Search Results (1,898)

Background/Objectives: Autism spectrum disorder (ASD) is traditionally classified as a neurodevelopmental condition, whereas neurodegenerative diseases are defined by progressive neuronal decline in later life. This separation has shaped research and clinical practice, yet emerging evidence suggests potential biological overlap. This review aims to evaluate whether ASD and neurodegenerative disorders represent distinct entities or are linked through shared mechanisms operating across the lifespan. Methods: This narrative review synthesizes findings from genetic, molecular, cellular, circuit-level, and epidemiological studies examining ASD and major neurodegenerative conditions, including Alzheimer’s disease, Parkinson’s disease, and Amyotrophic lateral sclerosis. Emphasis is placed on identifying convergent pathways and evaluating evidence within a lifespan-oriented framework. Results: Across multiple levels of analysis, ASD and neurodegenerative diseases share partially overlapping biological mechanisms, including mitochondrial dysfunction, impaired proteostasis, neuroimmune alterations, and network-level instability. Genetic and molecular data reveal pleiotropic pathways influencing both early neurodevelopment and later neuronal resilience. Circuit-level studies highlight shared principles of network vulnerability, including cerebellar involvement and excitation–inhibition imbalance. Epidemiological data further indicate increased risk of dementia and parkinsonian features in autistic adults. These convergences suggest that early neurodevelopmental alterations may establish latent vulnerabilities that, under specific conditions, intersect with neurodegenerative processes later in life. Conclusions: ASD and neurodegenerative diseases are best understood as distinct clinical conditions that share partially overlapping biological substrates. Rather than implying a deterministic progression, the evidence supports a model of lifespan convergence in which timing, context, and individual susceptibility shape outcomes. This framework highlights the need for integrated research and clinical approaches that consider brain health as a continuous process from development through aging. Full article

Neurodegenerative diseases represent a major and growing global health burden. Although these disorders are often clinically defined by symptoms and affected brain regions, many are mechanistically linked to abnormal protein accumulation, misfolding, impaired proteostasis, RNA dysregulation, mitochondrial dysfunction, and neuroinflammation. In this Perspective article, I discuss major neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, dementia with Lewy bodies, multiple system atrophy, amyotrophic lateral sclerosis, frontotemporal dementia, Huntington’s disease, prion diseases, spinocerebellar ataxias, and spinal muscular atrophy, through the lens of disease-associated proteins and experimental modeling. I argue that a protein-centered framework provides a useful approach for understanding disease mechanisms and selecting transgenic mouse models, while recognizing that aging, cellular context, neuroinflammation, mitochondrial dysfunction, vascular dysfunction, and other disease modifiers also shape neurodegeneration. Transgenic and genetically engineered mouse models have been essential for dissecting the pathogenic roles of amyloid-β, tau, α-synuclein, TDP-43, SOD1, FUS, C9ORF72-associated dipeptide repeat proteins, mutant huntingtin, prion protein, ataxins, and SMN deficiency. However, these models have important limitations, including artificial overexpression, familial mutation bias, species differences, and incomplete representation of aging-related sporadic diseases. Rather than seeking a single “best” model, a more productive strategy is to adopt model portfolios tailored to specific biological questions and to integrate mouse studies with human cellular models, postmortem tissue, omics approaches, and biomarker-based validation. Such an approach may improve mechanistic insight, strengthen translational relevance, and enhance the predictive value of preclinical neurodegenerative disease research. Full article

Background: Amyotrophic lateral sclerosis (ALS) is increasingly recognized as a multisystem disorder involving neurovascular dysfunction. The retina allows in vivo assessment of neurovascular changes. This study evaluated retinal structural and microvascular alterations in ALS using optical coherence tomography (OCT) and optical coherence tomography angiography (OCT-A). Methods: This cross-sectional study included 46 participants with ALS and 19 healthy controls. Retinal thickness and vascular density in the superficial and deep retinal capillary plexuses and the choriocapillaris were quantified using OCT and OCT-A. Group comparisons and logistic regression analyses were performed to assess associations with ALS. Subgroup analyses were conducted according to clinical phenotype. Results: In total, 124 eyes were analyzed. ALS was associated with increased average retinal thickness (p = 0.023) and reduced vascular density in the superficial retinal capillary plexus (p = 0.005), deep retinal capillary plexus (p < 0.001), and choriocapillaris (p = 0.004). In logistic regression analyses, retinal thickness was positively associated with ALS status (OR = 1.42, p = 0.023), whereas higher vascular density in the superficial plexus, deep plexus, and choriocapillaris was associated with lower odds of ALS. No significant differences were observed between bulbar- and spinal-onset ALS phenotypes. Conclusions: ALS is associated with structural and microvascular retinal alterations detectable by OCT and OCT-A. These findings support the presence of systemic neurovascular dysfunction and highlight retinal imaging as a promising, non-invasive approach for investigating disease mechanisms and developing potential biomarkers. Full article

