Alzheimer's disease

PDIA3 Expression Is Altered in the Limbic Brain Regions of Triple-Transgenic Mouse Model of Alzheimer's Disease

In the present study, we used a mouse model of Alzheimer's disease (AD) (3×Tg-AD mice) to longitudinally analyse the expression level of PDIA3, a protein disulfide isomerase and endoplasmic reticulum (ER) chaperone, in selected brain limbic areas strongly affected by AD-pathology (amygdala, entorhinal cortex, dorsal and ventral hippocampus). Our results suggest that, while in Non-Tg mice PDIA3 levels gradually reduce with aging in all brain regions analyzed, 3×Tg-AD mice showed an age-dependent increase in PDIA3 levels in the amygdala, entorhinal cortex, and ventral hippocampus. A significant reduction of PDIA3 was observed in 3×Tg-AD mice already at 6 months of age, as compared to age-matched Non-Tg mice. A comparative immunohistochemistry analysis performed on 3×Tg-AD mice at 6 (mild AD-like pathology) and 18 (severe AD-like pathology) months of age showed a direct correlation between the cellular level of Aβ and PDIA3 proteins in all the brain regions analysed, even if with different magnitudes. Additionally, an immunohistochemistry analysis showed the presence of PDIA3 in all post-mitotic neurons and astrocytes. Overall, altered PDIA3 levels appear to be age- and/or pathology-dependent, corroborating the ER chaperone's involvement in AD pathology, and supporting the PDIA3 protein as a potential novel therapeutic target for the treatment of AD.

Oleracone F Alleviates Cognitive Impairment and Neuropathology in APPswe/PSEN1dE9 Mice by Reducing the Expression of Vascular Cell Adhesion Molecule and Leukocyte Adhesion to Brain Vascular Endothelial Cells

Alzheimer's disease (AD) is the most common neurodegenerative disease and the blood-brain barrier dysfunction has been suggested as a key pathological feature of the disease. Our research group successfully established a synthetic protocol for oleracones, a novel series of flavonoids isolated from the plant extract of Portulaca oleracea L. (PO). PO extract was reported to have anti-inflammatory and antioxidant effects, enhancing cognitive function. Thus, we investigated the effects and mechanism of oleracones on cognition using AD model transgenic mice (Tg; APPswe/PSEN1dE9). Oleracone F treatment significantly improved memory dysfunction in Tg mice. Oleracone F decreased the number, burden, and immunoreactivity of amyloid plaques and amyloid precursor protein (APP) protein levels in the brains of Tg mice compared to wild-type mice. Oleracone F also alleviated inflammation observed in Tg mice brains. In vitro studies in human microvascular endothelial cells (HBMVECs) demonstrated that oleracones D, E, and F blocked the elevations in VCAM-1 protein induced by tumor necrosis factor-α (TNF-α), hindering leukocyte adhesion to HBMVECs. Taken together, our results suggest that oleracones ameliorated cognitive impairment by blocking TNF-α-induced increases in VCAM-1, thereby reducing leukocyte infiltration to the brain and modulating brain inflammation.

pKr-2 induces neurodegeneration via upregulation of microglial TLR4 in the hippocampus of AD brain

We recently demonstrated that prothrombin kringle-2 (pKr-2) derived from blood-brain barrier (BBB) disruption could induce hippocampal neurodegeneration and object recognition impairment through neurotoxic inflammatory responses in the five familial Alzheimer's disease mutation (5XFAD) mice. In the present study, we aimed to determine whether pKr-2 induces microglial activation by stimulating toll-like receptor 4 (TLR4) upregulation and examine whether this response contributes to pKr-2-induced neuroinflammatory damage in the hippocampi of mice models. We observed that inflammatory responses induced by pKr-2 administration in the hippocampi of wild-type mice were significantly abrogated in TLR4-deficient mice (TLR4^-/-), and caffeine supply or rivaroxaban treatment that inhibits the overexpression of hippocampal pKr-2 reduced TLR4 upregulation in 5XFAD mice, resulting in the inhibition of neuroinflammatory responses. Similar to the expression patterns of pKr-2, TLR4, and the TLR4 transcription factors, PU.1 and p-c-Jun, seen in the postmortem hippocampal tissues of Alzheimer's disease (AD) patients, our results additionally showed the influence of transcriptional regulation on TLR4 expression following pKr-2 expression in triggering the production of neurotoxic inflammatory mediators. Therefore, we conclude that pKr-2 may play a role in initiating upregulation of microglial TLR4, consequently inducing hippocampal neurodegeneration. Furthermore, the control of pKr-2-induced microglial TLR4 could be a useful therapeutic strategy against hippocampal neurodegeneration in AD.

Landscape of Double-Stranded DNA Breaks in Postmortem Brains from Alzheimer's Disease and Non-Demented Individuals

BACKGROUND

Alzheimer's disease (AD) brains accumulate DNA double-strand breaks (DSBs), which could contribute to neurodegeneration and dysfunction. The genomic distribution of AD brain DSBs is unclear.

OBJECTIVE

To map genome-wide DSB distributions in AD and age-matched control brains.

METHODS

We obtained autopsy brain tissue from 3 AD and 3 age-matched control individuals. The donors were men between the ages of 78 to 91. Nuclei extracted from frontal cortex tissue were subjected to Cleavage Under Targets & Release Using Nuclease (CUT&RUN) assay with an antibody against γH2AX, a marker of DSB formation. γH2AX-enriched chromatins were purified and analyzed via high-throughput genomic sequencing.

RESULTS

The AD brains contained 18 times more DSBs than the control brains and the pattern of AD DSBs differed from the control brain pattern. In conjunction with published genome, epigenome, and transcriptome analyses, our data revealed aberrant DSB formation correlates with AD-associated single-nucleotide polymorphisms, increased chromatin accessibility, and upregulated gene expression.

CONCLUSION

Our data suggest in AD, an accumulation of DSBs at ectopic genomic loci could contribute to an aberrant upregulation of gene expression.

Ultrasonographic/regional muscle measurements for diagnosing sarcopenia in older adults with and without dementia

BACKGROUND

Sarcopenia and dementia are growing concerns among older adults that muscle and brain atrophy may cooccur. We aimed to compare the age-related loss of muscle mass by using ultrasound (US), and skeletal muscle mass index (SMI) by bioelectrical impedance analysis in older adults with and without dementia.

METHODS

A total of 221 older adults aged ≥65 years were included in the study. The diagnosis of sarcopenia was established if low muscle mass according to either SMI or sonographic gastrocnemius (GC) muscle thickness was combined with low grip strength. The diagnosis of dementia was based on the National Institute of Aging and Alzheimer's Association criteria and the major neurocognitive disorder definition in the Diagnostic and Statistical Manual of Mental Disorders-V. Muscle strength was measured by hand dynamometer and physical performance was assessed by 4-meter usual gait speed.

RESULTS

There were similar/moderate correlation coefficients between GC muscle thickness and SMI with functional parameters (all p < 0.01). Forty-six patients (20.8%) had dementia, and 21 (45.7%) of them had sarcopenia diagnosed by GC thickness (p < 0.001). Age was older but weight, body mass index, and all sarcopenia-related parameters were lower in dementia patients (all p < 0.01). When clinical variables were taken into binary logistic regression analyses, age [OR = 1.095 (95% CI: 1.028-1.167)], weight [OR = 0.918 (95% CI: 0.887-0.950)], and presence of dementia [OR = 5.109 (95% CI: 2.002-13.033)] were independently associated with sarcopenia diagnosed with GC muscle thickness (all p < 0.05).

DISCUSSION

This study showed that sarcopenia is highly prevalent in older adults with dementia (45.7%) than without dementia (11.4%). Amongst different factors, increased age, having low body weight, and the presence of dementia independently increased the risk of sarcopenia diagnosed by GC muscle thickness (but not diagnosed by SMI) in older adults. Thus, we can evaluate easily and successfully the loss of (regional) muscle mass in dementia patients by using US in outpatient clinics.

