superoxide dismutase activity, Ferroportin 1 and glutathione peroxidase 4 expression. Moreover, the regulatory impact of electroacupuncture on ferroptosis may be attributed to its ability to enhance the expression and nuclear translocation of Nrf2.

CONCLUSIONS

This study suggested that electroacupuncture could inhibit the neuronal ferroptosis by activating the antioxidant function in neurons through p62/Keap1/Nrf2 signal pathway, thereby improve the cognitive function of AD mice by the neuronal protection effect.

Microglia as a Possible Alternative Therapeutic for Dementia

Dementia is a syndrome in which there is deterioration in memory, behavior, and the ability to perform everyday activities. Alzheimer's disease and vascular dementia are the most common forms of dementia. There is evidence supporting the hypothesis that inflammatory and immune mechanisms are involved in dementia. Microglia, the resident macrophage tissues in the central nervous system, play a significant role in neuroinflammation and play an important role in amyloid-β clearance in the brain, and impaired microglial clearance of amyloid-β has also been shown to be involved in the pathogenesis of Alzheimer's disease. However, there is also abundant evidence that microglia have harmful actions in dementia. Once activated, they can mediate uptake at neuronal synapses. They can also exacerbate tau pathology and secrete deleterious inflammatory factors that can directly or indirectly damage neurons. Thus, depending on the stage of the disease, microglia can act both protectively and detrimentally. Therefore, it is still necessary to continue with studies to better understand the role of microglia in the pathology of dementia. Currently available drugs can only improve cognitive symptoms, have no impact on progression and are not curative, so identifying and studying new therapeutic approaches is important. Considering the role played by microglia in this pathology, it has been pointed out as a possible therapeutic approach. This manuscript aims to address the relationship between microglia and dementia and how this relationship could be used for therapeutic purposes.

Antioxidative and neuroprotective potential of Acorus calamus linn. and Cordia dichotoma G. Forst. In Alzheimer's type dementia in rodent

The goal of this research study was to see how plant extracts of Acorus calamus Linn. and Cordia dichotoma G. Forst. overcome scopolamine-induced Alzheimer's type dementia in mice by activating the cholinergic system, anti-oxidant and protection of neuronal death in the brain (hippocampus region). Scopolamine (1 mg/kg i.p.) reduced mice's routine in behavioral parameters such as Morris Water Maze (MWM), Elevated Plus Maze (EPM), and also the locomotor activity. It also decreases antioxidant levels such as Reduced glutathione (GSH) and also Superoxide dismutase (SOD) but also increases the level of Acetylcholinesterase enzyme (AChE) in brain. Assessment of various behavioral, and biochemical parameters (AChE, SOD, GSH, and Nitrite level) were compared with each group. Acorus calamus (hydro-alcoholic 1:1) 600 mg/kg p.o. and the combination (Acorus calamus 600 mg/kg p.o. + Cordia dichotoma 750 mg/kg p.o.) group showed significant results as compared to Cordia dichotoma 750 mg/kg p.o.in behavioral as well as in biochemical parameters. Histological studies showed significant neuroprotection in the Acorus calamus-treated group and the combination-treated groups. In the future, the Acorus calamus and the combination are possibly helpful in the treatment of various cognitive disorders or it may be valuable to investigate the pharmacological potential of such plant extracts during the treatment of neurodegenerative disorders.

Genetic model of selective COX2 inhibition improve learning and memory ability and brain pathological changes in 5xFAD mouse

