Depression in neurodegenerative diseases: Common mechanisms and current treatment options

Psilocybin therapy for mood dysfunction in Parkinson's disease: an open-label pilot trial

Mood dysfunction is highly prevalent in Parkinson's disease (PD), a main predictor of functional decline, and difficult to treat-novel interventions are critically needed. Psilocybin shows early promise for treating depression and anxiety, but its potential in PD is unknown, as safety concerns have excluded people with neurodegenerative disease from previous trials. In this open-label pilot (NCT04932434), we examined the feasibility of psilocybin therapy among people with mild to moderate stage PD plus depression and/or anxiety. 12 participants (mean age 63.2 ± 8.2 years, 5 women) received psilocybin (one 10 mg followed by one 25 mg dose) with psychotherapy. There were no serious adverse events, no medical interventions required to manage effects of psilocybin, and no exacerbation of psychosis. Ten participants experienced treatment-emergent adverse events; the most frequent were anxiety, nausea, and increased blood pressure. We observed no worsening of PD symptomology measured by the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS). On the contrary, non-motor (MDS-UPDRS Part I: -13.8 ± 1.3, p < 0.001, Hedges' g = 3.0) and motor symptoms (Part II: -7.5 ± 0.9, p < 0.001, g = 1.2; Part III: -4.6 ± 1.3, p = 0.001; g = 0.3) as well as performance in select cognitive domains (Paired Associates Learning [-0.44 ± 0.14, p = .003, g = 0.4], Spatial Working Memory [-0.52 ± 0.17, p = 0.003, g = 0.7], and Probabilistic Reversal Learning [2.9 ± 0.9, p = 0.003, g = 1.3]) improved post-treatment, and improvements were sustained until the final safety assessment one month following drug exposure. Baseline Montgomery-Asberg Depression Rating Scale (MADRS) and Hamilton Anxiety Rating Scale (HAM-A) scores were 21.0 ± 8.7 and 17.0 ± 3.7, respectively. Both improved to a clinically meaningful degree post-treatment; these improvements persisted to the final assessment three months following drug exposure (MADRS: -9.3 ± 2.7, p = .001, g = 1.0; HAM-A: -3.8 ± 1.7; p = 0.031, g = 0.7). This study provides the first data on psilocybin's effects in any neurodegenerative disease. Results suggest that psilocybin therapy in PD warrants further investigation.

Neurodegenerative diseases: Epigenetic regulatory mechanisms and therapeutic potential

Neurodegenerative diseases (NDDs) are a class of diseases in which the progressive loss of subtype-specific neurons leads to dysfunction. NDDs include Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS), among others. Previous studies have demonstrated that the pathogenesis of NDDs involves various mechanisms, including genetic factors, oxidative stress, apoptosis, and the immune response. Recent studies have shown that epigenetic regulation mediates the interactions between DNA methylation, chromatin remodeling, histone modification, and non-coding RNAs, thus affecting gene transcription. A growing body of research links epigenetic modifications to crucial pathways involved in the occurrence and development of NDDs. Epigenetics has also been found to regulate and maintain nervous system function, and its imbalance is closely related to the occurrence and development of NDDs. The present review summarizes focuses on the role of epigenetic modifications in the pathogenesis of NDDs and provides an overview of the key genes regulated by DNA methylation, histone modification, and non-coding RNAs in NDDs. Further, the current research status of epigenetics in NDDs is summarized and the potential application of epigenetics in the clinical diagnosis and treatment of NDDs is discussed.

Bisphenol AF Induced Neurodevelopmental Toxicity of Human Neural Progenitor Cells via Nrf2/HO-1 Pathway

Bisphenol AF (BPAF) is widely utilized as an analog of bisphenol A (BPA) in the plastics industry. However, there is limited evidence on its neurodevelopmental toxicity. Existing studies suggest that BPAF has greater accumulation in vivo than other bisphenol analogs, and could pass through the placental barrier and the blood-brain barrier. In this study, we used the human neural progenitor cells line ReNcell CX, which was derived from 14-week human cortical brain tissue, as an in vitro model to investigate the neurodevelopmental toxicity effects of BPAF and BPA on ReNcell CX cells, and explored the possible mechanism by which BPAF induced neurodevelopmental toxicity on ReNcell CX cells. The results showed that BPAF reduced the proliferation of neural progenitor cells and changed the differentiation towards neurons after exposure for 24 h. Compared with BPA, ReNcell CX cells are more susceptible to BPAF exposure. In a 3D neurospheres model, BPAF affected the distance that neurons migrated outwards at the concentration of 2 μM. Furthermore, BPAF increased ROS levels in cells and reduced the expression of key proteins in the Nrf2/HO-1 pathway and its downstream molecules, such as SOD, GSH, and CAT. In conclusion, BPAF induces damage to critical nodes in neural progenitor cell development through the Nrf2/HO-1 pathway. Therefore, clarifying its neurodevelopmental toxicity and elaborating on the neurodevelopmental toxicity effects and mechanisms of bisphenol AF will help identify intervention targets for neurodevelopmental toxicity, and will have important public health significance for the safety assessment and risk prediction of bisphenol-related chemicals.

Neurobiological and therapeutic landmarks of depression associated with Alzheimer's disease dementia

Depression in Alzheimer's disease (AD) dementia has become an increasingly recognized public health concern due to its high prevalence and substantial impact on patient outcomes. Despite extensive research having been conducted over the past decades, the precise causal mechanisms and the nature of the relationship between depression and AD dementia remain incompletely understood. This narrative review examines the bidirectional interaction between depression and Alzheimer's disease, emphasizing shared neurobiological pathways, including neurotransmitter dysregulation, neuroinflammation, abnormalities in the hypothalamic-pituitary-adrenal (HPA) axis, and deficits in neuroplasticity. These mechanisms likely contribute to the acceleration of neurodegeneration in AD and the onset or worsening of depressive symptoms. Current therapeutic approaches remain largely nonspecific, with a lack of targeted therapies that address the unique pathophysiological context of depression in AD. While progress has been made, key research gaps remain, particularly in understanding the complex biological interactions between these two conditions. Future research should focus on identifying specific biomarkers and developing personalized treatment strategies tailored to the neurobiological features of both depression and AD. By addressing these neurobiological mechanisms, we can develop more effective and targeted interventions, ultimately improving patient outcomes and advancing clinical care for this dual pathology.

Differentiating Treatment-Resistant Depression With and Without Parkinsonism in the Elderly From a Psychiatric Perspective by 99mTc-TRODAT-1 SPECT Imaging

OBJECTIVES

Late-life depression often overlaps with neurodegenerative diseases leading to diagnostic and treatment challenges for neuropsychiatrists. This study aimed to differentiate elderly treatment-resistant depression (TRD) comorbid with parkinsonism from elderly TRD without Parkinsonism as well as elderly healthy controls using striatum dopamine transporter (DAT) imaging by 99mTc TRODAT-1 SPECT.

METHODS

Three groups were enrolled, including patients with TRD, patients with TRD comorbid with parkinsonism, and healthy controls. To obtain the DAT availability, the specific uptake ratios of the bilateral striatum were evaluated. Linear regression analyses were performed to evaluate the relationship between age and DAT level in the subregions of the striatum. Machine learning was applied to categorize the three groups with 10-fold cross-validation.

RESULTS

The study enrolled 32 patients with TRD (66.15 ± 6.82 $66.15\pm 6.82$ ), 36 TRD patients with parkinsonism (70.27 ± 5.63 $70.27\pm 5.63$ ), and 74 healthy elderly (66.95 ± 10.59 $66.95\pm 10.59$ ). A normative DAT concentration by age was established, providing a reference for clinical use. DAT levels differed among groups (all pairwise p < 0.01), with healthy controls exhibiting the highest levels, followed by patients with TRD, and then TRD patients with parkinsonism. Further, the Fine k-NN classifier emerged as the top performer to achieve 85.7% accuracy.

CONCLUSIONS

Besides clinical assessment, dopaminergic assessment may help differentiate parkinsonism from TRD in old age. The findings of lower DAT availability in TRD suggest that TRD may be a prodromal symptom of Parkinson's disease. Psychiatrists should consider comorbid neurodegenerative disorders in elderly, depressed patients and use clinical assessment, neurological examination, and brain imaging for early Parkinson's Disease screening.

Chronic stress induces depression-like behaviors and Parkinsonism via upregulating α-synuclein

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the aggregation of α-synuclein (α-syn) and the nigrostriatal dopaminergic neuronal degeneration. Depression is one of the most common non-motor symptoms of PD patients. However, the pathogenic connection between PD and depression is not well understood. Herein, we report that chronic stress upregulates the expression of α-syn in the mouse brain. Overexpression of α-syn in the hippocampus replicates depressive-like phenotypes, whereas the genetic deletion of α-syn enhances resistance to chronic stress. Furthermore, chronic stress in early life promoted the deposition of α-syn aggregates in a transgenic mouse model that overexpresses human A53T mutant α-syn (A53T mice). Chronic stress also exacerbated dopaminergic degeneration and motor impairments in A53T mice. Strikingly, α-syn inclusions were also observed in the brains of some aged non-transgenic mice subjected to chronic stress. Together, our findings suggest that chronic stress upregulates α-synuclein expression, resulting in depression-like behaviors and parkinsonism.

