Inflammation, insulin resistance and neuroprogression in depression

Depression and type 2 diabetes: A causal relationship and mechanistic pathway

Depression is a mood disorder that may increase risk for the development of insulin resistance (IR) and type 2 diabetes (T2D), and vice versa. However, the mechanistic pathway linking depression and T2D is not fully elucidated. The aim of this narrative review, therefore, was to discuss the possible link between depression and T2D. The coexistence of T2D and depression is twice as great compared to the occurrence of either condition independently. Hyperglycaemia and dyslipidaemia promote the incidence of depression by enhancing inflammation and reducing brain serotonin (5-hydroxytryptamine [5HT]). Dysregulation of insulin signalling in T2D impairs brain 5HT signalling, leading to the development of depression. Furthermore, depression is associated with the development of hyperglycaemia and poor glycaemic control. Psychological stress and depression promote the development of T2D. In conclusion, T2D could be a potential risk factor for the development of depression through the induction of inflammatory reactions and oxidative stress that affect brain neurotransmission. In addition, chronic stress in depression may induce the development of T2D through dysregulation of the hypothalamic-pituitary-adrenal axis and increase circulating cortisol levels, which triggers IR and T2D.

Association between the triglyceride glucose index and depression: a meta-analysis

Background

Obesity and diabetes have been associated with depressive symptoms. The aim of this systematic review and meta-analysis was to evaluate the association between the triglyceride glucose index (TyG index) a novel indicator of insulin resistance (IR) and depression in the adult population.

Methods

Relevant observational studies were acquired through comprehensive searches of the Medline, Web of Science, Embase, Wanfang, and China National Knowledge Internet databases. To account for heterogeneity, a random-effects model was employed to combine the findings. Additionally, multiple subgroup analyses were conducted to assess the impact of various study characteristics on the outcome.

Results

The meta-analysis comprised eight datasets from six cross-sectional studies, encompassing a total of 28,973 adults. The pooled findings suggested that subjects with a high TyG index, compared to those with a low TyG index, were associated with a higher prevalence of depression (odds ratio [OR]: 1.41, 95% confidence interval (CI): 1.28-1.56, p<0.001; I2 = 19%). Sensitivity analyses, by omitting one dataset at a time, showed consistent results (OR: 1.39-1.45, p<0.05). Further subgroup analyses showed consistent results in participants aged <50 years old and in those aged ≥50 years old, in men and in women, in studies with different cutoff values for the TyG index, and in studies with different methods for the diagnosis of depression (for each subgroup difference, p>0.05).

Conclusion

A high TyG index may be associated with a higher prevalence of depression in the adult population.

Gut bacteriome and mood disorders in women with PCOS

STUDY QUESTION

How does the gut bacteriome differ based on mood disorders (MDs) in women with polycystic ovary syndrome (PCOS), and how can the gut bacteriome contribute to the associations between these two conditions?

SUMMARY ANSWER

Women with PCOS who also have MDs exhibited a distinct gut bacteriome with reduced alpha diversity and a significantly lower abundance of Butyricicoccus compared to women with PCOS but without MDs.

WHAT IS KNOWN ALREADY

Women with PCOS have a 4- to 5-fold higher risk of having MDs compared to women without PCOS. The gut bacteriome has been suggested to influence the pathophysiology of both PCOS and MDs.

STUDY DESIGN, SIZE, DURATION

This population-based cohort study was derived from the Northern Finland Birth Cohort 1966 (NFBC1966), which includes all women born in Northern Finland in 1966. Women with PCOS who donated a stool sample at age 46 years (n = 102) and two BMI-matched controls for each case (n = 205), who also responded properly to the MD criteria scales, were included.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 102 women with PCOS and 205 age- and BMI-matched women without PCOS were included. Based on the validated MD criteria, the subjects were categorized into MD or no-MD groups, resulting in the following subgroups: PCOS no-MD (n = 84), PCOS MD (n = 18), control no-MD (n = 180), and control MD (n = 25). Clinical characteristics were assessed at age 31 years and age 46 years, and stool samples were collected from the women at age 46 years, followed by the gut bacteriome analysis using 16 s rRNA sequencing. Alpha diversity was assessed using observed features and Shannon's index, with a focus on genera, and beta diversity was characterized using principal components analysis (PCA) with Bray-Curtis Dissimilarity at the genus level. Associations between the gut bacteriome and PCOS-related clinical features were explored by Spearman's correlation coefficient. A P-value for multiple testing was adjusted with the Benjamini-Hochberg false discovery rate (FDR) method.

MAIN RESULTS AND THE ROLE OF CHANCE

We observed changes in the gut bacteriome associated with MDs, irrespective of whether the women also had PCOS. Similarly, PCOS MD cases showed a lower alpha diversity (Observed feature, PCOS no-MD, median 272; PCOS MD, median 208, FDR = 0.01; Shannon, PCOS no-MD, median 5.95; PCOS MD, median 5.57, FDR = 0.01) but also a lower abundance of Butyricicoccus (log-fold changeAnalysis of Compositions of Microbiomes with Bias Correction (ANCOM-BC)=-0.90, FDRANCOM-BC=0.04) compared to PCOS no-MD cases. In contrast, in the controls, the gut bacteriome did not differ based on MDs. Furthermore, in the PCOS group, Sutterella showed positive correlations with PCOS-related clinical parameters linked to obesity (BMI, r2=0.31, FDR = 0.01; waist circumference, r2=0.29, FDR = 0.02), glucose metabolism (fasting glucose, r2=0.46, FDR < 0.001; fasting insulin, r2=0.24, FDR = 0.05), and gut barrier integrity (zonulin, r2=0.25, FDR = 0.03).

LIMITATIONS, REASONS FOR CAUTION

Although this was the first study to assess the link between the gut bacteriome and MDs in PCOS and included the largest PCOS dataset for the gut microbiome analysis, the number of subjects stratified by the presence of MDs was limited when contrasted with previous studies that focused on MDs in a non-selected population.

WIDER IMPLICATIONS OF THE FINDINGS

The main finding is that gut bacteriome is associated with MDs irrespective of the PCOS status, but PCOS may also modulate further the connection between the gut bacteriome and MDs.

STUDY FUNDING/COMPETING INTEREST(S)

This research was funded by the European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement (MATER, No. 813707), the Academy of Finland (project grants 315921, 321763, 336449), the Sigrid Jusélius Foundation, Novo Nordisk Foundation (NNF21OC0070372), grant numbers PID2021-12728OB-100 (Endo-Map) and CNS2022-135999 (ROSY) funded by MCIN/AEI/10.13039/501100011033 and ERFD A Way of Making Europe. The study was also supported by EU QLG1-CT-2000-01643 (EUROBLCS) (E51560), NorFA (731, 20056, 30167), USA/NIH 2000 G DF682 (50945), the Estonian Research Council (PRG1076, PRG1414), EMBO Installation (3573), and Horizon 2020 Innovation Grant (ERIN, No. EU952516). The funders did not participate in any process of the study. We have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Efficacy and Safety of Antidiabetic Agents for Major Depressive Disorder and Bipolar Depression: A Meta-Analysis of Randomized, Double-Blind, Placebo-Controlled Trials

BACKGROUND

This meta-analysis aimed to determine the efficacy and safety of antidiabetic agents in the treatment of major depressive disorder and bipolar depression.

METHODS

Randomized controlled trials (RCTs) of antidiabetic agents in major depressive disorder or bipolar depression were searched in three electronic databases and three clinical trial registry websites from their inception up to October 2023. The differences in changes in the depression rating scale scores from baseline to endpoint or pre-defined sessions, response rate, remission rate, rate of side effects and dropout rate between antidiabetic agents and placebo were meta-analyzed.

RESULTS

Six RCTs involving 399 participants were included in the final meta-analysis, which did not find that antidiabetics outperformed the placebo in reducing depressive symptoms. The standardized mean difference (SMD) in the depression scores from baseline to endpoint was 0.25 (95% CI -0.1, 0.61). However, a subgroup analysis found a significant difference between antidiabetics and placebos in reducing depressive symptoms in Middle Eastern populations, with an SMD of 0.89 (95% CI 0.44, 1.34).

CONCLUSIONS

The current meta-analysis does not support the efficacy of antidiabetics being superior to the placebo in the treatment of unipolar and bipolar depression. However, a subgroup analysis indicates that patients from the Middle East may benefit from adding an antidiabetic medication to their ongoing medication(s) for their depression. Larger studies with good-quality study designs are warranted.

Trajectories and associations of symptoms of mental health and well-being with insulin resistance and metabolic health in women with gestational diabetes

BACKGROUND

Gestational diabetes mellitus (GDM) is characterized by increased insulin resistance and carries perinatal and long-term risks for the mother and her offspring. There is a link between perinatal depression or anxiety and GDM. Mental health problems are associated with higher insulin resistance and could explain the underlying association between GDM and depression or anxiety symptoms. We investigated the trajectories and associations between symptoms of mental health and well-being with insulin resistance and metabolic health in women with GDM.