Alzheimer's disease (AD) is the most common neurodegenerative disease that leads to dementia. Its pathogenesis is very complex, and inflammation is one of the main pathophysiological mechanisms of AD. Non-steroidal anti-inflammatory drugs (NSAIDs), which mainly target cyclooxygenase (COX) activity, are used to reduce the risk of AD, but several side effects limit their application. Here we assess the effect of Cyclooxygenase-2 (COX2) catalytic activity on learning ability and AD pathology using 5x Familial Alzheimer's Disease (FAD) mice with COX2 inhibition (5xFAD/COX2 KO), 5xFAD mice with cyclooxygenase inactivation of COX2 (5xFAD/COX2 Y385F), and 5xFAD mice with peroxidase (POX) inactivation of COX2 (5xFAD/COX2) H374Y), respectively. Our results indicate that learning ability of COX2 KO and mutants is improved compared to 5xFAD mice, further investigations show that Aβ depositions are reduced, microglia and astrocytes homeostasis are changed in COX2 KO and mutants. Especially, there is more responsive microglia in the brain of 5xFAD/COX2 Y385F mice, and Aβ depositions are more effectively cleaned at old age. Taken together, these results identify a role of COX2 Y385F in regulating microglia function and may have important implications for future treatment of AD.

Pentoxifylline as Add-On Treatment to Donepezil in Copper Sulphate-Induced Alzheimer's Disease-Like Neurodegeneration in Rats

Alzheimer's disease (AD), the most common neurodegenerative disorder, is characterized by behavioral, cognitive, and progressive memory impairments. Extensive neuronal loss, extracellular accumulation of insoluble senile amyloid-β (Aβ) plaques, and intracellular neurofibrillary tangles (NFTs) are the major pathological features. The present study aimed to investigate the therapeutic effect of donepezil (DON) and pentoxifylline (PTX) in combination to combat the neurodegenerative disorders (experimental AD) induced by CuSO4 intake in experimental rats. Thirty adult male Wistar rats (140-160 g) were used in this study. AD was first induced in rats by CuSO4 supplement to drinking water (10 mg/L) for 14 weeks. The AD group received no further treatment. Oral treatment with DON (10 mg/kg/day), PTX (100 mg/kg/day), or DON + PTX for the other three groups was started from the 10th week of CuSO4 intake for 4 weeks. Cortex markers like acetylcholine (ACh), acetylcholinesterase (AChE), total antioxidant capacity (TAC), and malondialdehyde (MDA) and hippocampus markers like β-amyloid precursor protein cleaving enzyme 1 (BACE1), phosphorylated Tau (p-tau), Clusterin (CLU), tumor necrosis factor-α (TNF-α), caspase-9 (CAS-9), Bax, and Bcl-2 were measured. The histopathology studies were done by using hematoxylin and eosin and Congo red stains as well as immunohistochemistry for neurofilament. CuSO4 induced adverse histological and biochemical changes. The histological injury in the hippocampus was inhibited following the administration of the DON and PTX. The brain tissue levels of AChE, MDA, BACE1, p-tau, CLU, CAS-9, Bax, and TNF-α were significantly increased, while brain tissue levels of ACh, TAC, and Bcl-2 were significantly decreased in CuSO4-treated rats as compared with the untreated control group. The effects induced by either DON or PTX on most studied parameters were comparable. Combined treatment of DON and PTX induced remarkable results compared with their individual use. However, more clinical and preclinical studies are still required to further confirm and prove the long-term efficacy of such combination.

Voglibose attenuates cognitive impairment, Aβ aggregation, oxidative stress, and neuroinflammation in streptozotocin-induced Alzheimer's disease rat model