A Bibliometric Analysis of Neuroinflammation in Depression from 2004 to 2023: Global Research Hotspots and Prospects

Background: Neuroinflammation lays a prominent impact in the pathophysiology of depression, and numerous studies have been conducted in recent decades. Bibliometric analysis is of important for understanding the hot spots and research trends in a certain subject field. However, no systematic bibliometric study exists in this field to date. The purpose of the study focused on the trends and hotspots in neuroinflammation of depression and provided future researchers with guidance and sights. Methods: Publications (2004-2023) were obtained from the WoSCC, and analyzed by HistCite, VOSviewer, CiteSpace, and Bibliometrix. The impact of publications was assessed by TGCS. Results: We analyzed 1,496 articles published in 409 journals and authored by 46,533 researchers across 72 countries and regions. The most prolific countries were China, the USA, and Brazil, and the most cited countries were the USA, followed with China and the UK, while the most prolific and cited institution was University Toronto (records=34, TGCS=2,137). Brain Behavior and Immunity is the leading journal that regularly published research in this field (records=93, TGCS=6,247). NLRP3 inflammasome, microglia, TNF-α, and brain-derived neurotrophic factor (BDNF) were the basis of neuroinflammation in depression. C-reactive protein, an important marker of inflammation, has been discussed for the longest time in this disease. In recent five years, two most frontier potential areas in studying depression were gut microbiota dysbiosis and BDNF. Conclusions: There remains a strong research basis for neuroinflammation in depression from this bibliometric analysis. Microglial activation, gut microbiota, cytokine signaling, and oxidative stress were research hotspots in recent years. In the future, chronic stress, hippocampal structure, and gut microbiota will continue to be studied in the field of neuroinflammation in depression. This study may benefit scientists in identifying potential directions for future study and providing clinicians with new ideas for treatment.

Can ketamine therapy overcome treatment-resistant depression in Alzheimer's disease and older adults? Preclinical and clinical evidence

Treatment-resistant depression (TRD) presents substantial clinical challenges, particularly in patients with Alzheimer's disease (AD) and older adults experiencing late-life depression. Traditional monoaminergic therapies often fail in this population due to neurodegenerative changes that impact receptor dynamics and neurotransmitter systems. Emerging evidence suggests that N-methyl-D-aspartate (NMDA) receptor antagonists, such as ketamine, esketamine, and arketamine, may offer new avenues for treatment. This review examines the potential of ketamine and its derivatives in treating TRD in older adults and individuals with AD, focusing on their mechanisms of action, clinical efficacy, and limitations in the context of neurodegenerative pathology. Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we conducted a systematic search of PubMed, Google Scholar, and Web of Science databases up until January 2025, with no year restrictions. Nineteen human clinical studies and eight preclinical studies met the inclusion criteria. Evidence suggests that ketamine may offer advantages over standard treatments for AD, potentially due to its broader mechanism of action compared to the NMDA antagonist memantine, as observed in animal models of AD. Clinical findings have demonstrated the rapid and robust antidepressant effects of ketamine and esketamine, alleviating depressive symptoms in both AD patients and older adults with TRD, indicating their potential as effective therapeutic options for these complex conditions.

Microglial cannabinoid receptor 2 and epigenetic regulation: Implications for the treatment of depression

Depression, often stress-induced, is closely related to neuroinflammation, in which microglia, the brain's immune cells, are the leading players. Microglia shift between a quiescent and an active state, promoting both pro- and anti-inflammatory responses. Cannabinoid type 2 (CB2) receptor encoded by the CNR2 gene is a key player to modulate inflammatory activity. CB2 receptor is highly controlled at the epigenetic level, especially in response to stressful stimuli, positioning it between stress, neuroinflammation, and depression. The following review addresses how epigenetic regulation of CNR2 expression affects depression and the dissection, further, of molecular pathways driving neuroinflammation-related depressive states. The present study emphasizes the therapeutic potential of CB2 receptor agonists that selectively interact with activated microglia and opens a new avenue for the treatment of depression associated with neuroinflammation. The review, therefore, provides a framework of underlying mechanisms for developing novel therapeutic strategies that focus on relieving symptoms by modulating the neuroinflammatory response. Finally, this review underlines the possibilities of therapeutic interventions taking into account CB2 receptors in combating depression.

Intranasal dantrolene nanoparticles inhibit lipopolysaccharide-induced helplessness and anxiety behavior in mice

This study investigates the therapeutic effectiveness of intranasal dantrolene nanoparticles pretreatment to inhibit lipopolysaccharide (LPS)-induced pathological inflammation and synapse destruction and depressive and anxiety behavior in mice. B6SJLF1/J adult mice were pretreated with intranasal dantrolene nanoparticles (dantrolene: 5mg/kg), daily, Monday to Friday, 5 days per week, for 4 weeks. Then, mice were treated with intraperitoneal injection of LPS (5mg/kg) for one time. Behavioral tests for depression and anxiety were performed 24 hours after a one-time LPS injection. Biomarkers for pyroptosis-related inflammation cytokines (IL-1β and IL-18) in blood and brains were measured using enzyme-linked immunosorbent assay (ELISA) and immunoblotting, respectively. The changes of primary proteins activation inflammatory pyroptosis (NLRP3: NLR family pyrin domain containing 3, Caspase-1, N-GSDMD: N terminal protein gasdermin D) and synapse proteins (PSD-95 and synpatin-1) in brains were measured using immunoblotting. Intranasal dantrolene nanoparticles robustly inhibited LPS-induced depression and anxiety behavior. Intranasal dantrolene nanoparticles significantly inhibited LPS-induced pathological elevation of IL-1β and IL-18 in the blood and brain and inhibited LPS induced activation of pyroptosis. Intranasal dantrolene nanoparticles significantly ameliorated decrease of PSD-95 and synpatin-1 proteins in brains. Thus, intranasal dantrolene nanoparticles has demonstrated neuroprotection against inflammation mediated depression and anxiety behaviors and should be studied furthermore as a future effective drug treatment of major depression disorder or anxiety psychiatric disorder.

The Potential of Selected Plants and Their Biologically Active Molecules in the Treatment of Depression and Anxiety Disorders

The incidence of anxiety and depression disorders is increasing worldwide. There is an increasing incidence of hard-to-treat depression with various aspects of origin. Almost 80% of people prefer to use natural remedies and supplements as their primary healthcare solution. Not surprisingly, around one-third of drugs were inspired by nature. Over the past three decades, the use of such remedies has increased significantly. Synthetic antidepressants may cause various negative side effects, whereas herbal medicines are favored because of their ability to relieve symptoms with minimal to no side effects and lower financial burden. This review provides an overview of herbs and biologically active compounds used to treat depression.

The microbiota-gut-brain axis in Huntington's disease: pathogenic mechanisms and therapeutic targets

Huntington's disease (HD) is a currently incurable neurogenerative disorder and is typically characterized by progressive movement disorder (including chorea), cognitive deficits (culminating in dementia), psychiatric abnormalities (the most common of which is depression), and peripheral symptoms (including gastrointestinal dysfunction). There are currently no approved disease-modifying therapies available for HD, with death usually occurring approximately 10-25 years after onset, but some therapies hold promising potential. HD subjects are often burdened by chronic diarrhea, constipation, esophageal and gastric inflammation, and a susceptibility to diabetes. Our understanding of the microbiota-gut-brain axis in HD is in its infancy and growing evidence from preclinical and clinical studies suggests a role of gut microbial population imbalance (gut dysbiosis) in HD pathophysiology. The gut and the brain can communicate through the enteric nervous system, immune system, vagus nerve, and microbiota-derived-metabolites including short-chain fatty acids, bile acids, and branched-chain amino acids. This review summarizes supporting evidence demonstrating the alterations in bacterial and fungal composition that may be associated with HD. We focus on mechanisms through which gut dysbiosis may compromise brain and gut health, thus triggering neuroinflammatory responses, and further highlight outcomes of attempts to modulate the gut microbiota as promising therapeutic strategies for HD. Ultimately, we discuss the dearth of data and the need for more longitudinal and translational studies in this nascent field. We suggest future directions to improve our understanding of the association between gut microbes and the pathogenesis of HD, and other 'brain and body disorders'.

AMPA receptor diffusional trapping machinery as an early therapeutic target in neurodegenerative and neuropsychiatric disorders

Over the past two decades, there has been a growing recognition of the physiological importance and pathological implications surrounding the surface diffusion of AMPA receptors (AMPARs) and their diffusional trapping at synapses. AMPAR surface diffusion entails the thermally powered random Brownian lateral movement of these receptors within the plasma membrane, facilitating dynamic exchanges between synaptic and extrasynaptic compartments. This process also enables the activity-dependent diffusional trapping and accumulation of AMPARs at synapses through transient binding to synaptic anchoring slots. Recent research highlights the critical role of synaptic recruitment of AMPARs via diffusional trapping in fundamental neural processes such as the development of the early phases of long-term potentiation (LTP), contextual fear memory, memory consolidation, and sensory input-induced cortical remapping. Furthermore, studies underscore that regulation of AMPAR diffusional trapping is altered across various neurological disease models, including Huntington's disease (HD), Alzheimer's disease (AD), and stress-related disorders like depression. Notably, pharmacological interventions aimed at correcting deficits in AMPAR diffusional trapping have demonstrated efficacy in restoring synapse numbers, LTP, and memory functions in these diverse disease models, despite their distinct pathogenic mechanisms. This review provides current insights into the molecular mechanisms underlying the dysregulation of AMPAR diffusional trapping, emphasizing its role as a converging point for multiple pathological signaling pathways. We propose that targeting AMPAR diffusional trapping represents a promising early therapeutic strategy to mitigate synaptic plasticity and memory deficits in a spectrum of brain disorders, encompassing but not limited to HD, AD, and stress-related conditions. This approach underscores an integrated therapeutic target amidst the complexity of these neurodegenerative and neuropsychiatric diseases.

Lessons from the physiological role of guanosine in neurodegeneration and cancer: Toward a multimodal mechanism of action?

Neurodegenerative diseases and brain tumours represent important health challenges due to their severe nature and debilitating consequences that require substantial medical care. Interestingly, these conditions share common physiological characteristics, namely increased glutamate, and adenosine transmission, which are often associated with cellular dysregulation and damage. Guanosine, an endogenous nucleoside, is safe and exerts neuroprotective effects in preclinical models of excitotoxicity, along with cytotoxic effects on tumour cells. However, the lack of well-defined mechanisms of action for guanosine hinders a comprehensive understanding of its physiological effects. In fact, the absence of specific receptors for guanosine impedes the development of structure-activity research programs to develop guanosine derivatives for therapeutic purposes. Alternatively, given its apparent interaction with the adenosinergic system, it is plausible that guanosine exerts its neuroprotective and anti-tumorigenic effects by modulating adenosine transmission through undisclosed mechanisms involving adenosine receptors, transporters, and purinergic metabolism. Here, several potential molecular mechanisms behind the protective actions of guanosine will be discussed. First, we explore its potential interaction with adenosine receptors (A1R and A2AR), including the A1R-A2AR heteromer. In addition, we consider the impact of guanosine on extracellular adenosine levels and the role of guanine-based purine-converting enzymes. Collectively, the diverse cellular functions of guanosine as neuroprotective and antiproliferative agent suggest a multimodal and complementary mechanism of action.