METHODS

This study included the control group (n = 106) of a randomized controlled trial in women with GDM that were followed-up during pregnancy and up to 1-year postpartum. We measured symptoms of mental health (Edinburgh Postnatal Depression Scale (EPDS), Anxiety subscale of the Hospital Anxiety and Depression Scale (HADS-A), well-being (The World Health Organization Well-Being Index (WHO-5)) and metabolic health, including insulin resistance variables (HOMA-insulin resistance (IR) and Matsuda Index of insulin sensitivity) as well as weight during pregnancy and in the postpartum.

RESULTS

Participants' pre pregnancy weight and BMI were 69.7 kg ± 16.1 and 25.9 kg/m2 ± 5.5 respectively. HOMA-IR was higher during pregnancy compared to 6-8 weeks postpartum and increased between 6-8 weeks and 1-year postpartum (all p < 0.05). Matsuda index decreased between 6-8 weeks and 1-year postpartum (p < 0.001). EPDS scores decreased between pregnancy and both 6-8 weeks and 1-year postpartum (all p < 0.05). HADS-A scores did not change between pregnancy and the postpartum. WHO-5 scores improved significantly from pregnancy and both 6-8 weeks and 1-year postpartum (p < 0.001). Correlation coefficients within outcome at the three different time points were high for metabolic measures and ranged between 0.94 and 0.96 for weight, from 0.77 to 0.89 for HOMA-IR and 0.64 for the Matsuda index (all p < 0.001). Mental health and well-being variables were moderately correlated in all three time points including r = 0.36-0.55 for the EPDS (p < 0.001), r = 0.58 for HADS (p < 0.001), and r = 0.43-0.52 for the WHO-5 (p < 0.01). After adjustment for age and pre-pregnancy BMI, Matsuda index was negatively associated with EPDS scores and positively associated to WHO-5 scores at 6-8 weeks postpartum. No other association between insulin resistance and mental health or well-being outcomes were found.

CONCLUSION

While insulin resistance fluctuated with values being lowest in the early postpartum and increasing thereafter, both depression and well-being scores decreased between pregnancy and the postpartum and did not change in the postpartum period. Intraindividual variability was larger for mental health and well-being than for metabolic health outcomes at different time points, indicating a higher plasticity for mental health and well-being outcomes that could be acted upon. We found only few associations between mental health and well-being and metabolic health outcomes.

Interplay of G-proteins and Serotonin in the Neuroimmunoinflammatory Model of Chronic Stress and Depression: A Narrative Review

INTRODUCTION

This narrative review addresses the clinical challenges in stress-related disorders such as depression, focusing on the interplay between neuron-specific and pro-inflammatory mechanisms at the cellular, cerebral, and systemic levels.

OBJECTIVE

We aim to elucidate the molecular mechanisms linking chronic psychological stress with low-grade neuroinflammation in key brain regions, particularly focusing on the roles of G proteins and serotonin (5-HT) receptors.

METHODS

This comprehensive review of the literature employs systematic, narrative, and scoping review methodologies, combined with systemic approaches to general pathology. It synthesizes current research on shared signaling pathways involved in stress responses and neuroinflammation, including calcium-dependent mechanisms, mitogen-activated protein kinases, and key transcription factors like NF-κB and p53. The review also focuses on the role of G protein-coupled neurotransmitter receptors (GPCRs) in immune and pro-inflammatory responses, with a detailed analysis of how 13 of 14 types of human 5-HT receptors contribute to depression and neuroinflammation.

RESULTS

The review reveals a complex interaction between neurotransmitter signals and immunoinflammatory responses in stress-related pathologies. It highlights the role of GPCRs and canonical inflammatory mediators in influencing both pathological and physiological processes in nervous tissue.

CONCLUSION

The proposed Neuroimmunoinflammatory Stress Model (NIIS Model) suggests that proinflammatory signaling pathways, mediated by metabotropic and ionotropic neurotransmitter receptors, are crucial for maintaining neuronal homeostasis. Chronic mental stress can disrupt this balance, leading to increased pro-inflammatory states in the brain and contributing to neuropsychiatric and psychosomatic disorders, including depression. This model integrates traditional theories on depression pathogenesis, offering a comprehensive understanding of the multifaceted nature of the condition.

A review on linking stress, depression, and insulin resistance via low-grade chronic inflammation

Stress is a disturbance in homeostasis caused by psychological, physiological, or environmental factors. Prolonged reactions to chronic stress can be detrimental, resulting in various metabolic abnormalities, referred to as metabolic syndrome (MS). There is a reciprocal increased risk between MS and major depressive disorder. Recent studies established an association between inflammation and insulin signaling in type 2 diabetes mellitus with depression. In the present review, we discuss chronic low-grade inflammation, pathways of insulin resistance, and brain glucose metabolism in the context of neuroinflammation and depression. Specific attention is given to psychotropic drugs such as bupropion, mirtazapine, and nefazodone, anti-inflammatory drugs like Celecoxib (COX-2 inhibitor), Etanercept, adalimumab, IL-4Ra antagonist, Anti-IL- 17A antibody (Ixekizumab) and lifestyle modifications including exercise, dietary changes, and sleep hygiene. These therapeutic solutions offer potential in treating depression by targeting metabolic conditions like insulin resistance and inflammatory pathways. The article further explains the significance of a nutrition and antioxidants-rich diet, emphasizing the role of omega-3 fatty acids, vitamin D, zinc, and polyphenols, to improve immunity and activate anti-inflammatory signaling pathways.

The association between insulin resistance and depressive symptoms - A national representative cross-sectional study

OBJECTIVE

Increasing evidence suggests a positive association between insulin resistance (IR) and depression. However, whether sex-or body mass index-specific differences exist remains controversial, and only few studies have analyzed specific symptom domains. Thus, the present study aimed to analyze the association between IR and depressive symptom domains and to clarify the effects of sex and body mass index.

METHODS

The study sample comprised 4007 participants, aged 19-79, from the Korea National Health and Nutrition Examination Study 2020. Participants completed health interviews and examinations, providing data on circulating insulin and glucose levels, the Patient Health Questionnaire-9 (PHQ-9), and related covariates. IR was calculated using the homeostasis model assessment of insulin resistance. Associations between IR and PHQ-9 were analyzed using negative binomial regression with adjustments for the complex survey design.

RESULTS

The association between log-transformed IR and PHQ-9 total scores was statistically significant (incidence rate ratio [IRR] = 1.17, 95% confidence interval [CI] = 1.07-1.29, p = 0.001). Only body mass index specific differences were statistically significant, as the association was only significant in those without obesity (IRR = 1.21, 95% CI = 1.06-1.38, p = 0.005). IR was associated with cognitive/affective (IRR = 1.23, 95% CI = 1.08-1.41, p = 0.002) and somatic (IRR = 1.14, 95% CI = 1.04-1.25, p = 0.005) depressive symptom domains. Sensitivity analyses revealed similar results.

CONCLUSIONS

IR was positively associated with cognitive/affective and somatic depressive symptoms in non-obese individuals.

Pharmacogenetics of angiotensin modulators according to APOE-ϵ4 alleles and the ACE insertion/deletion polymorphism in Alzheimer's disease

OBJECTIVE

In Alzheimer's disease (AD), angiotensin II receptor blockers (ARBs) could reduce cerebrovascular dysfunction, while angiotensin-converting enzyme inhibitors (ACEis) might increase brain amyloid-β by suppressing effects of the angiotensin-converting enzyme 1, an amyloid-β-degrading enzyme. However, ACEis could benefit patients with AD by reducing the amyloidogenic processing of the amyloid precursor protein, by central cholinergic and anti-inflammatory mechanisms, and by peripheral modulation of glucose homeostasis. We aimed to investigate whether the ACE insertion/deletion polymorphism is associated with clinical changes in patients with AD, while considering apolipoprotein E (APOE)-ϵ4 carrier status and blood pressure response to angiotensin modulators.

METHODS

Consecutive outpatients with late-onset AD were screened with cognitive tests and anthropometric measurements, while their caregivers were queried for functional and caregiver burden scores. Prospective pharmacogenetic associations were estimated for 1 year, taking APOE-ϵ4 carrier status and genotypes of the ACE insertion/deletion polymorphism into account, along with treatment with ACEis or ARBs.

RESULTS

For 193 patients (67.4% women, 53.4% APOE-ϵ4 carriers), the ACE insertion/deletion polymorphism was in Hardy-Weinberg equilibrium (p = 0.281), while arterial hypertension was prevalent in 80.3% (n = 124 used an ACEi, n = 21 used an ARB). ARBs benefitted mostly APOE-ϵ4 carriers concerning caregiver burden variations, cognitive and functional decline. ACEis benefitted APOE-ϵ4 non-carriers concerning cognitive and functional decline due to improved blood pressure control in addition to possible central mechanisms. The ACE insertion/deletion polymorphism led to variable response to angiotensin modulators concerning neurological outcomes and blood pressure variations.

CONCLUSION

Angiotensin modulators may be disease-modifiers in AD, while genetic stratification of samples is recommended in clinical studies.

