Brain-based Sex Differences in Depression: A Systematic Review of Neuroimaging Studies

Depressive symptoms are associated with hippocampal volume in the oldest-old: The LifeAfter90 study

Depressive symptoms are prevalent among those aged 90 and above, the oldest old, but studies examining associations with neuroimaging markers of brain health are sparse. Therefore, we tested the association between depressive symptoms and neuroimaging outcomes, and assessed whether these associations differ by gender. This cross-sectional study used data from 225 participants with imaging data from the LifeAfter90 study (mean [SD] age=93.1 [2.2] years, 56 % female, 22 % African American/Black, 25 % Asian, 18 % Hispanic/Latino, 28 % White, 7 % multiracial/other). Depressive symptoms were measured using the 15-item Geriatric Depression Scale (GDS), and neuroimaging markers were collected via 3T magnetic resonance imaging and amyloid positron emission tomography (PET) scans. Average GDS score was 2.6 ± 2.3. Greater GDS scores were associated with lower total (β=-0.06; 95 % CI -0.12,>-0.01; p = 0.04) and right (β=-0.07; 95 % CI -0.13,-0.01; p = 0.02) hippocampal volumes. While GDS-by-gender interactions were not significant (p's interaction>0.05), estimates of GDS with lower total and right hippocampal volume were stronger among women compared with men in gender-stratified models. GDS was not associated with other measures of cortical volume, amyloid PET, nor white matter integrity. In a racially and ethnically diverse cohort, greater depressive symptoms were cross-sectionally associated with lower hippocampal volume among participants aged 90+.

Application of Optogenetic Neuromodulation in Regulating Depression

Depression is a multifaceted disorder with a largely unresolved etiology influenced by a complex interplay of pathogenic factors. Despite decades of research, it remains a major condition that significantly diminishes patients' quality of life. Advances in optogenetics have introduced a powerful tool for exploring the neural mechanisms underlying depression. By selectively expressing optogenes in specific cell types in mice, researchers can study the roles of these cells through targeted light stimulation, offering new insights into central nervous system disorders. The use of viral vectors to express opsins in distinct neuronal subtypes enables precise activation or inhibition of these neurons via light. When combined with behavioral, morphological, and electrophysiological analyses, optogenetics provides an invaluable approach to investigating the neural mechanisms of psychiatric conditions. This review synthesizes current research on the application of optogenetics to understand the mechanisms of depression. This study aims to enhance our knowledge of optogenetic strategies for regulating depression and advancing antidepressant research.

Are changes in physical activity associated with depression? A follow-up study of 1,950 individuals

BACKGROUND

This study evaluated the association between changes in physical activity and depression among 1,950 Brazilians. Individuals who increased their physical activity and those who decreased it were not associated with reduced depression. Conversely, being consistently active was identified as an independent and significant protective factor against depression in this population. ■ Persistently active individuals have strong independent protective factors against depression. ■ BMI (kg/m) is an independent risk factor for depression. ■ Individuals with depression at follow-up were older than those without depression. ■ Perceived stress is a strong independent risk factor for depression.

OBJECTIVE

To evaluate the association between changes in physical activity and depression in 1,950 Brazilians.

METHODS

This follow-up study included 1,950 Brazilians, aged ≥18 years, of both sexes, who participated in a health screening initiative between 2008 and 2022. Physical activity levels were evaluated using the International Physical Activity Questionnaire at baseline and follow-up, and groups related to changes in physical activity were created. Depression was assessed using the Beck Depression Inventory. Clinical data and behavioral profiles were also analyzed. Comparative and logistic regression models were used.

RESULTS

The multivariate analysis demonstrated that persistently active individuals had reduced depression (odds ratio [OR], 0.70, 95%CI= 0.55-0.91, p=0.006). Individuals who became active and those who became less active were not associated with a reduction in depression (respectively, OR= 0.81, 95%CI= 0.63-1.05, p=0.109 and OR= 1.11, 95%CI= 0.82-1.51, p=0.481).

CONCLUSION

Persistent activity was an independent, strong protective factor against depression in 1,950 Brazilians. Furthermore, becoming active or less active was not associated with depression in the same population.

