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Cholinergic dysfunction is a key contributor to cognitive impairment observed in aging and neurodegenerative disorders such as Alzheimer's disease (AD). Although acetylcholinesterase (AChE) inhibitors have been the mainstay of symptomatic treatment for over two decades, their limited efficacy and adverse effects underscore the need for alternative therapeutic approaches. Recent evidence indicates that mechanical stimulation can modulate neuronal and glial signaling through mechanotransduction, suggesting a potential strategy to enhance cognitive function via non-pharmacological means. Here, we developed a head-mounted vibrotactile stimulation system (HVSS) that delivers controlled vibration to the cranium and evaluated its effects in a pharmacological model of acute cholinergic dysfunction induced by scopolamine. To this end, male C57BL/6 mice received scopolamine (1 mg/kg, i.p.; on days 7, 14, and 28) and were exposed to daily vibrotactile stimulation at 20, 40, or 80 Hz for 28 days. Behavioral performance was assessed using passive avoidance and Morris water maze tests, followed by biochemical and histological analyses. HVSS at 40 Hz and 80 Hz significantly improved cognitive performance, enhanced hippocampal cholinergic function, reduced oxidative damage, and upregulated memory-related signaling genes, including BDNF, PI3K, AKt, ERK1/2, CREB, and CAMK4. These findings suggest that high-frequency HVSS improves memory hippocampal cholinergic function via activation of memory-related signaling pathways, highlighting its potential as a safe, non-pharmacological neuromodulatory strategy for cholinergic dysfunction-related cognitive decline. Show less

BackgroundCognitive decline represents a major challenge in aging populations. Probiotics have been proposed to influence cognitive function through gut-brain interactions, but clinical findings remain inconsistent.ObjectiveThis study evaluated the effects of probiotic supplementation on cognitive function as the primary outcome, and on BDNF levels, inflammatory markers, and oxidative stress biomarkers as secondary outcomes in adults aged 50 years and older.MethodsA systematic search of PubMed, EBSCO, ProQuest, and Google Scholar was conducted through 1 May 2024 using predefined search terms related to probiotics, cognitive function, BDNF, inflammation, and antioxidant activity. Study quality was assessed using the RoB 2 tool. Meta-analyses were performed using random-effects models, and publication bias was explored using Egger's test where study counts permitted.ResultsSixteen studies demonstrated significant improvement in cognitive function among participants receiving probiotics compared to placebo. Cognitive function, measured using the Mini-Mental State Examination (MMSE), yielded a standardized mean difference (SMD) of 0.747 (95% CI 0.307-1.186) which corresponds to moderate-to-large effects. In comparison, the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) showed significant results with an SMD of 0.340 (95% CI 0.032-1.366) which corresponds to small-to-moderate effects. Probiotics also led to significant changes in several biochemical parameters, including BDNF, TNF-α, 8-OHdG, IL-6, IL-10, MDA, TAC, and GSH. Multi-strain probiotics showed better results compared to single-strain.ConclusionsProbiotic supplementation may offer modest cognitive benefits in aging populations, particularly in studies enrolling cognitively impaired individuals, but substantial heterogeneity and limited biomarker evidence restrict the certainty of these findings. Larger, longer-duration, and standardized trials are needed to clarify the clinical relevance and potential biological pathways underlying probiotic effects on cognition. Show less

Aging-related cognitive decline is a major concern in aging societies. Theobromine (TB), a cacao-derived methylxanthine, exerts neuroprotective effects through anti-inflammatory, antioxidant, and neurotrophic mechanisms; however, its efficacy in aging models remains unclear. This study investigated the mechanisms underlying neuroprotective effects of chronic TB administration in senescence-accelerated mouse prone 8 (SAMP8), a model of age-related memory impairment. SAMP8 and SAMR1 mice were fed either a control diet or a diet supplemented with 0.05% TB for 50 d. Cognitive performance was evaluated by the novel object recognition (NOR) test. Neurotrophic factors (BDNF and NT-3), synaptic proteins (PSD95 and synaptophysin), and plasticity-related signaling molecules (phosphorylated CREB and TrkB) were analyzed in the prefrontal cortex and hippocampus. Inflammatory cytokines, lipid peroxides, and antioxidant enzymes were quantified. Molecular docking was used to assess TB's interaction with phosphodiesterase (PDE) enzymes. TB improved short-term memory in SAMP8, increasing discrimination index in the NOR test. This was accompanied by increased BDNF, NT-3, PSD95, and synaptophysin levels and enhanced CREB and TrkB phosphorylation. Furthermore, TB lowered the levels of pro-inflammatory cytokines (IL-1β, TNF-α) and phosphorylated NF-κB, reduced lipid peroxidation, and increased the levels of antioxidant markers (HO-1, GSH). These effects were minimal in SAMR1. No adverse effects on body weight or blood parameters were observed. Molecular docking indicated that TB binds to PDE enzymes with weaker inhibitory activity than selective inhibitors. TB enhances short-term memory and synaptic function in aged mice via neurotrophic, antioxidant, and anti-inflammatory mechanisms, supporting its potential as a safe dietary intervention for age-related cognitive decline. Show less