Review on ginseng and its potential active substance G-Rg2 against age-related diseases: Traditional efficacy and mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

According to the Shen Nong Herbal Classic, Ginseng (Panax ginseng C.A. Meyer) is documented to possess life-prolonging effects and is extensively utilized in traditional Chinese medicine for the treatment of various ailments such as qi deficiency, temper deficiency, insomnia, and forgetfulness. Ginseng is commonly employed for replenishing qi and nourishing blood, fortifying the body and augmenting immunity; it has demonstrated efficacy in alleviating fatigue, enhancing memory, and retarding aging. Furthermore, it exhibits a notable ameliorative impact on age-related conditions including cardiovascular diseases and neurodegenerative disorders. One of its active constituents - ginsenoside Rg2 (G-Rg2) - exhibits potential therapeutic efficacy in addressing these ailments.

AIM OF THE REVIEW

The aim of this review is to explore the traditional efficacy of ginseng in anti-aging diseases and the modern pharmacological mechanism of its potential active substance G-Rg2, in order to provide strong theoretical support for further elucidating the mechanism of its anti-aging effect.

METHODS

This review provides a comprehensive analysis of the traditional efficacy of ginseng and the potential mechanisms underlying the anti-age-related disease properties of G-Rg2, based on an extensive literature review up to March 12, 2024, from PubMed, Web of Science, Scopus, Cochrane, and Google Scholar databases. Potential anti-aging mechanisms of G-Rg2 were predicted using network pharmacology and molecular docking analysis techniques.

RESULTS

In traditional Chinese medicine theory, ginseng has been shown to improve aging-related diseases with a variety of effects, including tonifying qi, strengthening the spleen and stomach, nourishing yin, regulating yin and yang, as well as calming the mind. Its potential active ingredient G-Rg2 has demonstrated significant therapeutic potential in age-related diseases, especially central nervous system and cardiovascular diseases. G-Rg2 exhibited a variety of pharmacological activities, including anti-apoptotic, anti-inflammatory and antioxidant effects. Meanwhile, the network pharmacological analyses and molecular docking results were consistent with the existing literature review, further validating the potential efficacy of G-Rg2 as an anti-aging agent.

CONCLUSION

The review firstly explores the ameliorative effects of ginseng on a wide range of age-related diseases based on TCM theories. Secondly, the article focuses on the remarkable significance and value demonstrated by G-Rg2 in age-related cardiovascular and neurodegenerative diseases. Consequently, G-Rg2 has broad prospects for development in intervening in aging and treating age-related health problems.

[Gynostemma pentaphyllum ethanol extract ameliorates motor dysfunction in a Parkinsons disease mouse model through inhibiting neuronal apoptosis]

OBJECTIVES

To investigate the protective effects and underlying mechanisms of Gynostemma pentaphyllum (GP)ethanol extract on motor dysfunction in a mouse model of Parkinson's disease (PD).

METHODS

Eighty C57BL/6 male mice were randomly divided into five groups: control group, model group, levodopa group (positive control group), low-dose GP group, and high-dose GP group, with 16 mice per group. The PD model was induced by injection of 6-hydroxydopamine into the substantia nigra pars reticulata of the mice. Two weeks after 6-hydroxydopamine, positive control group received intraperitoneal injection of levodopa 10 mg·kg－1·d－1, while low-dose GP and high-dose GP groups received GP extract 100 or 200 mg·kg－1·d－1 orally for three weeks. After a 3-week-treatment, the effects of GP on motor dysfunction in 6-hydroxydopamine-induced PD were assessed using open field and CatWalk gait tests, while the effects on muscle strength were evaluated by forelimb grip strength. Immunofluorescence staining was used to detect the number of tyrosine hydroxylase (TH) positive neurons. The levels of dopamine and serotonin in the midbrain were determined by enzyme-linked immunosorbent assay. In addition, Western blotting was performed to detect the expression of mitogen-activated protein kinase (MAPK) family proteins such as p-extracellular signal-regulated kinase (ERK)1/2, p-p38 and p-c-Jun N-terminal kinase (JNK)1/2, and mitochondrial apoptosis pathway proteins such as B-cell lymphoma (Bcl)-2, Bcl-2 associated X protein (Bax), and cleaved-cysteine aspartic acid specific protease (caspase)-3.

RESULTS

Behavioral experiments showed that GP significantly improved the spontaneous activity and motor coordination of PD mice (P<0.05). The forelimb grip strength was also increased by GP treatment (P<0.05), compared to the PD model group. In addition, compared with the model group, the number of TH-positive neurons in substantia nigra pars reticulata region, the levels of dopamine and serotonin in midbrain and the expression of p-ERK1/2 were significantly increased by GP treatment (all P<0.05), whereas the expression of p-p38 and p-JNK1/2, the ratio of Bax/Bcl-2 and cleaved-caspase-3/caspase-3 were significantly decreased (all P<0.05).

CONCLUSIONS

The results indicate that GP might increase dopamine and serotonin levels in the midbrain and promote the survival of dopaminergic neurons in substantia nigra pars reticulata by regulating the expression of phosphorylation of MAPK family proteins and the expression of mitochondrial apoptosis-related proteins, thereby ameliorating motor deficits in PD mice.

Translational Approach using Advanced Therapy Medicinal Products for Huntington's Disease

Current therapeutic approaches for Huntington's disease (HD) focus on symptomatic treatment. Therefore, the unavailability of efficient disease-modifying medicines is a significant challenge. Regarding the molecular etiology, targeting the mutant gene or advanced translational steps could be considered promising strategies. The evidence in gene therapy suggests various molecular techniques, including knocking down mHTT expression using antisense oligonucleotides and small interfering RNAs and gene editing with zinc finger proteins and CRISPR-Cas9-based techniques. Several post-transcriptional and post-translational modifications have also been proposed. However, the efficacy and long-term side effects of these modalities have yet to be verified. Currently, cell therapy can be employed in combination with conventional treatment and could be used for HD in which the structural and functional restoration of degenerated neurons can occur. Several animal models have been established recently to develop cell-based therapies using renewable cell sources such as embryonic stem cells, induced pluripotent stem cells, mesenchymal stromal cells, and neural stem cells. These models face numerous challenges in translation into clinics. Nevertheless, investigations in Advanced Therapy Medicinal Products (ATMPs) open a promising window for HD research and their clinical application. In this study, the ATMPs entry pathway in HD management was highlighted, and their advantages and disadvantages were discussed.

Intranasal Delivery of Lithium Salt Suppresses Inflammatory Pyroptosis in the brain and Ameliorates Memory Loss and Depression-like Behavior in 5XFAD mice

Background

Alzheimer's disease (AD) is a devastating neurodegenerative disease (AD) and has no treatment that can cure or halt the disease progression. This study explored the therapeutic potential of lithium salt dissolved in Ryanodex formulation vehicle (RFV) and delivered to the brain by intranasal application. We first compared lithium concentrations in the brain and blood of wild-type mice following intranasal or oral administration of lithium chloride (LiCl) dissolved in either RFV or water. The beneficial and side effects of intranasal versus oral LiCl in RFV in these mice were assessed and potential mechanisms underlying the efficacy of anti-inflammation and anti-pyroptosis in the brains were also investigated in both wild-type (WT) and 5XFAD Alzheimer's Disease (AD) mice brains.

Methods

For the study of brain versus blood lithium concentrations, WT B6SJLF1/J mice at 2 months of age were treated with intranasal or oral LiCl (3 mmol/kg) dissolved in RFV or in water. Brain and blood lithium concentrations were measured at various times after drugs administration. Brain/blood lithium concentration ratios were then determined. For studying therapeutic efficacy versus side effects and their underlying mechanisms, 5XFAD and WT B6SJLF1/J mice were treated with intranasal LiCl (3 mmol/kg) daily, Monday to Friday each week, in RFV beginning at 2 or 9 months of age with a 12-week treatment duration. Animal behaviors were assessed for depression (tail suspension), cognition (fear conditioning and Y maze), olfaction (buried food test), and motor functions (rotarod) at the age of 5 and 12 months. Blood and brain tissue were harvested from these mice at 13 months. Blood biomarkers for the functions of thyroid (thyroid stimulating hormone, TSH) and kidney (creatinine) were measured using ELISA. Changes in protein expression levels of the endoplasmic reticulum Ca2+ release channels type 1 InsP3 receptors (InsP3R-1), malondialdehyde (MDA)-modified proteins and 4-hydroxy-2-nonenal (4-HNE), pyroptosis regulatory proteins (NLR family pyrin domain containing 3 (NLRP3), cleaved caspase-1, N-terminal of Gasdermin D (GSDMD)), cytotoxic (IL-1β, IL-18, IL-6, TNF-α) and cytoprotective (IL-10) cytokines and synapse proteins (PSD-95, synapsin-1) were determined using immunoblotting. Mouse body weights were monitored regularly.