Microwave-Assisted Synthesis of Morpholine-Based Chalcones as Reversible MAO-A Inhibitors in the Management of Mental Depression

Background: Depression is one of the most serious and common health problems among the youth population and is responsible for the initiation of many diseases. As per the World Health Organization, 3.8% of the population suffers from mental depression, globally. The monoamine oxidase-A (MAO-A) enzyme is responsible for the degradation of neurotransmitters leading to lower levels of neurotransmitters. Methods: Chalcones (C1-C15) were synthesized by reacting substituted acetophenone with various benzaldehydes in a basic ethanolic solvent at 80 °C under microwave irradiation conditions. To compare the reaction time and product yield, a conventional method of synthesis of chalcones was also performed. The synthesized chalcones (C1-C15) were spectroscopically characterized and screened initially for inhibitory activities against MAO-A and MAO-B. The best active compounds were undertaken for IC50 determination against MAO-A enzyme followed by the reversibility of inhibition analysis and the antioxidant assay. Moreover, in silico molecular docking and ADME pharmacokinetic investigations were accomplished. Results: Most of the compounds inhibited MAO-A, specifically, compounds C14 and C6 exhibited the highest inhibition at IC50 values of 7.91 ± 0.08 μM and 8.45 ± 0.19 μM, respectively. Both these compounds exhibited a reversible MAO-A inhibition displaying up to 60% recovery of enzymatic activity when diluted with substrate (Tyramine). The results of the in silico study indicated docking scores of -9.56 Kcal/mol (C14) and -9.45 Kcal/mol (C6) and exhibited a π-π stacking interaction with the crucial amino acid Trp-397. The compounds were determined to cross the blood-brain barrier (BBB) and displayed favorable gastrointestinal (GI) absorption. Further, the antioxidant assay results demonstrated that the synthesized compounds possess modest free radical scavenging potential. Conclusions: This study displayed the MAO-A inhibitory potential of morpholine-substituted chalcones as a promising pharmacophore for the development of novel antidepressant lead compounds.

Early parent-child separation and adolescent depressive symptoms: the mediating role of self-perceived pleasure in social interactions

BACKGROUND

Depressive symptoms are highly prevalent among adolescents with a history of parent-child separation. This study investigates whether self-perceived pleasure in social interactions mediates the relationship between early parent-child separation and depressive symptoms among Chinese adolescents.

METHODS

1250 teenagers (mean age = 12.95 years, SD = 1.55; 54.6% male) completed self-report surveys assessing early parent-child separation, self-perceived pleasure in social interactions, and depressive symptoms. Mediation analysis was conducted using the bootstrap method.

RESULTS

Early parent-child separation increased the risk for depressive symptoms in adolescents by 1.743 times (95% CI, 1.348-2.253). Self-perceived pleasure in social interaction partially mediated the association between early parent-child separation and adolescent depressive symptoms, after adjusting for age and gender (β = 0.095; 95%CI, 0.032-0.168). The mediating effect was significant and accounted for 19.87% of the total effect.

CONCLUSIONS

This study highlights the impact of self-perceived pleasure from social interactions on adolescent depressive symptoms. Improving perceived pleasure from social interactions may help reduce the negative effects of parent-child separation on depressive symptoms.

Analysis of risk factors for depression in peritoneal dialysis patients and establishment of a risk nomogram model

OBJECTIVE

This study aims to analyze the risk factors for depression in peritoneal dialysis patients and to develop a predictive nomogram model for assessing these risks.

METHODS

A total of 326 peritoneal dialysis patients treated between August 2021 and December 2023 were selected as the training set. These patients were categorized into a non-depression group (229 cases) and a depression group (97 cases) based on the presence of depression. Additionally, 104 peritoneal dialysis patients from the same period were selected as the validation set. Clinical data were collected from all patients for analysis.

RESULTS

The depression group had higher proportions of female patients, non-employed individuals, those with a per capita monthly income of <2000-yuan, cardiovascular complications, cerebrovascular complications, and sleep disorders compared to the non-depression group. Additionally, the levels of hemoglobin and blood uric acid were lower in the depression group than in the non-depression group (p < 0.05). Gender, work status, per capita monthly income, cardiovascular complications, cerebrovascular complications, and sleep disorders are risk factors for depression in peritoneal dialysis patients (p < 0.05), while hemoglobin and blood uric acid are protective factors for depression in peritoneal dialysis patients (p < 0.05). Calibration curve analysis results showed that the predicted probability was basically consistent with the actual incidence rate. The results of the Decision Curve Analysis (DCA) demonstrated that the nomogram model developed in this study has strong clinical applicability.