Brain plasticity is often described as the capacity of the nervous system to change in response to development, experience, injury, disease, or treatment. That definition is useful, but it can obscure two clinically important points: plasticity is biologically constrained, and change is not always beneficial. This narrative review examines sex-dependent brain plasticity as a context-sensitive process rather than as a simple male–female contrast. We distinguish four operational outcomes of plasticity: (i) reparative plasticity, which restores structure or function; (ii) compensatory plasticity, which preserves performance through alternative or more costly strategies; (iii) insufficient plasticity, in which reorganization is too weak or unstable to sustain function; and (iv) maladaptive plasticity, in which plastic change reinforces dysfunction, pain, excitability, rigidity, or decline. We also define adaptive reserve as the integrated capacity of neural, glial, vascular, immune, metabolic, endocrine, and gene-regulatory systems to support useful reorganization under stress. The review evaluates endocrine, synaptic, neuroimmune, mitochondrial, vascular, stress-related, and epigenetic mechanisms, indicating where evidence for sex-dependent effects is relatively strong and where it remains indirect, inconsistent, or context-dependent. Disease examples include autism spectrum disorder, attention-deficit/hyperactivity disorder, epilepsy, intellectual disability, Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, Huntington’s disease, traumatic and ischemic injury, multiple sclerosis, chronic pain, aging, and systemic metabolic or inflammatory disorders. Throughout, biological sex is separated from gender-related social, diagnostic, and health-care determinants. We conclude that therapeutic strategies should not aim simply to enhance plasticity, but to guide it by matching intervention, timing, dose, biological readiness, and monitoring to the patient’s adaptive state. Full article

The kynurenine pathway (KP) constitutes the primary route of tryptophan catabolism, generating a spectrum of neuroactive metabolites that profoundly influence central nervous system function. Dysregulation of the KP is increasingly recognized as a critical pathogenic mechanism underlying diverse neuropathological conditions. This review critically evaluates the most widely cited mammalian cellular models currently utilized to delineate the causal role of KP alterations in neurological disease. Specifically, this article examines primary cell cultures, immortalized and tumor-derived cell lines, stem cell-derived systems, and ex vivo organotypic brain slices and tissues, highlighting their distinct methodological advantages, translational limitations, and specific enzymatic profiles. Across the described cellular systems, a recurring mechanistic theme emerges: quinolinic acid-driven mitochondrial dysfunction, oxidative stress, and NAD+ depletion converge in neurodegenerative conditions such as Alzheimer’s disease, Huntington’s disease, and amyotrophic lateral sclerosis. Conversely, kynurenic acid exhibits disorder-dependent—and at times opposing—roles, attenuating dopaminergic neurotoxicity in Parkinson’s disease models while contributing to synaptic pruning deficits in schizophrenia models. Furthermore, cellular models demonstrate that IDO1/TDO induction and downstream metabolite shifts are frequently cell type- and species-dependent, complicating direct extrapolation to human pathology. Because no single experimental system achieves complete physiological fidelity, elucidating the complex dynamics of the KP and identifying novel therapeutic targets requires the integration of data across complementary platforms. Full article

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive degeneration of upper and lower motor neurons. While monogenic causes account for a minority of cases, in most cases, ALS is sporadic and likely arises from multilayer interactions of genetic architecture, aging-associated loss of genome regulation, and inflammatory stress. Long interspersed nuclear element-1 (LINE-1) retrotransposons are endogenous mobile elements that are tightly controlled through various cellular mechanisms under normal conditions. When abnormally active, they are involved in gene inactivation, expression regulation, and genomic instability, leading to cellular processes such as innate immunity and cell death. Here, we present mechanistic links between LINE-1 and ALS. These include evidence that the burden of retrotransposition-competent LINE-1s (RC-L1s) is increased in ALS genomes, positioning RC-L1 load as a candidate contributor to missing heritability in sporadic disease. We also integrate emerging data showing that LINE-1 RNA can be intrinsically toxic independently of new insertions, as it promotes chromatin opening and transcriptional epigenetic noise, particularly when nuclear RNA surveillance pathways fail in TDP-43 pathology. Finally, we review how LINE-1-derived DNA/RNA intermediates can engage innate immune sensors, highlighting the cGAS–STING axis as a plausible route from LINE-1 de-repression to neuroinflammation. Together, these concepts support a model in which genetic RC-L1 load and age-/pathology-driven LINE-1 de-repression converge on nuclear dysfunction and inflammatory amplification, suggesting concrete molecular nodes for therapeutic intervention. Full article