Results

Compared to oral LiCl in RFV nanoparticles, intranasal treatment of WT mice with LiCl in RFV markedly decreased blood concentrations at the time frame of 30-120 minutes. The ratio of brain/blood lithium concentration after Intranasal lithium chloride in RFV significantly increased, in comparison to those after oral administration lithium chloride in RFV or intranasal administration of lithium chloride in water. Intranasal lithium chloride in RFV inhibited both memory loss and depressive behavior in adult and aged 5XFAD mice. Additionally intranasal treatment of aged 5XFAD mice with LiCl in RFV effectively suppressed the increases in InsP3R-1, intracellular oxidative stress markers (4-HNE-bound and MDA-modified proteins), pyroptosis activation proteins (NLRP3, cleaved caspase-1, N-terminal GSDMD) and cytotoxic cytokines (IL-1β, IL-6, TNF-α), but reversed the down-regulation of cytoprotective cytokine IL-10. Intranasal LiCl in RFV also alleviated the loss of the postsynaptic synapse protein PSD-95, but not synapsin-1, in aged 5XFAD mice. Blood level of the kidney function marker creatinine was significantly increased in 5XFAD than in WT mice in an age-dependent manner and this elevation was abolished by intranasal delivery of LiCl in RFV. Intranasal LiCl in RFV for 12 weeks in both WT or 5XFAD mice did not affect blood biomarkers for thyroid function, nor did it affect smell or muscle function or body weight.

Conclusion

Intranasal administration of LiCl in RFV significantly decreased lithium blood concentrations and increased brain/blood lithium concentration ratio, in comparison to its oral administration. Intranasal administration of LiCl in RFV robustly protected against both memory loss and depressive-like behavior, while had no side effects concerning thyroid and kidney toxicity in 5XFAD mice. These lithium-induced beneficial effects were strongly associated with lithium's suppression of InsP3R-1 Ca2+ channel receptor increase, pathological neuroinflammation and activation of the pyroptosis pathway, as well as the loss of some synaptic proteins. Intranasal delivery of lithium salt in RFV could become an effective and potent inhibitor of pathological inflammation/pyroptosis in the CNS and serve as a new treatment for both AD-associated dementia and depression with minimal unwanted side effects including peripheral organ toxicity.

Longitudinal associations between cerebrospinal fluid glial activation markers, depression, and dopamine transporter availability in patients with Parkinson's disease

BACKGROUND

Depression and decreased dopamine transporter (DAT) availability are prevalent in Parkinson's disease (PD), yet early predictive biomarkers are lacking. This study investigates the longitudinal associations between cerebrospinal fluid (CSF) neuroglial activation markers, sTREM2 and YKL-40, and depression, as well as DAT availability, in PD patients.

METHODS

We analyzed data from 172 PD subjects and 80 matched healthy controls from a large longitudinal study. A generalized linear mixed-effects model assessed the longitudinal associations of CSF sTREM2 and YKL-40 with depression and DAT availability. Causal mediation analysis determined if DAT decline mediated the effects of sTREM2 and YKL-40 on depression.

RESULTS

Cross-sectional analysis revealed a negative correlation between CSF sTREM2 and baseline depression scores in PD patients. CSF YKL-40 negatively correlated with baseline left caudate nucleus, left anterior putamen, and right anterior putamen specific binding ratios (SBR). Longitudinally, higher baseline CSF sTREM2 predicted faster depression progression (β = 0.828, p < 0.001) and a rapid decline in right putamen SBR (β = 0.072, p = 0.016). Similarly, higher baseline CSF YKL-40 predicted faster depression progression (β = 0.586, p = 0.004) and a decline in left anterior putamen SBR (β = 0.058, p = 0.035). Causal mediation analysis indicated that baseline CSF sTREM2 accelerated depression progression via its effect on right putamen and right anterior putamen SBR (Indirect effect = 0.103, p = 0.020; Indirect effect = 0.129, p = 0.016).

CONCLUSION

CSF sTREM2 and YKL-40 are effective predictors for depression and DAT decline in PD, suggesting that neuroglial activation-induced dopaminergic neuron apoptosis significantly contributes to depression onset in PD.

The pathobiology of depression in Huntington's disease: an unresolved puzzle

Huntington's disease (HD) is an autosomal-dominant progressive neurodegenerative disease that manifests with a triad of symptoms including motor dysfunctions, cognitive deficits, and prominent neuropsychiatric symptoms, the most common of which is depression, with a prevalence between 30 and 70%. Depressive symptoms occur in all stages of HD, beginning in presymptomatic HD gene carriers, and are strongly associated with suicidal ideation and suicidality, but their relationship with other clinical dimensions in HD is controversial and the underlying pathophysiology is poorly understood. Analysis of the available literature until November 2023 concerned the prevalence, clinical manifestations, neuroimaging, transgenic models, and treatment options of HD depression. While it was believed that depression in HD is due to psychosomatic factors in view of the fatal disease, studies in transgenic models of HD demonstrated molecular changes including neurotrophic and serotonergic dysregulation and disorders of the hypothalamic-pituitary-adrenal axis inducing depression-like changes. While relevant neuropathological data are missing, recent neuroimaging studies revealed correlations between depressive symptoms and dysfunctional connectivities in the default mode network, basal ganglia and prefrontal cortex, and changes in limbic and paralimbic structures related to the basic neurodegenerative process. The impact of response to antidepressants in HD patients is controversial; selective serotonin reuptake inhibitors are superior to serotonin-norepinephrine reuptake inhibitors, while electroconvulsive therapy may be effective for pharmacotherapy resistant cases. Since compared to major depressive disorder and depression in other neurodegenerative diseases, our knowledge of the molecular basis in HD depression is limited, further studies to elucidate the heterogeneous pathogenesis in this fatal disorder are warranted.

Neuroplasticity-related effects of vitamin D relevant to its neuroprotective effects: A narrative review

The pathophysiology of a wide range of central nervous system (CNS) disorders, such as neurodegenerative and psychiatric diseases, has been associated with impairment of neurogenic and synaptogenic processes. Therefore, pharmacological and/or nutritional strategies based on the stimulation and/or restoration of these processes may have beneficial effects against diseases in which these processes are impaired. In this context, vitamin D has emerged as a promising neuroprotective compound. Due to its pleiotropic properties, it can interact with multiple molecular targets and thereby affect different cell types, including neurons and glial cells. This neurosteroid contributes to CNS homeostasis by non-genomic and genomic mechanisms through its interaction with vitamin D receptors (VDRs). Among several properties of this vitamin, its role in neuronal proliferation and differentiation as well as in synaptic plasticity has received attention. Considering this background, this narrative review aims to highlight the neuroplasticity-related mechanisms of vitamin D that may be associated with its neuroprotective effects.

Bayesian Mendelian Randomization Analysis for Latent Exposures Leveraging GWAS Summary Statistics for Traits Co-Regulated by the Exposures

Mendelian Randomization analysis is a popular method to infer causal relationships between exposures and outcomes, utilizing data from genome-wide association studies (GWAS) to overcome limitations of observational research by treating genetic variants as instrumental variables. This study focuses on a specific problem setting, where causal signals may exist among a series of correlated traits, but the exposures of interest, such as biological functions or lower-dimensional latent factors that regulate the observable traits, are not directly observable. We propose a Bayesian Mendelian randomization analysis framework that allows joint analysis of the causal effects of multiple latent exposures on a disease outcome leveraging GWAS summary-level association statistics for traits co-regulated by the exposures. We conduct simulation studies to show the validity and superiority of the method in terms of type I error control and power due to a more flexible modeling framework and a more stable algorithm compared to an alternative approach and traditional single- and multi-exposure analysis approaches not specifically designed for the problem. We have also applied the method to reveal evidence of the causal effects of psychiatric factors, including compulsive, psychotic, neurodevelopmental, and internalizing factors, on neurodegenerative, autoimmune, digestive, and cardiometabolic diseases.

Depression like-behavior and memory loss induced by methylglyoxal is associated with tryptophan depletion and oxidative stress: a new in vivo model of neurodegeneration

BACKGROUND

Depression and memory loss are prevalent neurodegenerative disorders, with diabetic patients facing an elevated risk of brain dysfunction. Methylglyoxal (MGO) formation, which is heightened in diabetes owing to hyperglycemia and gut dysbiosis, may serve as a critical link between diabetes and brain diseases. Despite the high prevalence of MGO, the precise mechanisms underlying MGO-induced depression and memory loss remain unclear.

RESULTS

We investigated the effect of MGO stress on depression like-behavior and memory loss to elucidate the potential interplay between MGO-induced tryptophan (Trp) metabolism impairment and oxidative stress in the brain. It demonstrates that MGO induces depression-like behavior in mice, as confirmed by the OFT, TST, FST, SPT, and EPM behavioral tests. MGO led to the depletion of Trp and related neurotransmitters as 5-HT, EPI, and DA in the mouse brain. Additionally, MGO reduced the cell count in the DG, CA1, and CA3 hippocampal regions and modulated TPH2 levels in the brain. Notably, co-treatment with MGO and Trp mirrored the effects observed after Trp-null treatment in neurons, including reduced TPH1 and TPH2 levels and inhibition of neuronal outgrowth. Furthermore, MGO significantly altered the expression of key proteins associated with neurodegeneration, such as p-Tau, p-GSK-3β, APP, oAβ, BDNF, NGF, and p-TrkB. Concurrently, MGO activated MAPKs through ROS induction, triggering a redox imbalance by downregulating Nrf-2, Ho-1, TXNRD1, Trx, Sirt-3, and Sirt-5 expression levels, NAD+, and CAT activity in the mouse brain. This led to an accelerated neuroinflammatory response, as evidenced by increased expression of Iba-1, p-NF-κB, and the secretion of IL-6 and TNF-α. Importantly, Trp treatment ameliorated MGO-induced depression like-behavior and memory loss in mice and markedly mitigated increased expression of p-Tau, APP, p-ERK1/2, p-pJNK, and p-NF-κB in the brain. Likewise, Trp treatment also induced the expression of MGO detoxifying factors GLO-I and GLO-II and CAT activity, suggesting the induction of an antioxidant system and reduced inflammation by inhibiting IL-6 and TNF-α secretion.

CONCLUSIONS

Our data revealed that MGO-induced depression like-behavior and memory deficits resulted from disturbances in Trp, 5-HT, BDNF, and NGF levels, increased p-Tau and APP expression, neuroinflammation, and impaired redox status (Nrf-2/Ho-1/TXNRD1/Sirt3/5) in the brain.

