Sex differences in depression: An immunological perspective

Sex-stratified genome-wide association meta-analysis of Major Depressive Disorder

There are striking sex differences in the prevalence and symptomology of Major Depressive Disorder (MDD). We conducted the largest sex-stratified genome wide association and genotype-by-sex interaction meta-analyses of MDD to date (Females: 130,471 cases, 159,521 controls. Males: 64,805 cases, 132,185 controls). We found 16 and eight independent genome-wide significant SNPs in females and males, respectively, including one novel variant on the X chromosome. MDD in females and males shows substantial genetic overlap with a large proportion of MDD variants displaying similar effect sizes across sexes. However, we also provide evidence for a higher burden of genetic risk in females which could be due to female-specific variants. Additionally, sex-specific pleiotropic effects may contribute to the higher prevalence of metabolic symptoms in females with MDD. These findings underscore the importance of considering sex-specific genetic architectures in the study of health conditions, including MDD, paving the way for more targeted treatment strategies.

Systematic review and mega-analysis of the peripheral blood transcriptome in depression implicates dysregulation of lymphoid cells and histones

Background

Depression has been associated with transcriptomic changes in peripheral blood. However, the contribution of specific immune cell subsets or pathways remains unclear, and findings have been variable across previous studies, which have not tended to account for sample cellular composition.

Methods

We performed a systematic review of peripheral blood transcriptome studies in depression. For the five datasets meeting criteria (total N=6,011), we performed harmonized reprocessing and cell-composition-adjusted differential gene and transcript analyses, followed by a bias- and inflation-adjusted weighted Z-score mega-analysis. We investigated the biological pathways and cell subsets implicated by the results. We also performed a sex-stratified gene network mega-analysis using consensus weighted gene co-expression network analysis (WGCNA).

Results

Few genes showed robust differential gene expression (DGE) in depression. Depression was reproducibly associated with decreases in replication-dependent histones, and with a decrease in oxidative phosphorylation pathways in females only. Cell source analyses implicated lymphoid cells (T cells and NK cells) as likely contributors to the depression differential expression signature. WGCNA mega-analysis revealed multiple consensus modules associated with depression, with a PUF60-related module upregulated in both female and male depression in sex-stratified analyses. Two genes predicted to be causally relevant to depression by transcriptome-wide association studies (GPX4 and GYPE) showed significant DGE.

Conclusions

These results are convergent with immunogenetic evidence implicating lymphoid cell dysregulation in depression, while also highlighting histone alterations as a key molecular signature in depression. They also indicate the importance of large-scale datasets for biomarker discovery in the context of heterogeneous disorders like depression.

Sex-Specific Inflammatory Profiles Affect Neuropsychiatric Issues in COVID-19 Survivors

Post-COVID syndrome has unveiled intricate connections between inflammation, depressive psychopathology, and cognitive impairment. This study investigates these relationships in 101 COVID-19 survivors, focusing on sex-specific variations. Utilizing path modelling techniques, we analyzed the interplay of a one-month 48-biomarker inflammatory panel, with three-months of depressive symptoms and cognitive performance. The findings indicate that cognitive impairment is influenced by both inflammation and depression in the overall cohort. However, prominent sex-specific differences emerged. In females, a lingering imbalance between pro- and anti-inflammatory responses-likely reflecting the long-lasting immune alterations triggered by COVID-19-significantly affects cognitive functioning and shows a marginal, though not statistically significant, association with depressive symptoms. This suggests that a mixed inflammatory profile may contribute to these outcomes. Conversely, in males, inflammation was inversely associated with depression severity, with protective effects from regulatory mediators (IL-2, IL-4, IL-6, IL-15, LIF, TNF-α, β-NGF) against depression. In males, cognitive impairment appeared to be driven mainly by depressive symptoms, with minimal influence from inflammatory markers. These results highlight distinct sex-specific pathways in immune and inflammatory responses post-COVID-19, potentially shaped by endocrine mechanisms. The findings suggest that persistent inflammation may foster long-term neuropsychiatric sequelae, possibly through its effects on the brain, and underscore the need for sex-tailored therapeutic strategies to address the lasting impact of COVID-19.