Linking Cerebrovascular Dysfunction to Age-Related Hearing Loss and Alzheimer’s Disease—Are Systemic Approaches for Diagnosis and Therapy Required?

Alzheimer’s disease (AD), the most common cause of dementia in the elderly, is a neurodegenerative disorder associated with neurovascular dysfunction, cognitive decline, and the accumulation of amyloid β peptide (Aβ) in the brain and tau-related lesions in neurons termed neurofibrillary tangles (NFTs). Aβ deposits and NFT formation are the central pathological hallmarks in AD brains, and the majority of AD cases have been shown to exhibit a complex combination of systemic comorbidities. While AD is the foremost common cause of dementia in the elderly, age-related hearing loss (ARHL) is the most predominant sensory deficit in the elderly. During aging, chronic inflammation and resulting endothelial dysfunction have been described and might be key contributors to AD; we discuss an intriguing possible link between inner ear strial microvascular pathology and blood–brain barrier pathology and present ARHL as a potentially modifiable and treatable risk factor for AD development. We present compelling evidence that ARHL might well be seen as an important risk factor in AD development: progressive hearing impairment, leading to social isolation, and its comorbidities, such as frailty, falls, and late-onset depression, link ARHL with cognitive decline and increased risk of dementia, rendering it tempting to speculate that ARHL might be a potential common molecular and pathological trigger for AD. Additionally, one could speculate that amyloid-beta might damage the blood–labyrinth barrier as it does to the blood–brain barrier, leading to ARHL pathology. Finally, there are options for the treatment of ARHL by targeted neurotrophic factor supplementation to the cochlea to improve cognitive outcomes; they can also prevent AD development and AD-related comorbidity in the future.

Andrographolide Attenuates Short-Term Spatial and Recognition Memory Impairment and Neuroinflammation Induced by a Streptozotocin Rat Model of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder clinically manifested by a gradual cognitive decline. Intracerebroventricular injection (ICV) of streptozotocin (STZ), a model of sporadic AD (sAD), shows many aspects of sAD abnormalities (i.e., neuroinflammation, oxidative stress, protein aggregation), resulting in memory impairment. Andrographolide (ANDRO), a natural diterpene lactone, has numerous bioactivities including anti-inflammatory and antioxidant properties. Studies in rodents revealed that ANDRO has neuroprotective properties and restores cognitive impairment. In the present study, we investigated the effects of ANDRO in the ICV-STZ model relative to short-term spatial memory (object location test (OLT) and Y maze test), short-term recognition memory (object recognition test (ORT)), locomotor activity (open field test (OFT)), expression of amyloid precursor protein (APP), and activation of astrocytes (glial fibrillary acidic protein (GFAP) expression) and microglia (ionized calcium-binding adapter molecule-1 (Iba-1) immunohistochemistry) in the prefrontal cortex (PFC) and hippocampus (HIP). Wistar rats were injected ICV with STZ (3 mg/kg) or vehicle and treated with ANDRO (2 mg/kg, i.p.; three times per week). After four weeks, ANDRO attenuated the impairments of the Y maze and ORT performances, and the increase of astrocyte activation in the PFC induced by the ICV-STZ model. In addition, ANDRO decreased the number of activated microglia cells in the HIP of STZ-injected rats. The APP expression was not altered, neither by the STZ nor ANDRO. ANDRO showed a beneficial effect on memory impairment and neuroinflammation in the STZ model of AD.

SIRT7 Deficiency Protects against Aβ42-Induced Apoptosis through the Regulation of NOX4-Derived Reactive Oxygen Species Production in SH-SY5Y Cells

Alzheimer's disease (AD) is an age-related neurodegenerative disease that is characterized by irreversible memory loss and cognitive decline. The deposition of amyloid-β (Aβ), especially aggregation-prone Aβ₄₂, is considered to be an early event preceding neurodegeneration in AD. Sirtuins (SIRT1-7 in mammals) are nicotinamide adenine dinucleotide-dependent lysine deacetylases/deacylases, and several sirtuins play important roles in AD. However, the involvement of SIRT7 in AD pathogenesis is not known. Here, we demonstrate that SIRT7 mRNA expression is increased in the cortex, entorhinal cortex, and prefrontal cortex of AD patients. We also found that Aβ₄₂ treatment rapidly increased NADPH oxidase 4 (NOX4) expression at the post-transcriptional level, and induced reactive oxygen species (ROS) production and apoptosis in neuronal SH-SY5Y cells. In contrast, SIRT7 knockdown inhibited Aβ₄₂-induced ROS production and apoptosis by suppressing the upregulation of NOX4. Collectively, these findings suggest that the inhibition of SIRT7 may play a beneficial role in AD pathogenesis through the regulation of ROS production.

The Protective Effects of Acetazolamide Against Homocysteine-Induced Blood-Brain-Barrier Disruption by Regulating the Activation of the Wnt/β-Catenin Signaling Pathway

Acetazolamide (AZA) is a carbonic anhydrase inhibitor (CAI) with neuroprotective effects. Hyperhomocysteinemia is associated with blood-brain-barrier (BBB) disruption in brain disorders. A previous study indicated that AZA might have a new role in brain disorders. However, its function in hyperhomocysteinemia-related BBB disruption has not been reported. Here, we aim to clarify the role of AZA in homocysteine (Hcy)-mediated BBB dysfunction using both in vivo and in vitro assays. We found that AZA improved memory and cognitive function, and reduced brain edema in Hcy-stimulated hyperhomocysteinemia model rats. This protective effect of AZA on hyperhomocysteinemia rats was accompanied by improved BBB permeability and increased expression levels of the tight junction proteins, occludin, and claudin-5. The in vitro assay results show that AZA prevented Hcy-induced cell injury and attenuated the increased permeability in Hcy-treated bEnd.3 brain endothelial cells. The Hcy-induced decrease in occludin and claudin-5, and increase in MMP-2 and MMP-9 expression levels were attenuated by AZA in bEnd.3 cells. Moreover, the Hcy-induced downregulation of the Wnt/β-catenin signaling pathway in bEnd.3 cells was abolished by AZA. Inhibition of Wnt/β-catenin by ICG-001 reversed the protective effects of AZA in Hcy-treated bEnd.3 cells. We also prove that this process is mediated by WTAP. These findings suggest that acetazolamide mitigated the Hcy-induced compromised brain vascular endothelial integrity by regulating the activation of the Wnt/β-catenin signaling pathway.

Noradrenergic Add-on Therapy with Extended-Release Guanfacine in Alzheimer's Disease (NorAD): study protocol for a randomised clinical trial and COVID-19 amendments

BACKGROUND

Guanfacine is a α2A adrenergic receptor agonist approved for treating attention deficit hyperactivity disorder (ADHD). It is thought to act via postsynaptic receptors in the prefrontal cortex, modulating executive functions including the regulation of attention. Attention is affected early in Alzheimer's disease (AD), and this may relate to pathological changes within the locus coeruleus, the main source of noradrenergic pathways within the brain. Given that cholinergic pathways, also involved in attention, are disrupted in AD, the combination of noradrenergic and cholinergic treatments may have a synergistic effect on symptomatic AD. The primary objective of the NorAD trial is to evaluate the change in cognition with 12 weeks of treatment of extended-release guanfacine (GXR) against a placebo as a combination therapy with cholinesterase inhibitors in participants with mild to moderate Alzheimer's disease.