Alzheimer's disease (AD) is an age-dependent neurodegenerative disease hallmarked by Amyloid-β (Aβ) aggregation, cognitive impairment, and neuronal and synaptic loss. In this study, AD was induced in male Wistar rats (n = 6) by the administration of intracerebroventricular-streptozotocin (ICV-STZ-3 mg/kg/day), and Voglibose (Vog) was administered at various doses (10, 25, and 50 mg/kg), while Galantamine (3 mg/kg) acted as a reference standard drug. Behavioral alterations in both spatial and non-spatial memory functions were evaluated in the experimental rats. At the end of the study, all experimental rats were sacrificed, and their brain parts, the cortex and hippocampus, were subjected to biochemical, western blot, and histopathological analysis. In our study results, the statistically significant dose-dependent results from the behavioral tests show the Voglibose-treated groups significantly improved (p < 0.0001) spatial and non-spatial memory functions when compared with ICV-STZ-treated group. Meanwhile, when compared with ICV-STZ-treated rats, treatment with Voglibose (10, 25, and 50 mg/kg) showed the activities of both acetylcholinesterase (AChE) and malondialdehyde (MDA) were significantly attenuated (p < 0.0001), while the operation of antioxidant enzymes was considerably enhanced (p < 0.0001). The molecular estimation showed that it significantly attenuates (p < 0.0001) the TNF-α, IL-1β, and CRP activity, and the western blot results demonstrate the significantly attenuated Aβ aggregation. The histopathological results showed that the Voglibose treatment had an effective improvement in clear cytoplasm and healthy neuronal cells. In conclusion, our results suggest that Voglibose has potent neuroprotective effects against the ICV-STZ-induced AD model. Furthermore, these results support the possibility of Voglibose as a therapeutic approach to improving cognitive function, suggesting that controlling Aβ aggregation might be a novel target for the development of AD.

Exome-Wide Association Study Identified Clusters of Pleiotropic Genetic Associations with Alzheimer's Disease and Thirteen Cardiovascular Traits

Alzheimer's disease (AD) and cardiovascular traits might share underlying causes. We sought to identify clusters of cardiovascular traits that share genetic factors with AD. We conducted a univariate exome-wide association study and pair-wise pleiotropic analysis focused on AD and 16 cardiovascular traits-6 diseases and 10 cardio-metabolic risk factors-for 188,260 UK biobank participants. Our analysis pinpointed nine genetic markers in the APOE gene region and four loci mapped to the CDK11, OBP2B, TPM1, and SMARCA4 genes, which demonstrated associations with AD at p ≤ 5 × 10-4 and pleiotropic associations at p ≤ 5 × 10-8. Using hierarchical cluster analysis, we grouped the phenotypes from these pleiotropic associations into seven clusters. Lipids were divided into three clusters: low-density lipoprotein and total cholesterol, high-density lipoprotein cholesterol, and triglycerides. This split might differentiate the lipid-related mechanisms of AD. The clustering of body mass index (BMI) with weight but not height indicates that weight defines BMI-AD pleiotropy. The remaining two clusters included (i) coronary heart disease and myocardial infarction; and (ii) hypertension, diabetes mellitus (DM), systolic and diastolic blood pressure. We found that all AD protective alleles were associated with larger weight and higher DM risk. Three of the four (75%) clusters of traits, which were significantly correlated with AD, demonstrated antagonistic genetic heterogeneity, characterized by different directions of the genetic associations and trait correlations. Our findings suggest that shared genetic factors between AD and cardiovascular traits mostly affect them in an antagonistic manner.

Natural IgG antibodies to β amyloid are decreased in patients with Parkinson's disease

Natural antibodies (nAbs) against aggregation-prone proteins have been found in healthy normal subjects. These proteins likely have a pathogenetic role in neurodegenerative diseases of ageing. They include the amyloid β (Aβ) protein which may play an important role in Alzheimer's dementia (AD), and α-synuclein, a major determinant of Parkinson's disease (PD). We measured nAbs to Aβ in a group of Italian patients with AD, vascular dementia, non-demented PD patients and healthy elderly controls. We found that Aβ antibody levels in AD were similar to age- and sex-matched controls, but contrary to our expectations, they were significantly reduced in PD. This may identify patients that could be more prone to amyloid aggregation.

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.

Exosomes for the diagnosis and treatment of dementia

PURPOSE OF REVIEW

Dementia is a syndrome with several possible pathologies. To date, definitive methods for diagnosis and treatment of sub-types of dementia have not been established. Emerging evidence suggests that exosomes can provide important information for the diagnosis and treatment of several subtypes of dementia. This article reviews recent studies on the application of exosomes in dementia.

