Detecting Early Cognitive Decline in Alzheimer's Disease with Brain Synaptic Structural and Functional Evaluation

A study to determine the effect of nano-selenium and thymoquinone on the Nrf2 gene expression in Alzheimer's disease

INTRODUCTION

Alzheimer's disease is a developing public health concern in aging communities that affects a sizable section of the global population. The risk of Alzheimer's disease increases with age; it affects one-third of males and two-thirds of women. This research attempts to assess the effect of nano-selenium and thymoquinone on Nrf2 gene expression levels in Alzheimer's disease (AD).

METHODS

There were five identical groups of 50 albino male rats: a control group that was healthy; an AD positive control group; an AD group that received nano-selenium (5 mg/kg); an AD group that received thymoquinone (2 mg/kg); and an AD group that received both. The duration of treatment was 4 weeks. The levels of Nrf2 in brain tissues were evaluated using real-time PCR.

RESULTS

Nrf2 mean expression levels in the nano-selenium-treated rats, the thymoquinone-treated rats, and the rats that were given both treatments all increased significantly compared to AD rats with no treatment.

CONCLUSIONS

This study showed that nano-selenium and thymoquinone elevated Nrf2 gene expression levels in AD.

EEG-based graph network analysis in relation to regional tau in asymptomatic Alzheimer's disease

Tau aggregation in early affected regions in the asymptomatic stage of Alzheimer's disease marks a transitional phase between stable asymptomatic amyloid positivity and the clinically manifest stage. How this early region tau aggregation covertly affects brain function during this asymptomatic stage remains unclear. In this study, 83 participants underwent a 128 electrodes resting-state EEG, a dynamic 100 min tau PET scan (18F-MK6240), an amyloid PET scan, a structural T1 MRI scan and neuropsychological assessment. Tau PET data quality control led to a final sample of 66 subjects. Based on the clinical and cognitive status, amyloid and tau PET biomarkers, the group was composed of 37 cognitively unimpaired amyloid negative subjects, 14 cognitively unimpaired amyloid positive subjects and 15 patients with prodromal Alzheimer's disease. We calculated the average undirected weighted Phase Lag Index in the alpha frequency band with eyes closed and used this as weights for the graph and analysed the global clustering coefficient and characteristic path length in sensor space. As a primary objective, we assessed how these global graph measures correlated with tau PET values, in an a priori defined early metaVOI, comprised of the entorhinal and perirhinal cortex, hippocampus, parahippocampus and fusiform cortex. As secondary analyses, we investigated which specific brain regions were mainly implicated, what the contribution was of amyloid, the effect of electrode density and the relation to cognitive performance. In the overall group and within the cognitively unimpaired amyloid positive subgroup, tau aggregation was associated with a decrease in global clustering coefficient and an increase in characteristic path length. These changes reflect the initial disintegration of the small-world brain network during the transitional phase, even before clinical symptoms are apparent. The correlations are most prominent in the perirhinal cortex, indicating that global deterioration of the network is already present early in the Alzheimer's disease pathology. We obtained similar results with only taking 64 electrodes into account. To conclude, we found that in the asymptomatic stage of Alzheimer's disease, tau PET load in medial temporal cortex is associated with global electrophysiological measures of network disintegration. The study demonstrates the potential value of high-density EEG in the era of biologically defined Alzheimer's disease for characterizing brain function in the asymptomatic stage.

Screening tools for subjective cognitive decline and mild cognitive impairment based on task-state prefrontal functional connectivity: a functional near-infrared spectroscopy study

BACKGROUND

Subjective cognitive decline (SCD) and mild cognitive impairment (MCI) carry the risk of progression to dementia, and accurate screening methods for these conditions are urgently needed. Studies have suggested the potential ability of functional near-infrared spectroscopy (fNIRS) to identify MCI and SCD. The present fNIRS study aimed to develop an early screening method for SCD and MCI based on activated prefrontal functional connectivity (FC) during the performance of cognitive scales and subject-wise cross-validation via machine learning.

METHODS

Activated prefrontal FC data measured by fNIRS were collected from 55 normal controls, 80 SCD patients, and 111 MCI patients. Differences in FC were analyzed among the groups, and FC strength and cognitive scale performance were extracted as features to build classification and predictive models through machine learning. Model performance was assessed based on accuracy, specificity, sensitivity, and area under the curve (AUC) with 95 % confidence interval (CI) values.

