Exercise-Induced Benefits for Alzheimer's Disease by Stimulating Mitophagy and Improving Mitochondrial Function

Efficacy of exercise rehabilitation for managing patients with Alzheimer's disease

Alzheimer's disease (AD) is a progressive and degenerative neurological disease characterized by the deterioration of cognitive functions. While a definitive cure and optimal medication to impede disease progression are currently unavailable, a plethora of studies have highlighted the potential advantages of exercise rehabilitation for managing this condition. Those studies show that exercise rehabilitation can enhance cognitive function and improve the quality of life for individuals affected by AD. Therefore, exercise rehabilitation has been regarded as one of the most important strategies for managing patients with AD. Herein, we provide a comprehensive analysis of the currently available findings on exercise rehabilitation in patients with AD, with a focus on the exercise types which have shown efficacy when implemented alone or combined with other treatment methods, as well as the potential mechanisms underlying these positive effects. Specifically, we explain how exercise may improve the brain microenvironment and neuronal plasticity. In conclusion, exercise is a cost-effective intervention to enhance cognitive performance and improve quality of life in patients with mild to moderate cognitive dysfunction. Therefore, it can potentially become both a physical activity and a tailored intervention. This review may aid the development of more effective and individualized treatment strategies to address the challenges imposed by this debilitating disease, especially in low- and middle-income countries.

Promoting Alzheimer's disease research and therapy with stem cell technology

BACKGROUND

Alzheimer's disease (AD) is a prevalent form of dementia leading to memory loss, reduced cognitive and linguistic abilities, and decreased self-care. Current AD treatments aim to relieve symptoms and slow disease progression, but a cure is elusive due to limited understanding of the underlying disease mechanisms.

MAIN CONTENT

Stem cell technology has the potential to revolutionize AD research. With the ability to self-renew and differentiate into various cell types, stem cells are valuable tools for disease modeling, drug screening, and cell therapy. Recent advances have broadened our understanding beyond the deposition of amyloidβ (Aβ) or tau proteins in AD to encompass risk genes, immune system disorders, and neuron-glia mis-communication, relying heavily on stem cell-derived disease models. These stem cell-based models (e.g., organoids and microfluidic chips) simulate in vivo pathological processes with extraordinary spatial and temporal resolution. Stem cell technologies have the potential to alleviate AD pathology through various pathways, including immunomodulation, replacement of damaged neurons, and neurotrophic support. In recent years, transplantation of glial cells like oligodendrocytes and the infusion of exosomes have become hot research topics.

CONCLUSION

Although stem cell-based models and therapies for AD face several challenges, such as extended culture time and low differentiation efficiency, they still show considerable potential for AD treatment and are likely to become preferred tools for AD research.

Ribonucleotide reductase inhibition improves the symptoms of a Caenorhabditis elegans model of Alzheimer's disease

Alzheimer's disease is the main cause of aging-associated dementia, for which there is no effective treatment. In this work, we reanalyze the information of a previous genome wide association study, using a new pipeline design to identify novel potential drugs. With this approach, ribonucleoside-diphosphate reductase gene (RRM2B) emerged as a candidate target and its inhibitor, 2', 2'-difluoro 2'deoxycytidine (gemcitabine), as a potential pharmaceutical drug against Alzheimer's disease. We functionally verified the effect of inhibiting the RRM2B homolog, rnr-2, in an Alzheimer's model of Caenorhabditis elegans, which accumulates human Aβ1-42 peptide to an irreversible paralysis. RNA interference against rnr-2 and also treatment with 200 ng/ml of gemcitabine, showed an improvement of the phenotype. Gemcitabine treatment increased the intracellular ATP level 3.03 times, which may point to its mechanism of action. Gemcitabine has been extensively used in humans for cancer treatment but at higher concentrations. The 200 ng/ml concentration did not exert a significant effect over cell cycle, or affected cell viability when assayed in the microglia N13 cell line. Thus, the inhibitory drug of the RRM2B activity could be of potential use to treat Alzheimer's disease and particularly gemcitabine might be considered as a promising candidate to be repurposed for its treatment.