Growing evidence implicates accelerated biological aging in environmentally induced psychiatric disorders, yet its role in metal-associated depression remains unclear. Using NHANES data, we evaluated associations between heavy metal mixtures and depression. Bidirectional mediation analysis was used to assess reciprocal pathways linking heavy metals, biological aging, and depression. Simultaneously, candidate genes linking heavy metal exposure to depression and biological aging were identified by mining the Comparative Toxicogenomics Database, analyzing differentially expressed genes (DEGs) from the Gene Expression Omnibus, and integrating the resulting evidence within a toxicogenomic framework to explore potential molecular mechanisms. The prevalence of depression among participants was 8.66 %. Metal mixtures significantly increased depression risk. Notably, cadmium and antimony increased the risk of depression (OR: 1.52, 95 % CI: 1.19, 1.94 and OR: 1.54, 95 % CI: 1.22, 1.93). Both metals have low thresholds (0.227 μg/L and 0.053 μg/L, respectively). Additionally, lead, cobalt, and molybdenum showed positive associations in specific models. Although population-level exposure to heavy metals declined from 1999 to 2020, concentrations remained sufficient to elevate depression risk. Our correlation analysis also identified a strong correlation between PhenoAge and chronological age (r = 0.84, P < 0.001). Mechanistically, we found that accelerated PhenoAge partially mediated the associations of several metals with depression risk, including monomethylarsonic acid (β = 0.004; 95 %CI: 0.003,0.006), cadmium (β = 0.006; 95 %CI: 0.003, 0.010), lead (β = 0.009; 95 %CI: 0.006, 0.011), cobalt (β = 0.010; 95 %CI: 0.006, 0.013), molybdenum (β = 0.009; 95 %CI: 0.006, 0.011), and antimony (β = 0.008; 95 %CI: 0.005, 0.011). Pathway analysis and DEGs implicated the contribution of neurodegeneration-multiple diseases pathway, with core molecular targets centering on BDNF, IL6, GSK3B, PTGS2, and SOD1. These findings, which imply biological aging as a potential link between metal exposure and depression, call for revised safety thresholds and pinpoint molecular targets for intervention. Show less

Lactoferrin (LF) plays a positive role in attenuating aging. In this study, LF obtained using different processing methods (freeze-dried: F and spray-dried: S) and its gastrointestinal digesta (XF and XS) were supplemented in d-gal-induced mice to explore their antiaging effects. The results showed that LF and its digesta (LFs) effectively ameliorated cognitive decline. Mechanistically, LFs prevented neuronal and synaptic injury by restoring redox balance, inhibiting the activation of microglia and astrocytes, and activating the cAMP-response element binding protein (CREB)/brain-derived neurotrophic factor (BDNF) pathway. Additionally, LFs increased the tight junction proteins and mucin-2, regulated the gut microbiota, particularly enriching bacteria in Firmicutes and restoring the Firmicutes/Bacteroidota ratio to maintain intestinal homeostasis. Meanwhile, LFs altered phospholipids (PLs) and other metabolites involved in glycerophospholipid metabolism such as arachidonic acid. Correlation analysis showed a significant association among metabolites, microbiota, and behaviors. These results indicated that LF and especially its digesta exert antiaging effects through multitarget pathways involving neuronal protection, neuroinflammation suppression, and microbiota-gut-brain axis regulation. Show less

With the rapid progression of global population aging, the incidence of cognitive dysfunction-related disorders is steadily increasing. In recent years, growing attention has been directed toward the interaction between the gut microbiota and the central nervous system (CNS). The gut-brain axis (GBA), as a bidirectional communication pathway, plays an increasingly recognized role in regulating cognitive functions. Ganoderma lucidum polysaccharides (GLP), a traditional medicinal and edible substance, can regulate gut microbiota homeostasis and short-chain fatty acid (SCFAs) levels through the GBA. GLP reduces the Firmicutes/Bacteroidetes ratio, significantly increases the abundance of Lactobacillus, and further suppresses oxidative stress and inflammatory responses by controlling microglial overactivation and neuroinflammation, thereby enhancing the expression of synapse-associated proteins and brain-derived neurotrophic factor (BDNF). Consequently, GLP shows potential for improving cognitive dysfunction. This review systematically summarizes the bioactivities of GLP, explores the neurodegenerative mechanisms of aging, and proposes the possibility that GLP mitigates aging-induced inflammation and improves cognitive function via modulation of the gut microbiota. Show less