RESULTS

Statistical analysis revealed a trend toward more impaired prefrontal FC with declining cognitive function. Prediction models were built by combining features of prefrontal FC and cognitive scale performance and applying machine learning models, The models showed generally satisfactory abilities to differentiate among the three groups, especially those employing linear discriminant analysis, logistic regression, and support vector machine. Accuracies of 92.0 % for MCI vs. NC, 80.0 % for MCI vs. SCD, and 76.1 % for SCD vs. NC were achieved, and the highest AUC values were 97.0 % (95 % CI: 94.6 %-99.3 %) for MCI vs. NC, 87.0 % (95 % CI: 81.5 %-92.5 %) for MCI vs. SCD, and 79.2 % (95 % CI: 71.0 %-87.3 %) for SCD vs. NC.

CONCLUSION

The developed screening method based on fNIRS and machine learning has the potential to predict early-stage cognitive impairment based on prefrontal FC data collected during cognitive scale-induced activation.

Alterations in microarchitecture and network integrity in diffusion tensor images of children with marginal intelligence or intellectual disabilities

PURPOSE

To investigate damage to fiber bundles and brain networks in children with marginal intelligence (MI) or intellectual disability (ID) by using Diffusion Tensor Imaging (DTI) sequences.

METHODS

Thirty healthy children, 25 with MI, 35 with ID, and 32 with both ID and attention deficit hyperactivity disorder (ADHD) underwent 3.0 T MRI scans, including DTI sequences. Analysis of the DTI data yielded correlation tractography, network measures, and graph visualizations.

RESULTS

Children with MI, ID or both ID and ADHD have damage in the bilateral arcuate fasciculi, bilateral superior longitudinal fasciculi and thalamic radiations, corpus callosum's body, and right corticostriatal tracts. Furthermore, both the MI and ID-ADHD groups were affected in the right parietal aslant tract, bilateral corticospinal tracts, and bilateral medial lemnisci, which were not affected in patients with ID alone. The MI, ID and ID-ADHD groups exhibited a significantly lower density, global efficiency, and rich club coefficient than the controls. Patients with MI, ID, or both ID and ADHD had no nodes in the bilateral middle and inferior frontal gyri. Moreover, individuals with ID, alone or combined with ADHD, also lacked nodes in the bilateral temporal lobes.

CONCLUSION

Children with MI, ID, or comorbid ID and ADHD exhibited significant morphological abnormalities in fiber tracts, substantial reductions in fiber bundle volumes, and disrupted neural network connectivity. Furthermore, graph visualizations of the connectome reveal a progressive increase in the defect of hub nodes, worsening from MI to ID, whether alone or in conjunction with ADHD, when compared to normal controls.

Growth associated protein 43 (GAP-43) predicts brain amyloidosis in Alzheimer's dementia continuum: an [18 F] AV-45 study

BACKGROUND

Growth-associated protein 43 (GAP-43) is a key protein involved in neuronal growth and synaptic plasticity. Alterations in GAP-43 levels have been associated with Alzheimer's Disease (AD), potentially reflecting synaptic dysfunction. We evaluated the potential of GAP-43 as a biomarker for AD and explored its association with amyloid-beta (Aβ) levels, as well as its correlation with Aβ plaque burden in the brain.

METHODS

We screened 1,639 participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort. A total of 226 individuals met the eligibility criteria and were enrolled. Participants were classified into three groups: 77 cognitively normal (CN) individuals, 111 with mild cognitive impairment (MCI), and 38 with a diagnosis of AD. The associations between cerebrospinal fluid (CSF) GAP-43 levels with other biomarkers as well as [¹⁸F] AV-45 (Florbetapir) PET Standardized Uptake Value Ratios (SUVR) were investigated.

RESULTS

Our findings revealed significantly elevated CSF GAP-43 levels in individuals with AD compared to CN and MCI groups. Furthermore, GAP-43 levels showed a significant positive correlation with tau pathology. Notably, we observed a significant association between GAP-43 and [¹⁸F] Florbetapir PET SUVR in the MCI group, suggesting that GAP-43 may serve as a reliable biomarker in the early stages of AD.