Exhaustive exercise decreases tau phosphorylation and modifies biological processes associated with the protein translation and electron transport chain in P301L tau transgenic mice

Stress response is a fundamental mechanism for cell survival, providing protection under unfavorable conditions. Mitochondrial stress, in particular, can trigger mitophagy, a process that restores cellular health. Exhaustive exercise (EE) is a form of acute mitochondrial stress. The objective of this current study is to investigate the impact of EE on tau pathology in pR5 mice, as well as the potential underlying mechanisms. To evaluate this, we examined the levels of total and phosphorylated tau in the hippocampus of pR5 mice, both with and without EE treatment. Furthermore, the application of weighted correlation network analysis (WGCNA) was employed to identify protein modules associated with the phenotype following the proteomic experiment. The findings of our study demonstrated a significant decrease in tau phosphorylation levels upon EE treatment, in comparison to the pR5 group. Moreover, the proteomic analysis provided additional insights, revealing that the mitigation of tau pathology was primarily attributed to the modulation of various pathways, such as translation factors and oxidative phosphorylation. Additionally, the analysis of heatmaps revealed a significant impact of EE treatment on the translation process and electron transport chain in pR5 mice. Furthermore, biochemical analysis provided further confirmation that EE treatment effectively modulated the ATP level in pR5 mice. In conclusion, our study suggests that the observed decrease in tau phosphorylation resulting from EE treatment may primarily be attributed to its regulation of the translation process and enhancement of mitochondrial function.

Alzheimer's Disease Puzzle: Delving into Pathogenesis Hypotheses

Alzheimer's disease (AD) is a prevalent neurodegenerative disease characterized by both amnestic and non-amnestic clinical manifestations. It accounts for approximately 60-70% of all dementia cases worldwide. With the increasing number of AD patients, elucidating underlying mechanisms and developing corresponding interventional strategies are necessary. Hypotheses about AD such as amyloid cascade, Tau hyper-phosphorylation, neuroinflammation, oxidative stress, mitochondrial dysfunction, cholinergic, and vascular hypotheses are not mutually exclusive, and all of them play a certain role in the development of AD. The amyloid cascade hypothesis is currently the most widely studied; however, other hypotheses are also gaining support. This article summarizes the recent evidence regarding major pathological hypotheses of AD and their potential interplay, as well as the strengths and weaknesses of each hypothesis and their implications for the development of effective treatments. This could stimulate further studies and promote the development of more effective therapeutic strategies for AD.

Comparative Efficacy, Tolerability, and Acceptability of Donanemab, Lecanemab, Aducanumab, Melatonin, and Aerobic Exercise for a Short Time on Cognitive Function in Mild Cognitive Impairment and Mild Alzheimer's Disease: A Systematic Review and Network Meta-Analysis

Background

The Food and Drug Administration (FDA) has approved lecanemab and aducanumab and is reviewing donanemab, but they have questionable efficacy, serious side effects and are costly, whereas melatonin administration and aerobic exercise for a short time may overcome these problems.

Objective

We aim to compare the efficacy on cognitive function, tolerability and acceptability of melatonin administration and aerobic exercise for a short time with donanemab, lecanemab, and aducanumab in people with mild AD and MCI.

Methods

We systematically reviewed relevant randomized placebo-controlled trials (RCTs) in PubMed, the Cochrane Library, CINHAL, and ClinicalTrials.gov and performed network meta-analyses.

Results

The analysis included 10 randomized placebo-controlled trials with 4,599 patients. Although melatonin and aerobic exercise for a short time were significantly more effective than donanemab, lecanemab, aducanumab and placebo in the primary analysis, there was significant heterogeneity. In the sensitivity analysis excluding exercise, melatonin was significantly more effective than donanemab, lecanemab, aducanumab and placebo, with no significant heterogeneity. Aerobic exercise for a short time was significantly less acceptable than donanemab, aducanumab and placebo. Donanemab, lecanemab, and aducanumab were significantly less tolerable than placebo and donanemab and lecanemab were significantly less acceptable than placebo.

CONCLUSIONS

Melatonin may be a better potential disease-modifying treatment for cognitive decline in mild AD and MCI. Aerobic exercise for a short time might also be better than donanemab, lecanemab and aducanumab if continued, as it is well tolerated and more effective, although less valid due to heterogeneity. Another limitation is the small number of participants.

The Natural Alkaloid Palmatine Selectively Induces Mitophagy and Restores Mitochondrial Function in an Alzheimer's Disease Mouse Model

Palmatine, a natural alkaloid found in various plants, has been reported to have diverse pharmacological and biological effects, including anti-inflammatory, antioxidant, and cardiovascular effects. However, the role of palmatine in mitophagy, a fundamental process crucial for maintaining mitochondrial function, remains elusive. In this study, we found that palmatine efficiently induces mitophagy in various human cell lines. Palmatine specifically induces mitophagy and subsequently stimulates mitochondrial biogenesis. Palmatine did not interfere with mitochondrial function, similar to CCCP, suggesting that palmatine is not toxic to mitochondria. Importantly, palmatine treatment alleviated mitochondrial dysfunction in PINK1-knockout MEFs. Moreover, the administration of palmatine resulted in significant improvements in cognitive function and restored mitochondrial function in an Alzheimer's disease mouse model. This study identifies palmatine as a novel inducer of selective mitophagy. Our results suggest that palmatine-mediated mitophagy induction could be a potential strategy for Alzheimer's disease treatment and that natural alkaloids are potential sources of mitophagy inducers.