CONCLUSION

The nomogram model for predicting depression in peritoneal dialysis patients, which incorporates factors such as gender, work status, per capita monthly income, cardiovascular complications, cerebrovascular complications, sleep disorders, hemoglobin levels, and blood uric acid levels, demonstrates excellent calibration and discrimination. Additionally, it has high clinical applicability.

The research progress on effective connectivity in adolescent depression based on resting-state fMRI

Introduction

The brain's spontaneous neural activity can be recorded during rest using resting state functional magnetic resonance imaging (rs-fMRI), and intricate brain functional networks and interaction patterns can be discovered through correlation analysis. As a crucial component of rs-fMRI analysis, effective connectivity analysis (EC) may provide a detailed description of the causal relationship and information flow between different brain areas. It has been very helpful in identifying anomalies in the brain activity of depressed teenagers.

Methods

This study explored connectivity abnormalities in brain networks and their impact on clinical symptoms in patients with depression through resting state functional magnetic resonance imaging (rs-fMRI) and effective connectivity (EC) analysis. We first introduce some common EC analysis methods, discuss their application background and specific characteristics.

Results

EC analysis reveals information flow problems between different brain regions, such as the default mode network, the central executive network, and the salience network, which are closely related to symptoms of depression, such as low mood and cognitive impairment. This review discusses the limitations of existing studies while summarizing the current applications of EC analysis methods. Most of the early studies focused on the static connection mode, ignoring the causal relationship between brain regions. However, effective connection can reflect the upper and lower relationship of brain region interaction, and provide help for us to explore the mechanism of neurological diseases. Existing studies focus on the analysis of a single brain network, but rarely explore the interaction between multiple key networks.

Discussion

To do so, we can address these issues by integrating multiple technologies. The discussion of these issues is reflected in the text. Through reviewing various methods and applications of EC analysis, this paper aims to explore the abnormal connectivity patterns of brain networks in patients with depression, and further analyze the relationship between these abnormalities and clinical symptoms, so as to provide more accurate theoretical support for early diagnosis and personalized treatment of depression.

Neuronal Properties in the Lateral Habenula and Adult-Newborn Interactions in Virgin Female and Male Mice

The behavioral interactions between adults and newborns are decisive for the fitness and the survival of offspring across the animal kingdom. In laboratory mice, while virgin females display caregiving behaviors, virgin males are rather neglectful or aggressive toward pups. Despite the importance of these behavioral variations, the underlying neural mechanisms remain poorly understood. Brain regions encoding these behaviors may exhibit sex-dependent functional differences at the baseline. Additionally, these structures might undergo sex-specific plasticity after adults interact with the offspring. Emerging evidence suggests sex-based differences in input connectivity, genetics, and receptor expression of the epithalamic lateral habenula (LHb). Moreover, LHb neuronal activity is instrumental for adult-newborn interactions. However, whether LHb neuronal function varies between sexes and/or undergoes adaptations following interactions with pups has not been fully investigated. In this study, we used in vivo and ex vivo single-cell electrophysiology to examine the basal LHb neuronal activity of virgin female and male mice. In a second set of experiments, we exposed mice to pups and recapitulated sex-based divergent behaviors. Recordings in acute slices showed no alterations in LHb firing properties, regardless of sex or pup exposure. These findings suggest that, although the LHb participates in adult behaviors toward pups, this is not mediated by sex-dependent functional differences or adaptations in the neuronal firing properties. Thus, this study provides new insights into the neural basis of sex-specific adult-newborn behaviors and the role of the LHb in these processes.

Transposable Elements are Dysregulated in Brains of Individuals with Major Depressive Disorder

Transposable elements (TEs) are repetitive DNA sequences capable of being transcribed and reintegrated, or transposed, into distinct loci throughout the genome. While thought to be largely transcriptionally silenced in brain, TE transcription is increasingly recognized as dynamic and involved in human health and disease states, including in disorders of the brain. In this study, we annotated TE transcripts in publicly available RNA sequencing (RNAseq) of postmortem human brain tissue to investigate the expression profile of TE transcripts in individuals with Major Depressive Disorder (MDD) compared to healthy controls. Our findings reveal a robust and uniform downregulation of TE transcript expression in the brains of subjects with MDD relative to controls, this occurs most prominently in the orbitofrontal cortex (OFC) brain region, and MDD differentially impacts this TE expression by age and sex. This work points to the aberrant transcription of cortical TEs as a potentially overlooked molecular signature of MDD.

