Role of oxidative stress in depression

Berberine: An isoquinoline alkaloid targeting the oxidative stress and gut-brain axis in the models of depression

Depression seriously affects people's quality of life, and there is an urgent need to find novel drugs to cure treatment-resistant depression. Berberine (BBR), extracted from Coptis chinensis Franch., Phellodendron bark, Berberis vulgaris, and Berberis petiolaris, could be a potential multi-target drug for depression. To summarize the effects of BBR on depression in terms of in vitro or in vivo experiments, we searched electronic databases, such as PubMed, Web of Science, Google Scholar, Wanfang Database, and China National Knowledge Infrastructure, from inception until May 2024. Then, we summarize that BBR has indirect antidepressant properties to improve depressive symptoms, manifesting in modulating the gut microbial community, strengthening the intestinal barrier, increasing the abundance of short-chain fatty acid-producing bacteria, and regulating tryptophan metabolism. BBR also exerts antidepressant-like effects via remodulating nuclear factor-erythroid 2-related factor 2/antioxidant response element pathway, hypothalamic-pituitary-adrenal axis, and peroxisome proliferators-activated receptor-delta. Nevertheless, further clinical trials and more high-quality animal studies are needed to show the actual clinical value of BBR for depression.

Perimenopausal depression: Targeting inflammation and oxidative stress (Review)

Depressive disorder is a highly disabling condition that affects more than 300 million individuals worldwide, with women affected at a higher rate than men. With the aging of the population, the incidence of perimenopausal depression has risen markedly, seriously jeopardizing women's physical and mental health. Symptoms of perimenopausal depression include feelings of depression, stress, anxiety and endocrine dysfunctions, particularly hypogonadism and senescence. During perimenopause, estrogen and progesterone levels fluctuate erratically, adding to the risk of developing depression associated with perimenopause. As a result of these hormonal changes, proinflammatory mediators are produced and oxidative stress is induced, which finally leads to progressive neuronal damage. The present study mainly reviewed roles of neuroinflammation in perimenopausal depression and explained potential anti‑inflammatory and anti‑oxidative stress mechanisms for clinically effective therapeutic treatment.

Recent advances in biomimetic nanodelivery systems for the treatment of depression

Depression and cognitive disorders remain major challenges in healthcare, with conventional treatments often facing limitations such as slow onset, side effects, and poor drug delivery to the brain. Biomimetic nanodelivery systems, including nanozymes, cell membrane-based systems, and exosomes, have emerged as promising solutions to these issues. These systems leverage natural biological processes to enhance drug targeting, improve bioavailability, and regulate complex biological pathways. Nanoenzymes, with their catalytic properties, offer antioxidant and anti-inflammatory benefits, while cell membranes and exosomes provide efficient targeting and immune evasion. However, challenges remain, including the immaturity of large-scale production techniques, stability concerns, and incomplete understanding of their mechanisms of action. Moreover, the long-term safety, pharmacokinetics, and toxicity of these systems require further investigation. Despite these obstacles, the potential of biomimetic nanodelivery systems to revolutionize depression treatment is significant. Future research should focus on optimizing their preparation, improving drug targeting and release, and ensuring clinical safety. Multidisciplinary collaboration will be essential for advancing these systems from the laboratory to clinical practice, offering new therapeutic avenues for depression and other neurological disorders.

Antidepressant-like effects of the aqueous lyophilizate of the stems and leaves of Momordica foetida (Cucurbitaceae) in rats

M. foetida (Cucurbitaceae) is a perennial climbing herb, known in traditional medicine for the treatment of certain diseases, such as malaria, headaches, skin-related problems and many others. The objective of this work was to evaluate the antidepressant effect of the aqueous lyophilisate of the mixture of leaves and stem of M. foetida. The antidepressant effect of the aqueous lyophilisate of M. foetida at different doses (25 mg/kg, 50 mg/kg and 75 mg/kg) was evaluated in Wistar rats of both sexes submitted to chronic restriction for 14 days, using the forced swimming test, open field test and sucrose preference test. One hour following the last behavioural test, animals were sacrificed and their hippocampi were collected for biochemical assessment of oxidative parameters, including malondialdehyde (MDA), reduced Glutathione (GSH), Catalase activity, superoxide dismutase (SOD) and nitric oxide (NO) as well as monoamines levels including serotonin, noradrenaline and dopamine. The aqueous lyophilisate of M. foetida significantly decreased the immobility time and significantly increased sucrose consumption (P < 0.001), with no alteration of locomotor activity. The aqueous lyophilisate of M. foetida significantly increased the concentrations of GSH, SOD, as well as catalase activity, while reducing the concentrations of MDA and NO at all doses (P < 0.001). M. foetida at the doses 25 mg/kg and 50 mg/kg significantly increased the concentration of serotonin and dopamine. Only the dose 75 mg/kg significantly increased the concentration of noradrenaline (p < 0.001). These results suggest that M. foetida exerts antidepressant-like effects through the modulation of oxidative stress and monoaminergic pathways.

Association between dietary patterns and suicide ideation among depressed adults: Insights from NHANES 2007-2020

BACKGROUND

Dietary patterns are strongly linked to the risk of major depressive disorder (MDD). However, research on the relationship between dietary patterns and MDD with suicidal ideation (MDD + SI) are limited. The Healthy Eating Index (HEI)-2015, Dietary Inflammatory Index (DII), Comprehensive Dietary Antioxidant Index (CDAI), Oxidative Balance Score (OBS), and Dietary Index for Gut Microbiota (DI-GM) are five validated tools for assessing dietary patterns based on inflammation, antioxidant capacity, and gut microbiota diversity. This study aims to investigate the association between these dietary indices and MDD + SI.

METHODS

A total of 23,621 participants from the 2007-2020 National Health and Nutrition Examination Survey were included in this study. MDD and SI were assessed using the PHQ-9. Weighted multivariable logistic regression, subgroup analyses, and restricted cubic spline (RCS) models were applied to analyze the relationships between five dietary indices and the risks of MDD and MDD + SI.

RESULTS

All five dietary indices showed associations with MDD to varying degrees; however, only DI-GM exhibited a significant negative association with MDD + SI after adjustment for confounding factors. Subgroup and stratified linear trend analyses revealed that this association was stronger among former smokers, obese individuals and those with hypertension or diabetes. RCS analysis showed a significant non-linear relationship between DI-GM and MDD, while a significant linear dose-response relationship was observed for DI-GM and MDD + SI.

LIMITATIONS

Cross-sectional study designs cannot establish causality.

CONCLUSION

The findings of this study revealed a significant association between DI-GM and MDD + SI. Dietary interventions that promote gut microbiota diversity may help reduce the risk of MDD + SI.

Blood lipid profiles and mood disorders: A principal component analysis of UK Biobank data reveals distinct associations with depression and bipolar disorder

BACKGROUND

Growing evidence suggests that lipid metabolism may play a crucial role in mood disorder pathophysiology, and the correlation between blood lipids and mood disorder remains further clarified.

METHODS

This prospective, population-based cohort study utilized data from the UK Biobank. The study included 268,098 and 292,121 participants who had never been diagnosed with depression or bipolar disorder and who had complete data at both the baseline and follow-up points. A principal component analysis (PCA) was conducted on seven blood lipids, and the first three principal components (PCs) were derived. Cox regression analysis was employed to examine the correlation between the risk of mood disorders and the PCs. Multiplicative interaction and sensitivity analyses were also conducted. The relationship between blood lipids and neurological biomarkers was explored using Spearman's analysis.

RESULTS

PC1, primarily reflecting levels of Apolipoprotein B (ApoB), cholesterol, and low-density lipoprotein cholesterol (LDL-C), showed a protective effect against depression, with HRs of 0.98 (95 % CI: 0.96,1.00) in the fully adjusted Cox regression model. In contrast, PC2, characterized by opposite loadings for triglycerides and high-density lipoprotein cholesterol (HDLC), was positively associated with the risk of depression and bipolar disorder.(HR = 1.03,95 % CI: 1.01,1.06; HR = 1.11, 95 % CI: 1.01,1.23). Increased PC2 level was related to a significant increase in bipolar disorder risk among participants with high genetic risk (genetic risk score > 90 %, HR = 1.22, 95 % CI: 1.02,1.46). Complicated correlations between blood lipids and serum neuroproteins were detected.

CONCLUSION

These findings suggest complex associations between blood lipid profiles and the risk of depression and bipolar disorder.

Design of anti-depressant phosphodiester amino acidic Keap1-Nrf2 protein-protein interaction inhibitors

Inhibiting the protein-protein interaction (PPI) between Keap1 and Nrf2 is theoretically an effective and safe strategy for activation of Nrf2 pathway to treat major depressive disorder (MDD). In this study, through bioinformatic analysis of the brain tissues and peripheral blood of MDD patients and depressive mice, we confirmed the involvement of oxidative stress, inflammation, and the Keap1-Nrf2 pathway in depression. Subsequently, we developed a series of phosphodiester amino acidic diaminonaphthalene compounds as Keap1-Nrf2 PPI inhibitors for the first time. Screening using the LPS-stimulated SH-SY5Y and BV2 cell models identified compound 4-95 showing the best anti-oxidative stress and anti-inflammatory efficacy. The ability of 4-95 to penetrate the blood-brain-barrier was significantly enhanced. In a chronic unpredictable mild stress mouse model, treatment with 4-95 effectively ameliorated anxiety and depression behavior and restored serum neurotransmitter levels by promoting the Nrf2 nuclear translocation. Consequently, oxidative stress was reduced, and the expression of synaptic plasticity biomarkers, such as postsynaptic density protein 95 (PSD95) and synapsin 1 (SYN1) were significantly increased, suggesting the recovery of neuronal function. Collectively, our findings demonstrate that the Keap1-Nrf2 PPI inhibitor holds great promise as a preclinical candidate for the treatment of depression.