Aerobic Exercise in Male Mice Prevents Ventilator-Induced Lung Injury by Inhibiting Mitochondrial Damage from sirt1 Dysregulation

BACKGROUND

Ventilator-induced lung injury (VILI) is a common complication of mechanical ventilation under general anesthesia. Regular aerobic exercise before surgery improves postoperative recovery and reduces postoperative pulmonary complications, but the mechanism driving this protective effect is unclear.

METHODS

To determine how aerobic exercise prevents VILI, we investigated the effects of exercise and mechanical ventilation on the lungs of male mice and the effects of AMPK stimulation (simulating exercise) and cyclic stretching on human lung microvascular endothelial cells (HLMVEC). Sirtuin 1 (Sirt1) knockdown male mice were generated to explore the regulating mechanisms of sirt1 on mitochondrial function in male mice after mechanical ventilation was explored. Western blot, flow cytometry, live cell imaging, and mitochondrial function evaluations were used to determine the protective effects of aerobic exercise in preventing mitochondrial damage in VILI.

RESULTS

Mitochondrial function and cell junctions were destroyed by mechanical ventilation in male mice or cyclic stretching in HLMVEC, a model of VILI. However, mitochondrial function and cell junction dysfunction were improved by exercise before mechanical ventilation (male mice) or treatment with AMPK before cyclic stretching (HLMVEC). p66shc, a marker of oxidative stress, was increased, and PINK1, a marker of mitochondrial autophagy, was decreased by mechanical ventilation or cyclic stretching. Sirt1 knockdown increased p66shc and decreased PINK1. Increased sirt1 expression was observed in the exercise and exercise + ventilation groups, suggesting that sirt1 inhibits mitochondrial damage in VILI.

CONCLUSIONS

Mechanical ventilation induces mitochondrial damage in lung cells and leads to VILI. Regular aerobic exercise before ventilation may prevent VILI by improving mitochondrial function.

Effects of mind-body exercise Baduanjin on cognition in community-dwelling older people with mild cognitive impairment: A randomized controlled trial

OBJECTIVE

To determine the effect of a 6-month traditional Chinese mind-body Baduanjin exercise intervention on cognitive ability in older people with Mild cognitive impairment (MCI).

METHODS

A total of 135 community-dwelling seniors with MCI were randomized into either the Baduanjin group (BDJ), the brisk walking group (BWK) or the usual physical activity control group (UPA). Cognitive ability was assessed at baseline, 2, 4 and 6 months post-intervention, and 3 months after the intervention ended.

RESULTS

After 6 months of intervention, the MoCA score of the BDJ group was significantly higher than that of the UPA group (P < 0.05), The Go/No-go correct numbers of the BDJ group and BWK group were significantly higher than those of the UPA group (P < 0.05). There was no statistical difference in other outcomes, or there were only a tiny effect size. Three months after the intervention, there was no significant difference between the primary and secondary outcomes(P > 0.05).

CONCLUSION

The 6-month period of Baduanjin training has positive benefits on global cognitive function and attention function in community-dwelling elderly individuals with MCI. The effect seems to have been transient and needs to be confirmed by additional studies.

Exercise therapy to prevent and treat Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease in the elderly with dementia, memory loss, and severe cognitive impairment that imposes high medical costs on individuals. The causes of AD include increased deposition of amyloid beta (Aβ) and phosphorylated tau, age, mitochondrial defects, increased neuroinflammation, decreased synaptic connections, and decreased nerve growth factors (NGF). While in animals moderate-intensity exercise restores hippocampal and amygdala memory through increased levels of p-AKT, p-TrkB, and p-PKC and decreased levels of Aβ, tau phosphorylation, and amyloid precursor proteins (APP) in AD. Aerobic exercise (with an intensity of 50-75% of VO2 max) prevents hippocampal volume reduction, spatial memory reduction, and learning reduction through increasing synaptic flexibility. Exercise training induces the binding of brain-derived neurotrophic factor (BDNF) to TrkB and the binding of NGF to TrkA to induce cell survival and neuronal plasticity. After aerobic training and high-intensity interval training, the increase of VEGF, angiopoietin 1 and 2, NO, tPA, and HCAR1 in cerebral vessels causes increased blood flow and angiogenesis in the cerebellum, motor cortex, striatum, and hippocampus. In the hippocampus, exercise training decreases mitochondrial fragmentation, DRP1, and FIS1, improving OPA1, MFN1, MFN2, and mitochondrial morphology. In humans, acute exercise as an anti-inflammatory condition causes an acute increase in IL-6 and an increase in anti-inflammatory factors such as IL-1RA and IL-10. Moderate-intensity exercise also inhibits inflammatory markers such as IFN-γ, IL-1β, IL-6, CRP, TNF-α, sTNFR1, COX-2, and NF-κB. Aerobic exercise significantly increases plasma levels of BDNF, nerve growth factor, synaptic plasticity, motor activity, spatial memory, and exploratory behavior in AD subjects. Irisin is a myokine released from skeletal muscle during exercise and protects the hippocampus by suppressing Aβ accumulation and promoting hippocampal proliferation through STAT3 signaling. Therefore, combined exercise training such as aerobic training, strength training, balance and coordination training, and cognitive and social activities seems to provide important benefits for people with AD.