METHODS/DESIGN

NorAD is a 3-month, single-centre, randomised, double-blind, placebo-controlled, phase III trial of extended-release guanfacine (GXR) in participants with mild to moderate Alzheimer's disease. A total of 160 participants will be randomised to receive either daily guanfacine or placebo in combination with approved cholinesterase treatment for 12 weeks. The primary outcome is the change in cognition, as measured by the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), from baseline to follow-up in the treatment group compared to the placebo group. Secondary outcomes include the change in additional cognitive measures of attention (Tests of Attention: Trails A and B, digit-symbol substitution, Test of Everyday Attention and CANTAB-RVP), neuropsychiatric symptoms (Neuropsychiatric Inventory), caregiver burden (Zarit Burden Interview) and activities of daily living (Alzheimer's Disease Co-operative Study - Activities of Daily Living Inventory). From July 2020, observation of change following cessation of treatment is also being assessed.

DISCUSSION

There is strong evidence for early noradrenergic dysfunction in Alzheimer's disease. The NorAD trial aims to determine whether guanfacine, a noradrenergic alpha-2 agonist, improves attention and cognition when used in addition to standard cholinergic treatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03116126 . Registered on 14 April 2017 EudraCT: 2016-002598-36.

Pathophysiology of RAGE in inflammatory diseases

The receptor for advanced glycation end products (RAGE) is a non-specific multi-ligand pattern recognition receptor capable of binding to a range of structurally diverse ligands, expressed on a variety of cell types, and performing different functions. The ligand-RAGE axis can trigger a range of signaling events that are associated with diabetes and its complications, neurological disorders, cancer, inflammation and other diseases. Since RAGE is involved in the pathophysiological processes of many diseases, targeting RAGE may be an effective strategy to block RAGE signaling.

The Longitudinal Association of Lifestyle with Cognitive Health and Dementia Risk: Findings from the HELIAD Study

The aim of the current study was to investigate whether a Total Lifestyle Index (TLI), including adherence to the Mediterranean diet, sleep duration, physical activity and engagement in activities of daily living, is associated with cognitive health over time and dementia risk, in a representative cohort of older people. A total of 1018 non-demented community-dwelling older adults ≥65 years old (60% women) from the HELIAD study were included. A comprehensive neurological and neuropsychological assessment was conducted at baseline and at the 3-year follow-up evaluating cognitive functioning, and a dementia diagnosis was set. Diet, physical activity, sleep duration and engagement in activities of daily living were assessed using standard, validated questionnaires at baseline. Sixty-one participants developed dementia at follow-up; participants who developed dementia were older and had fewer years of education compared with participants with normal cognition. With the exception of sleep duration, participants with normal cognition at follow-up scored higher in the individual lifestyle factors compared to those who developed dementia. Regarding TLI, values were lower for participants with dementia compared with those with normal cognition. Each additional unit of the TLI was associated with 0.5% of a standard deviation less decline per year of the Global Cognition score, whereas for each additional unit of the TLI, the risk for dementia was reduced by 0.2% per year (p < 0.05). Our results suggest that greater adherence to a healthy lifestyle pattern is associated with a slower decline of cognitive function and reduced dementia risk.

Virtual Reality-based Cognitive Intervention for Enhancing Executive Functions in Community-dwelling Older Adults

With the rapid growth of the older population globally, it is anticipated that age-related cognitive decline in the prodromal phase and more severe pathological decline will increase. Moreover, currently, no effective treatment options for the disease exist. Thus, early and timely prevention actions are promising and prior strategies to preserve cognitive functions by preventing symptomatology from increasing the age-related deterioration of the functions in healthy older adults. This study aims to develop the virtual reality-based cognitive intervention for enhancing executive functions (EFs) and examine the EFs after training with the virtual reality-based cognitive intervention in community-dwelling older adults. Following inclusion/exclusion criteria, 60 community-dwelling older adults aged 60-69 years were involved in the study and randomly divided into passive control and experimental groups. Eight 60 min virtual reality-based cognitive intervention sessions were held twice a week and lasted for 1 month. The EFs (i.e., inhibition, updating, and shifting) of the participants were assessed by using standardized computerized tasks, i.e., Go/NoGo, forward and backward digit span, and Berg's card sorting tasks. Additionally, a repeated-measure ANCOVA and effect sizes were applied to investigate the effects of the developed intervention. The virtual reality-based intervention significantly improved the EFs of older adults in the experimental group. Specifically, the magnitudes of enhancement were observed for inhibitory as indexed by the response time, F(1) = 6.95, p < .05, η_p² = .11, updating as represented by the memory span, F(1) = 12.09, p < .01, η_p² = .18, and the response time, F(1) = 4.46, p = .04, η_p² = .07, and shifting abilities as indexed by the percentage of correct responses, F(1) = 5.30, p = .03, η_p² = .09, respectively. The results indicated that the simultaneous combined cognitive-motor control as embedded in the virtual-based intervention is safe and effective in enhancing EFs in older adults without cognitive impairment. Nevertheless, further studies are required to investigate the benefits of these enhancements to motor functions and emotional aspects relating to daily living and the well-being of older populations in communities.

Comparing Medial Temporal Atrophy Between Early-Onset Semantic Dementia and Early-Onset Alzheimer's Disease Using Voxel-Based Morphometry: A Multicenter MRI Study

BACKGROUND

Early-onset Semantic dementia (EOSD) and early-onset Alzheimer's disease (EOAD) are often difficult to clinically differentiate in the early stages of the diseases because of the overlaps of clinical symptoms such as language symptoms. We compared the degree of atrophy in medial temporal structures between the two types of dementia using the voxel-based specific regional analysis system for Alzheimer's disease (VSRAD).

METHODS

The participants included 29 (age: 61.7±4.5 years) and 39 (age: 60.2±4.9 years) patients with EOSD and EOAD, respectively. The degree of atrophy in medial temporal structures was quantified using the VSRAD for magnetic resonance imaging data. Receiver operating characteristic (ROC) analysis was performed to distinguish patients with EOSD and EOAD using the mean Z score (Z-score) in bilateral medial temporal structures and the absolute value (laterality score) of the laterality of Z-score (| right-left |) for indicating the degree of asymmetrical atrophy in medial temporal structures.

RESULTS

The EOSD group had significantly higher Z and laterality scores than the EOAD group (Zscores: mean ± standard deviation: 3.74±1.05 vs. 1.56±0.81, respectively; P<0.001; laterality score: mean ± standard deviation: 2.35±1.23 vs. 0.68±0.51, respectively; P<0.001). In ROC analysis, the sensitivity and specificity to differentiate EOSD from EOAD by a Z-score of 2.29 were 97% and 85%, respectively and by the laterality score of 1.05 were 93% and 85%, respectively.

CONCLUSION

EOSD leads to more severe and asymmetrical atrophy in medial temporal structures than EOAD. The VSRAD may be useful to distinguish between these dementias that have several clinically similar symptoms.

Platanic acid derived amides are more cytotoxic than their corresponding oximes

Abstract

Albeit platanic acid has been known since 1956, its potential to act as a valuable starting material for the synthesis of cytotoxic agents has been neglected for many years. Hereby we describe the synthesis of a small library of amides and oximes derived from 3-O-acetyl-platanic acid, and the results of their screening as cytotoxic agents for several human tumor cell lines. As a result, while the cytotoxicity of the oximes was diminished as compared to the parent amides, the homopiperazinyl amide 5 held the highest cytoxicity (EC50 = 0.9 μM for A375 human melanoma cells). Extra FACS and cell cycle measurements showed compound 5 to act onto A375 cells rather by apoptosis than by necrosis.

Clinical trial registration

No clinical trials are associated with this study

Potential Roles of Extracellular Vesicles as Diagnosis Biomarkers and Therapeutic Approaches for Cognitive Impairment in Alzheimer’s Disease

Cognitive dysfunction, the major clinical manifestation of Alzheimer’s disease (AD), is caused by irreversible progressive neurological dysfunction. With the aging of the population, the incidence of AD is increasing year by year. However, there is neither a simple and accurate early diagnosis method, nor an effective method to alleviate or prevent the occurrence and progression of AD. Extracellular vesicles (EVs) are a number of heterogeneous membrane structures that arise from the endosome system or shed from the plasma membrane. In the brain, almost every kind of cell may have EVs, which are related to cell-cell communication and regulate cellular function. At present, an increasing body of evidence suggests that EVs play a crucial role in the pathogenesis of AD, and it is of great significance to use them as specific biomarkers and novel therapeutic targets for cognitive impairment in AD. This article reviews the potential role of EVs as diagnostic biomarkers and treatments for cognitive dysfunction in AD.