CONCLUSION

This study provides evidence supporting the role of GAP-43 as a potential biomarker for AD, particularly in relation to predicting the amyloid pathology pattern in the brain in the MCI stage.

Longitudinal excitation-inhibition balance altered by sex and APOE-ε4

Neuronal hyperexcitation affects memory and neural processing across the Alzheimer's disease (AD) cognitive continuum. Levetiracetam, an antiepileptic, shows promise in improving cognitive impairment by restoring the neural excitation/inhibition balance in AD patients. We previously identified a hyper-excitable phenotype in cognitively unimpaired female APOE-ε4 carriers relative to male counterparts cross-sectionally. This sex difference lacks longitudinal validation; however, clarifying the vulnerability of female ε4-carriers could better inform antiepileptic treatment efficacy. Here, we investigated this sex-by-ε4 interaction using a longitudinal design. We used resting-state fMRI and diffusion tensor imaging collected longitudinally from 106 participants who were cognitively unimpaired for at least one scan event but may have been assessed to have clinical dementia ratings corresponding to early mild cognitive impairment over time. By including scan events where participants transitioned to mild cognitive impairment, we modeled the trajectory of the whole-brain excitation-inhibition ratio throughout the preclinical cognitively healthy continuum and extended to early impairment. A linear mixed model revealed a significant three-way interaction among sex, ε4-status, and time, with female ε4-carriers showing a significant hyper-excitable trajectory. These findings suggest a possible pathway for preventative therapy targeting preclinical hyperexcitation in female ε4-carriers.

Cortical structure of left superior parietal cortex is associated with cognition and dual tasking: A cross-sectional preliminary study between mild cognitive impairment and healthy controls

BACKGROUND

Individuals with mild cognitive impairment (MCI) exhibit poorer performance in cognition and dual-task paradigm, while the related cortical thickness and surface area alterations remains unclear.

METHODS

Thirty participants with MCI and thirty healthy controls (HC) were recruited. Magnetic resonance imaging, cognitive assessments and dual-task Timed Up and Go test (DT-TUG) were performed to assess cerebral cortical thickness and surface area, cognitive functions, and dual-task cost (DTC) of the execution time in TUG. Spearman correlations were conducted to assess the relationships between the cognitive, TUG performance with the cortical morphological measures.

RESULTS

MCI participants performed worse in the Montreal cognitive assessment (MoCA), WAIS Digit Span, TMT and the modified Posner peripheral cuing task. Their execution time on the DT-TUG was also prolonged. WAIS Digit Span Backwards was correlated with DT-TUG in HC group. A significant between-group difference was observed in the surface area of the left SPC. The cortical thickness of this brain region was positively correlated with the total scores and attention subdomain of MoCA in HC group. The cortical thickness and the surface area were correlated with the time of DT-TUG in HC group only.

CONCLUSIONS

Individuals with MCI demonstrated declines in both cognitive function and dual-task walking performance. This study provides further evidence of surface-based structural differences in the left SPC in individuals with and without MCI, and supports the role of the left SPC in cognition and dual-task walking.

Emerging biophysical techniques for probing synaptic transmission in neurodegenerative disorders

Plethora of research has shed light on the critical role of synaptic dysfunction in various neurodegenerative disorders (NDDs), including Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). Synapses, the fundamental units for neural communication in the brain, are highly vulnerable to pathological conditions and are central to the progression of neurological diseases. The presynaptic terminal, a key component of synapses responsible for neurotransmitter release and synaptic communication, undergoes structural and functional alterations in these disorders. Understanding synaptic transmission abnormalities is crucial for unravelling the pathophysiological mechanisms underlying neurodegeneration. In the quest to probe synaptic transmission in NDDs, emerging biophysical techniques play a pivotal role. These advanced methods offer insights into the structural and functional changes occurring at nerve terminals in conditions like AD, PD, HD & ALS. By investigating synaptic plasticity and alterations in neurotransmitter release dynamics, researchers can uncover valuable information about disease progression and potential therapeutic targets. The review articles highlighted provide a comprehensive overview of how synaptic vulnerability and pathology are shared mechanisms across a spectrum of neurological disorders. In major neurodegenerative diseases, synaptic dysfunction is a common thread linking these conditions. The intricate molecular machinery involved in neurotransmitter release, synaptic vesicle dynamics, and presynaptic protein regulation are key areas of focus for understanding synaptic alterations in neurodegenerative diseases.

