Sofía Díaz-Cintra

Blood-brain barrier (BBB) dysfunction is increasingly recognized as an early pathological event in sporadic Alzheimer’s disease (AD), which represents over 95% of cases. Vascular risk factors and cerebral insulin resistance are considered potential contributors to its initiation. This review synthesizes evidence available through March 2026 on the temporal progression of morphological, functional, and molecular BBB alterations in AD patients and experimental models. This review emphasizes the proposed role of BBB disruption in perpetuating neurodegeneration through feedback loops involving pericyte damage, hypoxia, perivascular inflammation, and dysregulation of amyloid-β transport systems. By integrating data from neuroimaging, fluid biomarkers, and post-mortem studies, available evidence suggests that BBB alterations can be detected from preclinical stages, most consistently in the hippocampus, and may exhibit sex-specific differences. The review compares findings from familial transgenic models with the more limited characterization available in sporadic AD models (notably the intracerebroventricular streptozotocin model), and highlights key knowledge gaps regarding temporal dynamics. This synthesis supports further exploration of strategies to preserve BBB integrity. An integrated vascular approach may usefully complement current amyloid- and tau-centered therapies, particularly in sporadic AD.

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder in which blood–brain barrier (BBB) dysfunction may arise early. We performed an age-stratified, cross-sectional analysis of pericyte- and endothelial-associated markers and junctional proteins (claudin-1, -3, -5, occludin, and VE-cadherin) in cerebral capillary-enriched fractions from male Non-Tg and 3xTg-AD mice at asymptomatic, early, and advanced stages (3, 6, 12, and 16 months of age). Protein abundance was assessed by Western blot, and BBB permeability to 3–5 kDa FITC-dextran was evaluated at 3 months in an independent cohort. At 3 months, the pSRC/SRC ratio and an MMP-9-immunoreactive band were also evaluated in a separate cohort as candidate signaling markers related to occludin dysregulation. We detected no significant age or genotype effects for the pericyte- and endothelial-associated markers or for most junctional protein outcomes. Occludin was the only protein outcome with a significant overall genotype effect, with the largest mean reductions observed at 3 (~80%) and 6 months (~68%). A small exploratory cohort showed a higher hemisphere-derived permeability index in 3xTg-AD mice at 3 months. Neither pSRC/SRC nor the abundance of the MMP-9-immunoreactive band differed significantly between genotypes. These findings identify lower occludin abundance as the principal BBB-associated protein alteration in the 3xTg-AD model and provide exploratory evidence of increased BBB permeability at 3 months. These independent observations warrant longitudinal and translational evaluation to determine whether occludin abundance and BBB permeability could serve as indicators of early neurovascular dysfunction in AD.

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder driven by intersecting pathological processes. Persistent attrition in AD drug‐development pipelines highlights the limited clinical impact of single‐target therapies and has increased interest in multi‐target approaches acting on shared biological hubs. Although recent strategies extend beyond amyloid‐centered interventions, much of the evidence supporting multifunctional compounds remains preclinical or shows heterogeneous outcomes in advanced clinical stages. This narrative review examines drug candidates that have entered Phase III clinical trials in the last decade, with emphasis on emerging multitarget pharmacotherapies such as muscarinic M1 receptor agonists, dual M1/sigma‐1 receptor (σ1R) agonists, and dual σ1R agonist/anti‐amyloid agents. We also discuss complementary non‐pharmacological interventions, including physical exercise and targeted nutrition, that may support cognitive and emotional outcomes. Finally, we propose the Synergistic Optimized Pharmacological and Holistic Interventions for AD (SOPHI‐AD) framework as a conceptual and testable approach integrating multitarget pharmacology with lifestyle‐based strategies for AD management.

Gait is a widely used functional biomarker for detecting motor alterations across various diseases and conditions, as it reflects changes in coordination, strength, balance, and sensorimotor integration. However, traditional methods to analyze gait in animal models often require expensive equipment, complex setups, or invasive procedures that can alter natural behavior. Here, we present a low-cost, markerless workflow based on DeepLabCut, an open-source pose estimation software, for the quantitative analysis of gait and spontaneous locomotion in freely moving mice. The method relies on single-camera video acquisition, markerless tracking of anatomical landmarks, and extraction of spatiotemporal locomotor parameters, without the need for physical markers or specialized hardware. To demonstrate the protocol's applicability, it was implemented in the triple transgenic mouse model of Alzheimer's disease (3xTg-AD) as a representative example of application. This approach preserves free movement and minimizes handling-related stress, enabling non-invasive assessment of motor behavior. The protocol is compatible with standard behavioral testing environments. Overall, this method provides an accessible and non-invasive framework for quantitative analysis of gait and locomotion in preclinical research.

Neuronal morphology analysis in health and disease is fundamental for understanding brain function and for assessing the effects of experimental interventions. Golgi-Cox staining remains a classical, yet highly relevant technique for visualizing complete neuronal arbors and dendritic spines. However, published protocols frequently differ in critical procedural steps and often lack essential methodological details, leading to substantial variability in staining quality and making laboratory standardization time-consuming and challenging. Here, a comprehensive, step-by-step Golgi-Cox protocol for adult mice is presented, encompassing the entire workflow from in vivo handling and tissue processing to imaging and morphometric data extraction. It details practical considerations and common pitfalls that influence impregnation efficiency, section integrity, and signal-to-noise ratio, and provide methodological guidance to improve reproducibility. Overall, this protocol enables reliable visualization and quantitative analysis of whole neurons, dendritic segments, and dendritic spines. It is anticipated that this resource will facilitate the implementation of Golgi-Cox staining with greater consistency, transparency, and technical rigor, while offering a clear framework for adapting the method to diverse laboratory settings.