The neurodegenerative hypothesis of depression and the influence of antidepressant medications

Depression is a complex neurological disease that holds many theories on its aetiology and pathophysiology. The monoamine strategy of treating depression with medications to increase levels of monoamines in the (extra)synapse, primarily through the inhibition of monoamine transporters, does not always work, as seen in patients that lack a response to multiple anti-depressant exposures, as well as a lack of depressive symptoms in healthy volunteers exposed to monoamine reduction. Depression is increasingly being understood not as a single condition, but as a complex interplay of adaptations in various systems, including inflammatory responses and neurotransmission pathways in the brain. This understanding has led to the development of the neurodegenerative hypothesis of depression. This hypothesis, which is gaining widespread acceptance posits that both oxidative stress and inflammation play significant roles in the pathophysiology of depression. This article is a review of the literature focused on neuroinflammation in depression, as well as summarised studies of anti-inflammatory and antioxidant effects of antidepressants.

Danshensu Interventions Mediate Rapid Antidepressant Effects by Activating the Mammalian Target of Rapamycin Signaling and Brain-Derived Neurotrophic Factor Release

OBJECTIVE

Danshensu, a phenylpropanoid compound, is derived from the dry root and rhizome of Danshen (Salvia miltiorrhiza), a traditional Chinese medicinal herb. Evidence suggests that danshensu protects isolated rat hearts against ischemia/reperfusion injury by activating the protein kinase B (Akt)/extracellular signal-regulated kinase (ERK) pathway or by inhibiting autophagy and apoptosis through the activation of mammalian target of rapamycin (mTOR) signaling. Furthermore, danshensu promotes the postischemic regeneration of brain cells by upregulating the expression of brain-derived neurotrophic factor (BDNF) in the peri-infarct region. However, basic and clinical studies are needed to investigate the antidepressant effects danshensu and determine whether brain mTOR signaling and BDNF activation mediate these effects. The aforementioned need prompted us to conduct the present study.

METHODS

Using a C57BL/6 mouse model, we investigated the antidepressant-like effects of danshensu and the mechanisms that mediate these effects. To elucidate the mechanisms, we analyzed the roles of Akt/ERK-mTOR signaling and BDNF activation in mediating the antidepressant-like effects of danshensu.

RESULTS

Danshensu exerted its antidepressant-like effects by activating the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) of Akt/ERK-mTOR signaling and promoting BDNF release. Treatment with danshensu increased the level of glutamate receptor 1 phosphorylation at the protein kinase A site.

CONCLUSION

Our study may be the first to demonstrate that the antidepressant effects of danshensu are dependent on the activation of the AMPAR-mTOR signaling pathway, are correlated with the elevation of BDNF level, and facilitate the insertion of AMPAR into the postsynaptic membrane. This study also pioneers in unveiling the potential of danshensu against depressive disorders.

P1 evoked by facial expression images is enhanced in Parkinson's disease patients with depressive symptoms

Introduction

Depressive symptoms are most common non-motor symptoms in Parkinson's disease (PD), which is often overlooked due to absence of rapid and objective diagnostic biomarkers. Electroencephalography (EEG)-based event-related potentials (ERPs) is commonly used to assess emotional processes. The aim of this study was to investigate changes in ERPs in PD patients exhibiting depressive symptoms and to provide a reliable biomarker for assisting in the diagnosis of PD with depressive symptoms.

Methods

We conducted a case-control study involving 30 PD patients with (dPD group) or without depressive symptoms (nPD group) and 13 age matched healthy controls (HC). We recorded EEG of the patients during the emotional picture stimulation task and analyzed the difference in the early ERPs potentials (P1, N170, early posterior negativity) and their correlation with the severity of symptoms in PD patients.

Results

Our results found that P1 amplitude in the occipital region of the dPD group in response to emotional faces was significantly higher than that of nPD and HC group, and it was positively correlated with severity of depressive symptoms in PD patients.

Conclusion

Our study shows that facial expression-induced enhancement of P1 amplitude can be utilized as a rapid and objective indicator to screen for depressive symptoms in PD.

Acupuncture for early Parkinson's disease with mild to moderate depression: a randomized controlled trial protocol with functional MRI

Introduction

Depression is a common non-motor symptom of Parkinson's disease (PD), which seriously affects the quality of life of patients with PD. The main clinical treatment method for depression in Parkinson's disease is medication treatment. However, the medication treatment has a long cycle and many adverse reactions. Acupuncture as a non-pharmacological intervention method, has been widely used in the treatment of patients with Parkinson's disease and depressive disorders in China. Therefore, the study of acupuncture in the treatment of early Parkinson's disease with mild to moderate depression has important practical significance.

Methods and analysis

In this randomized, single-blinded, and placebo-controlled study, a total of 88 patients with depression in Parkinson's disease (DPD) will be randomly allocated to either an acupuncture group or a control group in parallel in a 1:1 allocation ratio. Each group will receive 30 min acupuncture treatments or sham acupuncture treatments, 3 times a week, for 12 weeks, followed by a 36-week follow-up period. The primary outcome is the response rate of the Hamilton Depression Rating Scale-17 at 12 weeks. Data will be collected at baseline, at the end of the 12-week treatment period, and during the 12-week and 36-week follow-up.

Discussion

This study hypothesized that acupuncture may treat DPD by restoring pathological alterations in brain neural activity. The findings will provide scientific evidence for acupuncture in the treatment of early PD with mild to moderate depression.

Ethics and dissemination

This clinical trial has been approved by the Medical Ethics Committee of the Beijing Hospital of Traditional Chinese Medicine (Approval No. 2023BL02-013-01). This trial has been registered with the Chinese Clinical Trials Registry (Registration No. ChiCTR2300069310). The results will be published in a peer-reviewed academic journal.

Clinical trial registration

https://www.chictr.org.cn/, identifier ChiCTR2300069310.

Harnessing myelin water fraction as an imaging biomarker of human cerebral aging, neurodegenerative diseases, and risk factors influencing myelination: A review

Myelin water fraction (MWF) imaging has emerged as a promising magnetic resonance imaging (MRI) biomarker for investigating brain function and composition. This comprehensive review synthesizes the current state of knowledge on MWF as a biomarker of human cerebral aging, neurodegenerative diseases, and risk factors influencing myelination. The databases used include Web of Science, Scopus, Science Direct, and PubMed. We begin with a brief discussion of the theoretical foundations of MWF imaging, including its basis in MR physics and the mathematical modeling underlying its calculation, with an overview of the most adopted MRI methods of MWF imaging. Next, we delve into the clinical and research applications that have been explored to date, highlighting its advantages and limitations. Finally, we explore the potential of MWF to serve as a predictive biomarker for neurological disorders and identify future research directions for optimizing MWF imaging protocols and interpreting MWF in various contexts. By harnessing the power of MWF imaging, we may gain new insights into brain health and disease across the human lifespan, ultimately informing novel diagnostic and therapeutic strategies.

Changes in slow-wave sleep characteristics in Parkinson's disease patients with mild-moderate depression

INTRODUCTION

Depression and sleep disturbances are commonly seen non-motor symptoms in patients with Parkinson's disease (PD). This study used polysomnography to examine the relationship between mild-moderate depression in PD and sleep characteristics, particularly slow wave activities (SWA).

METHODS

59 PD patients were split into two groups: nd-PD (n = 27) (patients with PD without depression) and d-PD (n = 32) (patients with PD with mild-moderate depression). Their clinical features, polysomnography parameters, and demographics were evaluated. Early and late sleep SWA spectrum densities and overnight SWA decline in different brain regions were particularly analyzed.

RESULTS

Non-rapid eye movement 3 (N3) sleep duration and percentage were greater in the d-PD group. N3 percentage was linked to depression (p = 0.014). During late sleep, higher SWA (0.5-4Hz) in the frontal and central regions, higher low-SWA (0.5-2Hz) in the whole brain, central and occipital regions, and higher high-SWA (2-4Hz) in the frontal region was observed in the d-PD group. During early sleep, there was also higher low-SWA (0.5-2Hz) in the occipital region. Patients in d-PD group exhibited reduced overnight high-SWA (2-4Hz) decline (Δhigh-SWA) in the whole brain and occipital regions. Δhigh-SWA(2-4Hz) in the occipital region were associated with depression (p = 0.049).

CONCLUSION

PD patients with mild-moderate depression have impaired slow wave sleep, exhibiting as increased N3 sleep, SWA, and reduced overnight SWA decline. This implies that synaptic strength reduction during sleep and impaired synaptic homeostasis regulation may be associated with depression in PD. Reduced overnight high-SWA decline in the occipital region may serve as a novel electrophysiological biomarker for indicating depression in PD.

NMT2 alleviates depression-like behavior in a rat model of chronic unpredictable stress: An integrated proteomic and phosphoproteomic analysis

Proteomics has been widely used to investigate multiple diseases. Combining the analyses of proteomics with phosphoproteomics can be used to further explain the pathological mechanisms of depression. In this study, depression-like behavior was induced in a rat model of chronic unpredictable mild stress (CUMS). We subsequently conducted the sucrose preference test, open field experiment, and forced swimming test to assess depressive-like behavior. Proteomic and phosphoproteomic sequencing of the hippocampal tissues from depressive-like behavior and normal rats were analyzed to identify differentially expressed proteins (DEPs) and differentially phosphorylated proteins (DPPs). Differentially expressed phosphorylated proteins (DEPPs) were obtained by intersecting the DEPs and DPPs, and functional enrichment analysis, as well as ingenuity pathway analysis (IPA), were subsequently performed. The study also investigated correlations among the DEPPs and used qRT-PCR to quantify the expression levels of key genes. Five DEPPs were identified, Gys1, Nmt2, Lrp1, Bin1, and Atp1a1, which were found to activate the synaptogenesis signaling pathway, induce mitochondrial dysfunction, and activate the phosphoinositide biosynthesis and degradation pathways. The qRT-PCR results confirmed the proteomic findings for Gys1, Nmt2, Lrp1, and Atp1a1. Importantly, inhibiting Nmt2 was found to alleviate depression-like behavior and alleviate neuronal apoptosis in the hippocampus of CUMS rats. In conclusion, we identified five DEPPs associated with the synaptogenesis signaling pathway, mitochondrial dysfunction, and phosphoinositide biosynthesis and degradation in depression. Furthermore, NMT2 may be a potential target for the treatment or diagnosis of depression. Our findings provide novel insights into the molecular mechanisms of depression.