Identification of mitochondrial-related genes as potential biomarkers for the subtyping and prediction of Alzheimer's disease

Introduction

Alzheimer's disease (AD) is a progressive and debilitating neurodegenerative disorder prevalent among older adults. Although AD symptoms can be managed through certain treatments, advancing the understanding of underlying disease mechanisms and developing effective therapies is critical.

Methods

In this study, we systematically analyzed transcriptome data from temporal lobes of healthy individuals and patients with AD to investigate the relationship between AD and mitochondrial autophagy. Machine learning algorithms were used to identify six genes-FUNDC1, MAP1LC3A, CSNK2A1, VDAC1, CSNK2B, and ATG5-for the construction of an AD prediction model. Furthermore, AD was categorized into three subtypes through consensus clustering analysis.

Results

The identified genes are closely linked to the onset and progression of AD and can serve as reliable biomarkers. The differences in gene expression, clinical features, immune infiltration, and pathway enrichment were examined among the three AD subtypes. Potential drugs for the treatment of each subtype were also identified.

Discussion

The findings observed in the present study can help to deepen the understanding of the underlying disease mechanisms of AD and enable the development of precision medicine and personalized treatment approaches.

Buyang Huanwu Decoction alleviates cerebral ischemic injury through modulating caveolin-1-mediated mitochondrial quality control

Introduction: Mitochondrial quality control (MQC) is an important mechanism of neural repair after cerebral ischemia (CI). Recent studies have shown that caveolin-1 (Cav-1) is an important signaling molecule in the process of CI injury, but its mechanism of regulating MQC after CI is still unclear. Buyang Huanwu Decoction (BHD) is a classic traditional Chinese medicine formula that is often used to treat CI. Unfortunately, its mechanism of action is still obscure. Methods: In this study, we tested the hypothesis that BHD can regulate MQC through Cav-1 and exert an anti-cerebral ischemia injury effect. We used Cav-1 knockout mice and their homologous wild-type mice, replicated middle cerebral artery occlusion (MCAO) model and BHD intervention. Neurobehavioral scores and pathological detection were used to evaluate neurological function and neuron damage, transmission electron microscopy and enzymology detection of mitochondrial damage. Finally, western blot and RT-qPCR expression of MQC-related molecules were tested. Results: After CI, mice showed neurologic impairment, neuronal damage, and significant destruction of mitochondrial morphology and function, and MQC was imbalanced. Cav-1 deletion aggravated the damage to neurological function, neurons, mitochondrial morphology and mitochondrial function after CI, aggravated the imbalance of mitochondrial dynamics, and inhibited mitophagy and biosynthesis. BHD can maintain MQC homeostasis after CI through Cav-1 and improve CI injury. Discussion: Cav-1 can affect CI injury by regulating MQC, and this mechanism may be another target of BHD for anti-cerebral ischemia injury.

The Preventive Effect of Exercise and Oral Branched-Chain Amino Acid Supplementation on Obesity-Induced Brain Changes in Ldlr−/−.Leiden Mice

Exercise and dietary interventions are promising approaches to tackle obesity and its obesogenic effects on the brain. We investigated the impact of exercise and possible synergistic effects of exercise and branched-chain amino acids (BCAA) supplementation on the brain and behavior in high-fat-diet (HFD)-induced obese Ldlr−/−.Leiden mice. Baseline measurements were performed in chow-fed Ldlr−/−.Leiden mice to assess metabolic risk factors, cognition, and brain structure using magnetic resonance imaging. Thereafter, a subgroup was sacrificed, serving as a healthy reference. The remaining mice were fed an HFD and divided into three groups: (i) no exercise, (ii) exercise, or (iii) exercise and dietary BCAA. Mice were followed for 6 months and aforementioned tests were repeated. We found that exercise alone changed cerebral blood flow, attenuated white matter loss, and reduced neuroinflammation compared to non-exercising HFD-fed mice. Contrarily, no favorable effects of exercise on the brain were found in combination with BCAA, and neuroinflammation was increased. However, cognition was slightly improved in exercising mice on BCAA. Moreover, BCAA and exercise increased the percentage of epididymal white adipose tissue and muscle weight, decreased body weight and fasting insulin levels, improved the circadian rhythm, and transiently improved grip strength. In conclusion, BCAA should be supplemented with caution, although beneficial effects on metabolism, behavior, and cognition were observed.