Insulinemic potential of diet and psychological disorders: A cross-sectional, population-based study

BACKGROUND

Serum insulin levels and insulin sensitivity can impact mental disorders. This study investigates the association of the insulinemic potential of diet calculated using the empirical dietary indices for insulin resistance (EDIR) and hyperinsulinemia (EDIH) with psychological disorders, including depression, anxiety, and stress.

METHODS

This cross-sectional study was undertaken on 5405 individuals, aged 20-70, from the Yazd Health Study (YaHS). The food frequency questionnaire (FFQ) was used to collect dietary intakes. EDIR and EDIH were calculated from the FFQ data. Psychological disorders were assessed by an Iranian-validated version of the depression, anxiety, and stress scale questionnaire 21 (DASS 21). Multivariable logistic regression analysis was performed and odds ratio (OR) and 95 % confidence interval (CI) were reported.

RESULTS

The mean ± SD of EDIR and EDIH were 0.32 ± 0.17 and 0.11 ± 0.08 in the total population, respectively. In the final adjusted model, participants in the highest versus the lowest quartile of EDIR had statistically higher odds of depression (OR: 1.28; 95 % CI: 1.01-1.62, P-trend = 0.032). However, no statistically significant association was observed between the EDIH score and depression. Also, EDIR and EDIH scores were not significantly associated with the odds of anxiety and stress.

LIMITATIONS

The cross-sectional design of the study prevented the inference of causality.

CONCLUSIONS

Higher adherence to EDIR was positively associated with depression, but there was no significant association between EDIH and depression. EDIR and EDIH were also not significantly related to anxiety or stress.

Pterostilbene ameliorates type-2 diabetes mellitus - Induced depressive-like behavior by mitigating insulin resistance, inflammation and ameliorating HPA axis dysfunction in rat brain

One of the most serious mental health comorbidities associated with diabetes mellitus is depression. The occurrence is almost double in type 2 diabetes mellitus (T2DM) compared with the general population. Pterostilbene (PTE), a dimethylated analog of resveratrol, has been reported for significant neuroprotective, anti-inflammatory, hypolipidemic, hypoglycaemic and antioxidant effects. However, its effect on diabetes-induced depression-like behavior (DID) has not been studied. The current study aimed at studying the effects of PTE on depressive-like behavior in male Wistar rats with T2DM. It was induced by single dose administration of nicotinamide (NA) and streptozotocin (STZ). On day 21, forced swim test (FST) was conducted for the confirmation of DID. Rats demonstrating depressive-like behavior were treated with PTE (10, 20 and 40 mg/kg), metformin (MET; 500 mg/kg) and fluoxetine (FLX; 10 mg/kg) for 28 days, orally. At the end of the treatment, behavioral assessment for depression, blood glucose (BG) and lipid profile, oxidative stress markers, gene expression of Sirtuin 1 (SIRT1) and histopathological parameters were investigated. PTE significantly reduced weight loss and mitigated depressive-like behavior paradigms such as sucrose preference test (SPT), resident intruder test (RIT) and open field test (OFT). It significantly restored BG, lipid and liver profile, creatinine and antioxidant level. It Improved glucose tolerance, insulin resistance (IR) and reduced cortisol level as well as inflammatory markers. It showed improved morphology of the pancreas, brain, liver and kidney. Gene expression studies revealed that, PTE significantly increased SIRT1 expression. PTE by its virtue to maintain BG, reduced IR, amelioration of the HPA axis, anti-inflammatory, antioxidant activity and improvement of SIRT1 gene expression proved to be effective in the treatment of DID-like behavior in rats.

Neuroinflammation: A Modifiable Pathway Linking Obesity, Alzheimer's disease, and Depression

Obesity, depression and Alzheimer's disease (AD) are three major interrelated modern health conditions with complex relationships. Early-life depression may serve as a risk factor for AD, while late-life depression may be a prodrome of AD. Depression affects approximately 23% of obese individuals, and depression itself raises the risk of obesity by 37%. Mid-life obesity independently increases AD risk, while late-life obesity, particularly metabolically healthy obesity, may offer protection against AD pathology. Chronic inflammation serves as a key mechanism linking obesity, AD, and depression, encompassing systemic inflammation from metabolic disturbances, immune dysregulation through the gut microbiome, and direct interactions with amyloid pathology and neuroinflammation. In this review, we explore the biological mechanisms of neuroinflammation in relation to obesity, AD, and depression. We assess the efficacy of therapeutic interventions targeting neuroinflammation and discuss current and future radiological imaging initiatives for studying neuroinflammation. By comprehending the intricate interplay among depression, obesity, and AD, especially the role of neuroinflammation, we can advance our understanding and develop innovative strategies for prevention and treatment.

The impact of maternal diabetes on the future health and neurodevelopment of the offspring: a review of the evidence

Maternal health during gestational period is undoubtedly critical in shaping optimal fetal development and future health of the offspring. Gestational diabetes mellitus is a metabolic disorder occurring in pregnancy with an alarming increasing incidence worldwide during recent years. Over the years, there is a growing body of evidence that uncontrolled maternal hyperglycaemia during pregnancy can potentially have detrimental effect on the neurodevelopment of the offspring. Both human and animal data have linked maternal diabetes with motor and cognitive impairment, as well as autism spectrum disorders, attention deficit hyperactivity disorder, learning abilities and psychiatric disorders. This review presents the available data from current literature investigating the relationship between maternal diabetes and offspring neurodevelopmental impairment. Moreover, possible mechanisms accounting for the detrimental effects of maternal diabetes on fetal brain like fetal neuroinflammation, iron deficiency, epigenetic alterations, disordered lipid metabolism and structural brain abnormalities are also highlighted. On the basis of the evidence demonstrated in the literature, it is mandatory that hyperglycaemia during pregnancy will be optimally controlled and the impact of maternal diabetes on offspring neurodevelopment will be more thoroughly investigated.

Depression and macrophages: A bibliometric and visual analysis from 2000 to 2022

BACKGROUND

Macrophages are closely related to the occurrence and development of depression, but there are few bibliometric studies on the role of macrophages in depression. We aim to examine the current state and frontier trends of the research on macrophages in depression from 2000 to 2022 in this study, so as to establish a new direction for follow-up research.

METHODS

The literature scan covering the period 2000 to 2022 was performed on macrophages in depression, which were analyzed with Citespace 6.1.R2 and VOSviewer 1.6.18 after manual screening, including country publications, institutions, authors, journals, keywords, and references.

RESULTS

This study included 387 papers in total. There has been an increase in the number of published papers since 2009. In terms of productivity, the United States and Ohio State University are the most productive countries and institutions. The most cited author is Maes M, cited 173 times, which has made a great contribution to the study of macrophages in depression. In terms of publications, Pariante CM, Drexhage HA. have the largest number, each author with five. Brain Behavior and Immunity is the most published and cited journals. The highest burst intensity keyword is microglia, and the highest burst intensity reference is Dowlati Y, 2010.

CONCLUSION

Research hotspots and trends are analyzed and predicted in this study, which will facilitate the development of macrophage research in depression, so as to provide a reference for further research in this field.

Outcomes and clinical implications of intranasal insulin on cognition in humans: A systematic review and meta-analysis

BACKGROUND

Aberrant brain insulin signaling has been posited to lie at the crossroads of several metabolic and cognitive disorders. Intranasal insulin (INI) is a non-invasive approach that allows investigation and modulation of insulin signaling in the brain while limiting peripheral side effects.

OBJECTIVES

The objective of this systematic review and meta-analysis is to evaluate the effects of INI on cognition in diverse patient populations and healthy individuals.

METHODS

MEDLINE, EMBASE, PsycINFO, and Cochrane CENTRAL were systematically searched from 2000 to July 2021. Eligible studies were randomized controlled trials that studied the effects of INI on cognition. Two independent reviewers determined study eligibility and extracted relevant descriptive and outcome data.

RESULTS

Twenty-nine studies (pooled N = 1,726) in healthy individuals as well as those with Alzheimer's disease (AD)/mild cognitive impairment (MCI), mental health disorders, metabolic disorders, among others, were included in the quantitative meta-analysis. Patients with AD/MCI treated with INI were more likely to show an improvement in global cognition (SMD = 0.22, 95% CI: 0.05-0.38 p = <0.00001, N = 12 studies). Among studies with healthy individuals and other patient populations, no significant effects of INI were found for global cognition.

CONCLUSIONS

This review demonstrates that INI may be associated with pro-cognitive benefits for global cognition, specifically for individuals with AD/MCI. Further studies are required to better understand the neurobiological mechanisms and differences in etiology to dissect the intrinsic and extrinsic factors contributing to the treatment response of INI.