Hippocampal GPR35 is involved in the depression-like behaviors induced by inflammation and mediates the antidepressant effects of fluoxetine in mice

BACKGROUND

Neuroinflammation plays a pivotal role in the pathogenesis of depression. G protein-coupled receptor 35 (GPR35) is expressed in the brain and plays a role in regulating inflammatory processes. However, its specific role in depression remains unclear. Herein, we investigate the role of GPR35 in depressive behaviors induced by lipopolysaccharide (LPS) in mice.

METHODS

We employed an LPS-induced depression mouse model and conducted behavioral tests, molecular analyses, and morphological assessments, along with chemogenetic techniques, to investigate the role of GPR35 in depression.

RESULTS

Our results showed a significant increase in GPR35 expression in the brain of LPS-treated mice. Both pharmacological inhibition and genetic knockdown of GPR35 alleviated LPS-induced depressive-like behaviors by mitigating neuroinflammation, oxidative stress, synaptic plasticity deficits, and TLR4/NF-κB signaling in mice. Conversely, pharmacological activation of GPR35 notably exacerbated LPS-induced depressive-like behaviors in mice. Additionally, the GPR35 antagonist ML-145 effectively prevented LPS-induced inflammation responses in BV-2 microglia cells. Moreover, fluoxetine treatment effectively mitigated the upregulation of hippocampal GPR35 expression induced by LPS in mice. However, administration of the GPR35 agonist zaprinast reversed the antidepressant effects of fluoxetine. Chemogenetic activation of hippocampal glutamatergic neurons attenuated LPS-induced depression-like behaviors, accompanied by decreased GPR35 expression.

CONCLUSION

Hippocampal GPR35 is closely associated with depressive behaviors in the inflammatory model, highlighting its potential as a therapeutic target for antidepressant drug development.

The sigma-1 receptor: a mechanistically-informed therapeutic target for antidepressants

INTRODUCTION

The mechanism of action of antidepressants is not fully ascertained. In addition to monoamines, disparate other effectors are also implicated in the molecular and cellular effects of chronic stress including neurogenesis, neurodifferentiation, and neuroplasticity. Evidence suggests sigma-1 receptors (S1R) as a putative target and possible mediator of antidepressant activity.

AREAS COVERED

Data from preclinical and clinical trials was synthesized from inception to August 2024. Results showed that S1R regulate neurotransmitter availability and release (e.g. monoamines, glutamate), and influence intracellular Ca2+ levels as well as immune inflammatory responses. The introduction of the N-Methyl-D-aspartic Acid (NMDA) antagonist/S1R agonist dextromethorphan-bupropion in August of 2022 represented the first time the Food and Drug Administration (FDA) permitted language that the hypothesized mechanism of an antidepressant involved activity at S1R. We also describe the physiology, pathophysiology, and function of S1R.

EXPERT OPINION

Sigma-1 modulation is relevant to the mechanism of action of agents currently FDA-approved in major depressive disorder (MDD) (dextromethorphan-bupropion). Modulating sigma-1 systems is fit for purpose as it relates to future therapeutic discoveries and development in depressive and other mental disorders. Whether sigma-1 modulation is uniquely relevant to targeting dimensions of psychopathology that are more difficult to treat (i.e. anhedonia) awaits determination.

Association of uric acid/high-density lipoprotein cholesterol ratio (UHR) with depression risk in US adults: A cross-sectional study

BACKGROUND

The uric acid/high-density lipoprotein cholesterol ratio (UHR) is a new indicator of inflammation and metabolism that has been found to be strongly associated with several chronic diseases. However, the relationship between the UHR and depression has not been studied to date.

METHODS

The study included a total of 16,920 participants aged 20 years and older from NHANES 2005-2018. Logistic regression models with weights were used to evaluate the association between quintile levels of UHR and depression risk.

RESULTS

Elevated UHR levels were significantly associated with a 52 % increased risk of depression after multivariable adjustment (Q5 OR: 1.52, 95 % CI: 1.26, 1.83, P-trend <0.001). We found a significant interaction between UHR level and sex (P = 0.018), but no significant interaction between UHR and other factors, including age, smoking, alcohol consumption, education level, marital status, household income poverty ratio and physical activity. Stratified analyses of these factors showed that high levels of UHR were significantly associated with risk of depression in groups who were female, younger, had never smoked, were alcohol drinkers, had higher levels of education, were cohabiters, had the highest and lowest household incomes, and were physically active.

CONCLUSION

In conclusion, UHR was positively associated with an increased risk of depression, suggesting that UHR levels can be used as a comprehensive indicator for the early identification of depression risk.

Novel insights into dietary bioactive compounds and major depressive disorders: evidence from animal studies and future perspectives

Clinical depression, including major depressive disorder (MDD), is a chronic mental illness characterized by persistent sadness and indifference. Depression is associated with neuroinflammation, oxidative stress, and neuronal apoptosis in the brain, resulting in microglial overactivation, decreased neuronal and glial proliferation, monoamine depletion, structural abnormalities, and aberrant biochemical activity via the hypothalamic-pituitary-adrenal axis. Recent studies have exhibited the role of dietary bioactive compounds in the mitigation of MDD progression. Here, in this narrative review, we reported the effects of commonly consumed bioactive compounds (curcumin, saffron, garlic, resveratrol, omega-3 fatty acids, ginger, blueberry, tea, and creatine) on MDD and MDD-related neuroinflammation and oxidative stress. The evidence reviewed here is almost exclusively from animal studies and strongly suggest that these commonly consumed bioactive compounds have anti-MDD effects as shown in anti-depression-like behaviors, such as increased immobility, sucrose preference, and social interaction. Based on the literature/studies reviewed, the proposed molecular mechanisms include (i) the reduction of neuroinflammation activation and oxidative stress, (ii) the enhancement of anti-inflammatory and anti-oxidant properties, (iii) the reduction of monoamine oxidase-A production, and (iv) the elevation of brain-derived neurotropic factor and neurogenesis. In the future, dietary bioactive compounds on clinical randomized controlled trials are warranted to confirm the findings of preclinical efficacies using bioactive compounds in individuals with MDD.

Association between triglyceride glucose index and depression in polycystic ovary syndrome

OBJECTIVE

The relationship between the triglyceride glucose (TyG) index and the incidence of depression in populations with polycystic ovary syndrome (PCOS) remains unclear. This study aims to investigate the relationship between the TyG index and depression incidence in PCOS populations.

METHODS

We conducted a study on 725 women aged 18 to 45 who visited our hospital from January 2021 to December 2023. Demographic and anthropometric data were collected, and serum assays were performed. The Center for Epidemiologic Studies Depression Scale (CES-D) was used to assess the past week's feelings and determine depression status. Statistical methods such as binary logistic regression analysis were used to analyze the relationship between the TyG index, Homeostatic model assessment insulin resistance index(HOMA-IR), and depression in PCOS patients. The TyG index, HOMA-IR, was tested for its ability to predict depression using receiver operating characteristic (ROC) curves.

RESULTS

In logistic regression models, a significant positive association was observed between the TyG index and depression after the adjusted analysis(4.552(2.975 ∼ 6.966), P<0.001). Compared to HOMA-IR(1.224(1.122 ∼ 1.336), P<0.001), the TyG index was a more significant risk factor for depression. ROC analysis showed that the AUC of the TyG index(0.724, 0.684 ∼ 0.765) was higher than the HOMA-IR(0.698,0.656~0.74).

CONCLUSIONS

A high TyG index was associated with higher odds of having depression in the population with PCOS. This indicated that the TyG index may be an independent predictor of depression development.

CLINICAL TRIAL NUMBER

Not applicable.

Dysregulation of peripheral oxidative stress and the Nrf2 antioxidant system in Major Depressive Disorder

BACKGROUND

Oxidative stress and inflammation have been found to be involved in the development of major depressive disorder (MDD). The aim of this study was to investigate the peripheral levels of oxidative stress and the nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant system markers in patients with MDD and to evaluate the changes in these markers after 12 weeks of antidepressant treatment.

METHODS

We consecutively enrolled 104 drug-naïve or drug-free patients with an acute episode of MDD and 50 healthy controls (HCs). Plasma levels of Nrf2, phospho-Nrf2 (p-Nrf2), heme oxygenase-1 (HO-1), superoxide dismutase (SOD), malondialdehyde (MDA), phospholipase A2 (PLA2) and cyclooxygenase-2 (COX-2), were measured with the enzyme-linked immunosorbent assay.

RESULTS

Patients with MDD exhibited lower levels of the antioxidant system Nrf2, p-Nrf2, HO-1, SOD and higher levels of oxidative stress markers COX-2, PLA2, MDA compared to HCs (all p < 0.001). HO-1 levels differed significantly among melancholic, anxious, and atypical depression (p = 0.002). In addition, we found a negative correlation between somatic symptoms in HAMA scores and Nrf2 levels in MDD group (p = 0.04). At 12 weeks, COX-2 levels significantly increased in the non-remission group compared to baseline (p = 0.039), whereas no significant changes were observed in the remission group.

CONCLUSIONS

Peripheral oxidative stress and the Nrf2 antioxidant system were found to be dysregulated in patients with MDD. The Nrf2 antioxidant system might be a protective factor for somatic symptoms in MDD, whereas COX-2 might be a risk factor for poor antidepressant efficacy.