Subjective and objective cognitive functioning in untreated late-life depression: An exploration centered on comorbid generalized anxiety disorder

BACKGROUND

Late-Life Depression (LLD) is a prevalent mental health disorder that is often accompanied by cognitive impairments. The objective of this study is to investigate the influence of coexisting Generalized Anxiety Disorder (GAD) on both subjective and objective cognitive abilities in untreated LLD individuals.

METHODS

A total of 77 participants aged 60 years and above were recruited for this study, comprising 31 individuals with Major Depressive Disorder (LLD group), 46 with MDD and coexisting Generalized Anxiety Disorder (LLDA group), and 54 healthy controls (HC). Prior to the study, all patients had abstained from psychotropic medication for a minimum of two weeks. Comprehensive neuropsychological assessments were administered to all participants.

RESULTS

The LLDA group exhibited substantial disparities in memory, attention, processing speed,executive function,overall cognitive functioning, and subjective cognitive functioning when compared to the HC group. The LLD group displayed deficits in memory, SCWT-W in attention, SCWT-C in processing speed,overall cognitive functioning, and subjective cognitive functioning in comparison to the healthy controls. Although the LLD group achieved lower average scores in executive function, TMTA in processing speed, and DSST in attention than the HC group, no significant distinctions were identified between these groups in these domains. Linear regression analysis unveiled that anxiety symptoms had a significant impact on subjective cognitive deficits among MDD patients, but exhibited a milder influence on objective cognitive performance. After adjusting for the severity of depression, anxiety symptoms were found to affect TMTA in processing speed and subjective cognitive functioning in LLD patients.

CONCLUSION

Late-Life Depression (LLD) exhibits pervasive cognitive impairments, particularly in individuals with generalized anxiety disorder, presenting a crucial target for future therapeutic interventions. Among elderly individuals with depression, anxiety symptoms significantly impact subjective cognitive functioning, suggesting its potential utility in distinguishing between depression-associated cognitive decline and pre-dementia conditions.

Guanosine increases global SUMO1-ylation in the hippocampus of young and aged mice and improves the short-term memory of young mice

The nucleoside guanosine is an endogenous neuromodulator associated with neuroprotection. The roles of guanosine during aging are still not fully elucidated. Guanosine modulates SUMOylation in neurons and astrocytes in vitro, but it is not known whether guanosine can modulate SUMOylation in vivo and improve cognitive functions during aging. SUMOylation is a post-translational protein modification with potential neuroprotective roles. In this follow-up study, we investigated whether guanosine could modulate SUMOylation in vivo and behavior in young and aged mice. Young (3-month-old) and aged (24-month-old) C57BL/6 mice were treated with guanosine (8 mg/kg intraperitoneal) daily for 14 days. Starting on day 8 of treatment, the following behavioral tests were performed: open field, novel object location, Y-maze, sucrose splash test, and tail suspension test. Treatment with guanosine did not change the locomotor activity of young or aged mice in the open-field test. Treatment with guanosine improved short-term memory only for young mice but did not change the working memory of either young or aged mice, as evaluated using object recognition and the Y-maze tests, respectively. Depressive-like behaviors, such as impaired grooming evaluated through the splash test, did not change in either young or aged mice. However, young mice treated with guanosine increased their immobility time in the tail suspension test, suggesting an effect on behavioral coping strategies. Global SUMO1-ylation was significantly increased in the hippocampus of young and aged mice after 14 days of treatment with guanosine, whereas no changes were detected in the cerebral cortex of either young or aged mice. Our findings demonstrate that guanosine also targets hippocampal SUMOylation in vivo, thereby contributing to a deeper understanding of its mechanisms of action. This highlights the involvement of SUMOylation in guanosine's modulatory and neuroprotective effects.

Association of four metalloids in the serum and urine of individuals with major depressive disorders: a case-control study

Background

Major depressive disorder (MDD) pathogenesis may involve metalloids in a significant way. The aim of our study was to identify potential links between MDD and metalloid elements [boron (B), germanium (Ge), arsenic (As), antimony (Sb)].

Methods

A total of 72 MDD cases and 75 healthy controls (HCs) were recruited from Zhumadian Second People's Hospital in Henan Province, China. The levels of four metallic elements (B, Ge, As, and Sb) in the serum and urine were measured using inductively coupled plasma mass spectrometry (ICP-MS).

Results

In comparison to the HCs, the B, As, and Sb levels were considerably lower in the MDD group (p < 0.05) in the serum; the MDD group had significantly higher (p < 0.05) and significantly lower (p < 0.001) B and Sb levels in the urine. After adjusting for potential confounders, serum B (OR = 0.120; 95% CI, 0.048, 0.300; p < 0.001) and Sb (OR = 0.133; 95% CI, 0.055, 0.322; p < 0.001) showed a negative correlation with MDD. Urine B had a negative correlation (OR = 0.393; 95% CI, 0.193, 0.801; p = 0.01) with MDD, while urine Sb had a positive correlation (OR = 3.335; 95% CI, 1.654, 6.726; p = 0.001) with MDD.

Conclusion

Our current research offers insightful hints for future investigation into the function of metalloids in connection to MDD processes.

Depression in Alzheimer's Disease: Epidemiology, Mechanisms, and Treatment

Depression and Alzheimer's disease (AD) are substantial public health concerns. In the past decades, a link between the 2 disease entities has received extensive acknowledgment, yet the complex nature of this relationship demands further clarification. Some evidence indicates that midlife depression may be an AD risk factor, while a chronic course of depression in late life may be a precursor to or symptom of dementia. Recently, multiple pathophysiological mechanisms have been proposed to underlie the bidirectional relationship between depression and AD, including genetic predisposition, immune dysregulation, accumulation of AD-related biomarkers (e.g., amyloid-β and tau), and alterations in brain structure. Accordingly, numerous therapeutic approaches, such as pharmacology treatments, psychotherapy, and lifestyle interventions, have been suggested as potential means of interfering with these pathways. However, the current literature on this topic remains fragmented and lacks a comprehensive review characterizing the association between depression and AD. In this review, we aim to address these gaps by providing an overview of the co-occurrence and temporal relationship between depression and AD, as well as exploring their underlying mechanisms. We also examine the current therapeutic regimens for depression and their implications for AD management and outline key challenges facing the field.

Exploring molecular mechanisms, therapeutic strategies, and clinical manifestations of Huntington's disease

Huntington's disease (HD) is a paradigm of a genetic neurodegenerative disorder characterized by the expansion of CAG repeats in the HTT gene. This extensive review investigates the molecular complexities of HD by highlighting the pathogenic mechanisms initiated by the mutant huntingtin protein. Adverse outcomes of HD include mitochondrial dysfunction, compromised protein clearance, and disruption of intracellular signaling, consequently contributing to the gradual deterioration of neurons. Numerous therapeutic strategies, particularly precision medicine, are currently used for HD management. Antisense oligonucleotides, such as Tominersen, play a leading role in targeting and modulating the expression of mutant huntingtin. Despite the promise of these therapies, challenges persist, particularly in improving delivery systems and the necessity for long-term safety assessments. Considering the future landscape, the review delineates promising directions for HD research and treatment. Innovations such as Clustered regularly interspaced short palindromic repeats associated system therapies (CRISPR)-based genome editing and emerging neuroprotective approaches present unprecedented opportunities for intervention. Collaborative interdisciplinary endeavors and a more insightful understanding of HD pathogenesis are on the verge of reshaping the therapeutic landscape. As we navigate the intricate landscape of HD, this review serves as a guide for unraveling the intricacies of this disease and progressing toward transformative treatments.

Neuroimmune modulation by tryptophan derivatives in neurological and inflammatory disorders

The nervous and immune systems are highly developed, and each performs specialized physiological functions. However, they work together, and their dysfunction is associated with various diseases. Specialized molecules, such as neurotransmitters, cytokines, and more general metabolites, are essential for the appropriate regulation of both systems. Tryptophan, an essential amino acid, is converted into functional molecules such as serotonin and kynurenine, both of which play important roles in the nervous and immune systems. The role of kynurenine metabolites in neurodegenerative and psychiatric diseases has recently received particular attention. Recently, we found that hyperactivity of the kynurenine pathway is a critical risk factor for septic shock. In this review, we first outline neuroimmune interactions and tryptophan derivatives and then summarized the changes in tryptophan metabolism in neurological disorders. Finally, we discuss the potential of tryptophan derivatives as therapeutic targets for neuroimmune disorders.

The neuronal and synaptic dynamics underlying post-inhibitory rebound burst related to major depressive disorder in the lateral habenula neuron model

A burst behavior observed in the lateral habenula (LHb) neuron related to major depressive disorder has attracted much attention. The burst is induced from silence by the excitatory N-methyl-D-aspartate (NMDA) synapse or by the inhibitory stimulation, i.e., a post-inhibitory rebound (PIR) burst, which has not been explained clearly. In the present paper, the neuronal and synaptic dynamics for the PIR burst are acquired in a theoretical neuron model. At first, dynamic cooperations between the fast rise of inhibitory γ-aminobutyric acid (GABA) synapse, slow rise of NMDA synapse, and T-type calcium current to evoke the PIR burst are obtained. Similar to the inhibitory pulse stimulation, fast rising GABA current can reduce the membrane potential to a level low enough to de-inactivate the low threshold T-type calcium current to evoke a PIR spike, which can enhance the slow rising NMDA current activated at a time before or after the PIR spike. The NMDA current following the PIR spike exhibits slow decay to induce multiple spikes to form the PIR burst. Such results present a theoretical explanation and a candidate for the PIR burst in real LHb neurons. Then, the dynamical mechanism for the PIR spike mediated by the T-type calcium channel is obtained. At large conductance of T-type calcium channel, the resting state corresponds to a stable focus near Hopf bifurcation and exhibits an "uncommon" threshold curve with membrane potential much lower than the resting membrane potential. Inhibitory modulation induces membrane potential decreased to run across the threshold curve to evoke the PIR spike. At small conductance of the T-type calcium channel, a stable node appears and manifests a common threshold curve with higher membrane potential, resulting in non-PIR phenomenon. The results present the dynamic cooperations between neuronal dynamics and fast/slow dynamics of different synapses for the PIR burst observed in the LHb neuron, which is helpful for the modulations to major depressive disorder.