Association of triglyceride-glucose index with major depressive disorder: A cross-sectional study

The triglyceride-glucose (TyG) index has been proposed as a new marker for insulin resistance, which is associated with a risk of major depressive disorder (MDD). This study aims to explore whether the TyG index is correlated with MDD. In total, 321 patients with MDD and 325 non-MDD patients were included in the study. The presence of MDD was identified by trained clinical psychiatrists using the International Classification of Diseases 10th Revision. The TyG index was calculated as follows: Ln (fasting triglyceride [mg/dL] × fasting glucose [mg/dL]/2). The results revealed that the MDD group presented higher TyG index values than the non-MDD group (8.77 [8.34-9.17] vs 8.62 [8.18-9.01], P < .001). We also found significantly higher morbidity of MDD in the highest TyG index group than in the lower TyG index group (59.9% vs 41.4%, P < .001). Binary logistic regression revealed that TyG was an independent risk factor for MDD (odds ratio [OR] 1.750, 95% confidence interval: 1.284-2.384, P < .001). We further assessed the effect of TyG on depression in sex subgroups. The OR was 3.872 (OR 2.014, 95% confidence interval: 1.282-3.164, P = .002) for the subgroup of men. It is suggested that the TyG index could be closely associated with morbidity in MDD patients; thus, it may be a valuable marker for identifying MDD.

Integrated transcriptome and metabolome analysis to investigate the mechanism of intranasal insulin treatment in a rat model of vascular dementia

Introduction: Insulin has an effect on neurodegenerative diseases. However, the role and mechanism of insulin in vascular dementia (VD) and its underlying mechanism are unknown. In this study, we aimed to investigate the effects and mechanism of insulin on VD. Methods: Experimental rats were randomly assigned to control (CK), Sham, VD, and insulin (INS) + VD groups. Insulin was administered by intranasal spray. Cognitive function was evaluated using the Morris's water maze. Nissl's staining and immunohistochemical staining were used to assess morphological alterations. Apoptosis was evaluated using TUNEL-staining. Transcriptome and metabolome analyses were performed to identify differentially expressed genes (DEGs) and differentially expressed metabolites (DEMs), respectively. Results: Insulin significantly improved cognitive and memory functions in VD model rats (p < 0.05). Compared with the VD group, the insulin + VD group exhibited significantly reduced the number of Nissl's bodies numbers, apoptosis level, GFAP-positive cell numbers, apoptosis rates, and p-tau and tau levels in the hippocampal CA1 region (p < 0.05). Transcriptomic analysis found 1,257 and 938 DEGs in the VD vs. CK and insulin + VD vs. VD comparisons, respectively. The DEGs were mainly enriched in calcium signaling, cAMP signaling, axon guidance, and glutamatergic synapse signaling pathways. In addition, metabolomic analysis identified 1 and 14 DEMs between groups in negative and positive modes, respectively. KEGG pathway analysis indicated that DEGs and DEMs were mostly enriched in metabolic pathway. Conclusion: Insulin could effectively improve cognitive function in VD model rats by downregulating tau and p-tau expression, inhibiting astrocyte inflammation and neuron apoptosis, and regulating genes involved in calcium signaling, cAMP signaling, axon guidance, and glutamatergic synapse pathways, as well as metabolites involved in metabolic pathway.

The association between type 2 diabetes and attention- deficit/hyperactivity disorder: A systematic review, meta-analysis, and population-based sibling study

We conducted a systematic review and a meta-analysis to quantitatively summarize evidence on the association between attention-deficit/hyperactivity disorder (ADHD) and type 2 diabetes (T2D). Moreover, a register-based sibling study was conducted to simultaneously control for confounding factors. A systematic search identified four eligible observational studies (N = 5738,287). The meta-analysis showed that individuals with ADHD have a more than doubled risk of T2D when considering adjusted estimates (OR=2.29 [1.48-3.55], d=0.46). Results from the register-based Swedish data showed a significant association between ADHD and T2D (HR=2.35 [2.14-2.58]), with substance use disorder, depression, and anxiety being the main drivers of the association, and cardiovascular and familiar risk playing a smaller role. While results from the meta-analysis provide evidence for an increased risk of T2D in individuals with ADHD, the register-based analyses show that the association between ADHD and T2D is largely explained by psychiatric comorbidities. Pending further evidence of causal association, our findings suggest that early identification and treatment of ADHD comorbidities might greatly reduce the risk of developing T2D in individuals with ADHD.

Association between impaired glucose metabolism and long-term prognosis at the time of diagnosis of depression: Impaired glucose metabolism as a promising biomarker proposed through a machine-learning approach

BACKGROUND

Predicting the course of depression is necessary for personalized treatment. Impaired glucose metabolism (IGM) was introduced as a promising depression biomarker, but no consensus was made. This study aimed to predict IGM at the time of depression diagnosis and examine the relationship between long-term prognosis and predicted results.

METHODS

Clinical data were extracted from four electronic health records in South Korea. The study population included patients with depression, and the outcome was IGM within 1 year. One database was used to develop the model using three algorithms. External validation was performed using the best algorithm across the three databases. The area under the curve (AUC) was calculated to determine the model's performance. Kaplan-Meier and Cox survival analyses of the risk of hospitalization for depression as the long-term outcome were performed. A meta-analysis of the long-term outcome was performed across the four databases.

RESULTS

A prediction model was developed using the data of 3,668 people, with an AUC of 0.781 with least absolute shrinkage and selection operator (LASSO) logistic regression. In the external validation, the AUCs were 0.643, 0.610, and 0.515. Through the predicted results, survival analysis and meta-analysis were performed; the hazard ratios of risk of hospitalization for depression in patients predicted to have IGM was 1.20 (95% confidence interval [CI] 1.02-1.41, p = 0.027) at a 3-year follow-up.

CONCLUSIONS

We developed prediction models for IGM occurrence within a year. The predicted results were related to the long-term prognosis of depression, presenting as a promising IGM biomarker related to the prognosis of depression.

The association between dietary inflammation index and depression

Objective

We aimed to evaluate whether depression is associated with increased risk of dietary inflammatory index (DII) or energy-adjusted DII (E-DII) and whether the association is partly explained by insulin resistance (IR).

Methods

Base on the National Health and Nutrition Examination Survey (NHANES) 2005-2018. Univariate analyses of continuous and categorical variables were performed using t-test, ANOVA, and χ ² test, respectively. Logistic regression was used to analyze the relationship between DII or E-DII and depression in three different models. Mediation analysis was used to assess the potential mediation effects of homeostatic model assessment-IR (HOMA-IR).

Results

A total of 70,190 participants were included, and the DII score was higher in the depressed group. DII score was related to all participant characteristics except age (p < 0.05). After being included in covariates (Model 3), participants in the highest quartile of DII score have increased odds of depression (OR: 1.82, 95% CI: 1.28-2.58) compared with those in the first quartile of DII score. And, a significant dose-response relationship was found (p-trend <0.05). No interaction between DII and HOMA-IR was observed in terms of the risk of depression, and HOMA-IR did not find to play a mediating role in the association between DII and depression. Similar results were obtained for the association between E-DII and depression.

Conclusion

Our results suggest that a higher pro-inflammatory diet increases the risk of depression in U.S. adults, while there was no evidence of a multiplicative effect of DII or E-DII and HOMA-IR on disease risk, nor of a mediating effect of HOMA-IR.

Maternal Metabolites Indicative of Mental Health Status during Pregnancy

Approximately 25% of individuals report poor mental health during their pregnancy or postpartum period, which may impact fetal neurodevelopment, birth outcomes, and maternal behaviors. In the present study, maternal serum samples were collected from pregnancies at 28-32 weeks gestation from the All Our Families (Alberta, Canada) cohort and assessed using nuclear magnetic resonance spectroscopy (¹H-NMR) and inductively coupled plasma-mass spectrometry (ICP-MS). Individuals with poor mental health at 34-36 weeks gestation were age-matched with mentally healthy pregnant controls. Metabolites were examined against validated self-reported mental health questionnaires for associations with depressive symptoms (Edinburgh Perinatal Depression Scale) and anxiety symptoms (Spielberger State-Trait Anxiety Inventory). ¹H-NMR metabolites were identified for depression (alanine, leucine, valine, methionine, phenylalanine, glucose, lactate, 3-hydroxybutyrate, and pyruvate) and anxiety (3-hydroxybutyrate). For ICP-MS, antimony and zinc were significant for depression and anxiety, respectively. Upon false discovery rate (FDR) correction at 10%, five ¹H-NMR metabolites (alanine, leucine, lactate, glucose, and phenylalanine) for depression remained significantly increased. Although results warrant further validation, the identified metabolites may serve as a predictive tool for assessing mental health during pregnancy as earlier identification has the potential to aid intervention and management of poor mental health symptomology, thus avoiding harmful consequences to both mother and offspring.

Association of metformin and depression in patients with type 2 diabetes

BACKGROUND

Emerging evidence showed metformin may have pleiotropic effects on ameliorating depression. However, whether metformin was associated with decreased risk of depression remains unclear.

METHODS

A historical cohort study was conducted based on a medical claim database from 2010 to 2017 in Beijing, China. Patients newly diagnosed with T2D were classified into the metformin and non-metformin groups according to their initial antidiabetic prescription. The incidences of depression between the groups were compared using Cox proportional regression model.