Early-stage Alzheimer's disease: are skeletal muscle and exercise the key?

Alzheimer's disease (AD) is the most common form of dementia affecting approximately 6.5 million people in the United States alone. The development of AD progresses over a span of years to possibly decades before resulting in cognitive impairment and clinically diagnosed AD. The time leading up to a clinical diagnosis is known as the preclinical phase, a time in which recent literature has noted a more severe loss of body mass and more specifically lean muscle mass and strength prior to diagnosis. Mitochondria dysfunction in neurons is also closely associated with AD, and mitochondrial dysfunction has been seen to occur in skeletal muscle with mild cognitive impairment prior to AD manifestation. Evidence from animal models of AD suggests a close link among skeletal muscle mass, mitochondria function, and cognition. Exercise is a powerful stimulus for improving mitochondria function and muscle health, and its benefits to cognition have been suggested as a possible therapeutic strategy for AD. However, evidence for beneficial effects of exercise in AD-afflicted populations and animal models has produced conflicting results. In this mini-review, we discuss these findings and highlight potential avenues for further investigation that may lead to the implementation of exercise as a therapeutic intervention to delay or prevent the development of AD.

Recent advances on the molecular mechanisms of exercise-induced improvements of cognitive dysfunction

Physical exercise is of great significance for maintaining human health. Exercise can provide varying degrees of benefits to cognitive function at all stages of life cycle. Currently, with the aging of the world's population and increase of life expectancy, cognitive dysfunction has gradually become a disease of high incidence, which is accompanied by neurodegenerative diseases in elderly individuals. Patients often exhibit memory loss, aphasia and weakening of orientation once diagnosed, and are unable to have a normal life. Cognitive dysfunction largely affects the physical and mental health, reduces the quality of life, and causes a great economic burden to the society. At present, most of the interventions are aimed to maintain the current cognitive level and delay deterioration of cognition. In contrast, exercise as a nonpharmacological therapy has great advantages in its nontoxicity, low cost and universal application. The molecular mechanisms underlying the effect of exercise on cognition are complex, and studies have been extensively centered on neural plasticity, the direct target of exercise in the brain. In addition, mitochondrial stability and energy metabolism are essential for brain status. Meanwhile, the organ-brain axis responds to exercise and induces release of cytokines related to cognition. In this review, we summarize the latest evidence on the molecular mechanisms underlying the effects of exercise on cognition, and point out directions for future research.

Mitophagy: A promising therapeutic target for neuroprotection during ageing and age-related diseases

Mitochondria and mitochondria-mediated signalling pathways are known to control synaptic signalling, as well as long-lasting changes in neuronal structure and function. Mitochondrial impairment is linked to synaptic dysfunction in normal ageing and age-associated neurodegenerative ailments, including Parkinson's disease (PD) and Alzheimer's disease (AD). Both proteolysis and mitophagy perform a major role in neuroprotection, by maintaining a healthy mitochondrial population during ageing. Mitophagy, a highly evolutionarily conserved cellular process, helps in the clearance of damaged mitochondria and thereby maintains the mitochondrial and metabolic balance, energy supply, neuronal survival and neuronal health. Besides the maintenance of brain homeostasis, hippocampal mitophagy also helps in synapse formation, axonal development, dopamine release and long-term depression. In contrast, defective mitophagy contributes to ageing and age-related neurodegeneration by promoting the accumulation of damaged mitochondria leading to cellular dysfunction. Exercise, stress management, maintaining healthy mitochondrial dynamics and administering natural or synthetic pharmacological compounds are some of the strategies used for neuroprotection during ageing and age-related neurological diseases. The current review discusses the impact of defective mitophagy in ageing and age-associated neurodegenerative conditions, the underlying molecular pathways and potential therapies based on recently elucidated mitophagy-inducing strategies.