The effects and mechanisms of Far-infrared ray on depression-like behavior induced by CRS in mice

PURPOSE

Far-infrared ray (FIR) is an electromagnetic wave known to impart health benefits against various pathophysiological conditions, including diabetes mellitus, renocardiovascular disorders, stress, and depression, among others. However, the precise impact of FIR on major depressive disorder (MDD) and the underlying molecular mechanisms remain unclear. Here, we aimed to investigate the effects and elucidate the molecular mechanisms of FIR on depression-like behavior in mice.

METHODS

A mouse model of depression was established using chronic restraint stress (CRS). Behavioral tests were performed to assess alterations in depression-like behaviors. Biochemical methods were employed to measure the levels of IL-1β, IL-6, TNF-α, S100β, IL-17, melatonin (MT), 5-hydroxytryptamine (5-HT), glutathione (GSH), malondialdehyde (MDA), brain-derived neurotrophic factor (BDNF), and corticosterone (CORT) in mice serum. Similarly, the levels of IL-1β, IL-6, TNF-α, S100β, IL-17, and MT in mice brains were measured using biochemical methods. Hematoxylin-eosin and Nissl staining were utilized to detect morphological changes in the mice hippocampus. In addition, the structure and mitochondrial morphology of hippocampal neurons and microglia were studied using transmission electron microscopy (TEM).

RESULTS

The results of behavioral tests revealed that FIR mitigated the depression-like behaviors induced by CRS. FIR also reversed the levels of IL-1β, IL-6, TNF-α, and related cytokines in the periphery and brain. The results of hematoxylin-eosin and Nissl staining showed that FIR improved the damage of mice's hippocampus. Additionally, TEM revealed that FIR alleviated the damage of CRS to hippocampal neurons and microglia.

CONCLUSION

Our findings suggest that FIR can ameliorate depression-like behavior induced by CRS in mice. FIR can reverse the levels of related cytokines in the periphery and brain, and alleviate damage to neurons and microglia, which may constitute its underlying molecular mechanism.

Homocysteine-Responsive Covalent Organic Frameworks as Signaling Scaffolds: Modulating Transsulfuration for Depression Treatment

Depression is a significant global health concern with limited effective treatment strategies to date. Elevated homocysteine is identified as a critical factor contributing to the severity of depression by aggravating neuroinflammation. Herein, this study develops a diverse array of homocysteine-stimulated responsive covalent organic frameworks (COFs) as novel therapeutic agents. Using Schiff-base condensation reactions between cystamine/selenocystamine and various C2- and C3-symmetric aryl aldehydes, it successfully synthesized a library of 20 COFs. The sensitivity and specificity of the resultant COFs for homocysteine clearance are validated using serum samples from patients with depression and a mouse model. Non-targeted metabolomics and transcriptomics analyses revealed that these COFs not only exogenously and directly scavenge homocysteine but also synergistically enhance the transsulfuration pathway within the endogenous metabolic cycle for efficient clearance. Furthermore, these COFs mitigated neuroinflammation by inhibiting inflammatory responses, scavenging reactive oxygen species, and modulating neuronal and microglial activity. They also activated neuroactive ligand-receptor signaling pathways and preserved mitochondrial function, thereby maintaining oxidative phosphorylation. Collectively, these mechanisms resulted in significant improvements in anxiety and depressive behaviors in mice. This study pioneers the therapeutic application of homocysteine-responsive COFs for depression treatment, opening up tremendous opportunities for the biomedical applications of COFs.

Association between higher dietary lycopene intake and reduced depression risk among American adults: evidence from NHANES 2007-2016

Introduction

Although previous researches have suggested that certain dietary nutrients, such as carotenoids, have an effect on depression, epidemiological evidence on the relationship between lycopene and depression remains limited. This study aimed to investigate the association between dietary lycopene intake and depression risk in American adults.

Methods

Data from 18,664 participants in the National Health and Nutrition Examination Survey (NHANES, 2007-2016) were analyzed, with depression defined by a nine-item Patient Health Questionnaire (PHQ-9) score ≥ 10. Dietary lycopene intake was estimated from the mean of two 24-h dietary recalls. Binary logistic regression and restricted cubic spline (RCS) models were employed to assess the relationship.

Results

Depression prevalence was 8.98%, and adjusted analyses indicated that higher dietary lycopene intake was significantly associated with a reduced depression risk compared to the lowest quartile (ORs for the second, third, and fourth quartiles: 0.851 [95% CI, 0.737-0.982], 0.829 [95% CI, 0.716-0.960], and 0.807 [95% CI, 0.695-0.938], respectively). Additionally, a U-shaped relationship was observed, with a reduction in depression risk associated with dietary lycopene intake ranging from 0 to 10,072 μg/d (P-non-linear = 0.017).

Discussion

This study suggested that higher dietary lycopene intake may confer a protective effect against depression in American adults.

Review: Exploring correctness, usefulness, and feasibility of potential physiological operational welfare indicators for farmed insects to establish research priorities

While insects are already the largest group of terrestrial food and feed livestock animals in terms of absolute number of individuals, the insect farming industry is expected to continue growing rapidly in order to meet the nutritional demands of the human population during the 21st century. Accordingly, consumers, producers, legislators, and industry-adjacent researchers have expressed interest in further research and assessment of farmed insect welfare. Operational indicators of animal welfare are those that can be used to putatively assess the welfare of animals in the absence of true indicators of affective state (e.g., valenced/emotional state) and are commonly used for farmed vertebrate livestock species; however, significant behavioral and physiological differences between vertebrates and insects means these indicators must be examined for their correctness, usefulness, and feasibility prior to use with insect livestock. The most valuable operational welfare indicators would (1) correctly correspond to the insect's putative welfare state; (2) provide useful information about what is affecting the insect's welfare; and (3) be feasible for deployment at a large scale on farms. As there are many possible indicators that could be further researched in insects, evaluating the likely correctness, feasibility, and usefulness of these indicators in insects will allow researchers to prioritize which indicators to investigate first for use on farms. Thus, in this review, we explore whether physiological or somatic indicators of farmed vertebrate welfare, including whole-body, immune, neurobiological, and respiratory/cardiac indicators, may be correct, feasible, and useful for assessing farmed insect welfare. We review insect physiological systems, as well as any existing, welfare-relevant data from farmed or closely related insects. We end by proposing a priority list for physiological, operational welfare indicators that are most likely to correctly, usefully, and feasibly assess farmed insect welfare, which may guide indicator validation research priorities for insect welfare scientists.

Interplay of Endoplasmic Reticulum Stress, Inflammation, Apoptosis, and Oxidative Stress in Corticosteroid-Induced Anxiety and Depression: Exploring Therapeutic Potential of Hydrogen Sulfide and Sertraline

Prolonged exposure to corticosteroids (CORTs) triggers depression and anxiety symptoms either endogenously or exogenously via stimulating endoplasmic reticulum stress (ERS). The study assessed the therapeutic implications of hydrogen sulfide (H2S) versus sertraline (SERT) in alleviating anxiety and depression induced by CORTs through the modulation of ERS and its inflammatory, oxidative, and apoptotic consequences. Rats were subdivided into four groups: control, CORT (20 mg/kg), NaHS (100 μmol/kg), and SERT (10 mg/kg) for 21 days. Behavioral and histological examinations of the cerebral cortex were performed. The levels of CHOP, GADD34, EIF2AK3, GRP78, caspase 3, and miR-146a were analyzed using qRT-PCR. The levels of CORTs, serotonin, BDNF, TNF-α, BCL2, NRF2, and ATF4 were measured using ELISA, whereas those of IL-1β and BAX were measured using immunohistochemical techniques. Total and phosphorylated PERK were assessed via western blotting, whereas GSH and MDA were assessed via a colorimetric assay. In the present study, CORTs upregulated the gene expression of CHOP, GADD34, EIF2AK3, GRP78, and Caspase 3, whereas it downregulated that of miR-146a. The levels of serotonin, BDNF, BCL2, GSH, and NRF2 were decreased, whereas those of ATF4, TNF-α, IL-1β, BAX, and MDA were elevated. On the contrary, NaHS and SERT reversed all the above-mentioned changes. H2S shows promise in counteracting anxiety and depression symptoms induced by CORTs by targeting ERS cascades, mitigating inflammation, oxidative insults, and apoptosis in the cerebral cortex. H2S elicits neuroprotective effects by targeting the miR-146a-3p/GRP78/CHOP/PERK/ATF4/GADD34 signaling pathway and regulating apoptotic markers BAX/BCL2 and inflammatory markers TNF-α and/IL-1β. Compared with SERT, H2S exhibited superior anxiolytic and antidepressive effects.

Estrogen metabolites and hydrogen peroxide - Missing elements in the pathophysiology and possible treatment of treatment-resistant depression?

The pathogenesis of depression is complex and heterogeneous, and the management of this disease remains unsatisfactory, so mechanisms and therapeutic strategies are constantly being sought. This study aimed to determine the potential role of estrogen metabolites in the pathogenesis of treatment-resistant depression (TRD) based on the determination of concentrations of estrogens and their metabolites and hydrogen peroxide (H202) in the biological material of patients with TRD. In this study, we observed for the first time an association between unbalanced estrogen metabolism and elevated H202 levels in TRD patients. Reduced concentrations of 2-methoxyestradiol (2-ME2), 17α-estradiol (α-E2) and 17β-estradiol (β-E2) may be due to abnormal estrogen metabolism toward neurotoxic semiquinones and quinones which are a potential as yet undescribed mechanism responsible for generating oxidative stress (OS) in TRD.