RESULTS

There were 193,624 (37.4 %) and 323,930 (62.6 %) T2D patients in the metformin and non-metformin groups. The mean age was 54.9 (SD: 13.1) years and 53.9% were females. With a median follow-up of 3.2 years, 64,963 patients developed depression. The adjusted incidence of depression in the metformin group (30.6, 95 % CI: 30.1, 31.0 per 1000 person-years) was significantly lower than in the non-metformin group (39.6, 95 % CI: 39.3, 40.0 per 1000 person-years, P < 0.001). The metformin group was significantly associated with a lower risk of depression compared with the overall non-metformin group (HR: 0.77, 95% CI: 0.75, 0.78), as well as compared with α-glucosidase inhibitors (HR: 0.73, 95 % CI: 0.71, 0.74), sulfonylureas (HR: 0.84, 95 % CI: 0.82, 0.86), and glinides (HR: 0.85, 95 % CI: 0.82, 0.88), except for thiazolidinediones (HR: 0.96, 95 % CI: 0.91, 1.01). The association between metformin and lower depression risk was significant in all the age and sex subgroups.

CONCLUSIONS

Metformin was associated with a lower risk of depression compared with other oral hypoglycemic agents, indicating a potential pleiotropic effect on depression.

Changes in insulin resistance following antidepressant treatment mediate response in major depressive disorder

BACKGROUND

Insulin resistance (IR) is a potential predictor of antidepressant treatment response.

AIMS

We assess changes in IR after antidepressant treatment and whether these changes have any effect on treatment response. Also, to see whether changes in IR mediates relationship between C-reactive protein (CRP) and antidepressant efficacy.

METHODS

This is a secondary analysis of an 8-week, open-label clinical trial with 95 adults experiencing a major depressive episode. Response to vortioxetine was measured using the Montgomery-Åsberg Depression Rating Scale (MADRS). Generalized estimating equation models were utilized for this intent-to-treat analysis.

RESULTS

When adjusted for age, sex, and body mass index, there was a significant increase in IR following treatment in the overall sample (p = 0.035). This finding was detected in treatment non-responders (p = 0.019), whereas it was not observed in responders (p = 0.329). Mediation analysis revealed that change in IR during treatment was responsible for change in MADRS as well as the relationship between baseline CRP and treatment response.

CONCLUSIONS

Exacerbation of IR during antidepressant treatment mediated non-response. Conversely in treatment responders IR reduced. Like previous studies, baseline CRP moderated treatment response. This relationship was also mediated by changes in IR. These findings further elucidate the role of IR in terms of antidepressant response as well as potentially explain inflammation's relationship with the latter.

The Effects of Dietary Advanced Glycation End-Products on Neurocognitive and Mental Disorders

Advanced glycation end products (AGEs) are glycated proteins or lipids formed endogenously in the human body or consumed through diet. Ultra-processed foods and some culinary techniques, such as dry cooking methods, represent the main sources and drivers of dietary AGEs. Tissue accumulation of AGEs has been associated with cellular aging and implicated in various age-related diseases, including type-2 diabetes and cardiovascular disease. The current review summarizes the literature examining the associations between AGEs and neurocognitive and mental health disorders. Studies indicate that elevated circulating AGEs are cross-sectionally associated with poorer cognitive function and longitudinally increase the risk of developing dementia. Additionally, preliminary studies show that higher skin AGE accumulation may be associated with mental disorders, particularly depression and schizophrenia. Potential mechanisms underpinning the effects of AGEs include elevated oxidative stress and neuroinflammation, which are both key pathogenetic mechanisms underlying neurodegeneration and mental disorders. Decreasing dietary intake of AGEs may improve neurological and mental disorder outcomes. However, more sophisticated prospective studies and analytical approaches are required to verify directionality and the extent to which AGEs represent a mediator linking unhealthy dietary patterns with cognitive and mental disorders.

Long COVID, neuropsychiatric disorders, psychotropics, present and future

Long COVID refers to the lingering symptoms which persist or appear after the acute illness. The dominant long COVID symptoms in the two years since the pandemic began (2020-2021) have been depression, anxiety, fatigue, concentration and cognitive impairments with few reports of psychosis. Whether other symptoms will appear later on is not yet known. For example, dopamine-dependent movement disorders generally take many years before first symptoms are seen. Post-stroke depression and anxiety may explain many of the early long COVID cases. Hemorrhagic, hypoxic and inflammatory damages of the central nervous system, unresolved systematic inflammation, metabolic impairment, cerebral vascular accidents such as stroke, hypoxia from pulmonary damages and fibrotic changes are among the major causes of long COVID. Glucose metabolic and hypoxic brain issues likely predispose subjects with pre-existing diabetes, cardiovascular or lung problems to long COVID as well. Preliminary data suggest that psychotropic medications may not be a danger but could instead be beneficial in combating COVID-19 infection. The same is true for diabetes medications such as metformin. Thus, a focus on sigma-1 receptor ligands and glucose metabolism is expected to be useful for new drug development as well as the repurposing of current drugs. The reported protective effects of psychotropics and antihistamines against COVID-19, the earlier reports of reduced number of sigma-1 receptors in post-mortem schizophrenic brains, with many antidepressant and antipsychotic drugs being antihistamines with significant affinity for the sigma-1 receptor, support the role of sigma and histamine receptors in neuroinflammation and viral infections. Literature and data in all these areas are accumulating at a fast rate. We reviewed and discussed the relevant and important literature.

Allostasis, Action, and Affect in Depression: Insights from the Theory of Constructed Emotion

The theory of constructed emotion is a systems neuroscience approach to understanding the nature of emotion. It is also a general theoretical framework to guide hypothesis generation for how actions and experiences are constructed as the brain continually anticipates metabolic needs and attempts to meet those needs before they arise (termed allostasis). In this review, we introduce this framework and hypothesize that allostatic dysregulation is a trans-disorder vulnerability for mental and physical illness. We then review published findings consistent with the hypothesis that several symptoms in major depressive disorder (MDD), such as fatigue, distress, context insensitivity, reward insensitivity, and motor retardation, are associated with persistent problems in energy regulation. Our approach transforms the current understanding of MDD as resulting from enhanced emotional reactivity combined with reduced cognitive control and, in doing so, offers novel hypotheses regarding the development, progression, treatment, and prevention of MDD.

Myricitrin exhibits antidepressant-like effects and reduces IL-6 hippocampal levels in the chronic mild stress model

The flavonoid myricitrin showed an antidepressant-like effect in the tail suspension test and increased hippocampal neurogenesis, as well as demonstrating anti-inflammatory effects. Interestingly, inflammation has been linked to depression, and anti-inflammatory drugs showed promising results as antidepressant-like drugs. Thus, the present study evaluated the effects of myricitrin in the chronic mild stress (CMS) model, a translational and valid animal model of depression, using the mini-experiment design to improve the reproducibility of the findings. The sucrose preference test (SPT), forced swim test (FST), and tail suspension test (TST) were the readouts of depressive-like phenotypes induced by CMS. Relative adrenal weight was employed as an index of the hypothalamus-pituitary-adrenal (HPA) axis activation. Interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha levels were measured in the hippocampus. Myricitrin (10 mg/kg, intraperitoneally, for 14 days) reversed depressive-like behaviors induced by CMS (increased immobility in the FST, the TST and anhedonia), as well as decreased adrenal hypertrophy and hippocampal levels of IL-6 in stressed mice. Similar results were observed by imipramine (20 mg/kg, intraperitoneally, for 14 days), a serotonin and norepinephrine reuptake inhibitor (positive control). A significant correlation was observed between immobility time in the TST, and hippocampal IL-6 levels. Hippocampal TNF-α levels were not affected by CMS or drug treatment. In conclusion, myricitrin exhibited an antidepressant-like profile in CMS, and this effect may be associated with its anti-inflammatory activity.

LC/ESI/TOF-MS Characterization, Anxiolytic and Antidepressant-like Effects of Mitragyna speciosa Korth Extract in Diabetic Rats

In this study, the attenuative effects of the hydro-alcoholic extract from Mitragyna speciosa (MSE) against diabetes-induced anxiety and depression-like behaviors were examined. In addition, UPLC/ESI/TOF-MS analysis was performed to identify the phytochemical nature of MSE. DM was induced using a combination of high fructose/streptozotocin, and the diabetic rats were treated with MSE (50 and 200 mg/kg) for 5 weeks. After treatment, the animals were subjected to a forced swim test, open field test and elevated plus-maze tests. Additionally, proinflammatory cytokines and oxidative stress parameters were evaluated in the brain tissues of the rats. UPLC/ESI/TOF-MS analysis revealed that MSE is abundantly rich in polyphenolic constituents, notably flavonoid and phenolic glycosides. Behavioral tests and biochemical analyses indicated that diabetic rats showed significantly increased anxiety and depressive-like behavioral deficits, brain oxidative stress and pro-inflammatory cytokines levels (IL-1β, IL-6 and TNF-α). Treatment with MSE (50 and 200 mg/kg) significantly attenuated increased blood glucose level, depressive and anxiety-like behaviors in diabetic rats. Additionally, the antioxidant enzymes activities were markedly increased in MSE-treated animals, while TNF-α, IL-1β and IL-6 cytokines were notably suppressed. Taken together, these results suggested that MSE has potentials as antidepressant and anxiolytic-like effects and improves the brain oxido-inflammatory status in diabetic rats.