Prevalence of mild behavioural impairment domains: a meta-analysis

BACKGROUND

Mild behavioural impairment (MBI) is a neurobehavioural syndrome characterised by later life emergence of persistent neuropsychiatric symptoms. Our previous meta-analysis showed that MBI is prevalent among cognitively normal (CN), subjective cognitive impairment (SCI) and mild cognitive impairment (MCI) subjects. This study is to calculate the pooled prevalence of MBI domains among CN, SCI, and MCI subjects.

METHODS

A search of relevant literature published between 1 January 2003 and 6 August 2021 was conducted. Meta-analysis using a random effects model and meta-regression was performed.

RESULTS

Ten studies conducted among 12 067 subjects (9758 CN, 1057 SCI and 1252 MCI) with retrievable MBI domains data underwent meta-analysis, revealing pooled prevalence of affective dysregulation (AFD), impulse dyscontrol (IDS), decreased motivation (DMT), social inappropriateness (SIP) and abnormal perception/thought (APT) of 32.84% (95% CI 24.44-42.5%), 26.67% (95% CI 18.24-37.23%), 12.58% (95% CI 6.93-21.75%), 6.05% (95% CI 3.44-10.42%), and 2.81% (95% CI 1.67-4.69%) respectively. AFD and APT domains demonstrated ordinal increase in pooled prevalence from CN, SCI and MCI subgroups, but meta-regression demonstrated no significant difference in MBI domains prevalence among cognitive subgroups (in contrast to the significant increase in MBI prevalence from CN to SCI to MCI). The pooled prevalence of AFD and IDS are greater than that of DMT, SIP and APT among all cognitive subgroups. Several variables were found to explain the high heterogeneity.

CONCLUSIONS

AFD and IDS are the two most prevalent MBI domains and remain the same with cognitive deterioration. This finding is potentially relevant to clinical practice.

Neuroimaging Biomarkers Predicting the Efficacy of Multimodal Rehabilitative Intervention in the Alzheimer's Dementia Continuum Pathology

In this work we aimed to identify neural predictors of the efficacy of multimodal rehabilitative interventions in AD-continuum patients in the attempt to identify ideal candidates to improve the treatment outcome. Subjects in the AD continuum who participated in a multimodal rehabilitative treatment were included in the analysis [n = 82, 38 Males, mean age = 76 ± 5.30, mean education years = 9.09 ± 3.81, Mini Mental State Examination (MMSE) mean score = 23.31 ± 3.81]. All subjects underwent an MRI acquisition (1.5T) at baseline (T0) and a neuropsychological evaluation before (T0) and after intervention (T1). All subjects underwent an intensive multimodal cognitive rehabilitation (8–10 weeks). The MMSE and Neuropsychiatric Inventory (NPI) scores were considered as the main cognitive and behavioral outcome measures, and Delta change scores (T1–T0) were categorized in Improved (ΔMMSE > 0; ΔNPI < 0) and Not Improved (ΔMMSE ≤ 0; ΔNPI ≥ 0). Logistic Regression (LR) and Random Forest classification models were performed including neural markers (Medial Temporal Brain; Posterior Brain (PB); Frontal Brain (FB), Subcortical Brain indexes), neuropsychological (MMSE, NPI, verbal fluencies), and demographical variables (sex, age, education) at baseline. More than 50% of patients showed a positive effect of the treatment (ΔMMSE > 0: 51%, ΔNPI < 0: 52%). LR model on ΔMMSE (Improved vs. Not Improved) indicate a predictive role for MMSE score (p = 0.003) and PB index (p = 0.005), especially the right PB (p = 0.002) at baseline. The Random Forest analysis correctly classified 77% of cognitively improved and not improved AD patients. Concerning the NPI, LR model on ΔNPI (Improved vs. Not Improved) showed a predictive role of sex (p = 0.002), NPI (p = 0.005), PB index (p = 0.006), and FB index (p = 0.039) at baseline. The Random Forest reported a classification accuracy of 86%. Our data indicate that cognitive and behavioral status alone are not sufficient to identify best responders to a multidomain rehabilitation treatment. Increased neural reserve, especially in the parietal areas, is also relevant for the compensatory mechanisms activated by rehabilitative treatment. These data are relevant to support clinical decision by identifying target patients with high probability of success after rehabilitative programs on cognitive and behavioral functioning.

Gene regulation by antisense transcription: A focus on neurological and cancer diseases

Advances in high-throughput sequencing over the past decades have led to the identification of thousands of non-coding RNAs (ncRNAs), which play a major role in regulating gene expression. One emerging class of ncRNAs is the natural antisense transcripts (NATs), the RNA molecules transcribed from the opposite strand of a protein-coding gene locus. NATs are known to concordantly and discordantly regulate gene expression in both cis and trans manners at the transcriptional, post-transcriptional, translational, and epigenetic levels. Aberrant expression of NATs can therefore cause dysregulation in many biological pathways and has been observed in many genetic diseases. This review outlines the involvements and mechanisms of NATs in the pathogenesis of various diseases, with a special emphasis on neurodegenerative diseases and cancer. We also summarize recent findings on NAT knockdown and/or overexpression experiments and discuss the potential of NATs as promising targets for future gene therapies.

Interactions of the Aβ(1-42) Peptide with Boron Nitride Nanoparticles of Varying Curvature in an Aqueous Medium: Different Pathways to Inhibit β-Sheet Formation

The aggregation of amyloid β (Aβ) peptide triggered by its conformational changes leads to the commonly known neurodegenerative disease of Alzheimer's. It is believed that the formation of β sheets of the peptide plays a key role in its aggregation and subsequent fibrillization. In the current study, we have investigated the interactions of the Aβ(1-42) peptide with boron nitride nanoparticles and the effects of the latter on conformational transitions of the peptide through a series of molecular dynamics simulations. In particular, the effects of curvature of the nanoparticle surface are studied by considering boron nitride nanotubes (BNNTs) of varying diameter and also a planar boron nitride nanosheet (BNNS). Altogether, the current study involves the generation and analysis of 9.5 μs of dynamical trajectories of peptide-BNNT/BNNS pairs in an aqueous medium. It is found that BN nanoparticles of different curvatures that are studied in the present work inhibit the conformational transition of the peptide to its β-sheet form. However, such an inhibition effect follows different pathways for BN nanoparticles of different curvatures. For the BNNT with the highest surface curvature, i.e., (3,3) BNNT, the nanoparticle is found to inhibit β-sheet formation by stabilizing the helical structure of the peptide, whereas for planar BNNS, the β-sheet formation is prevented by making more favorable pathways available for transitions of the peptide to conformations of random coils and turns. The BNNTs with intermediate curvatures are found to exhibit diverse pathways of their interactions with the peptide, but in all cases, essentially no formation of the β sheet is found whereas substantial β-sheet formation is observed for Aβ(1-42) in water in the absence of any nanoparticle. The current study shows that BN nanoparticles have the potential to act as effective tools to prevent amyloid formation from Aβ peptides.

Efficiency of donepezil in elderly patients undergoing orthopaedic surgery due to underlying post-operative cognitive dysfunction: study protocol for a multicentre randomised controlled trial

BACKGROUND

Post-operative cognitive dysfunction (POCD) is an overarching term used to describe cognitive impairment identified in the preoperative or post-operative period. After surgical operations, older patients are particularly vulnerable to memory disturbances and other types of cognitive impairment. However, the pathogenesis of POCD remains unclear with no confirmed preventable or treatable strategy available. Our previous study demonstrated that the concentration of choline acetyl transferase in the cerebral spinal fluid was a predictive factor of POCD and that donepezil, which is an acetylcholinesterase inhibitor used in clinical settings for the treatment of Alzheimer's disease, can prevent learning and memory impairment after anaesthesia/surgery in aged mice. This study aimed to determine the critical role of donepezil in preventing cognitive impairment in elderly patients undergoing orthopaedic surgery.