RECENT FINDINGS

Exosomes are involved in the pathogenesis of Alzheimer's disease (AD) and Parkinson's disease (PD) through transporting toxic proteins such as amyloid beta (Aβ), tau, and α-synuclein. Exosomal microRNAs (miR) and proteins reflect the disease state, and therefore, exosomes can be used as diagnostic markers for diseases such as AD, PD, Huntington's disease (HD), vascular dementia (VaD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD). Mesenchymal stem cell (MSC)-derived exosomes have been shown to ameliorate disease pathology, and improve cognitive function in AD, PD, and VAD.

SUMMARY

Recent studies have shown that exosomes could be novel diagnostic agents for dementia because they contain molecules that could be potential biomarker candidates indicative of the type and stage of dementia. Therapeutic application of exosomes in dementia has revealed that exosomes only, or exosomes loaded with an active pharmaceutical ingredient (API), ameliorate disease phenotype of dementia. Further work is needed to exploit this potential.

Microglia and Alzheimer's Disease

There is a huge need for novel therapeutic and preventative approaches to Alzheimer's disease (AD) and neuroinflammation seems to be one of the most fascinating solutions. The primary cell type that performs immunosurveillance and helps clear out unwanted chemicals from the brain is the microglia. Microglia work to reestablish efficiency and stop further degeneration in the early stages of AD but mainly fail in the illness's later phases. This may be caused by a number of reasons, e.g., a protracted exposure to cytokines that induce inflammation and an inappropriate accumulation of amyloid beta (Aβ) peptide. Extracellular amyloid and/or intraneuronal phosphorylated tau in AD can both activate microglia. The activation of TLRs and scavenger receptors, inducing the activation of numerous inflammatory pathways, including the NF-kB, JAK-STAT, and NLRP3 inflammasome, facilitates microglial phagocytosis and activation in response to these mediators. Aβ/tau are taken up by microglia, and their removal from the extracellular space can also have protective effects, but if the illness worsens, an environment that is constantly inflamed and overexposed to an oxidative environment might encourage continuous microglial activation, which can lead to neuroinflammation, oxidative stress, iron overload, and neurotoxicity. The complexity and diversity of the roles that microglia play in health and disease necessitate the urgent development of new biomarkers that identify the activity of different microglia. It is imperative to comprehend the intricate mechanisms that result in microglial impairment to develop new immunomodulating therapies that primarily attempt to recover the physiological role of microglia, allowing them to carry out their core function of brain protection.

Improvement of brain perfusion in patients with chronic brain ischemia at epidural spinal cord electrical stimulation

Objective

Increasing life expectancy and aging of the population is accompanied by a steady increase in the number of elderly patients with chronic cerebral ischemia and age-related cognitive impairment associated with cerebral hypoperfusion and microangiopathy. The aim of this study was to identify long-term changes in cerebral blood flow (CBF) in patients with chronic cerebral ischemia at the epidural electrical stimulation of the spinal cord (SCS).

Materials and methods

Changes in cerebral blood flow were studied according to CT perfusion in 59 patients (aged 55–78 years) with vertebrogenic pain syndromes and chronic cerebral ischemia during epidural electrical stimulation of the spinal cord at the cervical (C3–C5) and lower thoracic (Th9–Th10) levels.

Results

In all patients, on the 5th day of trial SCS, an increase in cerebral blood flow by from 58.6 ± 1.13 ml/100 ml/min to 64.8 ± 1.21 ml/100 ml/min (p < 0.01) with stimulation at the Th9-Th10 level and from 58.8 ± 1.12 ml/100 ml/min to 68.2 ± 1.42 ml/100 ml/min (p < 0, 01) with stimulation at the C3-C5 level. These changes in brain perfusion were preserved during the follow-up examination 1 year after the implantation of chronic SCS system. The greatest increase in CBF was registered in the frontotemporal regions, subcortical structures and white matter of the brain. Changes in cerebral perfusion did not correlate with the degree of reduction in the severity of the accompanying pain syndrome. The change in CBF in the control group (32 patients) in all periods was not statistically significant.

Conclusion

Our results show that SCS is accompanied by a persistent improvement in brain perfusion, which may be potentially useful for developing methods for reducing age-related vascular disorders in the elderly.