Consumption of dopamine receptor 1 agonist SKF-38393 reduces constant-light-induced hyperactivity, depression-like, and anxiety-like behaviors in a sex specific manner in C57BL/6J mice

Artificial light exposure during nighttime, including constant light (LL), is an increasingly prevalent environmental occurrence linked to impaired mood and cognitive impairments in both humans and animal models. Dopamine and dopamine 1 receptors are well known to modulate circadian rhythms and mood. This study investigated the effects of LL on anxiety-like, depressive-like, and cognitive behaviors in male and female C57BL/6J mice and assessed whether consumption of SKF-38393, a dopamine 1 receptor agonist, can mitigate these negative behavioral outcomes. Mice were exposed to LL or a standard 12:12 light:dark cycle (LD) for 6 weeks, with subgroups receiving either SKF-38393 or water. All mice had their circadian rhythms continuously monitored and were placed within behavioral tests that assayed their anxiety-like, depressive-like, and learning and memory behaviors. Behavioral assays revealed that LL increased hyperactivity and anxiety-like behaviors, which were mitigated by SKF-38393 consumption in both sexes. In addition, male mice exhibited anhedonia under LL, which was alleviated by SKF-38393, whereas female mice were resistant to LL-induced anhedonia. Sex differences emerged in fluid consumption independent of lighting condition, with females consuming more SKF-38393, and in responses to DA on behavior, including novel object recognition and exploration. These results indicate that low dose oral consumption of dopamine 1 receptor agonists can ameliorate some of the negative behavioral effects of LL exposure. This study highlights the complex interplay between chronic light, dopamine, and sex in influencing mood and behavior, suggesting potential modulatory roles for dopamine 1 receptor agonists in regulating behavioral outcomes to circadian disturbances.

L-shaped association between leisure-time physical activity and depressive symptoms in individuals with chronic inflammatory airway disease: Data from the NHANES (2007-2018)

BACKGROUND

Chronic inflammatory airway diseases (CIAD) are well-known risk factors for depression symptoms. There exists a complex interplay between leisure-time physical activity (LTPA) and depressive symptoms. However, the relationship between LTPA duration and depressive symptoms in CIAD patients remains unclear.

OBJECTIVES

This study investigated NHANES data from 2007 to 2018 to investigate the relationship between LTPA and depressive symptoms in CIAD patients.

METHODS

We collected data from National Health and Nutrition Examination Survey (NHANES) 2007-2018. Weighted logistic regression was employed to analyze the correlation between CIAD and depressive symptoms. Next, CIAD patients with LTPA information, the similar method was also employed to examine the association between LTPA and depressive symptoms. Finally, the dose-response relationship between LTPA duration and depressive symptoms was explored using restricted cubic spline (RCS) plot.

RESULTS

Consistent with previous research findings, patients with CIAD are more prone to experiencing symptoms of depression (P < 0.0001). Compared to CIAD patients without LTPA, patients who engage in LTPA have a lower probability of experiencing depressive symptoms (P < 0.0001). Interestingly, we had discovered that there is an l-shaped relationship between the duration of LTPA and the prevalence of depressive symptoms (non-linear P = 0.001). There is a threshold effect between the duration of LTPA and depressive symptoms. Within12 h/week, the risk of depressive symptoms in CIAD patients decreases with increased duration of LTPA. However, beyond 12 h/week, this association no longer exists.

CONCLUSION

Our research indicates that CIAD patients can increase the prevalence of depressive symptoms. And LTPA over a period of time is negatively correlated with depressive symptoms, but only up to a total duration of 12 h/week.

The Balance in the Head: How Developmental Factors Explain Relationships Between Brain Asymmetries and Mental Diseases

Cerebral lateralisation is a core organising principle of the brain that is characterised by a complex pattern of hemispheric specialisations and interhemispheric interactions. In various mental disorders, functional and/or structural hemispheric asymmetries are changed compared to healthy controls, and these alterations may contribute to the primary symptoms and cognitive impairments of a specific disorder. Since multiple genetic and epigenetic factors influence both the pathogenesis of mental illness and the development of brain asymmetries, it is likely that the neural developmental pathways overlap or are even causally intertwined, although the timing, magnitude, and direction of interactions may vary depending on the specific disorder. However, the underlying developmental steps and neuronal mechanisms are still unclear. In this review article, we briefly summarise what we know about structural, functional, and developmental relationships and outline hypothetical connections, which could be investigated in appropriate animal models. Altered cerebral asymmetries may causally contribute to the development of the structural and/or functional features of a disorder, as neural mechanisms that trigger neuropathogenesis are embedded in the asymmetrical organisation of the developing brain. Therefore, the occurrence and severity of impairments in neural processing and cognition probably cannot be understood independently of the development of the lateralised organisation of intra- and interhemispheric neuronal networks. Conversely, impaired cellular processes can also hinder favourable asymmetry development and lead to cognitive deficits in particular.