Sex Differences in Depression: Insights from Multimodal Gray Matter Morphology and Peripheral Inflammatory Factors

Major depressive disorder (MDD) exhibits notable sex differences in prevalence and clinical and neurobiological manifestations. Though the relationship between peripheral inflammation and MDD-related brain changes is well studied, the role of sex as a modifying factor is underexplored. This study aims to assess how sex influences brain and inflammatory markers in MDD. We utilized voxel-based and surface-based morphometry to analyze gray matter (GM) structure, along with GM-based spatial statistics (GBSS) to examine GM microstructure among treatment-naive patients with depression (n = 174) and age-matched healthy controls (n = 133). We uncovered sex-by-diagnosis interactions in several limbic system structures, the frontoparietal operculum and temporal regions. Post hoc analyses revealed that male patients exhibit pronounced brain abnormalities, while no significant differences were noted in females despite their higher depressive scores. Additionally, heightened inflammation levels in MDD were observed in both sexes, with sex-specific effects on sex-specific brain phenotypes, particularly including a general negative correlation in males. Intriguingly, mediation analyses highlight the specific role of the parahippocampal gyrus (PHG) in mediating interleukin (IL)-8 and depression in men. The findings suggest that in clinical practice, it would be beneficial to prioritize sex-specific assessments and interventions for MDD. This includes recognizing the possibility that male patients may experience significant brain alterations, especially when identifying male patients who may underreport symptoms. Possible limitations encompass a small sample size and the cross-sectional design. In future research, the incorporation of longitudinal studies or diverse populations, while considering illness duration, will enhance our understanding of how inflammation interacts with brain changes in depression.

A study of impulsivity and adverse childhood experiences in a population health setting

As complex mental health traits and life histories are often poorly captured in hospital systems, the utility of using the Barratt Impulsivity Scale (BIS) and Adverse Childhood Experiences (ACEs) for assessing adult disease risks is unknown. Here, we use participants from the Healthy Nevada Project (HNP) to determine if two standard self-assessments could predict the incidence and onset of disease. We conducted a retrospective cohort study involving adult participants who completed the Behavioral and Mental Health Self-Assessment (HDSA) between September 2018 and March 2024. Impulsivity levels were measured using the BIS-15, and retrospective self-reports of ACEs were collected through a standardized questionnaire. In total, 17,482 HNP participants completed the HDSA. Our findings indicate that ACEs were significantly associated with impulsivity. Disease associations with impulsivity and ACEs were evaluated using a phenome-wide association study, identifying 230 significant associations with impulsivity. Among these, 44 were related to mental health diagnoses, including major depressive disorder (MDD). Kaplan-Meier survival estimates characterized the differences in the lifetime predicted probability between high and low impulsivity for major depressive disorder and essential hypertension. This analysis showed that having both high ACEs and high impulsivity confer substantial risk of MDD diagnosis (hazard ratios 2.81, 2.17, respectively). Additionally, lifetime predicted probability of MDD was approximately 40% higher for high ACEs and high impulsivity compared to no ACEs and low impulsivity. Essential hypertension demonstrated similar trends, with an approximate 20% increase in predicted lifetime probability of diagnosis. These results demonstrate that high ACES and elevated impulsivity scores are associated with a range of negative health outcomes and a simple self-assessment of complex traits and life history may significantly impact clinical risk assessments.

Depression and risk of stroke and mortality after percutaneous coronary intervention: A nationwide population study

BACKGROUND

Limited evidence exists on the role of depression in the risk of developing stroke and other cardiovascular outcomes in patients who have undergone percutaneous coronary interventions (PCI). We investigated this relationship with data from the Korean National Health Insurance Service database.

METHODS

Our nationwide retrospective cohort study included 164,198 patients who had undergone PCI between 2010 and 2017. Depression was defined with the ICD-10 codes recorded prior to the PCI. The primary outcome was a new-onset stroke following the PCI. Secondary outcomes included PCI with myocardial infarction (MI), revascularization (PCI or coronary artery bypass grafting), and all-cause mortality. A multivariable Cox proportional hazards regression analysis was used to calculate adjusted hazard ratios (aHR) and 95% confidence intervals (CI), adjusting for potential confounders, including sociodemographic and lifestyle factors, comorbidities, and MI at the index PCI.