The Plasma Levels of 3-Hydroxybutyrate, Dityrosine, and Other Markers of Oxidative Stress and Energy Metabolism in Major Depressive Disorder

Major depressive disorder (MDD) is a serious mental disease with a pathophysiology that is not yet fully clarified. An increasing number of studies show an association of MDD with energy metabolism alteration and the presence of oxidative stress. We aimed to evaluate plasma levels of 3-hydroxybutyrate (3HB), NADH, myeloperoxidase, and dityrosine (di-Tyr) in adolescent and adult patients with MDD, compare them with healthy age-matched controls, and assess the effect of antidepressant treatment during hospitalisation on these levels. In our study, plasmatic levels of 3HB were elevated in both adolescents (by 55%; p = 0.0004) and adults (by 88%; p < 0.0001) with MDD compared to controls. Levels of dityrosine were increased in MDD adults (by 19%; p = 0.0092) but not adolescents. We have not found any significant effect of antidepressants on the selected parameters during the short observation period. Our study supports the findings suggesting altered energy metabolism in MDD and demonstrates its presence independently of the age of the patients.

Longitudinal association between muscle strength and depression in middle-aged and older adults: A 7-year prospective cohort study in China

BACKGROUND

Evidence regarding the associations between muscle strength in different parts of the body and depression is lacking. This study examined whether poor muscle strength is associated with a higher incidence of depression in a large cohort of middle-aged and older adults.

METHODS

In total, 5,228 middle-aged and older adults from the China Health and Retirement Longitudinal Study without depression at baseline were followed for 7 years. Their demographic characteristics, chronic diseases and lifestyle behaviors were assessed. After adjusting for relevant variables, a Cox regression was used to determine the relationship between muscle strength and incident depression.

RESULTS

Over 32,544 person-years of follow-up, 1,490 participants developed depression. Low muscle strength at baseline was associated with a higher 7-year incident of depression, even after excluding those who developed depression within 2 years. After adjusting for confounding factors, it was found that a higher baseline relative handgrip strength was a protective factor against depression (HR [95% CI]=0.575 [0.430-0.768] for the lowest quartile vs. the highest quartile; p<0.001). Longer times on the 5TSTS test were a risk factor for depression (HR [95% CI]=1.321 [1.077-1.621] for the lowest quartile vs. the highest quartile; p = 0.007). When the strengths of the upper and lower limbs were considered together, the hazard ratio for depression in people with relatively greater muscle strength was 0.463 (95% CI=0.307-0.699; p<0.001).

CONCLUSIONS

Muscle strength could be predictive of depression, and the combined measurement of upper and lower limb muscle strength can improve the predictive ability.

Hormonal Regulation of Oxidative Phosphorylation in the Brain in Health and Disease

The developing and adult brain is a target organ for the vast majority of hormones produced by the body, which are able to cross the blood–brain barrier and bind to their specific receptors on neurons and glial cells. Hormones ensure proper communication between the brain and the body by activating adaptive mechanisms necessary to withstand and react to changes in internal and external conditions by regulating neuronal and synaptic plasticity, neurogenesis and metabolic activity of the brain. The influence of hormones on energy metabolism and mitochondrial function in the brain has gained much attention since mitochondrial dysfunctions are observed in many different pathological conditions of the central nervous system. Moreover, excess or deficiency of hormones is associated with cell damage and loss of function in mitochondria. This review aims to expound on the impact of hormones (GLP-1, insulin, thyroid hormones, glucocorticoids) on metabolic processes in the brain with special emphasis on oxidative phosphorylation dysregulation, which may contribute to the formation of pathological changes. Since the brain concentrations of sex hormones and neurosteroids decrease with age as well as in neurodegenerative diseases, in parallel with the occurrence of mitochondrial dysfunction and the weakening of cognitive functions, their beneficial effects on oxidative phosphorylation and expression of antioxidant enzymes are also discussed.

Dietary Control of Inflammation and Resolution

The healing of any injury requires a dynamic balance of initiation and resolution of inflammation. This hypothesis-generating review presents an overview of the various nutrients that can act as signaling agents to modify the metabolic responses essential for the optimal healing of injury-induced inflammation. In this hypothesis-generating review, we describe a defined nutritional program consisting of an integrated interaction of a calorie-restricted anti-inflammatory diet coupled with adequate levels of omega-3 fatty acids and sufficient levels of dietary polyphenols that can be used in clinical trials to treat conditions associated with insulin resistance. Each dietary intervention works in an orchestrated systems-based approach to reduce, resolve, and repair the tissue damage caused by any inflammation-inducing injury. The orchestration of these specific nutrients and their signaling metabolites to facilitate healing is termed the Resolution Response. The final stage of the Resolution Response is the activation of intracellular 5' adenosine monophosphate-activated protein kinase (AMPK), which is necessary to repair tissue damaged by the initial injury-induced inflammation. The dietary optimization of the Resolution Response can be personalized to the individual by using standard blood markers. Once each of those markers is in their appropriate ranges, activation of intracellular AMPK will be facilitated. Finally, we outline how the resulting activation of AMPK will affect a diverse number of other intercellular signaling systems leading to an extended healthspan.

Analysis of Major Depression Risk Genes Reveals Evolutionary Conservation, Shared Phenotypes, and Extensive Genetic Interactions

Major depressive disorder (MDD) affects around 15% of the population at some stage in their lifetime. It can be gravely disabling and it is associated with increased risk of suicide. Genetics play an important role; however, there are additional environmental contributions to the pathogenesis. A number of possible risk genes that increase liability for developing symptoms of MDD have been identified in genome-wide association studies (GWAS). The goal of this study was to characterize the MDD risk genes with respect to the degree of evolutionary conservation in simpler model organisms such as Caenorhabditis elegans and zebrafish, the phenotypes associated with variation in these genes and the extent of network connectivity. The MDD risk genes showed higher conservation in C. elegans and zebrafish than genome-to-genome comparisons. In addition, there were recurring themes among the phenotypes associated with variation of these risk genes in C. elegans. The phenotype analysis revealed enrichment for essential genes with pleiotropic effects. Moreover, the MDD risk genes participated in more interactions with each other than did randomly-selected genes from similar-sized gene sets. Syntenic blocks of risk genes with common functional activities were also identified. By characterizing evolutionarily-conserved counterparts to the MDD risk genes, we have gained new insights into pathogenetic processes relevant to the emergence of depressive symptoms in man.

Sex hormones, vascular factors and cognition

After more than a century of research, we have failed to develop a pharmacological prevention or cure for dementia. There are strong indicators that sex hormones influence cognition. In this paper we discuss the role of these hormones at the intersection between vascular disease and dementia, in light of the mounting literature covering the shared risk factors, pathological features alongside the timeline of hormonal change with the evolution of vascular and neurodegenerative disease. Interactive risk factors and the role of inflammation over the duration of disease evolution are highlighted. Our summary tables assessing the impact of estrogen-based hormone therapy on cognition over the past 45 years illustrate the effort expended to determine the ideal age for intervention and the type, dose, administration, and duration of therapy that might improve or protect cognition as well as alleviate menopausal symptoms. As the prevalence of dementia is rising and is higher in women, it is crucial we advance our knowledge from the "inconclusive" position statement on menopausal hormone therapy of the US Preventive Services Task Force.

Silencing circANKRD36 inhibits streptozotocin-induced insulin resistance and inflammation in diabetic rats by targeting miR-145 via XBP1

BACKGROUND

Diabetes mellitus (DM) is defined as a group of metabolic diseases characterized by hyperglycemia, which results from a deficiency in insulin secretion and/or insulin action. In diabetic patients, type 2 diabetes mellitus (T2DM) is in the majority. We explored the effects of circANKRD36 on streptozotocin (STZ)-induced insulin resistance and inflammation in diabetic rats with the aim of uncovering the underlying mechanism.

METHODS

STZ was used to induce the in vivo T2DM rat model. After circANKRD36 interference, blood glucose, insulin and adiponectin were respectively detected. Hematoxylin and eosin (H&E), enzyme-linked immunosorbent assay (ELISA) and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay (TUNEL) were conducted to examine inflammation and apoptosis in T2DM rats, and western blot was used for detecting apoptosis-related proteins. The binding relationships among circANKRD36, miR-145 and XBP1 were examined by luciferase reporter assay.

RESULTS

Results showed that circANKRD36 was expressed at a high level in T2DM rats, while silencing circANKRD36 led to decreased blood glucose and insulin, accompanied by increased adiponectin level, and ameliorating insulin resistance. Silencing circANKRD36 alleviated the inflammation and suppressed cell apoptosis in the pancreatic tissues of T2DM rats, which was abated by miR-145 inhibitor. The binding of miR-145 to XBP1 was then confirmed. Additionally, miR-145 inhibitor increased the level of XBP1 in T2DM rats, which was decreased in the presence of circANKRD36 silencing.