Glutathione alterations in depression: a meta-analysis and systematic review of proton magnetic resonance spectroscopy studies

BACKGROUND

Major depressive disorder (MDD) is a common and serious psychiatric disorder associated with significant morbidity. There is mounting evidence for the role of oxidative stress in the pathophysiology of depression.

OBJECTIVE

To investigate alterations in the brain antioxidant glutathione in depression by undertaking a meta-analysis of proton magnetic resonance spectroscopy (1H-MRS).

METHODS

MEDLINE, EMBASE and Psych Info databases were searched for case-control studies that reported brain glutathione levels in patients with depression and healthy controls. Means and variances (SDS) were extracted for each measure to calculate effect sizes. Hedges g was used to quantify mean differences. The Meta-analysis of Observational Studies in Epidemiology (MOOSE) and Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed.

RESULTS

8 studies that reported measurements for 230 patients with depression and 216 controls were included. Three studies included data for the occipital cortex and five studies for the medial frontal cortex. In the occipital cortex, GSH was lower in the patient group as compared to controls (g = -0.98, 95% [CI, -1.45--0.50], P = < 0.001). In both the medial frontal cortex and in the combined all areas analysis there was no significant difference in GSH levels between cases and controls.

CONCLUSIONS

This study found reduced levels of GSH specifically in the occipital region of patients with MDD. This provides some support for the role of oxidative stress in depression and suggests that targeting this system may provide future therapeutic opportunities. However, the meta-analysis was limited by the small number and quality of the included studies. More studies using high quality MRS methods in a variety of brain regions are needed in the future to test this putative hypothesis.

Association between urinary trace elements levels and depressive symptoms among the older population

BACKGROUND

Late-life depression is a prevalent public health issue among the elderly. Imbalances in trace elements are increasingly recognized as associated with depression; however, the majority of current research has concentrated on examining the link between blood-based trace elements levels and depressive symptoms. Our objective was to determine if a similar correlation is observed between urinary trace elements levels and depressive symptoms.

METHODS

We employed stratified, multi-stage random sampling to recruit 400 participants, aged 60 years or older, from a community-based population in a city located in southern China. The Patient Health Questionnaire-9 Items (PHQ-9) was utilized to evaluate depressive symptoms. The concentration of trace elements in urine was detected by inductively coupled plasma mass spectrometry. Multiple logistic regression analysis was conducted to assess the association between urinary trace elements levels and depressive symptoms, as well as the interactions between these levels and potential covariates. The Restricted Cubic Spline (RCS) model with four knots to further explore the association between urinary trace elements and depressive symptoms risk after adjusting for the confounders.

RESULTS

A total of 391 participants were investigated, including 50 (12.6 %) in depressive symptom group and 341 (87.4 %) in non-depressive symptom group. Urinary copper levels were positively correlated with depressive symptoms. Compared with the lowest tertile of urinary copper, the multivariate adjusted odds ratios of depressive symptom were 2.58 (1.18-5.64) in tertile 3. Furthermore, we found the interactions between urinary copper and gender were p < 0.05. The multivariate correction OR for T3 versus T1 in males was 21.10 (1.79-248.13) (Pfor trend = 0.002). RCS analysis revealed a positive association between copper levels and depressive symptoms (P-overall association = 0.025, and P-nonlinear = 0.161). No significant difference was observed in the risk of developing depressive symptoms among individuals with urinary copper concentrations below 8.22 μg/g creatinine. However, the risk of depressive symptoms increases progressively as the urinary copper concentration exceeds this threshold.

CONCLUSION

Urinary copper levels are correlated with the development of depressive symptoms, and copper exposure in men is more sensitive to depressive symptoms. Urinary copper, as a non-invasive test, is a promising indicator of depression symptoms in environmental exposure.

Luteolin and its antidepressant properties: From mechanism of action to potential therapeutic application

Luteolin is a natural flavonoid compound exists in various fruits and vegetables. Recent studies have indicated that luteolin has variety pharmacological effects, including a wide range of antidepressant properties. Here, we systematically review the preclinical studies and limited clinical evidence on the antidepressant and neuroprotective effects of luteolin to fully explore its antidepressant power. Network pharmacology and molecular docking analyses contribute to a better understanding of the preclinical models of depression and antidepressant properties of luteolin. Seventeen preclinical studies were included that combined network pharmacology and molecular docking analyses to clarify the antidepressant mechanism of luteolin and its antidepressant targets. The antidepressant effects of luteolin may involve promoting intracellular noradrenaline (NE) uptake; inhibiting 5-hydroxytryptamine (5-HT) reuptake; upregulating the expression of synaptophysin, postsynaptic density protein 95, brain-derived neurotrophic factor, B cell lymphoma protein-2, superoxide dismutase, and glutathione S-transferase; and decreasing the expression of malondialdehyde, caspase-3, and amyloid-beta peptides. The antidepressant effects of luteolin are mediated by various mechanisms, including anti-oxidative stress, anti-apoptosis, anti-inflammation, anti-endoplasmic reticulum stress, dopamine transport, synaptic protection, hypothalamic-pituitary-adrenal axis regulation, and 5-HT metabolism. Additionally, we identified insulin-like growth factor 1 receptor (IGF1R), AKT serine/threonine kinase 1 (AKT1), prostaglandin-endoperoxide synthase 2 (PTGS2), estrogen receptor alpha (ESR1), and epidermal growth factor receptor (EGFR) as potential targets, luteolin has an ideal affinity for these targets, suggesting that it may play a positive role in depression through multiple targets, mechanisms, and pathways. However, the clinical efficacy of luteolin and its potential direct targets must be confirmed in further multicenter clinical case-control and molecular targeting studies.

Luteolin Exhibits Anxiolytic and Antidepressant Potential in Parkinson's Disease Rat: Antioxidant and Anti-Inflammatory Effects

Parkinson's disease (PD) is accompanied by a complex array of nonmotor and motor manifestations. The exploration of anti-inflammatory and antioxidant active ingredient as potential therapeutic interventions in PD-associated mood alterations has gained significant attention. This study aimed to assess the antidepressant and anxiolytic properties of luteolin (LTN), a potent antioxidant and anti-inflammatory component, using a 6-hydroxydopamine (6-OHDA)-induced animal model of PD. Rats were administered LTN (10, 25, and 50 mg/kg, per oral) and fluoxetine (10 mg/kg/per oral) over a 28-day period. Behavioral tests were employed to estimate the depression- and anxiety-like behaviors. Rats treated with LTN exhibited significant improvement in 6-OHDA-induced mood alterations, as per behavioral tests. Additionally, LTN treatment led to increased hippocampal levels of catalase and superoxide dismutase, and a reduction in malondialdehyde. LTN downregulated the gene expression of nuclear factor kappa B (NF-κB)/nod-like receptor (NLR) pyrin domain-containing 3 (NLRP3) axis components, including NF-κB, NLRP3, ASC, and Caspase1 and reduced the protein level of pro-inflammatory cytokines, including interleukin (IL)-6, interleukin (IL)-1β, and tumor necrosis factor alpha (TNF-α), in addition to augmenting the protein levels of TNF-α, IL-1β, and IL-6. Furthermore, LTN exhibited an upregulatory effect on the anti-inflammatory cytokine IL-10 within the hippocampus of 6-OHDA-induced PD rats. Also, molecular docking showed higher affinity between LTN and NF-κB/NLRP3 axis components. These findings highlight the potential anxiolytic and antidepressant impacts of LTN through its antioxidant and anti-inflammatory mechanisms against 6-OHDA-induced alterations in a rat PD model.

Chronic stress-mediated dysregulations in inflammatory, immune and oxidative circuitry impairs the therapeutic response of methotrexate in experimental autoimmune disease models

Chronic stress is significantly implicated in the worsening of autoimmune disorders, contributing to elevated inflammation and diminished therapeutic efficacy. Here, in this study, we investigated the detrimental impact of an 8-week chronic unpredictable stress (CUS) protocol on the progression of arthritis and psoriasis using collagen-induced arthritis (CIA) and imiquimod (IMQ)-induced psoriasis rat models, respectively. Our objective was to elucidate how prolonged stress exacerbates disease severity and impairs the effectiveness of treatment drug. Following the induction of CIA and IMQ, rats were subjected to an 8-week CUS paradigm designed to simulate chronic stress conditions. Moreover, after 5 weeks of CUS, methotrexate (MTX; 2 mg/kg, administered once weekly for 3 weeks, intraperitoneally) was introduced as a therapeutic intervention. The severity of CUS-induced effects and the therapeutic impairment of MTX in arthritis and psoriasis rats were assessed through pathological examination of joint and epidermal tissues, respectively. Additionally, we measured various pro-inflammatory cytokine levels, including NF-κB (nuclear factor kappa B), IFN-γ (interferon-gamma), TNF-α (tumour necrosis factor alpha), IL (interleukin)-1β, IL-6, IL-17 and IL-23 using enzyme-linked immunosorbent assay (ELISA), analysed immune cells through complete haematological profiling and evaluated oxidative stress markers. Our findings revealed that CUS significantly aggravated the pathological features of both arthritis and psoriasis. Prolonged stress exposure led to heightened inflammatory responses, increased oxidative stress and more severe tissue damage. Moreover, the therapeutic efficacy of MTX was notably reduced in stressed rats compared to non-stressed, underscoring the detrimental effects of chronic stress on treatment outcomes. Taken together, our results emphasize the importance of considering chronic stress as a critical factor in the management of autoimmune diseases.