RESULTS

Over a median follow-up of 5.0 years, acute stroke occurred in 5.7% of patients with pre-existing depression (17.4% of the study population), compared to 3.5% of those without depression. Depression was associated with a 27% increased risk of acute stroke (aHR 1.27, 95% CI 1.20-1.35). Additionally, depression was linked with a 25% elevated risk of all-cause death (aHR 1.25, 95% CI, 1.21-1.29) and an 8% increased risk of revascularization (aHR 1.08, 95% CI 1.04-1.11). The associations with the risk of stroke and all-cause mortality were stronger in patients under 65 years.

CONCLUSIONS

Our findings suggest that pre-existing depression may increase the risk of stroke and all-cause mortality following PCI, particularly in patients under 65 years. Additionally, depression was significantly associated with an increased need for revascularization. This underscores the potential benefits of managing depression to reduce stroke risk and overall cardiovascular outcomes following PCI.

GSP1-111 Modulates the Microglial M1/M2 Phenotype by Inhibition of Toll-like Receptor 2: A Potential Therapeutic Strategy for Depression

Neuroinflammation plays a vital role in neurodegenerative diseases and neuropsychiatric disorders, and microglia and astrocytes chiefly modulate inflammatory responses in the central nervous system (CNS). Toll-like receptors (TLRs), which are expressed in neurons, astrocytes, and microglia in the CNS, are critical for innate immune responses; microglial TLRs can regulate the activity of these cells, inducing protective or harmful effects on the surrounding cells, including neurons. Therefore, regulating TLRs in microglia may be a potential therapeutic strategy for neurological disorders. We examined the protective effects of GSP1-111, a novel synthetic peptide for inhibiting TLR signaling, on neuroinflammation and depression-like behavior. GSP1-111 decreased TLR2 expression and remarkably reduced the mRNA expression of inflammatory M1-phenotype markers, including tumor necrosis factor (TNF)α, interleukin (IL)-1β, and IL-6, while elevating that of the M2 phenotype markers, Arg-1 and IL-10. In vivo, GSP1-111 administration significantly decreased the depression-like behavior induced by lipopolysaccharide (LPS) in a forced swim test and significantly reduced the brain levels of M1-specific inflammatory cytokines (TNFα, IL-1β, and IL-6). GSP1-111 prevented the LPS-induced microglial activation and TLR2 expression in the brain. Accordingly, GSP1-111 prevented inflammatory responses and induced microglial switching of the inflammatory M1 phenotype to the protective M2 phenotype. Thus, GSP1-111 could prevent depression-like behavior by inhibiting TLR2. Taken together, our results suggest that the TLR2 pathway is a promising therapeutic target for depression, and GSP1-111 could be a novel therapeutic candidate for various neurological disorders.

Exploring specific associations of childhood maltreatment with social cognition in drug-naive first-episode major depressive disorder: a sex-centric approach

Childhood maltreatment (CM) has been linked to social cognition deficits in major depressive disorder (MDD), but little is known about sex-specific effects. This study aimed to investigate the sex-specific associations of CM with social cognition in first-episode drug-naive patients with MDD. A total of 117 first-episode drug-naive patients with MDD and 134 healthy controls (HCs) were recruited and assessed for demographic and clinical characteristics. All participants completed the Childhood Trauma Questionnaire (CTQ), Toronto Alexithymia Scale (TAS-20), Interpersonal Reactivity Index-C (IRI), and Facial Emotion Recognition Test. Partial correlation analysis was used to explore the sex-specific association of CM with social cognition. Our findings revealed significant differences in the associations of CM with social cognition between males and females in MDD patients. In comparison to HCs, the associations of CM with social cognition displayed distinct and even contrasting sex-specific patterns in MDD patients. Specifically, male MDD patients exhibited unique imbalanced associations between emotional neglect and alexithymia, while both female and male MDD patients shared imbalanced associations of childhood abuse with empathy. These results emphasize the importance of considering the sex-specific associations of CM with social cognition in MDD and highlight the need for personalized interventions and treatments based on sex for MDD patients with a history of CM.

Effects of chronic daily headache with subclinical depression on brain volume: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

The relationship between chronic daily headache (CDH), depression symptoms, and brain volume remains unclear.