METHODS

A multicentre, double-blind, placebo-controlled, crossover clinical trial will be performed to assess the efficacy of donepezil in elderly patients undergoing orthopaedic surgery. Participants (n = 360) will receive donepezil (5 mg once daily) or placebo from 1 day prior to surgery until 5 days after surgery. Neuropsychological tests will be measured at 1 day before the operation and 1 week, 1 month, 6 months and 1 year after the operation.

DISCUSSION

This research project mainly aimed to study the effects of donepezil in elderly patients undergoing orthopaedic surgery due to underlying POCD and to investigate the underlying physiological and neurobiological mechanisms of these effects. The results may provide important implications for the development of effective interfering strategies, specifically regarding cognitive dysfunction therapy using drugs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04423276 . Registered on 14 June 2020.

Running exercise protects spinophilin-immunoreactive puncta and neurons in the medial prefrontal cortex of APP/PS1 transgenic mice

The medial prefrontal cortex (mPFC) is thought to be closely associated with emotional processes, decision making, and memory. Previous studies have identified the prefrontal cortex as one of the most vulnerable brain regions in Alzheimer's disease (AD). Running exercise has widely been recognized as a simple and effective method of physical activity that enhances brain function and slows the progression of AD. However, the effect of exercise on the mPFC of AD is unclear. To address these issues, we investigated the effects of 4 months of exercise on the numbers of spinophilin-immunoreactive puncta and neurons in the mPFC of 12-month-old APPswe/PSEN1dE9 (APP/PS1) transgenic AD model mice using stereological methods. The spatial learning and memory abilities of mice were tested using the Morris water maze. Four months of running exercise delayed declines in spatial learning and memory abilities. The stereological results showed significantly lower numbers of spinophilin-immunoreactive puncta and neurons in the mPFC of APP/PS1 mice than in the wild-type control group. The numbers of spinophilin-immunoreactive puncta and neurons in the mPFC of running APP/PS1 mice were significantly greater than those in the APP/PS1 control mice. In addition, running-induced improvements in spatial learning and memory were significantly associated with running-induced increases in spinophilin-immunoreactive puncta and neurons numbers in the mPFC. Running exercise could delay the loss of spinophilin-immunoreactive puncta and neurons in the mPFC of APP/PS1 mice. This finding might provide an important structural basis for exercise-induced improvements in the spatial learning and memory abilities of individuals with AD.

Control of hippocampal prothrombin kringle-2 (pKr-2) expression reduces neurotoxic symptoms in five familial Alzheimer's disease mice

Background and Purpose

There is a scarcity of information regarding the role of prothrombin kringle‐2 (pKr‐2), which can be generated by active thrombin, in hippocampal neurodegeneration and Alzheimer's disease (AD).

Experimental Approach

To assess the role of pKr‐2 in association with the neurotoxic symptoms of AD, we determined pKr‐2 protein levels in post‐mortem hippocampal tissues of patients with AD and the hippocampi of five familial AD (5XFAD) mice compared with those of age‐matched controls and wild‐type (WT) mice, respectively. In addition, we investigated whether the hippocampal neurodegeneration and object memory impairments shown in 5XFAD mice were mediated by changes to pKr‐2 up‐regulation.

Key Results

Our results demonstrated that pKr‐2 was up‐regulated in the hippocampi of patients with AD and 5XFAD mice, but was not associated with amyloid‐β aggregation in 5XFAD mice. The up‐regulation of pKr‐2 expression was inhibited by preservation of the blood–brain barrier (BBB) via addition of caffeine to their water supply or by treatment with rivaroxaban, an inhibitor of factor Xa that is associated with thrombin production. Moreover, the prevention of up‐regulation of pKr‐2 expression reduced neurotoxic symptoms, such as hippocampal neurodegeneration and object recognition decline due to neurotoxic inflammatory responses in 5XFAD mice.

Conclusion and Implications

We identified a novel pathological mechanism of AD mediated by abnormal accumulation of pKr‐2, which functions as an important pathogenic factor in the adult brain via blood brain barrier (BBB) breakdown. Thus, pKr‐2 represents a novel target for AD therapeutic strategies and those for related conditions.

Ten-year trends in hospitalizations due to Alzheimer's disease in Brazil: a national-based study

Brazil has the second highest age-standardized prevalence of Alzheimer's disease worldwide. However, information about Alzheimer's disease-related hospitalizations in Brazil is scarce despite its economic and social impact. We described temporal trends in hospitalizations related to Alzheimer's disease in Brazil from 2010 to 2019. We conducted a time-series, retrospective, descriptive, national-based study using data from the DATASUS database of the Brazilian Ministry of Health. Hospitalizations, mean days hospitalized, and economic costs from those hospitalizations were extracted from 2010 to 2019. Hospitalizations by Alzheimer's disease increased 87.7% from 2010 to 2019, with greater increase among men (97.4%), mixed ethnicity (224%), 80 years or older (115.1%), and in the Northeast (172.1%) and Central West (144.2%) regions. Although mean days hospitalized decreased in all subgroups, an increasing time trend in hospital admission was observed in the Central West Region. Costs per hospitalization increased for patients aged 50 years or younger and in admissions related to emergency services. Compared with other non-communicable chronic diseases, Alzheimer's disease had the highest increase in absolute number and rate of hospitalizations in Brazil from 2010 to 2019. AD is a public health problem in Brazil. Strategies to reduce its burden are necessary but only if accompanied by greater equality and awareness of this disease.

Evaluation of γ-carboline-phenothiazine conjugates as simultaneous NMDA receptor blockers and cholinesterase inhibitors

Alzheimer's disease (AD) is the most common form of dementia. It is associated with the impairment of memory and other cognitive functions that are mainly caused by progressive defects in cholinergic and glutamatergic signaling in the central nervous system. Inhibitors of acetylcholinesterase (AChE) and ionotropic glutamate receptors of the N-methyl-d-aspartate (NMDA) receptor family are currently approved as AD therapeutics. We previously showed using a cell-based assay of NMDA receptor-mediated glutamate-induced excitotoxicity that bis-γ-carbolinium conjugates are useful NMDA receptor blockers. However, these compounds also act as subnanomolar AChE inhibitors, which may cause serious anticholinergic side effects when applied in vivo. Here, we evaluated new structures containing γ-carbolines linked to phenothiazine via a propionyl spacer. These compounds were superior to the previously characterized bis-γ-carbolinium conjugates because they blocked NMDA receptors without requiring a quaternary pyridine N-atom and inhibited AChE with moderate IC₅₀ values of 0.54-5.3 µM. In addition, these new compounds displayed considerable selectivity for the inhibition of butyrylcholinesterase (BChE; IC₅₀ = 0.008-0.041 µM), which may be favorable for AD treatment. Inhibitory activities towards the NMDA receptors and AChE were in the same micromolar range, which may be beneficial for equal dosing against multiple targets in AD patients.