Altered neurovascular coupling in depression with childhood maltreatment

BACKGROUND

Childhood maltreatment (CM) is a well-established risk to major depressive disorder (MDD) worldwide. However, most previous research has predominantly examined single imaging modalities, ignoring the potential impact of aberrant couplings between cerebral perfusion and neuronal activity in MDD psychopathology. This study aims to investigate alterations of neurovascular coupling (NVC) in CM-related MDD.

METHODS

A cross-sectional study recruited 59 MDD with CM, 36 MDD without CM, 23 healthy controls with CM, and 45 healthy controls without CM. For each participant, NVC was calculated using cerebral blood flow and regional homogeneity. Main and interactive effects were determined using two-way ANCOVA, and correlations between aberrant NVC and clinical measurements were explored via post-hoc partial correlation analyses. Furthermore, support vector machine was applied to assess the diagnostic value of NVC abnormalities in pairwise classifications.

RESULTS

NVC analyses identified significant main effects of MDD in the visual, temporal, sensorimotor, and reward-related areas, alongside notable main effects of CM in sensorimotor areas. In the sensory-motor circuit, including the fusiform area, lateral prefrontal cortex, precentral gyrus, postcentral gyrus, and supramarginal gyrus/angular gyrus, MDD × CM interactive effects were observed. These aberrant NVCs correlated with the severity of CM or depression, particularly with physical neglect and cognitive disorder. Importantly, these aberrant NVCs facilitated effective pairwise classifications of CM-related MDD.

CONCLUSIONS

These results underscored the vulnerability of sensory-motor circuit NVC to CM in MDD patients, shedding insights into the psychopathology of MDD and its potential classification implications.

Assessing the joint effects of mitochondrial genes and physical activity on the psychiatric phenotype of subjective well-being based on the UK Biobank data

Subjective well-being (SWB) is an important measure for mental health status. Previous research has shown that physical activity can affect an individual's well-being, yet the underlying molecular mechanism remains to be clarified. In this study, we aim to evaluate the potential interactions between mitochondrial genes and physical activity (PA) as well as their combined effects on individual well-being. SWB phenotype data in UK Biobank were enrolled for this study including nine aspects such as work/job satisfaction, health satisfaction, family relationship satisfaction, friendships satisfaction, financial situation satisfaction, ever depressed for a whole week, general happiness, general happiness with own health and belief that own life is meaningful. We made analysis for each aspects separately. Firstly, mitochondria-wide association studies (MiWAS) was conducted to assess the association of mitochondrial Single Nucleotide Polymorphisms SNP with each aspect of SWB. Then an interaction analysis of mitochondrial DNA (mtDNA) mutation and PA was performed to evaluate their joint effect on SWB status. Meanwhile, these two analysis were made for female and male group separately as well as the total samples, all under the control of possible confounding factors including gender, age, Townsend Deprivation Index (TDI), education, alcohol consumption, smoking habits, and 10 principal components. MiWAS analysis identified 45 mtSNPs associated with 9 phenotypes of SWB. For example, m.15218A > G on MT-CYB in the health satisfaction phenotype of the total subjects. Gender-specific analyses found 30 mtSNPs in females and 58 in males, involving 13 mtGenes. In mtDNA-PA interaction analysis, we also identified 10 significant mtDNA-PA interaction sets for SWB. For instance, m.13020 T > C (MT-ND5) was associated with the SWB financial situation satisfaction phenotype in all subjects (P = 0.00577). In addition, MiWAS analysis identified 12 mtGene variants associated with SWB, as MT-ND1 and MT-ND2. However, in mtDNA-PA interactions we detected 7 mtDNA affecting psychiatric disorders occurring, as in the friendships satisfaction phenotype (m.3394 T > C on MT-ND1). Our study results suggest an implication of the interaction between mitochondrial function and physical activity in the risk of psychiatric disorder development.

New Dawn of Edible and Medicinal Fungi Unlocking Central Nervous System Diseases

Central nervous system (CNS) diseases present unique clinical challenges characterized by insidious symptom onset, complex pathophysiology with incomplete mechanistic understanding, and substantial difficulties in therapeutic evaluation, thereby these inherent complexities create substantial obstacles for developing effective CNS diseases management strategies. Certain edible and medicinal fungi contain bioactive components, including polysaccharides, triterpenoids, alkaloids, and so on, which have therapeutic promise for CNS diseases. This paper reviews the current research advancements regarding the use of edible and medicinal fungi in the context of CNS diseases, highlighting their advantages as prospective therapeutic options and potential roles in both prevention and treatment. Through a comprehensive analysis of existing studies, the mechanisms and applications of these fungi are elucidated, providing valuable insights for the development of novel pharmaceuticals or functional foods aimed at combating CNS diseases.

Untargeted metabolomics revealed that quercetin improved adrenal gland metabolism disorders and modulated the HPA axis in perimenopausal depression model rats

Perimenopausal depression is a psychiatric disorder that occurs around the time of menopause and seriously affects women's health. The pathogenesis of perimenopausal depression is unclear which affects its prevention and treatment. Quercetin is a flavonoid compound with antidepressant and estrogen-like effects. The aim of this research was to investigate the role of quercetin on adrenal gland metabolic disorders in perimenopausal depressed rats based on untargeted metabolomics. Female Wistar rats with no difference in sucrose preference were randomly separated into four groups (n = 12): sham-operated group; perimenopausal depression model group; model + 50 mg/kg.bw quercetin group; model + 0.27 mg/kg.bw 17β-estradiol group. After successful modeling, adrenal gland and hypothalamic samples were collected for metabolomics experiments and detection of related indicators. A total of 22 differential metabolites were identified in the model group, and pathway analysis revealed adrenal gland metabolism abnormalities including steroid hormone biosynthesis, arachidonic acid metabolism, and linoleic acid metabolism. Notably, Spearman's rank correlation analysis between differential metabolites and rat behavioral results showed strong positive or negative correlations (P < 0.01). Meanwhile, the hypothalamus of the model group showed TrkB-BDNF signaling pathway abnormality, and the HPA axis was found to play an important role in perimenopausal depression. Treatment with quercetin or 17β-estradiol restored these abnormal changes. It suggested that quercetin can regulate adrenal metabolic disorders through multiple pathways, thereby ameliorating perimenopausal depression.Further more, quercetin can modulate HPA axis through the TrkB-BDNF signaling pathway. This research provides new ideas for the application of quercetin in the precaution and treatment of perimenopausal depression.

Non-Linear Association Between Physical Activities and Type 2 Diabetes in 2.4 Million Korean Population, 2009-2022: A Nationwide Representative Study

BACKGROUND

Although excessive physical activity (PA) does not always confer additional health benefits, there is a paucity of studies that have quantitatively examined the dose-response relationship between PA and type 2 diabetes. Therefore, this study investigated the relationship between the type 2 diabetes prevalence and intensity, frequency, and metabolic equivalent of task (MET) score of PA in a large population sample.

METHODS

We conducted a nationwide cross-sectional analysis examining sociodemographic variables, PA habits, and type 2 diabetes prevalence in 2,428,448 participants included in the Korea Community Health Survey. The non-linear association between MET score and odds ratios (ORs) for type 2 diabetes prevalence was plotted using a weighted generalized additive model. Categorical analysis was used to examine the joint association of moderate-intensity PA (MPA) and vigorous-intensity PA (VPA), and the influence of PA frequency.

RESULTS

MET score and diabetes prevalence revealed a non-linear association with the nadir at 1,028 MET-min/week, beyond which ORs increased with additional PA. Joint analysis of MPA and VPA showed the lowest OR of 0.79 (95% confidence interval, 0.75-0.84) for those engaging in 300-600 MET-min/week of MPA and > 600 MET-min/week of VPA concurrently, corresponding with World Health Organization recommendations. Additionally, both "weekend warriors" and "regularly active" individuals showed lower ORs compared to the inactive, although no significant difference was noted between the active groups.

CONCLUSION

In a large South Korean sample, higher PA is not always associated with a lower prevalence of type 2 diabetes, as the association follows a non-linear pattern; differences existed across sociodemographic variables. Considering the joint association, an adequate combination of MPA and VPA is recommended. The frequency of PA does not significantly influence the type 2 diabetes prevalence.

Association Between Red Cell Index and Depressive Symptoms in NHANES (2005-2018): A Cross-sectional Study

BACKGROUND

Physical symptoms and emotional distress, such as melancholy, are common among cancer survivors. Misinterpreting these as normal reactions delays depression diagnosis and worsens prognosis. Patients may hide depressive symptoms during treatment, whereas clinicians and families often dismiss them as expected disease adaptation. Emerging evidence links depression to inflammatory responses and symptoms such as fatigue/cognitive decline to hypoxia, suggesting relevance of the Red Cell Index (RCI).

OBJECTIVE

To identify depression risk factors in cancer survivors and evaluate RCI as a potential biomarker.

METHODS

We included and analyzed 2890 patients from the National Health and Nutrition Examination Survey database in this study. The 9-item Patient Health Questionnaire was used to evaluate the depressive symptoms. We employed multivariable logistic regression and stratified analyses to evaluate the association between RCI and depressive symptoms.

RESULTS

Higher RCI inversely correlated with depression risk in unadjusted analysis, persisting after full adjustment. Subgroup findings were consistent. A significant nonlinear RCI-depression connection was found by dose-response analysis.

CONCLUSIONS

As the RCI increased, the likelihood of depression in patients diagnosed with cancer decreased. Nevertheless, cross-sectional studies can merely establish the link, necessitating further research to validate causality and assess the practicality of clinical use.