β-asarone inhibits autophagy by activating the PI3K/Akt/mTOR pathway in a rat model of depression in Parkinson's disease

OBJECTIVE

It is unclear whether β-asarone has a good antidepressant effect and what is the main mechanism in Depression in Parkinson's disease (DPD) model rats.

METHODS

In this study, DPD model rats were screened from 6-OHDA induced rats by sucrose preference test (SPT) and forced swimming test (FST). DPD model rats were divided into eight groups: model group, pramipexole group, β-asarone low-dose group (β-asarone 7.5 group), β-asarone medium-dose group (β-asarone 15 group), β-asarone high-dose group (β-asarone 30 group), 3-MA group, rapamycin group, and PI3K inhibitor group. 28 days after the end of treatment, open field test (OFT), SPT and FST were conducted in rats. The level of α-synuclein (α-syn) in the striatum was determined by enzyme-linked immunosorbent assay (ELISA). The expression of Beclin-1, p62 in the striatum was determined by western blot. The expression of PI3K, p-PI3K, Akt, p-Akt, mTOR, p-mTOR, Beclin-1, and p62 in the hippocampus was determined by western blot. The spine density of neurons in the hippocampus was detected by golgi staining.

RESULTS

The results showed that 4-week oral administration of β-asarone improve the motor and depressive symptoms of DPD model rats, and decrease the content of α-syn in the striatum. β-asarone inhibited the expression of autophagy in the striatum of DPD model rats. Furthermore, β-asarone decreased the levels of Beclin-1 protein, increased the expression of p62, p-PI3K, p-AKT, and p-mTOR, and improved the density of neuron dendritic spine in the hippocampus.

CONCLUSIONS

We concluded that β-asarone might improve the behavior of DPD model rats by activating the PI3K/Akt/mTOR pathway, inhibiting autophagy and protecting neuron.

New Advances in the Pharmacology and Toxicology of Lithium: A Neurobiologically Oriented Overview

Over the last six decades, lithium has been considered the gold standard treatment for the long-term management of bipolar disorder due to its efficacy in preventing both manic and depressive episodes as well as suicidal behaviors. Nevertheless, despite numerous observed effects on various cellular pathways and biologic systems, the precise mechanism through which lithium stabilizes mood remains elusive. Furthermore, there is recent support for the therapeutic potential of lithium in other brain diseases. This review offers a comprehensive examination of contemporary understanding and predominant theories concerning the diverse mechanisms underlying lithium's effects. These findings are based on investigations utilizing cellular and animal models of neurodegenerative and psychiatric disorders. Recent studies have provided additional support for the significance of glycogen synthase kinase-3 (GSK3) inhibition as a crucial mechanism. Furthermore, research has shed more light on the interconnections between GSK3-mediated neuroprotective, antioxidant, and neuroplasticity processes. Moreover, recent advancements in animal and human models have provided valuable insights into how lithium-induced modifications at the homeostatic synaptic plasticity level may play a pivotal role in its clinical effectiveness. We focused on findings from translational studies suggesting that lithium may interface with microRNA expression. Finally, we are exploring the repurposing potential of lithium beyond bipolar disorder. These recent findings on the therapeutic mechanisms of lithium have provided important clues toward developing predictive models of response to lithium treatment and identifying new biologic targets. SIGNIFICANCE STATEMENT: Lithium is the drug of choice for the treatment of bipolar disorder, but its mechanism of action in stabilizing mood remains elusive. This review presents the latest evidence on lithium's various mechanisms of action. Recent evidence has strengthened glycogen synthase kinase-3 (GSK3) inhibition, changes at the level of homeostatic synaptic plasticity, and regulation of microRNA expression as key mechanisms, providing an intriguing perspective that may help bridge the mechanistic gap between molecular functions and its clinical efficacy as a mood stabilizer.

Identification of clinical disease trajectories in neurodegenerative disorders with natural language processing

Neurodegenerative disorders exhibit considerable clinical heterogeneity and are frequently misdiagnosed. This heterogeneity is often neglected and difficult to study. Therefore, innovative data-driven approaches utilizing substantial autopsy cohorts are needed to address this complexity and improve diagnosis, prognosis and fundamental research. We present clinical disease trajectories from 3,042 Netherlands Brain Bank donors, encompassing 84 neuropsychiatric signs and symptoms identified through natural language processing. This unique resource provides valuable new insights into neurodegenerative disorder symptomatology. To illustrate, we identified signs and symptoms that differed between frequently misdiagnosed disorders. In addition, we performed predictive modeling and identified clinical subtypes of various brain disorders, indicative of neural substructures being differently affected. Finally, integrating clinical diagnosis information revealed a substantial proportion of inaccurately diagnosed donors that masquerade as another disorder. The unique datasets allow researchers to study the clinical manifestation of signs and symptoms across neurodegenerative disorders, and identify associated molecular and cellular features.

The enigma of depression in corticobasal degeneration, a frequent but poorly understood co-morbidity

Depression is one of the most frequent neuropsychiatric symptoms in corticobasal degeneration (CBD), a rare, sporadic, and late-onset progressive neurodegenerative disorder of unknown etiology. It is clinically characterized by a levodopa-poorly responsible akinetic-rigid syndrome, apraxia, limb dystonia, cognitive, mood, behavioral, and language disorders. This 4-repeat (4R) tauopathy is morphologically featured by asymmetric frontoparietal atrophy, neuronal loss, and gliosis in cortex and subcortex including substantia nigra, ballooned/achromatic neurons with filamentous 4R tau aggregates in cortex and striatum, widespread thread-like structures, pathognomonic "astroglial plaques", "tufted astrocytes", and numerous "coiled bodies" (in astrocytes and oligodendroglia) in cerebral white matter. CBD is non-specific, as pathologically proven cases include several clinical phenotypes. Pubmed and Google Scholar were systematically analyzed until October 2023, with focus on the prevalence, clinical manifestation, neuroimaging data, and treatment options of depression in CBD. Its prevalence is about 30-40% which is more frequent than in most other atypical parkinsonian syndromes. Depression usually does not correlate with motor and other clinical parameters, suggesting different pathophysiological mechanisms. Asymmetric atrophy and hypometabolism of frontoparietal cortical areas are associated with disruption of fronto-subcortical circuits, nigrostriatal dopaminergic, and cholinergic deficiency. Since no specific neuroimaging, neuropathological, or biomarker studies of depression in CBD are available, its pathobiological mechanisms and pathogenesis are poorly understood. Antidepressive therapy may be useful, but is often poorly tolerated. Depression in CBD, like in other parkinsonian syndromes, may be related to multi-regional patterns of cerebral disturbances and complex pathogenic mechanisms that deserve further elucidation as a basis for early diagnosis and adequate treatment to improve the quality of life in this fatal disease.

Depressive symptoms in the entire spectrum of cognitive ageing in Greece: evidence from the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD)

OBJECTIVES

To study (i) the prevalence of mild and moderate-to-severe depressive symptoms in the entire spectrum of cognitive ageing in Greece and (ii) the relationship between these symptoms and demographic and clinical data.

METHODS

The study was based on the randomly selected cohort of the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD). Depressive symptoms were assessed with the 15-item version of the Geriatric Depression Scale. Participants also received a comprehensive neuropsychological assessment, while the clinical diagnoses of dementia and mild cognitive impairment were established according to international diagnostic criteria. Statistical analyses relied on comparison tests and a logistic (proportional odds) ordinal regression model.

RESULTS

Depressive symptoms were detected in 19.5% of the 1936 study participants, while 11.3% of both people with MCI and dementia had moderate-to-severe depressive symptoms. The regression model revealed that older adults with more severe depressive symptoms were more likely female, cognitively impaired, less educated, were treated with psychotropic medication and lived in Attica versus Thessaly.

CONCLUSIONS

Since depressive symptoms were detected in almost one in five older adults, healthcare professionals in Greece should safeguard the timely detection and effective treatment of such symptoms and the post-diagnostic care of older adults with depression.

Pathogenesis of Depression in Alzheimer's Disease

Depression is a prevalent occurrence among Alzheimer's disease (AD) patients, yet its underlying mechanism remains unclear. Recent investigations have revealed that several pathophysiological changes associated with Alzheimer's disease can lead to mood disorders. These alterations include irregularities in monoamine neurotransmitters, disruptions in glutamatergic synaptic transmission, neuro-inflammation, dysfunction within the hypothalamic-pituitary-adrenocortical (HPA) axis, diminished levels of brain-derived neurotrophic factor (BDNF), and hippocampal atrophy. This review consolidates research findings from pertinent fields to elucidate the mechanisms underlying depression in Alzheimer's disease, aiming to provide valuable insights for the study of its mechanisms and clinical treatment.

Relative synonymous codon usage and codon pair analysis of depression associated genes

Depression negatively impacts mood, behavior, and mental and physical health. It is the third leading cause of suicides worldwide and leads to decreased quality of life. We examined 18 genes available at the genetic testing registry (GTR) from the National Center for Biotechnological Information to investigate molecular patterns present in depression-associated genes. Different genotypes and differential expression of the genes are responsible for ensuing depression. The present study, investigated codon pattern analysis, which might play imperative roles in modulating gene expression of depression-associated genes. Of the 18 genes, seven and two genes tended to up- and down-regulate, respectively, and, for the remaining genes, different genotypes, an outcome of SNPs were responsible alone or in combination with differential expression for different conditions associated with depression. Codon context analysis revealed the abundance of identical GTG-GTG and CTG-CTG pairs, and the rarity of methionine-initiated codon pairs. Information based on codon usage, preferred codons, rare, and codon context might be used in constructing a deliverable synthetic construct to correct the gene expression level of the human body, which is altered in the depressive state. Other molecular signatures also revealed the role of evolutionary forces in shaping codon usage.