The role of exerkines on brain mitochondria: a mini-review

Exercise benefits many organ systems, including having a panacea-like effect on the brain. For example, aerobic exercise improves cognition and attention and reduces the risk of brain-related diseases, such as dementia, stress, and depression. Recent advances suggest that endocrine signaling from peripheral systems, such as skeletal muscle, mediates the effects of exercise on the brain. Consequently, it has been proposed that factors secreted by all organs in response to physical exercise should be more broadly termed the "exerkines." Accumulating findings suggest that exerkines derived from skeletal muscle, liver, and adipose tissues directly impact brain mitochondrial function. Mitochondria play a pivotal role in regulating neuronal energy metabolism, neurotransmission, cell repair, and maintenance in the brain, and therefore exerkines may act via impacting brain mitochondria to improve brain function and disease resistance. Therefore, herein we review studies investigating the impact of muscle-, liver-, and adipose tissue-derived exerkines on brain cognitive and metabolic function via modulating mitochondrial bioenergetics, content, and dynamics under healthy and/or disease conditions.

Anxiety, depression, and memory loss in Chagas disease: a puzzle far beyond neuroinflammation to be unpicked and solved

Mental disorders such as anxiety, depression, and memory loss have been described in patients with chronic Chagas disease (CD), a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi. Social, psychological, and biological stressors may take part in these processes. There is a consensus on the recognition of an acute nervous form of CD. In chronic CD patients, a neurological form is associated with immunosuppression and neurobehavioural changes as sequelae of stroke. The chronic nervous form of CD has been refuted, based on the absence of histopathological lesions and neuroinflammation; however, computed tomography shows brain atrophy. Overall, in preclinical models of chronic T. cruzi infection in the absence of neuroinflammation, behavioural disorders such as anxiety and depression, and memory loss are related to brain atrophy, parasite persistence, oxidative stress, and cytokine production in the central nervous system. Interferon-gamma (IFNγ)-bearing microglial cells are colocalised with astrocytes carrying T. cruzi amastigote forms. In vitro studies suggest that IFNγ fuels astrocyte infection by T. cruzi and implicate IFNγ-stimulated infected astrocytes as sources of TNF and nitric oxide, which may also contribute to parasite persistence in the brain tissue and promote behavioural and neurocognitive changes. Preclinical trials in chronically infected mice targeting the TNF pathway or the parasite opened paths for therapeutic approaches with a beneficial impact on depression and memory loss. Despite the path taken, replicating aspects of the chronic CD and testing therapeutic schemes in preclinical models, these findings may get lost in translation as the chronic nervous form of CD does not fulfil biomedical model requirements, as the presence of neuroinflammation, to be recognised. It is hoped that brain atrophy and behavioural and neurocognitive changes are sufficient traits to bring the attention of researchers to study the biological and molecular basis of the central nervous system commitment in chronic CD.

The Therapeutic Potential of Mitochondria Transplantation Therapy in Neurodegenerative and Neurovascular Disorders

Neurodegenerative and neurovascular disorders affect millions of people worldwide and account for a large and increasing health burden on the general population. Thus, there is a critical need to identify potential disease-modifying treatments that can prevent or slow the disease progression. Mitochondria are highly dynamic organelles and play an important role in energy metabolism and redox homeostasis, and mitochondrial dysfunction threatens cell homeostasis, perturbs energy production, and ultimately leads to cell death and diseases. Impaired mitochondrial function has been linked to the pathogenesis of several human neurological disorders. Given the significant contribution of mitochondrial dysfunction in neurological disorders, there has been considerable interest in developing therapies that can attenuate mitochondrial abnormalities and proffer neuroprotective effects. Unfortunately, therapies that target specific components of mitochondria or oxidative stress pathways have exhibited limited translatability. To this end, mitochondrial transplantation therapy (MTT) presents a new paradigm of therapeutic intervention, which involves the supplementation of healthy mitochondria to replace the damaged mitochondria for the treatment of neurological disorders. Prior studies demonstrated that the supplementation of healthy donor mitochondria to damaged neurons promotes neuronal viability, activity, and neurite growth and has been shown to provide benefits for neural and extra-neural diseases. In this review, we discuss the significance of mitochondria and summarize an overview of the recent advances and development of MTT in neurodegenerative and neurovascular disorders, particularly Parkinson's disease, Alzheimer's disease, and stroke. The significance of MTT is emerging as they meet a critical need to develop a diseasemodifying intervention for neurodegenerative and neurovascular disorders.