Evaluating remyelination compounds for new applications in opioid use disorder management

Opioid use disorder (OUD) is associated with a reduction in brain white matter, affecting critical areas involved in decision-making, impulse control, and reward processing. The FDA has approved several drugs and natural compounds that enhance myelination, targeting oligodendrocyte progenitor cells (OPCs), directly enhancing oligodendrocyte (OL) function, or acting as cofactors for myelin production. This retrospective case study aimed to assess whether current clinical evidence supports the use of myelin-enhancing agents to promote remission in OUD. We evaluated a range of compounds with demonstrated effects on myelination, including muscarinic antagonists, cholesterol and lipid homeostatic agents, anti-aging drugs, immunomodulatory agents, anti-inflammatory medications, and others (25 medications in total), as well as 17 vitamins and supplements. Buprenorphine and methadone were used as positive controls. Sequential analyses were performed to identify individual drugs driving significant changes in remission rates (p ≤ 0.01; N ≥ 3,000) and their effects across age, sex, and Body Mass Index (BMI) categories. Three key findings emerged: (1) melatonin improved remission rates in males but showed no effect in females; (2) ibuprofen significantly increased remission rates, particularly in individuals aged 20-39 and 40-59 years; and (3) thiamin was associated with decreased remission rates in males and individuals with a BMI ranging from normal weight to obese. Additionally, buprenorphine and methadone were confirmed as effective in promoting remission. These findings highlight the importance of personalized medicine in treating OUD and suggest that further research is needed to explore individualized treatment strategies based on sex, age, and BMI.

Mendelian randomization in Alzheimer's disease and mild cognitive impairment: Hippocampal volume associations

This study investigates the association between cognitive dysfunction and hippocampal volumes in Alzheimer's Disease (AD) and Mild Cognitive Impairment (MCI) using Mendelian randomization. A meta-analysis of 503 healthy controls, 562 MCI patients, and 389 CE patients revealed significant reductions in hippocampal and subregion volumes in MCI and AD compared to controls. While various subregions showed volume reductions, no causal relationship between hippocampal volume and AD was established through Mendelian randomization analysis. In conclusion, significant volume reductions were observed in MCI and AD patients, highlighting the complexity of the relationship between hippocampal volume and cognitive impairment.

From Plaques to Pathways in Alzheimer's Disease: The Mitochondrial-Neurovascular-Metabolic Hypothesis

Alzheimer's disease (AD) presents a public health challenge due to its progressive neurodegeneration, cognitive decline, and memory loss. The amyloid cascade hypothesis, which postulates that the accumulation of amyloid-beta (Aβ) peptides initiates a cascade leading to AD, has dominated research and therapeutic strategies. The failure of recent Aβ-targeted therapies to yield conclusive benefits necessitates further exploration of AD pathology. This review proposes the Mitochondrial-Neurovascular-Metabolic (MNM) hypothesis, which integrates mitochondrial dysfunction, impaired neurovascular regulation, and systemic metabolic disturbances as interrelated contributors to AD pathogenesis. Mitochondrial dysfunction, a hallmark of AD, leads to oxidative stress and bioenergetic failure. Concurrently, the breakdown of the blood-brain barrier (BBB) and impaired cerebral blood flow, which characterize neurovascular dysregulation, accelerate neurodegeneration. Metabolic disturbances such as glucose hypometabolism and insulin resistance further impair neuronal function and survival. This hypothesis highlights the interconnectedness of these pathways and suggests that therapeutic strategies targeting mitochondrial health, neurovascular integrity, and metabolic regulation may offer more effective interventions. The MNM hypothesis addresses these multifaceted aspects of AD, providing a comprehensive framework for understanding disease progression and developing novel therapeutic approaches. This approach paves the way for developing innovative therapeutic strategies that could significantly improve outcomes for millions affected worldwide.