SARS-CoV-2 infection and COVID-19 outcomes across mental disorders and the role of sex: A register-based study from Catalonia

INTRODUCTION

This study investigated the risk of SARS-CoV-2 infection and severe COVID-19 outcomes among different mental health diagnoses and the role of sex in these associations.

METHODS

Using electronic records from Catalonia, we identified adults receiving mental health care from 2017-2019 with diagnoses of non-affective psychosis (NAP), bipolar disorder (BD), depressive disorder (DEP), stress-related disorders, neurotic/somatoform disorders (NSD), and substance misuse (SUB) (exposed). The outcomes assessed were SARS-CoV-2 infection, COVID-19 hospitalization, and COVID-19-related death, compared to matched individuals without these mental disorders (unexposed). Adjusted logistic regression analyses were conducted.

RESULTS

785,378 adults were included (70.3% < 65 years old; 57.1% women). Compared to unexposed, those with NAP, BD, DEP, and SUB had a lower risk of SARS-CoV-2 infection, while those with NSD had an increased risk. Infected individuals with DEP, NSD, and SUB had a lower risk of hospitalization but a higher risk of COVID-19-related death. Higher COVID-19-related death was also observed in individuals with NAP and BD. Sex-stratified analysis revealed that women with NSD were especially vulnerable to infection, and women with DEP and NSD had a higher risk of COVID-19-related death.

CONCLUSIONS

These findings emphasize the need for tailored public health strategies to reduce excess mortality risk among individuals with certain mental disorders, while accounting for sex differences.

Metformin treatment improves depressive symptoms associated with type 2 diabetes: A 24-week longitudinal study

OBJECTIVE

Metformin is a medication that is widely used for lowering blood sugar in patients with type 2 diabetes. Metformin was shown to have significant antidepressant effects; however, it is not clear whether metformin treatment improves outcomes in patients with type 2 diabetes who have concomitant depressive symptoms.

METHODS

A total of 475 patients with type 2 diabetes mellitus with depressive symptoms were included in this study and divided into metformin and nonmetformin groups according to whether they were taking metformin. The DASS-21 was used to assess patients' depression and anxiety scores before and after a 24-week intervention. In addition, general information about whether the patients had developed complications from diabetes and whether they had been diagnosed with other diseases was assessed.

RESULTS

(1) After 24 weeks, anxiety and depression scores were significantly lower in the metformin group than in the nonmetformin group. (2) The prevalence of depressive symptoms was significantly greater in female type 2 diabetic patients than in male patients (OR = 2.039, 95 % CI = 1.160-3.568). (3) People with type 2 diabetes who develop complications from diabetes (OR = 1.794, 95 % CI = 1.015-3.171) and those diagnosed with other conditions are more likely to experience depressive symptoms.

CONCLUSION

Metformin has an ameliorative effect on type 2 diabetes. However, women, those with diabetes complications, and those with type 2 diabetes who are also diagnosed with other conditions are more likely to experience depressive symptoms.

Sex differences in the inflammation-depression link: A systematic review and meta-analysis

Major Depressive Disorder (MDD) is a heterogeneous disorder that affects twice as many women than men. Precluding advances in more tailored and efficacious treatments for depression is the lack of reliable biomarkers. While depression is linked to elevations in inflammatory immune system functioning, this relationship is not evident among all individuals with depression and may vary based on symptom subtypes and/or sex. This systematic review and meta-analysis examined whether inflammatory immune peripheral markers of depression are sex-specific. PRISMA guidelines were followed for the systematic review, and a comprehensive search strategy that identified studies from PubMed and PsycInfo was applied. Studies were included if they reported C-reactive protein (CRP), interleukin (IL)-6, tumor necrosis factor (TNF)-α and/or IL-1β for males and/or females among depressed and healthy adults. We identified 23 studies that satisfied these inclusion criteria. Random-effects meta-analysis models were fit, and measures of association were summarized between levels of circulating markers of inflammation in depressed and healthy males and females. Sex-based analyses revealed elevated levels of CRP among females with depression (Cohen's d = 0.19) relative to their healthy counterparts (p = 0.02), an effect not apparent among males (Cohen's d = -0.01). Similarly, levels of IL-6 were increased among females with depression compared to healthy controls (Cohen's d = 0.51; p = 0.04), but once again this was not found among males (Cohen's d = 0.16). While TNF-α levels were elevated among individuals with depression compared to controls (p = 0.01), no statistically significant sex differences were found. The meta-analysis for IL-1β resulted in only three articles, and thus, results are presented in the supplemental section. This meta-analysis advances our understanding of the unique involvement of inflammatory biomarkers in depression among men and women, which may help inform more tailored sex-specific treatment approaches in the future.