IMPLICATIONS FOR PRACTICE

Possible connections between hematological markers and depression symptoms are revealed by this investigation. The RCI-depression correlation offers new perspectives for nursing practice. For cancer survivor care, integrating validated hematological indicators into assessments alongside monitoring physical/psychological symptoms is recommended. Future research should prioritize RCI-depression risk assessment and early interventions in oncology patients.

Exploring Male-Specific Synaptic Plasticity in Major Depressive Disorder: A Single-Nucleus Transcriptomic Analysis Using Bioinformatics Methods

Major depressive disorder (MDD) is a complex psychiatric illness, with synaptic plasticity playing a key role in its pathology. Our study aims to investigate the molecular basis of MDD by analyzing synaptic plasticity-related gene expression at the single-cell level. Utilizing a published snRNA-seq dataset (GSE144136), we identified Excitatory.neurons_1 as the cell cluster most associated with MDD and synaptic plasticity through cell clustering, gene set enrichment analysis (GSEA), and pseudotime analysis. Integrating the bulk RNA-seq data (GSE38206), we identified CASKIN1 and CSTB as hub genes via differential expression analysis and machine learning methods. Further exploration of the relevant mechanisms was performed via cell-cell communication and ligand-receptor interaction analysis, functional enrichment analysis, and the construction of molecular regulatory networks, highlighting miR-21-5p as a key biomarker. We propose that elevated miR-21-5p in MDD downregulates CASKIN1 in Excitatory.neurons_1 cells, resulting in decreased neural connectivity and altered synaptic plasticity. As our analyzed snRNA-seq dataset consists solely of male samples, these findings may be male-specific. Our findings shed light on potential mechanisms underlying synaptic plasticity in MDD, offering novel insights into the disorder's cellular and molecular dynamics.

Association between Body Roundness Index and Depression Among Middle-aged and Older Adults in Chinese Communities: An Empirical Analysis Based on CHARLS Data

BACKGROUND

The relationship between depression and obesity has been confirmed by multiple studies. Compared to conventional measurement indicators such as body mass index or waist circumference, the body roundness index (BRI) demonstrates higher accuracy in assessing body fat content, especially visceral adiposity. Nevertheless, despite the advantages of BRI in measuring fat, the specific link between BRI and depression remains unclear. This study aims to clarify the potential correlation using data from the China Health and Retirement Longitudinal Study (CHARLS).

METHODS

This study used CHARLS data from 2015 and 2020. We screened and included 7,258 middle-aged and older adults without depressive symptoms at baseline. We explored the connection between BRI and depression risk through logistic regression analyses, restricted cubic spline analyses, subgroup analyses, and interaction tests.

RESULTS

After adjusting for covariates, a positive correlation was observed between BRI and depression risk. Specifically, a one-unit increase in BRI led to a 14% increase in depression risk (OR =  1.14, 95% CI: 1.09-1.20, P <  0.001).

CONCLUSION

BRI is linked to a higher risk of depression in middle-aged and older adults in China and can be used as a simple indicator to predict depression.

Single subanesthetic dose of ketamine exerts antioxidant and antidepressive-like effect in ACTH-induced preclinical model of depression

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis and oxidative stress represent important mechanisms that have been implicated in etiopathology of depression. Although first antidepressants were introduced in clinical practice more than six decades ago, approximately 30 % of patients with a diagnosis of depression show treatment resistance. A noncompetitive N-methyl-d-aspartate receptor antagonist ketamine has shown promising rapid antidepressant effects and has been approved for treatment-resistant depression (TRD). In the present study, we investigated antioxidant and antidepressant-like activity of a single subanesthetic dose of ketamine (10 mg/kg, ip) in a rodent model of TRD induced by adrenocorticotropic hormone (10 μg ACTH/day, sc, 21 days). Behavioral assessment was performed, and plasma biomarkers of oxidative stress and DNA damage in peripheral blood lymphocytes (PBLs) were determined. We observed that ACTH produced depressive-like behavior and significant increase in superoxide anion (O2·-), advanced oxidation protein products (AOPP), malondialdehyde (MDA) and total oxidant status (TOS) in male Wistar rats. This effect was accompanied by reduced activity of antioxidant enzymes - superoxide dismutase (SOD) and paraoxonase1 (PON1) in plasma and increase in DNA damage in PBLs. In the described model of TRD, we have demonstrated antidepressant effects of ketamine for the first time. Our results reveal that ketamine was effective in reducing O2.-, AOPP, MDA and TOS, while enhancing SOD and PON1 activity in ACTH-rats. Collectively, our study sheds light on molecular mechanisms implicated in antioxidant activity of ketamine, thus incentivizing further investigation of its effects on ROS metabolism and antioxidant defenses in clinical trials, particularly in depression.

The impact of climatic factors on negative sentiments: An analysis of human expressions from X platform in Germany

Expressions in social media can provide a rapid insight into people's reactions to events, such as periods of climatic stress. This study explored the link between climatic stressors and negative sentiment on the X platform in Germany to inform climate-related health policies and interventions. Natural language processing was used to standardize the text, and a comprehensive approach for sentiment analysis was utilized. We then conducted spatiotemporal modeling fitted using integrated nested laplace approximation (INLA). Our findings indicate that higher and lower level of temperature and precipitation is correlated with an increase and decrease in the relative risk of negative sentiments, respectively. The findings of this study illustrate that human sentiment of distress in social media varies with space and time about exposure to climate stressors. This emotional indicator of human exposure and responses to climate stress indicates potential physical and mental health impacts among the affected populations.

Update on the roles and applications of extracellular vesicles in depression

Depression is a prevalent mental disorder that affects numerous individuals, manifesting as persistent anhedonia, sadness, and hopelessness. Despite extensive research, the exact causes and optimal treatment approaches for depression remain unclear. Extracellular vesicles (EVs), which carry biological molecules such as proteins, lipids, nucleic acids, and metabolites, have emerged as crucial players in both pathological and physiological processes. EVs derived from various sources exert distinct effects on depression. Specifically, EVs released by neurons, astrocytes, microglia, oligodendrocytes, immune cells, stem cells, and even bacteria contribute to the pathogenesis of depression. Moreover, there is growing interest in potential of EVs as diagnostic and therapeutic tools for depression. This review provides a comprehensive overview of recent research on EVs from different sources, their roles in depression, and their potential clinical applications.

Ferroptosis-associated signaling pathways and therapeutic approaches in depression

Ferroptosis, a newly identified form of cell death, is characterized by excessive iron accumulation and lipid peroxidation. Studies indicate a strong association between ferroptosis and depression; however, the precise signaling pathways and underlying molecular mechanisms remain unclear. This review summarizes the role of ferroptosis in depression and its associated signaling pathways. Additionally, therapeutic approaches for depression based on ferroptosis theory are reviewed, providing novel targets for the prevention and treatment of depression and laying a foundation for future research on the relationship between ferroptosis and depression.

Association between oxidative balance score and risk of postpartum depression in Iranian women: a prospective cohort study

The oxidative balance score (OBS) serves as a comprehensive measure of exposures related to oxidative stress, considering both dietary antioxidants and lifestyle exposures. There is no evidence regarding the relation between OBS and postpartum depression (PPD). In this study, we aimed to determine the relationship between OBS during pregnancy and PPD. In this cohort study, 243 Iranian pregnant women were recruited using a convenience sampling method from 2022 to 2023. Dietary intakes were obtained using a validated food frequency questionnaire. OBS was separately constructed based on nutrients/lifestyle (NLOBS) and food groups/lifestyle (FLOBS) according to the previously proposed methods. PPD was diagnosed 4 to 6 weeks after delivery using the Edinburgh Postpartum Depression Scale. Cox proportional hazards regression was utilized to examine the relationship between OBS and PPD. Participants had a mean (SD) age of 30.9 ± 6.12 years. In total, 43 females were diagnosed with PPD. Findings revealed that, after controlling all confounders, subjects with the highest level of NLOBS, compared to the lowest, had a 69% lower risk of PPD (HR: 0.31; 95% CI: 0.12-0.83). Although a significant inverse relation was found between FLOBS and PPD in the crude model (HR: 0.43; 95% CI: 0.19-0.96); this association was not significant in fully adjusted model (HR: 0.53; 95% CI: 0.22-1.27). Considering subtypes of each score, inverse relations were significant for NOBS and LOBS, but not for FOBS. This study suggests that a higher OBS, particularly nutrient-based OBS, during pregnancy may be associated with a reduced risk of PPD. Further research is necessary to validate these findings.

Adherence to the Mediterranean Diet and Risk of Depression: A Cohort Study in Chinese Community Residents

Objectives: Limited studies have investigated the association between compliance with a Mediterranean diet and depression in China. We sought to explore the potential association between the adherence to an alternate Mediterranean diet score (aMED) and the risk of developing depression among adults in Eastern China. Methods: This study used a prospective cohort design that involved a total of 52,232 individuals in the Shanghai Suburban Adult Cohort and Biobank (SSACB). A reliable food frequency questionnaire (FFQ) was utilized to evaluate dietary intake, and we calculated the aMED score for each participant, dividing them into 3 groups accordingly (score 0-3, 4-5, 6-9). Cox proportional hazards regression analyses were performed to compute the hazard ratios (HR) and 95% confidence intervals (CI). Results: The median age of participants was 58 years (IQR: 50-65), with a male-to-female ratio of 1:1.59. Throughout an average 6.29 years of follow up, 1220 incident cases of depression were recorded through the ICD-10 classification codes F32 and F33. A higher level of adherence to the aMED was notably linked to a decreased risk of incident depression (HRhigh vs. low adherence = 0.83, 95% CI = 0.70-0.98; HRmoderate vs. low adherence = 0.87, 95% CI = 0.76-0.99; P-trend = 0.009) after multivariate adjustment. Each 1-score increase in the aMED score was associated with a 5% lower risk of depression (HR = 0.95, 95% CI = 0.91-0.99), and this association was more pronounced among participants aged ≥65 years (P-interaction = 0.008). Conclusions: Our results suggest that following a Mediterranean diet might potentially provide mental health benefits, particularly for individuals aged 65 years and above.