Carotenoid Supplementation for Alleviating the Symptoms of Alzheimer's Disease

Alzheimer's disease (AD) is characterized by, among other things, dementia and a decline in cognitive performance. In AD, dementia has neurodegenerative features and starts with mild cognitive impairment (MCI). Research indicates that apoptosis and neuronal loss occur in AD, in which oxidative stress plays an important role. Therefore, reducing oxidative stress with antioxidants is a natural strategy to prevent and slow down the progression of AD. Carotenoids are natural pigments commonly found in fruits and vegetables. They include lipophilic carotenes, such as lycopene, α- and β-carotenes, and more polar xanthophylls, for example, lutein, zeaxanthin, canthaxanthin, and β-cryptoxanthin. Carotenoids can cross the blood-brain barrier (BBB) and scavenge free radicals, especially singlet oxygen, which helps prevent the peroxidation of lipids abundant in the brain. As a result, carotenoids have neuroprotective potential. Numerous in vivo and in vitro studies, as well as randomized controlled trials, have mostly confirmed that carotenoids can help prevent neurodegeneration and alleviate cognitive impairment in AD. While carotenoids have not been officially approved as an AD therapy, they are indicated in the diet recommended for AD, including the consumption of products rich in carotenoids. This review summarizes the latest research findings supporting the potential use of carotenoids in preventing and alleviating AD symptoms. A literature review suggests that a diet rich in carotenoids should be promoted to avoid cognitive decline in AD. One of the goals of the food industry should be to encourage the enrichment of food products with functional substances, such as carotenoids, which may reduce the risk of neurodegenerative diseases.

Exploring Dimethylsulfoniopropionate as a potential treatment for Alzheimer's disease: A study using the 3 × Tg-AD mouse model

BACKGROUND

Alzheimer's disease (AD), the most common neurodegenerative disorder, affects a broad spectrum of aging populations. AD is characterized by pathological amyloid-β (Aβ) plaques and neurofibrillary tangles, leading to neural degeneration and cognitive decline. The lack of effective treatments for AD highlights the urgent need for novel therapeutic agents, particularly in the early stages. Dimethylsulfoniopropionate (DMSP) is a natural marine compound with antioxidant and neuroprotective properties. However, studies on the efficacy of DMSP in the treatment of AD and its associated mechanisms are limited.

PURPOSE

This study aimed to explore the therapeutic effects and mechanisms of action of DMSP as an AD treatment using a preclinical 3 × Tg-AD mouse model.

METHODS

The research involved administering DMSP (7 μg/mL and 11 μg/mL in drinking water) to four-month-old 3 × Tg-AD mice consecutively for three months. The Y-maze test, novel object recognition test, and Morris water maze test were used to assess memory and learning ability. The relative expression levels and distribution of proteins relevant to Aβ and tau pathology, synapses, and glial cells were analyzed using western blotting and immunofluorescence assays. Additionally, proteomic and bioinformatics approaches were used to explore the potential targets of DMSP treatment.

RESULTS

DMSP-treated AD mice showed significantly enhanced cognitive function, suggesting that DMSP mitigates memory and learning impairments in AD. Moreover, DMSP diminished the abnormal accumulation of Aβ and phosphorylated tau in both the cortex and hippocampus, which are crucial hallmarks of AD pathology. In addition to its neuroprotective properties, DMSP restored synaptic density and the expression of synaptic and neuronal proteins, which are essential for proper brain function. DMSP displayed anti-inflammatory properties, as evidenced by its ability to suppress inflammatory astrocytes and maintain microglial homeostasis. Notably, DMSP facilitated the maturation of oligodendrocytes (OLs) from oligodendrocyte progenitor cells (OPCs), a critical process in the development of the brain myelination architecture. Proteomic analysis revealed that DMSP positively influenced biological processes crucial for oligodendrocyte development, myelination, and axonal ensheathment, which are often compromised in patients with AD. Protein validation and brain tissue staining supported the role of DMSP in preserving myelin enrichment and sheath integrity. These therapeutic effects were largely attributed to the enhanced expression of myelin-associated glycoprotein (Mag) and tetraspanin Cd9.

CONCLUSION

Overall, our findings highlight DMSP as a promising novel therapeutic candidate for AD, offering multifaceted benefits in cognitive and memory enhancement, reduction of Aβ and tau pathology, neuronal synapse protection, anti-inflammatory effects, and myelin sheath restoration as an innovative target compared to other studies. In addition to being a potentially effective treatment for AD, DMSP may also have the potential to address other neurodegenerative diseases that are closely associated with myelin impairment.