Amaryllidaceae Alkaloids of Norbelladine-Type as Inspiration for Development of Highly Selective Butyrylcholinesterase Inhibitors: Synthesis, Biological Activity Evaluation, and Docking Studies

Alzheimer's disease (AD) is a multifactorial neurodegenerative condition of the central nervous system (CNS) that is currently treated by cholinesterase inhibitors and the N-methyl-d-aspartate receptor antagonist, memantine. Emerging evidence strongly supports the relevance of targeting butyrylcholinesterase (BuChE) in the more advanced stages of AD. Within this study, we have generated a pilot series of compounds (1-20) structurally inspired from belladine-type Amaryllidaceae alkaloids, namely carltonine A and B, and evaluated their acetylcholinesterase (AChE) and BuChE inhibition properties. Some of the compounds exhibited intriguing inhibition activity for human BuChE (hBuChE), with a preference for BuChE over AChE. Seven compounds were found to possess a hBuChE inhibition profile, with IC50 values below 1 µM. The most potent one, compound 6, showed nanomolar range activity with an IC50 value of 72 nM and an excellent selectivity pattern over AChE, reaching a selectivity index of almost 1400. Compound 6 was further studied by enzyme kinetics, along with in-silico techniques, to reveal the mode of inhibition. The prediction of CNS availability estimates that all the compounds in this survey can pass through the blood-brain barrier (BBB), as disclosed by the BBB score.

The Conspicuous Link between Ear, Brain and Heart-Could Neurotrophin-Treatment of Age-Related Hearing Loss Help Prevent Alzheimer's Disease and Associated Amyloid Cardiomyopathy?

Alzheimer's disease (AD), the most common cause of dementia in the elderly, is a neurodegenerative disorder associated with neurovascular dysfunction and cognitive decline. While the deposition of amyloid β peptide (Aβ) and the formation of neurofibrillary tangles (NFTs) are the pathological hallmarks of AD-affected brains, the majority of cases exhibits a combination of comorbidities that ultimately lead to multi-organ failure. Of particular interest, it can be demonstrated that Aβ pathology is present in the hearts of patients with AD, while the formation of NFT in the auditory system can be detected much earlier than the onset of symptoms. Progressive hearing impairment may beget social isolation and accelerate cognitive decline and increase the risk of developing dementia. The current review discusses the concept of a brain-ear-heart axis by which Aβ and NFT inhibition could be achieved through targeted supplementation of neurotrophic factors to the cochlea and the brain. Such amyloid inhibition might also indirectly affect amyloid accumulation in the heart, thus reducing the risk of developing AD-associated amyloid cardiomyopathy and cardiovascular disease.

The neural economics of brain aging

Despite remarkable advances, research into neurodegeneration and Alzheimer Disease (AD) has nonetheless been dominated by inconsistent and conflicting theory. Basic questions regarding how and why the brain changes over time remain unanswered. In this work, we lay novel foundations for a consistent, integrated view of the aging brain. We develop neural economics—the study of the brain’s infrastructure, brain capital. Using mathematical modeling, we create ABC (Aging Brain Capital), a simple linear simultaneous-equation model that unites aspects of neuroscience, economics, and thermodynamics to explain the rise and fall of brain capital, and thus function, over the human lifespan. Solving and simulating this model, we show that in each of us, the resource budget constraints of our finite brains cause brain capital to reach an upper limit. The thermodynamics of our working brains cause persistent pathologies to inevitably accumulate. With time, the brain becomes damaged causing brain capital to depreciate and decline. Using derivative models, we suggest that this endogenous aging process underpins the pathogenesis and spectrum of neurodegenerative disease. We develop amyloid–tau interaction theory, a paradigm that bridges the unnecessary conflict between amyloid- and tau-centered hypotheses of AD. Finally, we discuss profound implications for therapeutic strategy and development.

Prospective and retrospective timing in mild cognitive impairment and Alzheimer's disease patients: A systematic review and meta-analysis

Performance on timing tasks changes with age. Whether these changes reflect a real "clock" problem due to aging or a secondary effect of the reduced cognitive resources of older adults is still an unsettled question. Research on processing of time in aged populations marked by severe mnemonic and/or attentional deficits, such as patients with Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI), may help elucidate the role of cognitive resources in age-related temporal distortions. To this end, we conducted a systematic review and meta-analysis of timing studies in AD and MCI patients; both prospective and retrospective timing tasks were considered and analysed separately. As concerns prospective timing, a first random-effect model showed a medium overall effect of neurodegeneration on timing performance. When considering the role of moderator variables(i.e., neurodegenerative condition, type of measure, participants' age and years of education, interval length, and type of timing task), mean score appeared to be a less sensitive measure than accuracy and variability, and the observed temporal impairment was smaller in older samples. In addition, AD patients only exhibited medium-to-high impairment on prospective timing tasks, whereas MCI patients did not significantly differ from controls. However, assuming a mean age of 70 years old and absolute error as dependent variable, a second fitted meta-regression model predicted a significant outcome also for MCI patients. Concerning retrospective timing, a significant but small effect of neurodegeneration was observed for retrospective judgments. None of the moderators, however, explained between-studies variability. Collectively, our findings highlight a clear deficit in prospective timing for AD patients and underscore several issues that future work should carefully consider to better investigate the effect of MCI on prospective temporal judgements. Results from retrospective timing also point to a possible impairment of retrospective judgments in neurodegenerative conditions, albeit more studies are needed to substantiate this finding.

Modulation of γ-Secretase Activity by a Carborane-Based Flurbiprofen Analogue

All over the world, societies are facing rapidly aging populations combined with a growing number of patients suffering from Alzheimer's disease (AD). One focus in pharmaceutical research to address this issue is on the reduction of the longer amyloid-β (Aβ) fragments in the brain by modulation of γ-secretase, a membrane-bound protease. R-Flurbiprofen (tarenflurbil) was studied in this regard but failed to show significant improvement in AD patients in a phase 3 clinical trial. This was mainly attributed to its low ability to cross the blood-brain barrier (BBB). Here, we present the synthesis and in vitro evaluation of a racemic meta-carborane analogue of flurbiprofen. By introducing the carborane moiety, the hydrophobicity could be shifted into a more favourable range for the penetration of the blood-brain barrier, evident by a logD7.4 value of 2.0. Furthermore, our analogue retained γ-secretase modulator activity in comparison to racemic flurbiprofen in a cell-based assay. These findings demonstrate the potential of carboranes as phenyl mimetics also in AD research.

Role of Microglia in Regulating Cholesterol and Tau Pathology in Alzheimer's Disease

Cholesterol, a principal constituent of the cell membrane, plays a crucial role in the brain by regulating the synaptic transmission, neuronal signaling, as well as neurodegenerative diseases. Defects in the cholesterol trafficking are associated with enhanced generation of hyperphosphorylated Tau and Amyloid-β protein. Tau, a major microtubule-associated protein in the brain, is the key regulator of the mature neuron. Abnormally hyperphosphorylated Tau hampers the major functions related to microtubule assembly by promoting neurofibrillary tangles of paired helical filaments, twisted ribbons, and straight filaments. The observed pathological changes due to impaired cholesterol and Tau protein accumulation cause Alzheimer's disease. Thus, in order to regulate the pathogenesis of Alzheimer's disease, regulation of cholesterol metabolism, as well as Tau phosphorylation, is essential. The current review provides an overview of (1) cholesterol synthesis in the brain, neurons, astrocytes, and microglia; (2) the mechanism involved in modulating cholesterol concentration between the astrocytes and brain; (3) major mechanisms involved in the hyperphosphorylation of Tau and amyloid-β protein; and (4) microglial involvement in its regulation. Thus, the answering key questions will provide an in-depth information on microglia involvement in managing the pathogenesis of cholesterol-modulated hyperphosphorylated Tau protein.

Effect of clinical pharmacists' interventions on dementia treatment adherence and caregivers' knowledge

AIM

Poor adherence with dementia medications is common among patients and caregivers, owing to the absence of perceived effect, polypharmacy, and adverse effects. The aim of this study was to evaluate the effect of clinical pharmacists' interventions on the adherence to dementia treatment and the caregivers' knowledge of dementia.

METHODS

This study was conducted at a geriatric outpatient clinic of the university hospital between October 2018 and April 2019. The Morisky Green Levine Adherence Scale (MGLS) to patients or caregivers and the Dementia Knowledge Assessment Tool Version Two (DKAT2) to caregivers were applied at the beginning of the study and 4 months later by a clinical pharmacist. After the scales were applied in the first interview, verbal information about the importance of adherence to dementia treatment, and incorrect answers of caregivers in DKAT2 were provided by the clinical pharmacist.