METHODS

To investigate the effects of CDH on brain volume and the impact of depressive symptoms (DSs) as well as the effects of demography and medication overuse, PubMed, Embase, and Web of Science databases were systematically searched using appropriate keyword strings to retrieve observational studies from inception to May 2023.

RESULTS

Two distinct comparisons were made in CDH patients: (1) those with DSs versus their pain-free counterparts and (2) those without DSs versus pain-free controls. The first comprised nine studies enrolling 225 CDH patients with DSs and 234 controls. Beck depression inventory, Hamilton depression scale, and Hospital anxiety/depression scale were used to assess DSs, revealing significantly more DSs in CDH patients with DSs compared to their controls (all p < 0.05). Besides, the second analysed four studies involving 117 CDH patients without DSs and 155 comparators. Compared to CDH patients without DSs, those with DSs had a smaller brain volume than controls (p = 0.03). Furthermore, CDH patients with DSs who did not overuse medications showed a smaller right cerebral cortical volume than overusers (p = 0.003). A significant inverse correlation between female prevalence and brain volume (p = 0.02) was revealed using regression analysis.

CONCLUSIONS

Pain-induced persistent depressive symptoms not only incur structural alterations but also encompass affective-motivational changes, involving medication use and gender-specific health concerns.

SIGNIFICANCE

This study highlighted the importance of an integrated CDH treatment, emphasizing psychological interventions for the affective-motivational component alongside pain management.

Do the Gender and the Number of Comorbidities and the Use of Tertiary Prevention Play a Role in the Severity of Anxiety and Depression in Patients with Coronary Artery Disease? A POLASPIRE II Study

Background/Objectives: The need to conduct research on anxiety and depression in patients with coronary artery disease in connection with factors such as gender or implemented tertiary prevention is very important for drawing practical conclusions and, consequently, implementing new recommendations and procedures. The aim of the study was to attempt to answer the question whether gender and the number of comorbidities, as well as the application of tertiary prevention principles, play a role in the severity of anxiety and depression in the studied group of patients with coronary artery disease. Material: The study involved 765 patients from 11 Polish cardiology centers. The presented material is part of the multicenter POLASPIRE II study. Methods: All patients completed The Hospital Anxiety and Depression Scale (HADS) questionnaire, and a medical interview was conducted with them. Conclusions: Although the intensity of anxiety and depression in the studied group of patients was low, gender differentiated them, which, however, did not influence undertaking tertiary prevention activities. In the study group of patients, the number of comorbidities and cardiac incidents/procedures after the event qualifying for the study, as well as preventive actions undertaken, were not associated with the severity of anxiety and depression. In the studied group of patients with coronary heart disease, there was still a large group of people who did not take preventive measures. Therefore, there is a need for systematic education regarding the benefits of implementing them to prevent the progression of the disease and premature death.

[Depression in the field of tension of gender roles]

BACKGROUND

The distribution of depression and suicidal ideation by gender reveals a gender paradox: women are at least twice as likely to be diagnosed with depressive disorders but have a lower suicide rate than men. In contrast, the suicide rate of men is at least three times higher than women, while the prevalence of depressive disorders is only half as high. Although these differences have long been known the reasons for this paradox are still not fully understood.

AIM OF THE ARTICLE AND METHOD

The aim of this narrative review article is to discuss possible explanatory models regarding gender differences in depressive disorders. Aspects related to stress processing and traumatization are considered as well as sociological and biological factors. This article summarizes information that was considered particularly relevant in the interdisciplinary dialogue regarding possible explanatory factors for gender differences in depressive disorders.

RESULTS

The summarized studies indicate that women and men differ in certain aspects of stress processing and trauma exposure but men do not have a lower risk of disease as a result. On the contrary, the frequency of depressive disorders in men seems to be underestimated due to an atypical symptom manifestation.

DISCUSSION

The implementation of knowledge about gender-specific vulnerability in the training of physicians and psychotherapists, the systematic assessment of gender beyond binary classifications as well as further diversity domains in research and healthcare as well as gender-sensitive and diversity-sensitive prevention strategies could contribute to the resolution of the gender paradox.