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal neurodegenerative disease primarily affecting upper and lower motor neurons. Although cerebrovascular disease (CVD) and ALS have traditionally been studied as distinct entities, a growing body of evidence indicates meaningful epidemiological, pathophysiological, and clinical overlap between the two conditions. This narrative review synthesizes current evidence on the coexistence of ALS and cerebrovascular disease, examines shared mechanistic pathways, addresses diagnostic challenges, including stroke mimicry, considers clinical management implications, and identifies priorities for future research. A search of PubMed, Scopus, Web of Science, and EMBASE was conducted through February 2026 using the terms “amyotrophic lateral sclerosis,” “motor neuron disease,” “cerebrovascular disease,” “stroke,” “ischemic stroke,” “blood-brain barrier,” “neuroinflammation,” and “neurovascular coupling,” alone and in combination. Peer-reviewed original research, systematic reviews, meta-analyses, population-based studies, registry analyses, and expert consensus statements were included. Studies were assessed for methodological quality and relevance to the review objectives. This review is reported as a narrative synthesis. Population-based data demonstrate a bidirectional relationship between ALS and cerebrovascular events. ALS patients face an approximately 2.6-fold elevated risk of ischemic stroke, and prior cerebrovascular injury modestly increases subsequent ALS risk. Shared pathophysiological mechanisms include neuroinflammation with microglial M1/M2 polarization imbalance, pro-inflammatory cytokine cascades mediated via NF-κB signaling, oxidative stress and SOD1 pathway dysregulation, glutamate excitotoxicity, blood–brain barrier (BBB) dysfunction, and impaired neurovascular coupling. Diagnostic confusion arises because upper motor neuron–predominant ALS can closely mimic acute ischemic stroke. Concurrent cerebrovascular disease appears to accelerate functional decline and reduce survival in ALS. Resource-limited settings face compounded challenges from diagnostic misclassification, restricted EMG access, and limited specialist availability. The ALS–cerebrovascular overlap is clinically relevant, biologically plausible, and systematically understudied. Integrated multidisciplinary management, prospective longitudinal cohort studies, and linked registry analyses are urgently needed to clarify causal relationships, characterize shared disease mechanisms, and improve patient outcomes. Full article

Copper is an essential trace element required for numerous enzymatic processes in the brain, including mitochondrial metabolism, antioxidant defense, and gene expression regulation. Recent studies have further implicated copper in a newly defined form of regulated cell death termed cuproptosis, providing a mechanistic framework for copper-dependent cytotoxicity. Increasing evidence indicates that copper dyshomeostasis is a common feature of major neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS), where it is associated with protein misfolding, redox imbalance, and neuronal vulnerability. Nevertheless, the mechanistic link between copper dysregulation and neuronal cell death remains incompletely defined. In this review, we systematically summarize the molecular mechanisms governing copper homeostasis and intracellular copper trafficking, while providing a timely, updated, and in-depth overview of the mechanistic basis and emerging biology of cuproptosis. We further comprehensively evaluate the current evidence linking copper dysregulation and cuproptosis-related pathways to neurodegenerative diseases, with particular emphasis on distinguishing mechanistic causation from pathological correlation. Importantly, we discuss current therapeutic strategies and emerging clinical efforts targeting copper metabolism, while highlighting the major challenges in defining the pathological significance and mechanistic contribution of cuproptosis in neurodegenerative diseases. Collectively, this review provides an updated framework for understanding the pathological significance and translational potential of cuproptosis in neurodegenerative diseases. Full article