CONCLUSION

This study is the first to prove that silencing circANKRD36 inhibits STZ-induced insulin resistance and inflammation in diabetic rats by targeting miR- 145 via XBP1. The results warrant the importance of circRNAs as drug target and thereby pave way for the development of newer therapeutic measures for T2DM.

[Energy metabolism disorder and functional magnetic resonance imaging of the medial prefrontal cortex in mice with chronic unpredictable mild stress]

OBJECTIVE

To analyze spontaneous activities and energy metabolism in the medial prefrontal cortex (mPFC) of mice with chronic unpredictable mild stress (CUMS) and explore the correlation of these changes with the mTORC1 signaling pathway.

OBJECTIVE

Normal C57Bl/6 mice were randomly divided into control group (n=16) and depression model group (n= 16), and the mice in the latter group were subjected to 8 weeks of modeling with CUMS. Behavioral tests including open field test, sucrose consumption test, tail suspension test and forced swimming test were performed, and the changes in prefrontal gray matter volume and the amplitude of low frequency fluctuation (ALFF) in the mice were detected with functional magnetic resonance imaging. The CUMS mice were then randomized into two groups for treatment with ketamine (n=8) or saline (n=8). The mPFC tissues of the mice were collected for detecting the phosphorylation levels of mTORC1-related proteins with Western blotting and ATP level and NADP ⁺/NADPH ratio with ELISA in the 3 groups.

OBJECTIVE

Compared with the control mice, CUMS mice exhibited a distinct depressive phenotype with significantly decreased sucrose preference (P < 0.05) and shortened total distances (P < 0.01) and central exercise distances (P < 0.05) in the open field test without obvious changes of immobile time in tail suspension test and forced swimming test (P>0.05). Prefrontal gray matter volume and mALFF increased (P < 0.01), and the phosphorylation level of mTORC1- related proteins, ATP level and NADP ⁺/NADPH ratio all decreased significantly (P < 0.05) in CUMS mice. After ketamine treatment, the phosphorylation level of mTORC1-related proteins and ATP level increased significantly in CUMS mice (P < 0.05), but the increase of NADP ⁺/NADPH ratio was not statistically significant.

OBJECTIVE

The mPFC of CUMS mice shows increased spontaneous activities but lowered productivity efficiency, indicating the presence of energy metabolism disorder in the mPFC, which is related with reduced mTORC1 phosphorylation and can be alleviated by activating the mTORC1 pathway with ketamine.

The receptor hypothesis and the pathogenesis of depression: Genetic bases and biological correlates

Depression has become one of the most prevalent neuropsychiatric disorders characterized by anhedonia, anxiety, pessimism, or even suicidal thoughts. Receptor theory has been pointed out to explain the pathogenesis of depression, while it is still subject to debate. Additionally, gene abnormality accounts for nearly 40-50% of depression risk, which is a significant factor contributing to the onset of depression. Accordingly, studying on receptors and their gene abnormality are critical parts of the research on internal causes of depression. This review summarizes the pathogenesis of depression from six of the most related receptors and their associated genes, including N-methyl-D-aspartate receptor, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor, glucocorticoid receptor, 5-hydroxytryptamine receptor, GABA_A receptor α2, and dopamine receptor; and several "non-classic" receptors, such as metabotropic glutamate receptor, opioid receptor, and insulin receptor. These receptors have received considerable critical attention and are highly implicated in the onset of depression. We begin by providing the biological mechanisms of action of these receptors on the pathogenesis of depression. Then we review the historical and social context about these receptors. Finally, we discuss the limitations of the current state of knowledge and outline insights on future research directions, aiming to provide more novel targets and theoretical basis for the early prevention, accurate diagnosis and prompt treatment of depression.

Insulin resistance is associated with deficits in hedonic, self-reported cognitive, and psychosocial functional response to antidepressant treatment in individuals with major depressive disorder

BACKGROUND

To assess the effect of insulin resistance (IR) on treatment response to the antidepressant, vortioxetine, in patients with Major Depressive Disorder (MDD).

METHODS

This is a secondary analysis of an 8-week, open-label clinical trial. Ninety-five adults in a primary care setting experiencing a major depressive episode were included. Response to vortioxetine was measured using the THINC-integrated tool, Montgomery Åsberg Depression Rating Scale (MADRS), the Snaith-Hamilton Pleasure Scale (SHAPS), the Perceived Deficits Questionnaire (PDQ-5), and the Sheehan Disability Scale (SDS). Generalized estimating equation models were utilized for data analysis.

RESULTS

When adjusted for age, gender, dose, and BMI, there was a significant baseline IR by time interaction for SHAPS (p = 0.022), PDQ-5 (p = 0.037), and SDS (p = 0.013). Higher baseline IR predicted decreased early improvements in anhedonia. It also predicted poorer subjective assessments of cognition and increased functional impairment at the endpoint of treatment. For functional capacity (i.e. SDS) other covariates including severity of symptoms, illness course, other metabolic factors (e.g. cholesterol), and physical activity were included with no changes to the moderating effect of baseline IR.

LIMITATIONS

This was a post-hoc analysis of a primarily non-diabetic sample. Also, only one agent was assessed.

CONCLUSIONS

IR was a predictor of response to vortioxetine. This persisted after controlling for other factors including, but not limited to, BMI. These findings strengthen the link between depression and IR and may point to another novel metabolic predictor of response. These findings should be replicated using other antidepressants.

Mechanisms Underlying the Cognitive and Behavioural Effects of Maternal Obesity

The widespread consumption of 'western'-style diets along with sedentary lifestyles has led to a global epidemic of obesity. Epidemiological, clinical and preclinical evidence suggests that maternal obesity, overnutrition and unhealthy dietary patterns programs have lasting adverse effects on the physical and mental health of offspring. We review currently available preclinical and clinical evidence and summarise possible underlying neurobiological mechanisms by which maternal overnutrition may perturb offspring cognitive function, affective state and psychosocial behaviour, with a focus on (1) neuroinflammation; (2) disrupted neuronal circuities and connectivity; and (3) dysregulated brain hormones. We briefly summarise research implicating the gut microbiota in maternal obesity-induced changes to offspring behaviour. In animal models, maternal obesogenic diet consumption disrupts CNS homeostasis in offspring, which is critical for healthy neurodevelopment, by altering hypothalamic and hippocampal development and recruitment of glial cells, which subsequently dysregulates dopaminergic and serotonergic systems. The adverse effects of maternal obesogenic diets are also conferred through changes to hormones including leptin, insulin and oxytocin which interact with these brain regions and neuronal circuits. Furthermore, accumulating evidence suggests that the gut microbiome may directly and indirectly contribute to these maternal diet effects in both human and animal studies. As the specific pathways shaping abnormal behaviour in offspring in the context of maternal obesogenic diet exposure remain unknown, further investigations are needed to address this knowledge gap. Use of animal models permits investigation of changes in neuroinflammation, neurotransmitter activity and hormones across global brain network and sex differences, which could be directly and indirectly modulated by the gut microbiome.

Bibliometrics Analysis of the Research Status and Trends of the Association Between Depression and Insulin From 2010 to 2020

Depression is one of the common mental illnesses. Because it is an important complication of diabetes, its association with changes in insulin levels and insulin resistance, the causative factors of diabetes, has attracted widespread attention. However, the association between insulin and depression has not been systematically studied through bibliometric and visual analysis. This study is based on 3131 publications of Web of Science to identify the current research status and research trends in this field. The results show that since 2010, the number of publications has been growing rapidly. Cooperative network analysis shows that the United States, the University of Toronto and Roger S Mcintyre are the most influential countries, research institutes and scholars, respectively. Insulin resistance, obesity, and metabolic syndrome are hot topics in this field. Analysis of keywords and references reveals that "sex hormones," is new research area that constantly emerging. As far as we know, this study is the first one to visualize the association between depression and insulin and predict potential future research trends through bibliometric and visual analysis.

The Combination of Insulin Resistance and Serum Interleukin-1β Correlates with Post-Stroke Depression in Patients with Acute Ischemic Stroke

PURPOSE

Previous studies have shown that insulin resistance and inflammation may be associated with the pathophysiological mechanisms of mood disorders. Here, we investigated whether homeostatic model assessment of insulin resistance (HOMA-IR) and serum interleukin-1β (IL-1β) in acute ischemic stroke patients might be associated with post-stroke depression (PSD).

MATERIALS AND METHODS

The prospective study was conducted in China from February 2019 to September 2020. HOMA-IR and clinical data were collected at the time of admission. Serum levels of IL-1β were determined with enzyme-linked immunosorbent assays. Symptoms of depression and anxiety were screened by using the Hamilton Depression and Anxiety Scale at 6 months after stroke, and PSD was diagnosed on the basis of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) criteria. The association of potential risk factors with PSD was analyzed with multivariate logistic regression analysis. Finally, the ability of HOMA-IR and IL-1β to predict PSD was assessed with receiver operating characteristic curve.