New insights into sodium phenylbutyrate as a pharmacotherapeutic option for neurological disorders

Neurological disorders (NDs) are diseases of the central and peripheral nervous systems that affect more than one billion people worldwide. The risk of developing an ND increases with age due to the vulnerability of the different organs and systems to genetic, environmental, and social changes that consequently cause motor and cognitive deficits that disable the person from their daily activities and individual and social productivity. Intrinsic factors (genetic factors, age, gender) and extrinsic factors (addictions, infections, or lifestyle) favor the persistence of systemic inflammatory processes that contribute to the evolution of NDs. Neuroinflammation is recognized as a common etiopathogenic factor of ND. The study of new pharmacological options for the treatment of ND should focus on improving the characteristic symptoms and attacking specific molecular targets that allow the delay of damage processes such as neuroinflammation, oxidative stress, cellular metabolic dysfunction, and deregulation of transcriptional processes. In this review, we describe the possible role of sodium phenylbutyrate (NaPB) in the pathogenesis of Alzheimer's disease, hepatic encephalopathy, aging, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis; in addition, we describe the mechanism of action of NaPB and its beneficial effects that have been shown in various in vivo and in vitro studies to delay the evolution of any ND.

Development of dietary small molecules as multi-targeting treatment strategies for Alzheimer's disease

Cognitive dysfunction can occur both in normal aging and age-related neurological disorders, such as mild cognitive impairment and Alzheimer's disease (AD). These disorders have few treatment options due to side effects and limited efficacy. New approaches to slow cognitive decline are urgently needed. Dietary interventions (nutraceuticals) have received considerable attention because they exhibit strong neuroprotective properties and may help prevent or minimize AD symptoms. Biological aging is driven by a series of interrelated mechanisms, including oxidative stress, neuroinflammation, neuronal apoptosis, and autophagy, which function through various signaling pathways. Recent clinical and preclinical studies have shown that dietary small molecules derived from natural sources, including flavonoids, carotenoids, and polyphenolic acids, can modulate oxidative damage, cognitive impairments, mitochondrial dysfunction, neuroinflammation, neuronal apoptosis, autophagy dysregulation, and gut microbiota dysbiosis. This paper reviews research on different dietary small molecules and their bioactive constituents in the treatment of AD. Additionally, the chemical structure, effective dose, and specific molecular mechanisms of action are comprehensively explored. This paper also discusses the advantages of using nanotechnology-based drug delivery, which significantly enhances oral bioavailability, safety, and therapeutic effect, and lowers the risk of adverse effects. These agents have considerable potential as novel and safe therapeutic agents that can prevent and combat age-related AD.

Taurine reduces microglia activation in the brain of aged senescence-accelerated mice by increasing the level of TREM2

Alzheimer's disease (AD), a chronic neurodegenerative disorder, is the leading cause of dementia. Over-activated microglia is related to amyloid-beta (Aβ) and phosphorylated tau (phospho-tau) accumulation in the AD brain. Taurine is an amino acid with multiple physiological functions including anti-inflammatory effects, and has been reported to be neuroprotective in AD. However, the role of taurine in microglia-mediated AD remains unclear. Here, we examined the effects of taurine on the brains of senescence-accelerated mouse prone 8 (SAMP8) mice by comparing those administered 1% taurine water with those administered distilled water (DW). We observed increased levels of taurine and taurine transporter (TAUT) in the brains of the taurine-treated mice compared with those of control mice. Immunohistochemical and Western blot analyses revealed that taurine significantly reduced the number of activated microglia, levels of phospho-tau and Aβ deposit in the hippocampus and cortex. Triggering receptors expressed on myeloid cells-2 (TREM2) are known to protect against AD pathogenesis. Taurine upregulated TREM2 expression in the hippocampus and cortex. In conclusion, the present study suggests that taurine treatment may upregulate TREM2 to protect against microglia over-activation by decreasing the accumulation of phospho-tau and Aβ; providing an insight into a novel preventive strategy in AD.

The Effects of Different Exercise Interventions on Patients with Subjective Cognitive Decline: A Systematic Review and Network Meta-Analysis

BACKGROUND AND OBJECTIVE

Exercise is a promising non-pharmacological therapy for subjective cognitive decline, but it is unclear which type of exercise is most effective. The objective was to assess the comparative effects and ranks of all exercise-based interventions on cognitive function in patients with subjective cognitive decline (SCD).