Background: Neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS), differ in etiology but share several convergent pathological mechanisms. Pterostilbene (PTR) is a natural stilbene with reported antioxidant, anti-inflammatory, and neuroprotective properties. This study aimed to prioritize putative PTR-associated targets and biological processes potentially relevant to shared neurodegenerative mechanisms. Methods: An integrative in silico workflow combining network pharmacology, protein–protein interaction (PPI) analysis, GO Biological Process (GO BP) enrichment, molecular docking, and molecular dynamics (MD) simulations was applied. GO BP terms were filtered, focused on neurodegeneration- and neuroprotection-related processes, and subjected to REVIGO-based redundancy reduction. Selected targets were further evaluated by docking and 500 ns MD simulations. Results: A total of 181, 165, 128, and 109 shared PTR–disease targets were identified for AD, PD, HD, and ALS, respectively. Redundancy-reduced GO BP analysis indicated associations with neuroinflammation, oxidative stress and reactive oxygen species-related responses, programmed cell death, MAPK/ERK- and PI3K/AKT-related signaling, ion and calcium transport, and lipid-, steroid-, or hormone-associated regulation. PPI topology prioritized SRC, ESR1, and HSP90AA1 as recurrent hub–bottleneck proteins, whereas MD-based structural interpretation focused on ESR1 and HSP90AA1. MD analyses indicated stable PTR interactions with both proteins, with ESR1 showing the most favorable predicted interaction profile. Conclusions: These findings suggest that PTR may interact with shared neurodegeneration-relevant molecular systems, particularly through ESR1- and HSP90AA1-associated mechanisms. However, the results are exclusively computational and should be interpreted as hypothesis-generating, requiring further experimental validation. Full article

TAR DNA binding protein (TARDBP) is one of the major causative genes of amyotrophic lateral sclerosis (ALS), which drives disease progression through both gain-of-toxicity (GOT) and loss-of-function (LOF) mechanisms. The mutant TDP-43 exhibits aberrant nucleocytoplasmic distribution and forms cytotoxic hyperphosphorylated aggregates, a process that can be robustly recapitulated in vitro. Thus, functional assays in cell lines serve as a reliable metric for the pathogenicity classification of TARDBP variants. In this study, we performed in vitro experiments to classify the pathogenicity of 28 TARDBP variants of uncertain significance (VUS) among the 172 previously reported TARDBP variants. 22 of these VUS were determined to be functionally abnormal, of which 12 could be further classified as likely pathogenic (LP) variants according to American College of Medical Genetics (ACMG) and the ClinGen Sequence Variant Interpretation (SVI) Working Group guidelines. We also summarized the clinical characteristics of 35 ALS patients carrying 12 variants in the TARDBP gene. Pathogenic missense variants were predominantly clustered in the C-terminal domain (CTD) of TARDBP. Variants in TARDBP exon 6 may lead to an earlier age at onset. ALS caused by TARDBP mutations exhibits marked phenotypic heterogeneity, along with incomplete penetrance in carriers. Patient-derived primary skin fibroblasts serve as a feasible cellular model for the functional assessment of variant pathogenicity. Our findings expand the TARDBP mutation spectrum, and provides a preliminary basis for preclinical research on TARDBP-targeted therapies for ALS. Full article

Neurodegenerative diseases, such as Alzheimer’s, Parkinson’s, and Amyotrophic lateral sclerosis, are distinguished by progressive neuronal dysfunction caused primarily by oxidative stress, mitochondrial impairment, neuroinflammation, and redox imbalance. Growing evidence suggests that indole-derived compounds have significant neuroprotective potential due to their antioxidant, anti-inflammatory, and redox-modulating properties. This review summarizes the structural and biological significance of indole scaffolds, focusing on the mechanisms by which natural, endogenous, microbiota-derived, and synthetic indole compounds protect neuronal networks. Indole-3-carbinol, 3,3′-diindolylmethane, indole-3-propionic acid, and melatonin are major indole derivatives that control important neuroprotective pathways like Nrf2/ARE signaling, mitochondrial bioenergetics, neurotrophic factor expression, apoptotic regulation, and suppression of proinflammatory mediators. These compounds also maintain synaptic plasticity, reduce reactive oxygen species production, and improve neuronal survival in neurodegenerative disease models. Additionally, updated information from translational and clinical research indicates that indole-based compounds may have promising therapeutic applications; however, obstacles like low bioavailability, metabolic instability, and blood–brain barrier penetration continue to be major obstacles to clinical application. Development in nanoparticle delivery systems, microbiome-targeted interventions, and rational structural optimization may improve therapeutic efficacy and translational potential. Overall, indole-derived compounds are a versatile class of redox modulators with potential applications in the prevention and treatment of neurodegenerative diseases via integrated antioxidant and neuroprotective mechanisms. Full article