Chronic mild stress dysregulates autophagy, membrane dynamics, and lysosomal status in frontal cortex and hippocampus of rats

Inflammation has been related to major depressive disorder pathophysiology. Autophagy, a degradative pathway regulating inflammation and immunity, has emerged as a potential contributor. Among others, we characterized, in frontal cortex (FC) and hippocampus (Hp), autophagy markers (upregulations in mTOR, ATG7, and ATG 16L1, and downregulations in ULK1, BECLIN1, phospho-SQSTM1, ATG3, ATG12, and ATG 16L1), effectors of the endosomal sorting complexes required for transport (overexpression in HRS, VPS37A, CHMP6, and GALECTIN 3, and downregulations in STAM2, TSG101, VPS28, VPS37A, CHMP5, VPS4B, and GALECTIN 9), and lysosomal proteins (LAMP1, LAMP2A, MANNOSE RECEPTOR, HSC70, HSP70, CATHEPSIN D and B, and CYSTATIN C, whose variations are dependent on lysosomal nature and brain region) of male rats exposed to chronic mild stress, a model of depression, compared to control rats. Results indicate that chronic stress alters protein expression of autophagy and the endosomal sorting complexes required for transport markers in a region-specific manner, plus increases lysosomal presence, oppositely modulating lysosomal proteins in each structure. Additionally, astrocytes seemed to exert an essential role in the regulation of the autophagy adaptor SQSTM1/p62. In conclusion, stress-induced protein disruptions in these pathways highlight their differential modulation after chronic stress exposure and their potential role in maintaining brain homeostasis during the stress response, making them promising targets for new therapeutic strategies in stress-related pathologies.

The role of senescence-related genes in major depressive disorder: insights from machine learning and single cell analysis

BACKGROUND

Evidence indicates that patients with Major Depressive Disorder (MDD) exhibit a senescence phenotype or an increased susceptibility to premature senescence. However, the relationship between senescence-related genes (SRGs) and MDD remains underexplored.

METHODS

We analyzed 144 MDD samples and 72 healthy controls from the GEO database to compare SRGs expression. Using Random Forest (RF) and Support Vector Machine-Recursive Feature Elimination (SVM-RFE), we identified five hub SRGs to construct a logistic regression model. Consensus cluster analysis, based on SRGs expression patterns, identified subclusters of MDD patients. Weighted Gene Co-expression Network Analysis (WGCNA) identified gene modules strongly linked to each cluster. Single-cell RNA sequencing was used to analyze MDD SRGs functions.

RESULTS

The five hub SRGs: ALOX15B, TNFSF13, MARCH 15, UBTD1, and MAPK14 showed differential expression between MDD patients and controls. Diagnostics models based on these hub genes demonstrated high accuracy. The hub SRGs correlated positively with neutrophils and negatively with T lymphocytes. SRGs expression pattern revealed two distinct MDD subclusters. WGCNA identified significant gene modules within these subclusters. Additionally, individual endothelial cells with high senescence scores were found to interact with astrocytes via the Notch signaling pathway, suggesting a specific role in MDD pathogenesis.

CONCLUSION

This comprehensive study elucidates the significant role of SRGs in MDD, highlighting the importance of the Notch signaling pathway in mediating senescence effects.

New perspectives on galectin in major depressive disorder treatment

Galectins, a family of carbohydrate-binding proteins, regulate immune responses, neuroinflammation, and neurogenesis within the central nervous system (CNS). Among the 15 known galectins, galectins-1, -3, -4, -8, and -9 play significant roles in neuroinflammation and have been investigated in the context of CNS pathologies. This review synthesizes recent advancements in understanding galectins' involvement in the neurobiology of brain disorders, focusing on their interplay with signaling pathways underlying major depressive disorder (MDD). It explores their impact on neuroinflammation, neurogenesis, and brain signaling, highlighting the therapeutic potential of targeting galectins while addressing challenges in translating these findings into clinical practice. Comprehensive studies are essential to unravel the complex mechanisms of galectin-mediated pathways and unlock their full potential for managing neuropsychiatric conditions.

Effect of serum antioxidants on cognitive dysfunction in first-episode and drug-naïve patients with major depressive disorder

BACKGROUND

Cognitive dysfunction is a persistent and difficult-to-treat symptom of major depressive disorder (MDD) and is receiving increasing attention. A balanced state of oxidative stress sustained by antioxidants is essential for normal functioning of brain, including learning capacity, emotional regulation, and cognitive function. The correlation between cognition and oxidative stress may also be altered in patients with mental disorders. This study aimed to explore the relationship between serum antioxidant levels and cognitive dysfunction in patients with MDD.

METHODS

We collected and matched cognitive performance data using the Measurement and Treatment Research to Improve Cognition in Schizophrenia Consensus Cognitive Battery (MCCB), serum antioxidants, and demographic and clinical characteristics of 105 first-episode drug-naïve patients with MDD and 53 healthy controls (HC) from February 2022 to October 2023, and then analyzed the differences between the two groups. HamiltonDepressionScale-17 and Young Mania Rating Scale (YMRS) were used to evaluate the clinical symptoms of the participants with MDD. Serum antioxidants, including albumin (ALB), uric acid (UA), and superoxide dismutase (SOD) were used to detect the level of oxidative stress in participants and its correlation with cognitive function. We then used a threshold for cognitive dysfunction of 1.5 standard deviations below the mean of the standard score to divide the participants with MDD into two groups to detect the relevant elements of the five different domains of cognitive dysfunction in MDD.

RESULTS

ALB levels were significantly lower in the MDD group (p = 0.001) after adjusting for years of education. The performance in all five domains of cognitive function was significantly worse in the MDD group than in the HC group (p < 0.001). Speed of processing (SOP) in the MDD group correlated with ALB (r = 0.261, p = 0.008), and UA (r = 0.295, p = 0.002) levels. We also explored the correlation between the attention/vigilance (AV) domain and the UA (r = 0.239, p = 0.015). YMRS score was risk factor of impairment of SOP domain in patients with MDD. Yet UA was a protective factor against SOP impairment, with a 0.006-fold reduction in the risk of SOP impairment for each 1-unit increase in UA.

CONCLUSIONS

As serum antioxidants, ALB and UA may serve as biomarkers of cognitive function in patients with MDD. Our findings contribute to the understanding of the potential ability of serum antioxidants to predict cognitive decline in patients with MDD.

The association between adverse experiences and longitudinal allostatic load changes with the depression symptoms trajectories in middle-aged and older adults in China: A longitudinal study

BACKGROUND

This study investigated the associations between adverse childhood experiences (ACEs), adverse adulthood experiences (AAEs), allostatic load (AL) changes, and later depression symptoms trajectories in middle-aged and older Chinese longitudinally.

METHODS

1921 individuals aged ≥45 years at baseline were included from the China Health and Retirement Longitudinal Study (CHARLS). Measures included ACEs, AAEs, depression symptoms scores, health-related factors, and demographic characteristics. AL changes were assessed by the difference in AL scores between wave 3 (2015) and wave 1(2011).

RESULTS

Compared to consistently low trajectory, 2 or more ACEs (OR 1.78, 95 % CI 1.28-2.46), 2 or more AAEs (OR 1.82, 95 % CI 1.26-2.64), decreasing metabolic AL over time (OR 0.63, 95 % CI 0.46-0.86), increasing inflammatory AL over time (OR 1.60, 95 % CI 1.07-2.37), and decreasing renal AL over time (OR 1.38, 95 % CI 1.01-1.87) were associated with the low-moderate depression symptoms trajectory. Furthermore, 2 or more ACEs (OR 1.48, 95 % CI 1.10-2.00), 2 or more AAEs (OR 1.85, 95 % CI 1.32-2.60), decreasing metabolic AL over time (OR 0.75, 95 % CI 0.57-1.00), increasing inflammatory AL over time (OR 1.69, 95 % CI 1.19-2.42) were associated with the high-moderate depression symptoms trajectory.

CONCLUSION

Experiencing more ACEs and AAEs was associated with higher depression symptoms trajectories. Moreover, participants with decreasing metabolic AL over time showed a low depression symptoms trajectory, while those with increasing inflammatory AL over time and decreasing renal AL over time showed a worse depression symptoms trajectory. These findings highlighted the physiological damage caused by stress on mental health outcomes.