Treadmill Exercise Improves PINK1/Parkin-Mediated Mitophagy Activity Against Alzheimer's Disease Pathologies by Upregulated SIRT1-FOXO1/3 Axis in APP/PS1 Mice

Although treadmill exercise is effective against Alzheimer's disease (AD), the molecular mechanisms underlying these effects are not fully understood. Recent literature has linked the accumulation of damaged mitochondria and defective mitophagy to AD progression. Here, we determined that abnormally activated PINK1/Parkin pathway-mediated mitophagy plays an important role in AD progression and pathogenesis in 6-month-old APP/PS1 mice. We used the lysosomal inhibitor chloroquine and demonstrated that a 12-week treadmill exercise program improved mitochondrial function, decreased accumulation of β-amyloid plaques, and ameliorated loss of learning and memory ability by enhancing PINK1/Parkin-mediated mitophagy activity in the hippocampus of APP/PS1 mice. Moreover, using the SIRT1 inhibitor EX527, we found that 12 weeks of treadmill exercise rescued PINK1/Parkin-mediated mitophagy by activating the SIRT1-FOXO1/3 axis in the hippocampus of APP/PS1 mice. These findings reveal that activating PINK1/Parkin-mediated mitophagy is a promising strategy for AD treatment, and that the SIRT1-FOXO1/3 axis is a potential candidate for the development of mitophagy enhancers.

Mitochondrial dysfunction in microglia: a novel perspective for pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disease in the elderly globally. Emerging evidence has demonstrated microglia-driven neuroinflammation as a key contributor to the onset and progression of AD, however, the mechanisms that mediate neuroinflammation remain largely unknown. Recent studies have suggested mitochondrial dysfunction including mitochondrial DNA (mtDNA) damage, metabolic defects, and quality control (QC) disorders precedes microglial activation and subsequent neuroinflammation. Therefore, an in-depth understanding of the relationship between mitochondrial dysfunction and microglial activation in AD is important to unveil the pathogenesis of AD and develop effective approaches for early AD diagnosis and treatment. In this review, we summarized current progress in the roles of mtDNA, mitochondrial metabolism, mitochondrial QC changes in microglial activation in AD, and provide comprehensive thoughts for targeting microglial mitochondria as potential therapeutic strategies of AD.

Therapeutic non-invasive brain treatments in Alzheimer's disease: recent advances and challenges

Alzheimer's disease (AD) is one of the major neurodegenerative diseases and the most common form of dementia. Characterized by the loss of learning, memory, problem-solving, language, and other thinking abilities, AD exerts a detrimental effect on both patients' and families' quality of life. Although there have been significant advances in understanding the mechanism underlying the pathogenesis and progression of AD, there is no cure for AD. The failure of numerous molecular targeted pharmacologic clinical trials leads to an emerging research shift toward non-invasive therapies, especially multiple targeted non-invasive treatments. In this paper, we reviewed the advances of the most widely studied non-invasive therapies, including photobiomodulation (PBM), transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and exercise therapy. Firstly, we reviewed the pathological changes of AD and the challenges for AD studies. We then introduced these non-invasive therapies and discussed the factors that may affect the effects of these therapies. Additionally, we review the effects of these therapies and the possible mechanisms underlying these effects. Finally, we summarized the challenges of the non-invasive treatments in future AD studies and clinical applications. We concluded that it would be critical to understand the exact underlying mechanisms and find the optimal treatment parameters to improve the translational value of these non-invasive therapies. Moreover, the combined use of non-invasive treatments is also a promising research direction for future studies and sheds light on the future treatment or prevention of AD.

Research trends and hotspots of exercise for Alzheimer’s disease: A bibliometric analysis

Objective

Alzheimer’s disease (AD) is a socially significant neurodegenerative disorder among the elderly worldwide. An increasing number of studies have revealed that as a non-pharmacological intervention, exercise can prevent and treat AD. However, information regarding the research status of this field remains minimal. Therefore, this study aimed to analyze trends and topics in exercise and AD research by using a bibliometric method.

Methods

We systematically searched the Web of Science Core Collection for published papers on exercise and AD. The retrieved data regarding institutions, journals, countries, authors, journal distribution, and keywords were analyzed using CiteSpace software. Meanwhile, the co-occurrence of keywords was constructed.

Results

A total of 1,104 papers were ultimately included in accordance with our specified inclusion criteria. The data showed that the number of published papers on exercise and AD is increasing each year, with papers published in 64 countries/regions and 396 academic journals. The Journal of Alzheimer’s Disease published the most papers (73 publications). Journals are concentrated in the fields of neuroscience and geriatrics gerontology. The University of Kansas and the United States are the major institution and country, respectively. The cited keywords show that oxidative stress, amyloid beta, and physical exercise are the research hotspots in recent years. After analysis, the neuroprotective effect of exercise was identified as the development trend in this field.

Conclusions

Based on a bibliometric analysis, the number of publications on exercise and AD has been increasing rapidly, especially in the past 10 years. “Amyloid beta,” “oxidative stress,” and “exercise program” trigger the most interest among researchers in this field. The study of exercise program and mechanism of exercise in AD is still the focus of future research.