Sex differences in the transcriptional response to acute inflammatory challenge: A randomized controlled trial of endotoxin

Background

Sex differences in immune-based disorders are well-established, with female sex associated with a markedly heightened risk of autoimmune disease. Female sex is also overrepresented in other conditions associated with elevated inflammation, including depression, chronic pain, and chronic fatigue. The mechanisms underlying these disparities are unclear. This study used an experimental model of inflammatory challenge to interrogate molecular mechanisms that may contribute to female vulnerability to disorders with an inflammatory basis.

Method

In this analysis of a secondary outcome from a randomized controlled trial, 111 participants (67 female) received either a bolus injection of endotoxin (n = 59) or placebo (n = 52). Participants provided blood samples before and 0.5 h post-injection for assessment of differential activation of key pro-inflammatory (i.e., activator protein (AP)-1; nuclear factor (NF)-κB) and immunoregulatory (i.e., glucocorticoid receptor (GR); cAMP response element binding protein (CREB)) signaling pathways via genome-wide expression profiling and promoter-based bioinformatics analyses.

Results

Relative to males, females exhibited greater endotoxin-induced increases in bioinformatic measures of CREB transcription factor activity (p's < 0.01). However, contrary to hypotheses, female vs. male sex was not associated with greater increases in activation of NF-κB, AP-1, or GR in response to endotoxin vs. placebo administration.

Conclusions

This work suggests CREB signaling as a critical upstream biological pathway that should be further interrogated as a mechanism of female vulnerability to immune-related disorders. Future work should clarify whether increased CREB signaling indicates sex differences in activity of the sympathetic nervous system or other physiological pathways that signal through CREB, such as prostaglandin release.

Connecting the dots: sex, depression, and musculoskeletal health

Depression and multiple musculoskeletal disorders are overrepresented in women compared with men. Given that depression is a modifiable risk factor and improvement of depressive symptoms increases positive outcomes following orthopedic intervention, efforts to improve clinical recognition of depressive symptoms and increased action toward ameliorating depressive symptoms among orthopedic patients are positioned to reduce complications and positively affect patient-reported outcomes. Although psychosocial factors play a role in the manifestation and remittance of depression, it is also well appreciated that primary biochemical changes are capable of causing and perpetuating depression. Unique insight for novel treatments of depression may be facilitated by query of the bidirectional relationship between musculoskeletal health and depression. This Review aims to synthesize the diverse literature on sex, depression, and orthopedics and emphasize the potential for common underlying biological substrates. Given the overrepresentation of depression and musculoskeletal disorders among women, increased emphasis on the biological drivers of the co-occurrence of these disorders is positioned to improve women's health.

Association between pregnancy loss and depressive symptoms in women: a population-based study

BACKGROUND

Depression is a common mental disorder with a much higher prevalence in women than in men. Although there has been a gradual increase in research on the association between reproductive health and depression, there is still some inconsistency in the evidence of the relationship between pregnancy loss and depression. This study aimed to investigate the relationship between pregnancy loss and depressive symptoms.

METHODS

We analyzed data from the 2007-2020 National Health and Nutrition Examination Survey (NHANES), which included female participants aged 20 to 80 years. Pregnancy loss was determined based on participants' self-reported number of pregnancies and pregnancy outcomes. Depressive symptoms were measured using the Patient Health Questionnaire (PHQ-9, score ≥ 10). Multivariate logistic regression, smoothed curve fitting, and generalized additive modeling were used to examine the association between pregnancy loss and depression. We also performed sensitivity analyses and subgroup analyses to verify the robustness and specificity of the findings.