Memory processes are susceptible to impairment induced by excessive consumption of hypercaloric diets, particularly those rich in saturated fats and fructose. Such dietary patterns have been linked to disrupted neurotransmission in the prefrontal cortex (PFC), where the balance between excitation and inhibition depends on efficient glucose metabolism and the synthesis of neuroactive amino acids. However, the molecular mechanisms underlying these effects remain poorly understood. Here, male C57BL/6 mice were fed for 10 weeks with a control diet, a high-fat diet (HFD), a high-fructose diet (HFrD), or a combined high-fat/high-fructose diet (HFFrD). Their body weight gain and visceral adiposity were primarily driven by saturated fat intake, whereas hyperglycemia was observed across all diets. Also, we assessed metabolic outcomes, recognition memory, and PFC molecular profiles, including neuroactive amino acids (GABA, glutamate, glutamine, aspartate, alanine, glycine, and taurine) and the expression of genes related to glucose metabolism ( Slc2a1 , Pcx , G6pd , Gck , Pck1 , Irs2 ) and the glutamate/GABA–glutamine cycle ( Glul , Glud1 , Gad1 , Gad2 ). Behaviorally, HFFrD reduced locomotor activity and caused the most significant impairment in recognition memory. In the PFC, diet composition generated distinct amino acid profiles, revealing vulnerability of the glutamine–glutamate–GABA cycle to hypercaloric intake. Transcriptional responses were diet-specific, with consistent Gad1 upregulation and broader induction of glucose metabolism–related genes. Together, these findings demonstrate diet-dependent metabolic and neurochemical remodeling in the PFC and support a link between excessive fat and/or fructose intake with disrupted glutamine–glutamate homeostasis and memory deficits.

Alzheimer’s disease (AD) is characterized by the accumulation of amyloid-β (Aβ) and chronic neuroinflammation, with microglia playing a central role in its pathogenesis. Alterations in microglial metabolism have been proposed to contribute to AD-related inflammatory responses and reduced Aβ clearance, suggesting that thiamine-dependent pathways may be relevant in this context. Thiamine pyrophosphate (TPP), the active form of vitamin B1, is essential for glucose metabolism and mitochondrial function; however, its association with microglial changes in AD remains unclear. In this study, 9-month-old female triple-transgenic AD (3xTg-AD) mice and non-transgenic controls (NoTg) received TPP (2.0 mg/mL) or saline as a vehicle for six weeks via osmotic pumps. Nesting, a hippocampus-dependent behavioral test, as well analyses of Aβ burden, microglial morphology, and the expression of genes related to metabolic and immune pathways were evaluated. Differences in nesting behavior between experimental groups were observed, but TPP treatment was not associated with an evident change in 3xTg-AD mice. In the subiculum and CA1 regions of the hippocampus of female 3xTg-AD mice exposed to TPP, a lower Aβ burden was observed, and morphological variations in microglia were detected in both groups (3xTg-AD and NoTg). Additionally, in the brain of the TPP-treated group, some changes in mRNA gene expression were recorded. Together, these findings describe hippocampal microglial and amyloid profiles following TPP treatment in 3xTg-AD mice and provide a basis for further investigation of thiamine-dependent pathways in AD-related neuroinflammatory contexts.

Introduction: Alzheimer’s disease (AD) is the most common neurodegenerative disease worldwide, characterized by progressive cognitive decline and, in advanced stages, marked motor impairments. These motor deficits are associated with muscle atrophy, mitochondrial dysfunction, and amyloid- β (Aβ) pathology affecting both motor brain areas and peripheral tissues, ultimately contributing to disability, fall risk, and reduced quality of life. Although physical exercise has been shown to confer cognitive and functional benefits in AD, to date, no studies have directly examined the relationship between motor performance and the underlying pathological mechanisms. This study introduces a novel approach by simultaneously addressing muscle pathology and mitochondrial alterations associated with motor decline. Methods: Twelve-month-old male triple-transgenic (3xTg-AD) and non-transgenic (Non-Tg) mice were assigned to sedentary or exercise groups ( n = 16 each group). The exercise protocol combined voluntary wheel running and forced treadmill training, 5 days/week for 4 months. Motor performance was evaluated using open-field, gait analysis, grip strength, and beam walking tests. Post-intervention, histological analyses evaluated Aβ deposition and mitochondrial morphology, biochemical assays assessed mitochondrial function, and ELISA estimated Aβ levels in the brain and muscle. Results: Physical exercise improved locomotion, balance, and strength in advanced stages of the disease, with modest benefits for memory. Histology showed reduced muscle atrophy and cortical amyloid, but not hippocampal. ELISA detected lower relative levels of Aβ only in the brain. Exercise restored reduced muscle Complex I activity, increased brain Complex IV and ATPase in both tissues, and pronounced changes in mitochondrial morphology in muscle. Conclusion: This study provides the first evidence that physical exercise improves motor function and attenuates muscle and brain pathology in advanced stages of 3xTg-AD, supporting its potential as a complementary therapeutic strategy with translational relevance to humans.