The Potential Role of miRNA-Regulated Autophagy in Alzheimer’s Disease

As a neurodegenerative disease, Alzheimer’s disease (AD) shows a higher incidence during the aging process, mainly revealing the characteristics of a significant decrease in cognition, uncontrolled emotion, and reduced learning and memory capacity, even leading to death. In the prevention and treatment of AD, some pharmacological therapy has been applied in clinical practice. Unfortunately, there are still limited effective treatments for AD due to the absence of clear and defined targets. Currently, it is recognized that the leading causes of AD include amyloid-β peptide (Aβ) deposition, hyperphosphorylation of tau protein, neurofibrillary tangles, mitochondrial dysfunction, and inflammation. With in-depth mechanistic exploration, it has been found that these causes are highly correlated with the dysfunctional status of autophagy. Numerous experimental results have also confirmed that the development and progression of AD is accompanied by an abnormal functional status of autophagy; therefore, regulating the functional status of autophagy has become one of the important strategies for alleviating or arresting the progression of AD. With the increasing attention given to microRNAs (miRNAs), more and more studies have found that a series of miRNAs are involved in the development and progression of AD through the indirect regulation of autophagy. Therefore, regulating autophagy through targeting these miRNAs may be an essential breakthrough for the prevention and treatment of AD. This article summarizes the regulation of miRNAs in autophagy, with the aim of providing a new theoretical reference point for the prevention and treatment of AD through the indirect regulation of miRNA-mediated autophagy.

A Review of ApoE4 Interference Targeting Mitophagy Molecular Pathways for Alzheimer's Disease

Alzheimer's disease (AD) is one of the major worldwide causes of dementia that is characterized by irreversible decline in learning, memory loss, and behavioral impairments. Mitophagy is selective autophagy through the clearance of aberrant mitochondria, specifically for degradation to maintain energy generation and neuronal and synaptic function in the brain. Accumulating evidence shows that defective mitophagy is believed to be as one of the early and prominent features in AD pathogenesis and has drawn attention in the recent few years. APOE ε4 allele is the greatest genetic determinant for AD and is widely reported to mediate detrimental effects on mitochondria function and mitophagic process. Given the continuity of the physiological process, this review takes the mitochondrial dynamic and mitophagic core events into consideration, which highlights the current knowledge about the molecular alterations from an APOE-genotype perspective, synthesizes ApoE4-associated regulations, and the cross-talk between these signaling, along with the focuses on general autophagic process and several pivotal processes of mitophagy, including mitochondrial dynamic (DRP1, MFN-1), mitophagic induction (PINK1, Parkin). These may shed new light on the link between ApoE4 and AD and provide novel insights for promising mitophagy-targeted therapeutic strategies for AD.

Alterations in hippocampal mitochondrial dynamics are associated with neurodegeneration and recognition memory decline in old male mice

Mitochondrial dynamics is a key process that modulates the ultrastructure, quality and function of mitochondria. It is disrupted in numerous major neurodegenerative disorders including Parkinson's, Alzheimer's and Huntington's disease. Mitochondrial dysfunction has been correlated with the loss of memory. Previous studies suggest the involvement of Vdac1 and Drp1 in outer mitochondrial membrane permeabilization and promotion of mitochondrial fragmentation through Drp1 phosphorylation at S616. However, alterations in mitochondrial dynamics with respect to aging, memory loss and neurodegeneration remain unexplored. Therefore, the present study focuses on the involvement of mitochondrial dynamics in neurodegeneration and recognition memory decline during aging. The recognition memory decline was validated by the novel object recognition test and measurement of hippocampal Arc protein level during aging. The ultrastructure analysis revealed a decline in mitochondrial length and area, while an increase in the number of fragmented, round and disrupted mitochondria in the hippocampus during aging. Disruption was also evident in mitochondrial cristae and membrane with advancing age. The change in mitochondrial morphology was corroborated by an increase in the expression of phospho-Drp1 (S616) and Cyt-c proteins but decline in Mfn2, LC3B, Vdac1, Bcl-XL and Bcl-2 proteins in the hippocampus during aging. Taken together, our findings reveal that an increase in the expression of phospho-Drp1 (S616) and decrease in Mfn2 and LC3B proteins in the hippocampus bring about a reduction in mitochondrial length and area, and rise in mitochondrial fragmentation leading to reduced neuronal cell density, increased neurodegeneration and recognition memory decline in old male mice. Diagram depicts the increase in hippocampal mitochondrial fragmentation during aging of mice. Increased mitochondrial fragmentation causes distorted mitochondrial function such as decrease in ATP/ADP transportation due to decrease in Vdac1 protein level and increase in oxidative damage. These alterations result in hippocampal neurodegeneration and consequently impairment in recognition memory during aging.