METHOD

In this network meta-analysis, Online databases for Web of Science, PubMed, Embase, Medline, Cochrane Library and PsycINFO were searched from inception to April 30, 2023. The included studies are randomized controlled trials assessing the efficacy of exercise interventions for individuals with SCD. The primary outcome measure is memory, while secondary outcome measures encompass executive function, attention, verbal fluency, and global cognitive function. Represented using Standardized Mean Differences (SMDs) along with their 95% Confidence Intervals (CIs). Bias assessment was conducted in accordance with the 'Cochrane Risk of Bias Assessment Tool, 2nd Edition' (RoB 2). Pairwise meta-analysis was carried out using the 'meta-analysis' module within STATA 14.0, and network meta-analysis was performed using the 'mvmeta' and 'network' packages available in STATA 14.0. Registration number CRD42023289687.

RESULT

This study included a total of 11 randomized controlled trials, encompassing 1,166 patients. Mind-body exercise was found to be efficacious in enhancing or sustaining memory (SMD: 0.58, 95%CI: 0.06 ~ 1.10) and executive function (SMD: 0.41, 95%CI: 0.09 ~ 0.73) in individuals with subjective cognitive decline. Furthermore, mind-body exercise exhibited the highest probability of being the most effective measures for improving or preventing the decline in memory (surface under cumulative ranking curve (SUCRA) value: 90.4) and executive function (SUCRA value: 91.8). The second-ranked moderate-intensity aerobic exercise has also shown a positive effect on the improvement of executive function in patients with subjective cognitive decline (SMD: 0.23, 95%CI: 0.03 ~ 0.43, SUCRA value: 68.2). However, we did not observe a significant effectiveness of exercise interventions on verbal fluency, attention, and overall cognitive function in subjective cognitive decline.

CONCLUSION

Mind-body exercise may potentially be the optimal strategies for enhancing memory and executive function in individuals with subjective cognitive decline. Additionally, moderate-intensity aerobic exercise has shown a modest positive effect on executive function in subjective cognitive decline. When resources permit, practical application of these findings may be considered. Nevertheless, further support for the conclusions of this study is warranted through larger sample sizes and well-designed multicenter trials.

Mitigating cognitive impairment in aging mice: Exploring the therapeutic potential of ischelium

To deeply explore the intervention effects of ischelium on the cognitive memory decline in naturally aging mice and its potential mechanisms, we randomly divided mice into four groups: young control group (C), elderly group (M), ischelium low-dose group (L), and ischelium high-dose group (H). The experiment lasted for 12 weeks. We employed the Y-maze test, open field test, and conditioned fear test to evaluate the memory functions of each group. Through HE staining and electron microscopy, we observed morphological changes in the mouse hippocampus. RT-PCR was used to detect changes in the expression of factors related to cognitive function in the hippocampus of elderly mice. We analyzed the changes in the Nrf2/HO-1 pathway and the inflammatory factors IL-1β and TNF-α using elisa. Additionally, we examined the enzymatic activities of SOD, CAT, GSH-Px, and MDA in the hippocampus and analyzed the compositional changes of gut microbiota in mice using 16S technology. Our results indicate that ischelium effectively ameliorates cognitive impairments in elderly mice.

A systematic review of the neuropathology and memory decline induced by monosodium glutamate in the Alzheimer's disease-like animal model

This systematic review analyzes monosodium glutamate (MSG) in the Alzheimer's disease-like condition to enhance translational research. Our review seeks to understand how MSG affects the brain and causes degenerative disorders. Due to significant preclinical data linking glutamate toxicity to Alzheimer's disease and the lack of a comprehensive review or meta-analysis, we initiated a study on MSG's potential link. We searched PubMed, ScienceDirect, ProQuest, DOAJ, and Scopus for animal research and English language papers without time constraints. This study used the PRISMA-P framework and PICO technique to collect population, intervention or exposure, comparison, and result data. It was registered in PROSPERO as CRD42022371502. MSG affected mice's exploratory behaviors and short-term working memory. The brain, hippocampus, and cerebellar tissue demonstrated neuronal injury-related histological and histomorphometric changes. A total of 70% of MSG-treated mice had poor nesting behavior. The treated mice also had more hyperphosphorylated tau protein in their cortical and hippocampus neurons. Glutamate and glutamine levels in the brain increased with MSG, and dose-dependent mixed horizontal locomotor, grooming, and anxiety responses reduced. MSG treatment significantly decreased phospho-CREB protein levels, supporting the idea that neurons were harmed, despite the increased CREB mRNA expression. High MSG doses drastically lower brain tissue and serum serotonin levels. In conclusion, MSG showed AD-like pathology, neuronal atrophy, and short-term memory impairment. Further research with a longer time span and deeper behavioral characterization is needed. Systematic review registration: https://www.crd.york.ac.uk/prospero/, identifier [CRD42022371502].