Intravenous Reelin rescues despair-like behavior, Reelin cells in the dentate sub-granular zone, and spleen atrophy in the cyclic corticosterone model of recurring depressive episodes

Novel antidepressants are predominantly evaluated preclinically in rodent models of chronic stress in which animals experience a single prolonged exposure to chronic stress prior to treatment. Rodent models of a single episode of chronic stress translate poorly to human depressive disorders, which are commonly marked by recurring depressive episodes. Intravenous administration of Reelin has previously been shown to resolve immobility in the forced swim test of rats exposed to a single prolonged exposure to chronic stress. To determine whether Reelin has antidepressant-like properties in a model of recurring depressive episodes, Long-Evans rats (N = 57) were exposed to multiple cycles of chronic stress and stress-free periods before the administration of a single injection of Reelin during the final cycle of chronic stress. The animals then performed in the forced swim test and open field test before the post-mortem evaluation of Reelin cell counts in the sub-granular zone of the dentate gyrus to determine the impact of treatment on hippocampal Reelin levels and spleen white pulp to evaluate the role of Reelin treatment in peripheral inflammation. The results show a single Reelin injection reversed elevated levels of immobility in the forced swim test in both male and female subjects exposed to the cyclic chronic stress model of recurring depressive episodes. Treatment with Reelin also restored Reelin-positive cell counts in the dentate gyrus sub-granular zone and reversed atrophy of spleen white pulp. The results shown here indicate that treatment with Reelin could effectively resolve alterations in forced swim test behavior caused by the cyclic corticosterone model of recurring depressive episodes and that Reelin homeostasis is important for regulating stress-related inflammation. Future preclinical antidepressant research should incorporate models of multiple depressive episodes to improve the translation of preclinical rodent research to human depressive disorders.

Exploring gender differences in the relationship between gut microbiome and depression - a scoping review

Background

Major depressive disorder (MDD) exhibits gender disparities, and emerging evidence suggests the involvement of the gut microbiome, necessitating exploration of sex-specific differences.

Methods

A review was conducted, encompassing a thorough examination of relevant studies available in Medline via Ovid, Embase via OvidSP, CINAHL, and PsycINFO databases from their inception to June 2023. The search strategy employed specific keywords and Medical Subject Headings (MeSH) terms tailored to major depressive disorder in women, encompassing unipolar depression, depressive symptoms, and dysbiosis.

Results

Five studies were included. Among the four studies, alterations in alpha (n=1) and beta diversity (n=3) in the gut microbiome of individuals with MDD were revealed compared to controls. Gender-specific differences were observed in four studies, demonstrating the abundance of specific bacterial taxa and highlighting potential sex-specific implications in MDD pathophysiology. Correlation analyses (n=4) indicated associations between certain bacterial taxa and the severity of depressive symptoms, with varying patterns between males and females. Studies (n=3) also highlighted promising findings regarding the potential utility of microbial markers in diagnosing MDD, emphasizing the crucial role of sex stratification in understanding the disease pathophysiology.

Conclusions

The findings underscore the importance of recognizing gender-specific differences in the composition of the gut microbiome and its relationship with MDD. Further comprehensive robust studies are required to unravel the intricate mechanisms underlying these disparities.

In situ fNIRS measurements during cognitive behavioral emotion regulation training in rumination-focused therapy: A randomized-controlled trial

Repetitive negative thinking (RNT), including rumination, plays a key role in various psychopathologies. Although several psychotherapeutic treatments have been developed to reduce RNT, the neural correlates of those specific treatments and of psychotherapy in general are largely unknown. Functional near-infrared spectroscopy (fNIRS) offers the potential to investigate the neural correlates of psychotherapeutic techniques in situ. Therefore, in this study we investigated the efficacy and neural correlates of a fNIRS adapted Mindfulness-based Emotion Regulation Training (MBERT) for the treatment of depressive rumination in 42 subjects with major depressive disorder (MDD) in a cross-over designed randomized controlled trial. Using psychometric measures, subjective ratings and fNIRS, we analyzed in situ changes in depressive symptom severity, ruminative thoughts and cortical activity in the Cognitive Control Network (CCN). Our results show that MBERT is effective in treating depressive symptoms and rumination. On a neural level, we found consistently higher cortical activation during emotion regulation training compared to control trials in the bilateral inferior frontal gyrus (IFG) and dorsolateral prefrontal cortex (DLPFC). Furthermore, cortical oxygenation decreased from session to session in the bilateral DLPFC. The relevance of the results for the psychotherapeutic treatment of MDD as well as further necessary investigations are discussed.