RESULTS

A total of 94 patients and 91 caregivers were included in the study. High adherence to treatment was determined in 70.2% of the patients in the first interview and in 95.7% in the second interview (P < 0.001). The mean score of DKAT2 was 15.53 ± 2.44 in the first interview, while the median score of DKAT2 in the second interview was 19.11 ± 1.25 (P < 0.001).

CONCLUSION

The intervention of clinical pharmacists significantly increased the adherence to dementia treatment and the caregivers' knowledge of dementia. Close monitoring of dementia patients and caregivers by clinical pharmacists and collaboration with a multidisciplinary team play an important role in dementia care. Geriatr Gerontol Int 2021; 21: 506-511.

Amyloid-β: A double agent in Alzheimer's disease?

Amyloid-β (Aβ) accumulation is one of the cardinal pathological hallmarks of Alzheimer's disease and plays an important role in its pathogenesis. Although the neurotoxic effects of Aβ has been extensively studied, recent studies have revealed that it may also have protective effects. Here, we review novel findings that have shifted our understanding of the role of Aβ in the pathogenesis of Alzheimer's disease. An in-depth and comprehensive understanding of Aβ will provide us with a broader perspective on the treatment of Alzheimer's disease.

Alzheimer's Disease Pathogenesis: Role of Autophagy and Mitophagy Focusing in Microglia

Alzheimer's disease (AD) is a debilitating neurological disorder, and currently, there is no cure for it. Several pathologic alterations have been described in the brain of AD patients, but the ultimate causative mechanisms of AD are still elusive. The classic hallmarks of AD, including amyloid plaques (Aβ) and tau tangles (tau), are the most studied features of AD. Unfortunately, all the efforts targeting these pathologies have failed to show the desired efficacy in AD patients so far. Neuroinflammation and impaired autophagy are two other main known pathologies in AD. It has been reported that these pathologies exist in AD brain long before the emergence of any clinical manifestation of AD. Microglia are the main inflammatory cells in the brain and are considered by many researchers as the next hope for finding a viable therapeutic target in AD. Interestingly, it appears that the autophagy and mitophagy are also changed in these cells in AD. Inside the cells, autophagy and inflammation interact in a bidirectional manner. In the current review, we briefly discussed an overview on autophagy and mitophagy in AD and then provided a comprehensive discussion on the role of these pathways in microglia and their involvement in AD pathogenesis.

Therapeutic Potential of AAV1-Rheb(S16H) Transduction against Neurodegenerative Diseases

Neurotrophic factors (NTFs) are essential for cell growth, survival, synaptic plasticity, and maintenance of specific neuronal population in the central nervous system. Multiple studies have demonstrated that alterations in the levels and activities of NTFs are related to the pathology and symptoms of neurodegenerative disorders, such as Parkinson’s disease (PD), Alzheimer’s disease (AD), and Huntington’s disease. Hence, the key molecule that can regulate the expression of NTFs is an important target for gene therapy coupling adeno-associated virus vector (AAV) gene. We have previously reported that the Ras homolog protein enriched in brain (Rheb)–mammalian target of rapamycin complex 1 (mTORC1) axis plays a vital role in preventing neuronal death in the brain of AD and PD patients. AAV transduction using a constitutively active form of Rheb exerts a neuroprotective effect through the upregulation of NTFs, thereby promoting the neurotrophic interaction between astrocytes and neurons in AD conditions. These findings suggest the role of Rheb as an important regulator of the regulatory system of NTFs to treat neurodegenerative diseases. In this review, we present an overview of the role of Rheb in neurodegenerative diseases and summarize the therapeutic potential of AAV serotype 1 (AAV1)-Rheb(S16H) transduction in the treatment of neurodegenerative disorders, focusing on diseases, such as AD and PD.

Plasmonic Nanoparticles as Optical Sensing Probes for the Detection of Alzheimer's Disease

Alzheimer's disease (AD), considered a common type of dementia, is mainly characterized by a progressive loss of memory and cognitive functions. Although its cause is multifactorial, it has been associated with the accumulation of toxic aggregates of the amyloid-β peptide (Aβ) and neurofibrillary tangles (NFTs) of tau protein. At present, the development of highly sensitive, high cost-effective, and non-invasive diagnostic tools for AD remains a challenge. In the last decades, nanomaterials have emerged as an interesting and useful tool in nanomedicine for diagnostics and therapy. In particular, plasmonic nanoparticles are well-known to display unique optical properties derived from their localized surface plasmon resonance (LSPR), allowing their use as transducers in various sensing configurations and enhancing detection sensitivity. Herein, this review focuses on current advances in in vitro sensing techniques such as Surface-enhanced Raman scattering (SERS), Surface-enhanced fluorescence (SEF), colorimetric, and LSPR using plasmonic nanoparticles for improving the sensitivity in the detection of main biomarkers related to AD in body fluids. Additionally, we refer to the use of plasmonic nanoparticles for in vivo imaging studies in AD.

Molecular imaging of Alzheimer's disease-related gamma-secretase in mice and nonhuman primates

The pathogenesis of Alzheimer’s disease (AD) is primarily driven by brain accumulation of the amyloid-β-42 (Aβ₄₂) peptide generated from the amyloid-β precursor protein (APP) via cleavages by β- and γ-secretase. γ-Secretase is a prime drug target for AD; however, its brain regional expression and distribution remain largely unknown. Here, we are aimed at developing molecular imaging tools for visualizing γ-secretase. We used our recently developed γ-secretase modulators (GSMs) and synthesized our GSM-based imaging agent, [¹¹C]SGSM-15606. We subsequently performed molecular imaging in rodents, including AD transgenic animals, and macaques, which revealed that our probe displayed good brain uptake and selectivity, stable metabolism, and appropriate kinetics and distribution for imaging γ-secretase in the brain. Interestingly, rodents and macaques shared certain brain areas with high γ-secretase expression, suggesting a functional conservation of γ-secretase. Collectively, we have provided the first molecular brain imaging of γ-secretase, which may not only accelerate our drug discovery for AD but also advance our understanding of AD.

The Association Between Early Age-Related Hearing Loss and Brain β-Amyloid

OBJECTIVES/HYPOTHESIS

To analyze the association between early audiometric age-related hearing loss and brain β-amyloid, the pathologic hallmark of Alzheimer's disease (AD).

STUDY DESIGN

Cross-sectional analysis of a prospective cohort study.

METHODS

A cross-sectional analysis was performed on 98 participants in a cohort study of hearing and brain biomarkers of AD. The primary outcome was whole brain β-amyloid standardized uptake value ratio (SUVR) on positron emission tomography (PET). The exposure was hearing, as measured by either pure-tone average or word recognition score in the better ear. Covariates included age, gender, education, cardiovascular disease, and hearing aid use. Linear regression was performed to analyze the association between β-amyloid and hearing, adjusting for potentially confounding covariates.

RESULTS

The mean age ± standard deviation was 64.6 ± 3.5 years. In multivariable regression, adjusting for demographics, education, cardiovascular disease, and hearing aid use, whole brain β-amyloid SUVR increased by 0.029 (95% confidence interval [CI]: 0.003-0.056) for every 10 dB increase in pure-tone average (P = .030). Similarly, whole brain β-amyloid SUVR increased by 0.061 (95% CI: 0.009-0.112) for every 10% increase in word recognition score (P = .012).

CONCLUSIONS

Worsening hearing was associated with higher β-amyloid burden, a pathologic hallmark of AD, measured in vivo with PET scans.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:633-638, 2021.