RESULTS

A total of 305 people was included in the study; 65% were male, and the median age was 69.5±11.8 years. At the 6-month follow-up, 113 patients (37.5%) showed depressive symptoms. In multivariate logistic regression analysis, HOMA-IR and IL-1β as graded variables were associated with an increased risk of PSD (P < 0.05). Receiver operating characteristic curve analysis indicated the highest sensitivity and specificity when the HOMA-IR and IL-1β were 1.96 and 38.71 pg/mL, respectively (P < 0.001). IL-1β improved the ability of HOMA-IR to diagnose PSD combined model area under the curve (AUC): 0.78; 95% CI: 0.72-0.83; P < 0.001).

CONCLUSION

This study suggests that HOMA-IR and IL-1β are strongly associated with PSD at 6 months after stroke in patients with acute ischemic stroke. These two factors together improve the ability for early PSD assessment.

Antidiabetes Agents and Incident Depression: A Nationwide Population-Based Study

OBJECTIVE

Diabetes is associated with an increased risk of depression. Some antidiabetes agents, specifically metformin and pioglitazone, have been suggested to have beneficial effects on depression, but associations between antidiabetes drugs and depression have not been systematically investigated.

RESEARCH DESIGN AND METHODS

We combined four Danish population-based registers to investigate whether the 20 most widely used orally administered antidiabetes drugs were associated with an altered risk of incident depression. Analyses of insulin were included for comparisons. All persons in Denmark in 2005 were included in the study and followed until 2015. Two different outcome measures of incident depression were included: 1) a diagnosis of depressive disorder at a psychiatric hospital as an inpatient or outpatient and 2) a combined measure of a diagnosis of depression or use of antidepressants. Data were analyzed using Cox regression models.

RESULTS

A total of 360,205 individuals using orally administered antidiabetes drugs and 64,582 using insulin at any time during the study period were included in the analyses. Continued use of metformin and combinations of drugs including metformin were associated with decreased rates of incident depression. Pioglitazone was not associated with a decreased rate of incident depression. No other antidiabetes drugs or insulin showed significant associations with depression.

CONCLUSIONS

Real-life population-based data suggest a positive effect of metformin on depression rates. This evidence should be used in guiding prescriptions for patients with type 2 diabetes who are at risk for developing depression, including those with prior depression or anxiety and patients with a family history of depression.

Targeting the renin angiotensin system for the treatment of anxiety and depression

Emotional disorders like anxiety and depression are responsible for considerable morbidity and mortality all over the world. Several antidepressant and anxiolytic medications are available for the treatment of anxiety and depression. However, a significant number of patients either do not respond to these medications or respond inadequately. Hence, there is a need to identify novel targets for the treatment of anxiety and depression. In this review we focus on the renin angiotensin system (RAS) as a potential target for the treatment of these disorders. We review work that has evaluated the effects of various compounds targeting the RAS on anxiety- and depression-like behaviors. Further, we suggest future work that must be carried out to fully exploit the RAS for the treatment of anxiety and depression. The RAS provides an attractive target for both the identification of novel anxiolytic and antidepressant medications and/or for enhancing the efficacy of currently available medications used for the treatment of anxiety and depression.

Relationship of prenatal maternal obesity and diabetes to offspring neurodevelopmental and psychiatric disorders: a narrative review

Obesity and diabetes is a worldwide public health problem among women of reproductive age. This narrative review highlights recent epidemiological studies regarding associations of maternal obesity and diabetes with neurodevelopmental and psychiatric disorders in offspring, and provides an overview of plausible underlying mechanisms and challenges for future human studies. A comprehensive search strategy selected terms that corresponded to the domains of interest (maternal obesity, different types of diabetes, offspring cognitive functions and neuropsychiatric disorders). The databases searched for articles published between January 2010 and April 2019 were PubMed, Web of Science and CINAHL. Evidence from epidemiological studies strongly suggests that maternal pre-pregnancy obesity is associated with increased risks for autism spectrum disorder, attention-deficit hyperactivity disorder and cognitive dysfunction with modest effect sizes, and that maternal diabetes is associated with the risk of the former two disorders. The influence of maternal obesity on other psychiatric disorders is less well studied, but there are reports of associations with increased risks for offspring depression, anxiety, schizophrenia and eating disorders, at modest effect sizes. It remains unclear whether these associations are due to intrauterine mechanisms or explained by confounding family-based sociodemographic, lifestyle and genetic factors. The plausible underlying mechanisms have been explored primarily in animal models, and are yet to be further investigated in human studies.

Gene-disease association study of tumor necrosis factor-α G-308A gene polymorphism with risk of major depressive disorder: A systematic review and meta-analysis

INTRODUCTION

The single nucleotide polymorphism (SNP) of the tumor necrosis factor-α (TNF-α) G-308A gene is the most studied regarding susceptibility to major depressive disorder (MDD). However, results have been controversial perhaps due to the heterogeneous genetic backgrounds influenced by race as well as subtypes of depression.

METHODS AND MATERIALS

A systematic MEDLINE search was performed to retrieve all published studies that identified the connection between the TNF-α G-308A gene polymorphism and the risk of MDD.

RESULTS

There was no statistical difference between the allele frequencies or genotypes of TNF-α G-308A gene and the depressive patients or healthy subjects in the five models tested. Further, subgroup analyses showed that the TNF-α G-308A gene polymorphism also did not confer susceptibility to poststroke, late-life, maternal, or major depression. Publication bias analysis showed p values were more than .05, suggesting that the 9 articles included in the current analysis had no publication bias.

CONCLUSION

Neither the allele frequencies nor genotypes of TNF-α G-308A gene could be served as an independent risk factor of depression.

Potential role of insulin on the pathogenesis of depression

The regulation of insulin on depression and depression-like behaviour has been widely reported. Insulin and activation of its receptor can promote learning and memory, affect the hypothalamic-pituitary-adrenal axis (HPA) balance, regulate the secretion of neurotrophic factors and neurotransmitters, interact with gastrointestinal microbiome, exert neuroprotective effects and have an impact on depression. However, the role of insulin on depression remains largely unclear. Therefore, in this review, we summarized the potential role of insulin on depression. It may provide new insight for clarifying role of insulin on the pathogenesis of depression.

Rapid effects of S-ketamine on the morphology of hippocampal astrocytes and BDNF serum levels in a sex-dependent manner

The prevalence of major depressive disorder (MDD) is higher in women than men. Importantly, a differential behavioral response by sex to the antidepressant response to ketamine in rodents has been reported. Mechanistically, male depressed-like animals showed an increased spine density after ketamine treatment via restoration of synaptic protein levels while those proteins were not altered in female rats. In addition, preclinical studies indicate that the impairment of astrocytic plasticity is one of the contributing mechanisms in the pathophysiology of MDD. Accordingly, in this study, we determined the effect of sex on the rapid morphological alteration of hippocampal astrocytes and the serum level of BDNF one hour after S-ketamine injection. A single intraperitoneal dose of S-ketamine (15 mg/kg) or saline was injected to the male and female Flinders Sensitive Line (FSL) rats, a genetic animal model of depression and their brains were perfused one hour after treatment. The size of the GFAP positive astrocytes in the hippocampal subregions was measured. The volume of different hippocampal subregions was assessed using the Cavalieri estimator. Moreover, serum levels of BDNF were measured with enzyme-linked immunosorbent assay (ELISA) kits. The volume of hippocampal subregions significantly increased one hour after S-ketamine in both male and female FSL animals. However, a substantial alteration in the morphology of the hippocampal astrocytes was observed only in the female rats. Additionally, significantly increased serum BDNF levels in the female depressed rats were observed one hour after S-ketamine treatment. Our results indicate that the rapid effects of S-ketamine on the morphology of the hippocampal astrocytes and the serum level of BDNF are sex-dependent.

Curcumin in Depression: Potential Mechanisms of Action and Current Evidence-A Narrative Review

Major depressive disorder (MDD) is one of the most prevalent and debilitating disorders. Current available treatments are somehow limited, so alternative therapeutic approaches targeting different biological pathways are being investigated to improve treatment outcomes. Curcumin is the main active component in the spice turmeric that has been used for centuries in Ayurvedic medicine to treat a variety of conditions, including anxiety and depressive disorders. In the past decades, curcumin has drawn researchers' attention and displays a broad range of properties that seem relevant to depression pathophysiology. In this review, we break down the potential mechanisms of action of curcumin with emphasis on the diverse systems that can be disrupted in MDD. Curcumin has displayed, in a number of studies, a potency in modulating neurotransmitter concentrations, inflammatory pathways, excitotoxicity, neuroplasticity, hypothalamic-pituitary-adrenal disturbances, insulin resistance, oxidative and nitrosative stress, and endocannabinoid system, all of which can be involved in MDD pathophysiology. To date, a handful of clinical trials have been published and suggest a benefit of curcumin in MDD. With evidence that is progressively growing, curcumin appears as a promising alternative option in the management of MDD.