Sex-specific differences in peripheral blood metabolites and biological functions in major depressive disorder: A systematic review and meta-analysis

To explore the sex-specific peripheral blood metabolites and biological functions altered in patients with major depressive disorder (MDD). A search was conducted on PubMed, Cochrane, Embase, Web of Science, and other databases published up to 11/2023. To maximize the search, we also reviewed systematic reviews and meta-analyses on the same topic. We included studies that conducted metabolic characterizations during current depressive episodes or after antidepressant treatments, with all data stratified by sex. Fifty-eight studies involving 83 cohorts with 5285 MDD participants were included in this meta-analysis. Random effects meta-analysis was conducted for data from ≥3 cohorts. We identified 5 sex-specific metabolites from 22 candidate peripheral blood metabolites. In males with MDD, we observed lower levels of estradiol and progesterone, alongside higher levels of androstenedione, dihydrotestosterone, and uric acid compared with female MDD patients. In addition, steroid hormone biosynthesis has been identified as a potentially sex-specific pathway. Our findings highlight significant evidence for targeting sex hormones as a broad understanding of MDD, providing potentially objective diagnostic and therapeutic insights.

Impaired lipid homeostasis and elevated lipid oxidation of erythrocyte membrane in adolescent depression

Adolescent depression is a globally concerned mental health issue, the pathophysiological mechanisms of which remain elusive. Membrane lipids play a crucial role in brain development and function, potentially serving as a crossroad for the abnormalities in neurotransmitters, neuroendocrine, inflammation, oxidative stress, and energy metabolism observed in depressed adolescents. The primary aim of this study was to investigate the erythrocyte membrane lipid profile in adolescent depression. A total of 2838 erythrocyte membrane lipids were detected and quantified in 81 adolescents with depression and 67 matched healthy adolescents using ultra-high performance liquid chromatography-mass spectrometry. Depressed adolescents exhibited significantly different membrane lipid characteristics compared to healthy controls. Specifically, the levels of cholesterol, sphingomyelins, and ceramides were increased, while ether lipids were decreased in patients. Moreover, the patients showed reduced polyunsaturated fatty acids and elevated lipophilic index in membrane, suggesting diminished membrane fluidity. The higher oxidized membrane lipids and plasma malondialdehyde were observed in adolescent depression, indicating the presence of oxidative stress. Importantly, membrane lipid damage was associated with more severe depressive symptoms and worse cognitive function in patients. In addition, reduced polyunsaturated fatty acids and membrane fluidity may be partly responsible for the blunted niacin skin flushing response found in depressed adolescents. In conclusion, our results reveal impaired erythrocyte membrane lipid homeostasis in adolescents with depression, which may implicate membrane dysfunction in the brain. These findings offer new insights into the underlying molecular mechanisms of adolescent depression, highlighting the potential of counteracting membrane damage as a promising avenue for future therapeutic interventions.

Selenium metabolism and selenoproteins function in brain and encephalopathy

Selenium (Se) is an essential trace element of the utmost importance to human health. Its deficiency induces various disorders. Se species can be absorbed by organisms and metabolized to hydrogen selenide for the biosynthesis of selenoproteins, selenonucleic acids, or selenosugars. Se in mammals mainly acts as selenoproteins to exert their biological functions. The brain ranks highest in the specific hierarchy of organs to maintain the level of Se and the expression of selenoproteins under the circumstances of Se deficiency. Dyshomeostasis of Se and dysregulation of selenoproteins result in encephalopathy such as Alzheimer's disease, Parkinson's disease, depression, amyotrophic lateral sclerosis, and multiple sclerosis. This review provides a summary and discussion of Se metabolism, selenoprotein function, and their roles in modulating brain diseases based on the most currently published literature. It focuses on how Se is utilized and transported to the brain, how selenoproteins are biosynthesized and function physiologically in the brain, and how selenoproteins are involved in neurodegenerative diseases. At the end of this review, the perspectives and problems are outlined regarding Se and selenoproteins in the regulation of encephalopathy.

Ketogenic metabolic therapy in the remission of chronic major depressive disorder: a retrospective case study

Background

There is limited evidence describing the use of ketogenic metabolic therapy (KMT), also known as a ketogenic diet (KD), to achieve full remission of treatment-resistant major depressive disorder (MDD) in real-world clinical settings. This case study examines a 47-year-old woman with lifelong treatment-resistant MDD who achieved complete remission of depressive symptoms and improved functioning through a ketogenic diet.

Methods

The patient engaged in KMT with a 1.5:1 macronutrient ratio under the supervision of a treatment team consisting of a medical professional, psychotherapist, and ketogenic-informed nutrition professional through an online program that provided both individual and group support. Interventions included dietary modifications, micronutrient supplementation, and participation in a group coaching program. Outcomes were assessed using validated tools for symptom severity, including PHQ-9 for depression and GAD-7 for anxiety, at baseline, 2 months, and 4 months post-intervention. Qualitative data on patient experiences and functional improvements were also collected.

Results

The patient achieved remission of MDD within 8 weeks of initiating KMT, with PHQ-9 scores decreasing from 25 (severe depression) at baseline to 0 at 2- and 4-month assessments. GAD-7 scores decreased from 3 (minimal anxiety) to 0 over the same period. Qualitative findings revealed significant improvements in emotional regulation, energy levels, and cognitive function.

Conclusion

This case study demonstrates the potential of KMT as a non-pharmacological intervention for achieving full remission in treatment-resistant MDD. These findings suggest further research to evaluate feasibility, efficacy, and broader applicability in diverse clinical settings.

Impact of short wavelength light exposure on body weight, mobility, anxiety like behaviour and cytokine expression

Mitochondria absorb short wavelengths around 420 nm. This is associated with reduced ATP and restricted mobility. The 420-450 nm range is a significant element of LED lighting and computer monitors. Here we expose freely moving mice to 420-450 nm lighting and show rapidly weight gain within a week. This may be due to reduced mitochondrial demand for circulating carbohydrates. Both groups displayed marked shifts in serum cytokines. Open field mobility was examined. The distance travelled was similar between both experimental groups and their controls. However, both experimental groups showed avoidance of central regions consistent with anxiety-like behaviours. This was significant in the 420 nm group whose wavelength exposure is closer to peak mitochondrial absorbance. These data demonstrate the potential hazards of exposure to specific short wavelengths in the visual range now common in the built environment. Data are consistent with a wider literature on systemic problems arising from exposure to short wavelength light.

Lipopolysaccharide preconditioning disrupts the behavioral and molecular response to restraint stress in male mice

Major depressive disorder (MDD) is a complex neuropsychiatric disorder potentially influenced by factors such as stress and inflammation. Chronic stress can lead to maladaptive brain changes that may trigger immune hyperactivation, contributing to MDD's pathogenesis. While the involvement of inflammation in MDD is well established, the effects of inflammatory preconditioning in animals subsequently exposed to chronic stress remain unclear. This study aimed to investigate the impact of inflammatory preconditioning on behavioral, biochemical, and molecular changes in adult male Swiss mice subjected to chronic restraint stress (CRS). The mice received a single injection of lipopolysaccharide (LPS) 24 h before thefirst CRS and performed 6 h daily for 28 days. Behavioral tests were conducted 24 h after the last CRS, across 4 days, and euthanasia followed 24 h after the final tests. Results indicated that only the LPS + CRS group exhibited depressive- and anxiety-like behaviors, accompanied by demotivation and apathy. Biochemical and molecular analyses revealed anoxidative imbalance in the hippocampus, marked by elevated H2O2 levels and MPO activity. In the prefrontal cortex, theLPS + CRS group demonstrated a central inflammatory imbalance, with reduced IL-10 levels, increased Iba1 gene expression, and decreased Gfap and Bdnf gene expression. A trend toward elevated IL-17 levels was also observed at the peripheral level. These findings indicate that inflammatory preconditioning contributes significantly to behaviors phenotypically associated with MDD. Furthermore, the study suggests that these behavioral changes are linked to a dysfunctional immune response and impaired neuroplasticity.

A systematic review and meta-analysis of pteridines in mild cognitive impairment and Alzheimer's disease

BACKGROUND

Alterations in specific pteridine metabolites, particularly neopterin, biopterin, and tetrahydrobiopterin have been reported in mild cognitive impairment, Alzheimer's disease, and other types of dementia. However, the available evidence regarding such alterations has not been comprehensively and critically appraised.

METHODS

We systematically reviewed studies reporting the concentrations of biopterin, tetrahydrobiopterin, and neopterin in different biological fluids in patients with mild cognitive impairment, Alzheimer's disease or other types of dementia, and healthy controls. Electronic databases were searched from inception to 29 February 2024.

RESULTS

Overall, there were no significant differences in plasma/serum concentrations of neopterin between patients with mild cognitive impairment, Alzheimer's disease, or other types of dementia, when grouped together, and healthy controls after adjusting for publication bias (11 studies, standard mean difference, SMD = 0.20, 95% CI -0.02 to 0.41, p = 0.076). In meta-regression and subgroup analysis, the effect size was significantly associated with age, number of participants, study continent, presence of mild cognitive impairment, presence of Alzheimer's disease, analytical method, and assessment of serum vs. plasma. One study reported higher urine neopterin in patients with Alzheimer's disease vs. controls whereas another study reported non-significant between-group differences in cerebrospinal neopterin. The cerebrospinal fluid concentrations of biopterin were significantly lower in patients with Alzheimer's disease vs. controls (two studies, SMD = -0.75, 95% CI -1.23 to -0.27, p = 0.002; I2 = 0.0%, p = 0.46). One study showed non-significant between-group differences in plasma biopterin whereas another study showed higher concentrations of urine biopterin in patients with Alzheimer's disease. Our search did not identify studies investigating tetrahydrobiopterin.

CONCLUSION

Our study showed no significant differences in circulating neopterin between patients with mild cognitive impairment, Alzheimer's disease, or other types of dementia, when grouped together, and healthy controls. The significant associations observed between the effect size and mild cognitive impairment and Alzheimer's disease in subgroup analysis warrant further investigation. (PROSPERO registration number: CRD42024523478).