Preservation of dendritic spine morphology and postsynaptic signaling markers after treatment with solid lipid curcumin particles in the 5xFAD mouse model of Alzheimer's amyloidosis

BACKGROUND

Synaptic failure is one of the principal events associated with cognitive dysfunction in Alzheimer's disease (AD). Preservation of existing synapses and prevention of synaptic loss are promising strategies to preserve cognitive function in AD patients. As a potent natural anti-oxidant, anti-amyloid, and anti-inflammatory polyphenol, curcumin (Cur) shows great promise as a therapy for AD. However, hydrophobicity of natural Cur limits its solubility, stability, bioavailability, and clinical utility for AD therapy. We have demonstrated that solid lipid curcumin particles (SLCP) have greater therapeutic potential than natural Cur in vitro and in vivo models of AD. In the present study, we have investigated whether SLCP has any preservative role on affected dendritic spines and synaptic markers in 5xFAD mice.

METHODS

Six- and 12-month-old 5xFAD and age-matched wild-type mice received oral administration of SLCP (100 mg/kg body weight) or equivalent amounts of vehicle for 2 months. Neuronal morphology, neurodegeneration, and amyloid plaque load were investigated from prefrontal cortex (PFC), entorhinal cortex (EC), CA1, CA3, and the subicular complex (SC). In addition, the dendritic spine density from apical and basal branches was studied by Golgi-Cox stain. Further, synaptic markers, such as synaptophysin, PSD95, Shank, Homer, Drebrin, Kalirin-7, CREB, and phosphorylated CREB (pCREB) were studied using Western blots. Finally, cognitive and motor functions were assessed using open-field, novel object recognition (NOR) and Morris water maze (MWM) tasks after treatment with SLCP.

RESULTS

We observed an increased number of pyknotic and degenerated cells in all these brain areas in 5xFAD mice and SLCP treatment partially protected against those losses. Decrease in dendritic arborization and dendritic spine density from primary, secondary, and tertiary apical and basal branches were observed in PFC, EC, CA1, and CA3 in both 6- and 12-month-old 5xFAD mice, and SLCP treatments partially preserved the normal morphology of these dendritic spines. In addition, pre- and postsynaptic protein markers were also restored by SLCP treatment. Furthermore, SLCP treatment improved NOR and cognitive function in 5xFAD mice.

CONCLUSIONS

Overall, these findings indicate that use of SLCP exerts neuroprotective properties by decreasing amyloid plaque burden, preventing neuronal death, and preserving dendritic spine density and synaptic markers in the 5xFAD mice.

Oral Health Status in Older People with Dementia: A Case-Control Study

Dementia is characterized by a range of cognitive defects with impaired activities of daily living that have implications for patient oral health. Objectives. A case-control study was made of the impact of dementia upon oral health. A total of 152 patients were included: 69 with dementia and 83 controls from the region of Murcia (Spain). The Global Deterioration Scale (GDS) was used to classify the patients and an oral exploration was carried out. Odds ratios (ORs) and confidence intervals (CIs) were estimated using regression models. The patients with more severe disease were significantly more likely to have fewer natural teeth (OR 11.00, 95%CI 1.28–23.22; p = 0.001), a higher plaque index (p = 0.001), and a greater bleeding index (p = 0.001) than the control group. These findings suggest that older adults with dementia have deficient oral health. A higher bleeding index increases the risk of deterioration of cognitive function. The oral hygiene and health of older people with dementia need to be improved.

Cholinesterase inhibitory activity of highly functionalized fluorinated spiropyrrolidine heterocyclic hybrids

Two series of dimethoxyindanone imbedded novel fluorinated spiropyrrolidine heterocyclic hybrids were synthesized employing two different less explored azomethine ylides and were measured for their efficiency as inhibitors for Alzheimer’s disease. Among the spiropyrrolidine heterocyclic hybrids, the indole based fluorinated compound with a methoxy substituent at the meta- position of the aryl ring exhibited the utmost potent AChE and BChE inhibitory activities with an IC₅₀ of 1.97 ± 0.19 µM and 7.08 ± 0.20 µM respectively. The plausible mechanism of inhibition on ChE receptors was unveiled via molecular docking studies.

Impact of Tau on Neurovascular Pathology in Alzheimer's Disease

Alzheimer's disease (AD) is a chronic neurodegenerative disorder and the most prevalent cause of dementia. The main cerebral histological hallmarks are represented by parenchymal insoluble deposits of amyloid beta (Aβ plaques) and neurofibrillary tangles (NFT), intracellular filamentous inclusions of tau, a microtubule-associated protein. It is well-established that cerebrovascular dysfunction is an early feature of AD pathology, but the detrimental mechanisms leading to blood vessel impairment and the associated neurovascular deregulation are not fully understood. In 90% of AD cases, Aβ deposition around the brain vasculature, known as cerebral amyloid angiopathy (CAA), alters blood brain barrier (BBB) essential functions. While the effects of vascular Aβ accumulation are better documented, the scientific community has only recently started to consider the impact of tau on neurovascular pathology in AD. Emerging compelling evidence points to transmission of neuronal tau to different brain cells, including astrocytes, as well as to the release of tau into brain interstitial fluids, which may lead to perivascular neurofibrillar tau accumulation and toxicity, affecting vessel architecture, cerebral blood flow (CBF), and vascular permeability. BBB integrity and functionality may therefore be impacted by pathological tau, consequentially accelerating the progression of the disease. Tau aggregates have also been shown to induce mitochondrial damage: it is known that tau impairs mitochondrial localization, distribution and dynamics, alters ATP and reactive oxygen species production, and compromises oxidative phosphorylation systems. In light of this previous knowledge, we postulate that tau can initiate neurovascular pathology in AD through mitochondrial dysregulation. In this review, we will explore the literature investigating tau pathology contribution to the malfunction of the brain vasculature and neurovascular unit, and its association with mitochondrial alterations and caspase activation, in cellular, animal, and human studies of AD and tauopathies.

Are patients with cognitive impairment fit to fly? Current evidence and practical recommendations

BACKGROUND

The worldwide prevalence of dementia is increasing and represents a major public health concern. In the last decades, air travel services have undergone an impressive expansion and one of ten passengers is aged 65 years and older. While air travel can be stressful at all ages and health conditions, older individuals with cognitive impairment carry a greater risk for air-travel-related complications. Consequently, demands to general practitioners for assessing their older patient's fitness to fly are increasing.

METHODS

We conducted a search of the literature in PubMed on the impact of in-flight environmental changes on passengers with cognitive impairment and possible resulting complications. This set the base for a discussion on pharmacological and non-pharmacological interventions aimed at preventing in-flight complications in this vulnerable population.

RESULTS

While our research strategy identified a total of 11 articles related to older age and air travel, only three focused on passengers with cognitive impairment. Our literature review showed that the airplane environment may lead to a large spectrum of symptoms in passengers of all age groups. However, passengers with cognitive impairment due to neurodegenerative diseases are at increased risk for experiencing the most extreme symptoms such as acute confusional state. Non-pharmacological and pharmacological interventions at different stages of the travel process (before, during and after) can help prevent complications in this vulnerable population.

CONCLUSION

The decision to let a patient with cognitive impairment fly requires a solid understanding of the in-flight environmental changes and their impact on older patients with cognitive impairment. Moreover, a sound weighing of the risks and benefits while considering different aspects of the patient's history is demanded. In this regard, the role of the treating physicians and caregivers is essential along with the support of the medical department of the airline.

Therapeutic Strategies and Nano-Drug Delivery Applications in Management of Aging Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder in which the death of brain cells causes memory loss and cognitive decline. Existing drugs only suppress symptoms or delay further deterioration but do not address the cause of the disease. In spite of screening numerous drug candidates against various molecular targets of AD, only a few candidates, such as acetylcholinesterase inhibitors, are currently utilized as an effective clinical therapy. Currently, nano-based therapies can make a difference, providing new therapeutic options by helping drugs to cross the blood-brain barrier and enter the brain more effectively. The main aim of this review was to highlight advances in research on the development of nano-based therapeutics for improved treatment of AD.