Neurodegenerative diseases (NDs), such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Amyotrophic lateral sclerosis (ALS), and Huntington’s disease (HD), involve the gradual loss of structure or function of neurons in the nervous system and are an increasing threat to the aging population worldwide. Although these disorders have different clinical features which affect cognition, movement and other vital body functions, they share key underlying molecular and cellular processes. This starts with protein misfolding and aggregation, mitochondrial dysfunction, oxidative stress, dysregulated protein homeostasis, neuroinflammation, and disrupted cell death pathways. Recent findings have added disease-specific processes, like amyloid-β and tau aggregates in AD, α-synuclein aggregation and mitophagy failure in PD’s, TDP-43-related impaired RNA metabolism in ALS, and mutant huntingtin causing transcription aberrations in HD. Protein interactome network analysis showed mechanistic crosstalk between pathogenic proteins of AD and PD. New evidence highlights how lysosomal dysfunction, endoplasmic reticulum stress, and microglial activation, act as a common axis in neurodegeneration. Advancements in genomics and epigenomics have found shared genetic risk loci and regulatory processes that affect how diseases develop and progress. Simultaneously, new biomarkers like circulating microRNAs, exosome-related pathological proteins, neurofilament light chain, inflammatory cytokines, and microglial activation markers are powering early diagnosis tools and disease variations. New imaging techniques also allow for the identification of protein aggregations before symptoms appear. Overall, these findings are accelerating targeted treatments and personalized medicine aimed at disease progression. This review highlights current insights into the molecular mechanisms of NDs and discusses new biomarkers and treatment targets that help future diagnostic and treatment strategies. Full article

Vitamin D has long been recognized for its role in calcium homeostasis and bone metabolism; however, it is now emerging as an important regulator of central nervous system (CNS) function. Recent evidence suggests that vitamin D signaling contributes to the pathogenesis and progression of several neurodegenerative disorders. Vitamin D exerts neuroprotective effects through multiple mechanisms, including regulation of calcium homeostasis, modulation of immune responses, reduction in oxidative stress, stimulation of neurotrophic factors, and maintenance of blood–brain barrier (BBB) integrity. Vitamin D receptors and metabolizing enzymes are widely distributed across several brain regions, highlighting their direct involvement in neuronal function. This review summarizes the biosynthesis, metabolism, and signaling pathways of vitamin D. It explores its role in neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), stroke, and traumatic brain injury (TBI). Evidence from experimental and clinical studies indicates that vitamin D deficiency is associated with an increased risk and severity of these conditions, while supplementation may provide therapeutic benefits. Full article

Neurodegenerative diseases are characterized by the accumulation of misfolded and aggregation-prone proteins, reflecting a failure of proteostasis. The ubiquitin–proteasome system (UPS), a major pathway for selective intracellular protein degradation, is essential for maintaining neuronal protein homeostasis. Proteasome dysfunction has been implicated in several major neurodegenerative disorders, including Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington’s disease (HD), although its extent and mechanisms vary across disease contexts. In this review, we examine current evidence for proteasome dysfunction in neurodegeneration and discuss how disease-associated proteins impair proteasome function through direct inhibition, defective substrate processing, and sequestration into protein aggregates. We also address the contribution of oxidative stress, neuroinflammation, and aging to proteasome dysregulation. Finally, we highlight emerging therapeutic strategies aimed at restoring proteasome function, including pharmacological activation, modulation of proteasome assembly and stability, and targeted protein degradation approaches. Understanding the context-dependent nature of proteasome dysfunction will be important for developing effective proteostasis-based therapies. Full article

Introduction: Vaccination against COVID-19 has been crucial in controlling the pandemic. While side effects are typically mild, rare neurological complications have been reported. This is a case series of ten patients who reported of persistent fasciculations after COVID-19 vaccination. Methods: We describe the clinical presentation and diagnostic work-up of ten patients with new-onset fasciculations in temporal proximity to COVID-19 vaccination. Patients with prior SARS-CoV-2 infection or known alternative causes of fasciculations were excluded. Routine clinical data, including neurological examination, laboratory results, and electrophysiology (electromyography and nerve conduction studies), were analyzed. Results: Ten patients (5 male, 5 female; mean age 42.4 years) reported fasciculations beginning within 6 h to 13 days post-vaccination and persisting for 2–12 months at the time of presentation. Fasciculations were accompanied by additional symptoms such as paresthesia and fatigue. Laboratory results were mostly unremarkable; two patients had positive myositis antibodies without clinical correlates. Electrophysiology was unremarkable in six patients, while fasciculation potentials were detected in four patients. Nine were diagnosed with probable benign fasciculation syndrome (BFS), and one met diagnostic criteria for amyotrophic lateral sclerosis (ALS). Discussion: In this small, retrospective case series, most cases of post-vaccination fasciculations were benign and compatible with BFS. Whether BFS onset was causally linked to vaccination or due to a nocebo effect remains unclear. One patient was diagnosed with ALS, though a causal link remains speculative given the study’s limitations and rarity of similar reports. Larger, prospective studies are needed to validate these observations and explore underlying pathophysiological mechanisms. Full article