Cognitive Normal Older Adults with APOE-2 Allele Show a Distinctive Functional Connectivity Pattern in Response to Cerebral Aβ Deposition

The ε2 allele of apolipoprotein E (ε2) has neuroprotective effects against beta-amyloid (Aβ) pathology in Alzheimer's disease (AD). However, its impact on the functional connectivity and hub efficiency in cognitively normal older adults (CN) with ε2 is unclear. We investigated the functional connectivity differences in the default mode network (DMN), salience network, and central executive network (CEN) between A-PET-negative (N = 29) and A-PET-positive (N = 15) CNs with ε2/ε2 or ε2/ε3 genotypes. The A-PET-positive CNs exhibited a lower anterior DMN functional connectivity, higher posterior DMN functional connectivity, and increased CEN functional connectivity compared to the A-PET-negative CNs. Cerebral Aβ retention was negatively correlated with anterior DMN functional connectivity and positively correlated with posterior DMN and anterior CEN functional connectivity. A graph theory analysis showed that the A-PET-positive CNs displayed a higher betweenness centrality in the middle frontal gyrus (left) and medial fronto-parietal regions (left). The betweenness centrality in the middle frontal gyrus (left) was positively correlated with Aβ retention. Our findings reveal a reversed anterior-posterior dissociation in the DMN functional connectivity and heightened CEN functional connectivity in A-PET-positive CNs with ε2. Hub efficiencies, measured by betweenness centrality, were increased in the DMN and CEN of the A-PET-positive CNs with ε2. These results suggest unique functional connectivity responses to Aβ pathology in CN individuals with ε2.

Anti-oxidative-initiated cognitive impairment amelioration in Alzheimer's Disease model rats through preventive transcutaneous electrical acupoint stimulation

Background

Alzheimer's disease (AD) is a chronic and irreversible neurodegenerative disease. Oxidative stress emerges at the early AD stage. As a non-invasive therapy with few adverse reactions, transcutaneous electrical acupoint stimulation (TEAS) combines acupuncture points of traditional Chinese medicine (TCM) and electrical stimulation. This study aimed to investigate the amelioration effects of preventive TEAS treatment (P-TEAS) on cognitive impairment and oxidative stress in AD model rats.

Methods

The AD model was established via subcutaneous injections of D-galactose (D-gal, 120 mg/kg/d) into the back of neck for 9 weeks in Sprague Dawley (SD) rats to simulate the oxidative stress in the early AD stage. On the first day of the 10th week, Aβ_1-42 (1 μg/μl) was injected into the CA1 regions of the bilateral hippocampus. P-TEAS was synchronized from the first day of subcutaneous D-gal injections for 9 weeks.

Results

Empirical measurements showed that P-TEAS can improve the spatial memory ability of AD model rats in the Morris water maze. Superoxide dismutase (SOD) was upregulated in the P-TEAS group. Through the detection of the anti-oxidative stress signaling pathway, namely, Kelch-like ECH-associated protein 1 (Keap1)/ NFE2-related factor 2 (Nrf2), it was found that P-TEAS could promote Nrf2 entering into the nucleus and upregulating the production of protective factors heme oxygenase 1 (HO-1) and NADPH quinone oxidoreductase 1 (NQO1). It was also found that P-TEAS could downregulate the expressions of BCL2-associated X-protein (Bax), caspase 3, and caspase 9 to inhibit neuronal apoptosis.

Conclusions

P-TEAS has similar efficacy to electroacupuncture in preventing AD occurrence and development. P-TEAS is a new non-invasive intervention therapy for the prevention of AD.