Antidepressant-like Effect of the Eburnamine-Type Molecule Vindeburnol in Rat and Mouse Models of Ultrasound-Induced Depression

Vindeburnol (VIND, RU24722, BC19), a synthetic molecule derived from the eburnamine-vincamine alkaloid group, has many neuropsychopharmacological effects, but its antidepressant-like effects are poorly understood and have only been described in a few patents. To reliably estimate this effect, vindeburnol was studied in a model of long-term variable-frequency ultrasound (US) exposure at 20-45 kHz in male Wistar rats and BALB/c mice. Vindeburnol was administered chronically for 21 days against a background of simultaneous ultrasound exposure at a dose of 20 mg/kg intraperitoneally (IP). Using four behavioral tests, the sucrose preference test (SPT), the social interaction test (SIT), the open field test (OFT), and the forced swimming test (FST), we found that the treatment with the compound diminished depression-like symptoms in mice and rats. The compound restored the ultrasound-related reduced sucrose consumption to control levels and increased social interaction time in mice and rats compared with those in ultrasound-exposed animals. Vindeburnol showed contraversive results of horizontal and vertical activity in both species and generally did not increase locomotor activity. At the same time, the compound showed a specific effect in the FST, significantly reducing the immobility time. Moreover, we found an increase in norepinephrine, dopamine, and its metabolite levels in the brainstem, as well as an increase in dopamine, 3-methoxytyramine, and 3,4-dihydroxyphenylacetic acid levels in the striatum. We also observed a statistically significant increase in tyrosine hydroxylase (TH) levels in the region containing the locus coeruleus (LC). We suggest that using its distinct chemical structure and pharmacological activity as a starting point could boost antidepressant drug discovery.

Glyphosate: Impact on the microbiota-gut-brain axis and the immune-nervous system, and clinical cases of multiorgan toxicity

Glyphosate (GLP) and GLP-based herbicides (GBHs), such as polyethoxylated tallow amine-based GLP surfactants (GLP-SH), developed in the late 70', have become the most popular and controversial agrochemicals ever produced. Nowadays, GBHs have reached 350 million hectares of crops in over 140 countries, with an annual turnover of 5 billion and 11 billion USD in the U.S.A. and worldwide, respectively. Because of the highly efficient inhibitory activity of GLP targeted to the 5-enolpyruvylshikimate-3-phosphate synthase pathway, present in plants and several bacterial strains, the GLP-resistant crop-based genetic agricultural revolution has decreased famine and improved the costs and quality of living in developing countries. However, this progress has come at the cost of the 50-year GBH overuse, leading to environmental pollution, animal intoxication, bacterial resistance, and sustained occupational exposure of the herbicide farm and companies' workers. According to preclinical and clinical studies covered in the present review, poisoning with GLP, GLP-SH, and GBHs devastatingly affects gut microbiota and the microbiota-gut-brain (MGB) axis, leading to dysbiosis and gastrointestinal (GI) ailments, as well as immunosuppression and inappropriate immunostimulation, cholinergic neurotransmission dysregulation, neuroendocrinal system disarray, and neurodevelopmental and neurobehavioral alterations. Herein, we mainly focus on the contribution of gut microbiota (GM) to neurological impairments, e.g., stroke and neurodegenerative and neuropsychiatric disorders. The current review provides a comprehensive introduction to GLP's microbiological and neurochemical activities, including deviation of the intestinal Firmicutes-to-Bacteroidetes ratio, acetylcholinesterase inhibition, excitotoxicity, and mind-altering processes. Besides, it summarizes and critically discusses recent preclinical studies and clinical case reports concerning the harmful impacts of GBHs on the GI tract, MGB axis, and nervous system. Finally, an insightful comparison of toxic effects caused by GLP, GBH-SH, and GBHs is presented. To this end, we propose a first-to-date survey of clinical case reports on intoxications with these herbicides.

Single-cell transcriptomics analysis of cellular heterogeneity and immune mechanisms in neurodegenerative diseases

Single-cell transcriptomics analysis is an advanced technology that can describe the intracellular transcriptome in complex tissues. It profiles and analyses datasets by single-cell RNA sequencing. Neurodegenerative diseases are identified by the abnormal apoptosis of neurons in the brain with few or no effective therapy strategies at present, which has been a growing healthcare concern and brought a great burden to society. The transcriptome of individual cells provides deep insights into previously unforeseen cellular heterogeneity and gene expression differences in neurodegenerative disorders. It detects multiple cell subsets and functional changes during pathological progression, which deepens the understanding of the molecular underpinnings and cellular basis of neurodegenerative diseases. Furthermore, the transcriptome analysis of immune cells shows the regulation of immune response. Different subtypes of immune cells and their interaction are found to contribute to disease progression. This finding enables the discovery of novel targets and biomarkers for early diagnosis. In this review, we emphasize the principles of the technology, and its recent progress in the study of cellular heterogeneity and immune mechanisms in neurodegenerative diseases. The application of single-cell transcriptomics analysis in neurodegenerative disorders would help explore the pathogenesis of these diseases and develop novel therapeutic methods.

Repetitive transcranial magnetic stimulation and fluoxetine attenuate astroglial activation and benefit behaviours in a chronic unpredictable mild stress mouse model of depression

Objectives: Repetitive transcranial magnetic stimulation (rTMS) has been considered as an effective antidepressant treatment; however, the mechanism of its antidepressant effect is still unclear. Fluoxetine, a selective serotonin reuptake inhibitor antidepressant, may be neuroprotective. The objective of the present study was to evaluate the effect and underlying possible neuroprotective mechanism of rTMS and fluoxetine on abnormal behaviours in a depressive mouse model induced by chronic unpredictable mild stress (CUMS).Methods: After 28 days of CUMS exposure, mice were chronically treated with rTMS (10 Hz for 5 s per train, total 20 trains per day) and (or) fluoxetine (5 mg/kg/day, intraperitoneally) for 28 days targeting on the frontal cortex. After the behavioural tests, the protein expressions of glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (TrkB) were measured by immunohistochemistry and (or) Western Blot.Results: The results showed rTMS and (or) fluoxetine attenuated the locomotion decrease, anxiety and depressive like behaviours in the CUMS-exposed mice.Conclusion: Our results suggest that both rTMS and fluoxetine could benefit the CUMS-induced abnormal behaviours including depressive-like behaviours, and the beneficial effects of rTMS as well as fluoxetine on depression might be partly related to their neuroprotective effect on attenuating astroglial activation and BDNF decrease.

Converged avenues: depression and Alzheimer's disease- shared pathophysiology and novel therapeutics

Depression, a highly prevalent disorder affecting over 280 million people worldwide, is comorbid with many neurological disorders, particularly Alzheimer's disease (AD). Depression and AD share overlapping pathophysiology, and the search for accountable biological substrates made it an essential and intriguing field of research. The paper outlines the neurobiological pathways coinciding with depression and AD, including neurotrophin signalling, the hypothalamic-pituitary-adrenal axis (HPA), cellular apoptosis, neuroinflammation, and other aetiological factors. Understanding overlapping pathways is crucial in identifying common pathophysiological substrates that can be targeted for effective management of disease state. Antidepressants, particularly monoaminergic drugs (first-line therapy), are shown to have modest or no clinical benefits. Regardless of the ineffectiveness of conventional antidepressants, these drugs remain the mainstay for treating depressive symptoms in AD. To overcome the ineffectiveness of traditional pharmacological agents in treating comorbid conditions, a novel therapeutic class has been discussed in the paper. This includes neurotransmitter modulators, glutamatergic system modulators, mitochondrial modulators, antioxidant agents, HPA axis targeted therapy, inflammatory system targeted therapy, neurogenesis targeted therapy, repurposed anti-diabetic agents, and others. The primary clinical challenge is the development of therapeutic agents and the effective diagnosis of the comorbid condition for which no specific diagnosable scale is present. Hence, introducing Artificial Intelligence (AI) into the healthcare system is revolutionary. AI implemented with interdisciplinary strategies (neuroimaging, EEG, molecular biomarkers) bound to have accurate clinical interpretation of symptoms. Moreover, AI has the potential to forecast neurodegenerative and psychiatric illness much in advance before visible/observable clinical symptoms get precipitated.

Effect of Transcranial Direct Current Stimulation (tDCS) on Depression in Parkinson's Disease-A Narrative Review

INTRODUCTION

Depression is the most prevalent comorbid neuropsychiatric condition in individuals with Parkinson's disease (PD), and its underlying mechanisms are not yet fully understood. Current treatment methods are characterised by moderate effectiveness and possible side effects, prompting the search for new non-invasive and safe treatment methods.

METHODS

This narrative review explores the use of transcranial direct current stimulation (tDCS) in the treatment of depression in PD, based on neuropsychological measures. Searches were conducted in the PubMed/Medline, Research Gate, and Cochrane databases.

RESULTS

Nine relevant studies were identified, where depression scores served as either primary or secondary outcomes. Stimulation protocols displayed heterogeneity, especially concerning choice of stimulation site. Patient samples were also heterogeneous. The majority of the studies incorporated anodal stimulation targeting the left dorsolateral prefrontal cortex (DLPFC). The results revealed a reduction in depression scores among PD patients following tDCS. Potential mechanisms through which tDCS may alleviate depression in PD were discussed and recommendations for future research were made.

CONCLUSIONS

Preliminary evidence suggests that tDCS applied anodally to the left DLPFC reduces depression scores in people with PD; however, due to the heterogeneity of the studies analysed, the use of tDCS in this field should be approached with caution and warrants further validation and confirmation.