RESULTS

A total of 12,873 female participants were included in our study, of which 1,595 (12.39%) were categorized as depressed. Multivariate logistic regression results indicated that experiencing a pregnancy loss increased the risk of prevalence of depression in women (for 1 loss: OR = 1.31, 95% CI 1.15,1.50; for 2 or more losses: OR = 1.58, 95% CI 1.38, 1.81). When sensitivity analyses were performed, an association between pregnancy loss and depression was found in both multivariate linear regressions with PHQ-9 scores as a continuous variable and multivariate logistic regressions with a threshold of 5 PHQ-9 scores. The association between pregnancy loss and depression remained stable across subgroups.

CONCLUSION

Pregnancy loss correlated with elevated PHQ-9 scores and a heightened risk of depression in adult women across the United States. Focusing on the incidence of adverse pregnancy events in the female population may help prevent or early recognize the onset of depression.

The association between the number of pregnancies and depressive symptoms: A population-based study

BACKGROUND

Depression is a psychosomatic disorder that affects reproductive health. The number of pregnancies is an important indicator of reproductive health. Multiple pregnancies and births may aggravate the risk of depression in females. However, the evidence of the connection between the number of pregnancies and depression is unclear. We aimed to investigate the relationship between the number of pregnancies and depressive symptoms.

METHODS

We used the National Health and Nutrition Examination Survey (NHANES) data with a total of 17,216 women from 2005 to 2020. The number of pregnancies obtained from the self-report questionnaire. Depressive symptoms were measured by the nine-item patient health questionnaire (PHQ-9). Multivariate logistic regression models were used to examine the risk factors of depression. The restricted cubic spline (RCS) was applied to explore the nonlinear relationship. In addition, subgroup analysis was used to support the accuracy of our findings.

RESULTS

We found that the number of pregnancies is positively associated with the prevalence of depression. According to the multivariable logistic regression analysis, pregnant women was 1.52-fold higher than the normal group to experience depression in the fully-adjusted model. No interaction between number of pregnancies and covariates in subgroups.

LIMITATIONS

This study was cross-sectional, which limits its ability to draw conclusions about the causal relationship between the number of pregnancies and depression.

CONCLUSION

In the United States, the number of pregnancies was positively associated with the prevalence of depression. It is critical to register the number of pregnancies for monitoring depressive symptoms.

The missing hallmark of health: psychosocial adaptation

The eight biological hallmarks of health that we initially postulated (Cell. 2021 Jan 7;184(1):33-63) include features of spatial compartmentalization (integrity of barriers, containment of local perturbations), maintenance of homeostasis over time (recycling & turnover, integration of circuitries, rhythmic oscillations) and an array of adequate responses to stress (homeostatic resilience, hormetic regulation, repair & regeneration). These hallmarks affect all eight somatic strata of the human body (molecules, organelles, cells, supracellular units, organs, organ systems, systemic circuitries and meta-organism). Here we postulate that mental and socioeconomic factors must be added to this 8×8 matrix as an additional hallmark of health ("psychosocial adaptation") and as an additional stratum ("psychosocial interactions"), hence building a 9×9 matrix. Potentially, perturbation of each of the somatic hallmarks and strata affects psychosocial factors and vice versa. Finally, we discuss the (patho)physiological bases of these interactions and their implications for mental health improvement.

Challenges with embedding an integrated sex and gender perspective into pain research: Recommendations and opportunities

The focus of this article, within this BBI horizons special issue, is on sex, gender, and pain. We summarise what is currently known about sex- and gender-related variations in pain, exploring intersectional biological and psychosocial mechanisms, and highlight gaps in knowledge and understanding. Five key challenges with the exploration of sex and gender in pain research are presented, relating to: conceptual imprecision, research bias, limitations with binary descriptions, integrating sex and gender, and timely adoption/implementation of good research practice. Guidance on how to overcome such challenges is provided. Despite clear evidence for sex and gender differences in pain, there are conceptual and methodological barriers to overcome. Innovation in methods and approach can help develop more effective and tailored treatment approaches for men, women, boys, girls, and gender-diverse people.

NAPE-PLD regulates specific baseline affective behaviors but is dispensable for inflammatory hyperalgesia

N-acyl-ethanolamine (NAEs) serve as key endogenous lipid mediators as revealed by manipulation of fatty acid amide hydrolase (FAAH), the primary enzyme responsible for metabolizing NAEs. Preclinical studies focused on FAAH or NAE receptors indicate an important role for NAE signaling in nociception and affective behaviors. However, there is limited information on the role of NAE biosynthesis in these same behavioral paradigms. Biosynthesis of NAEs has been attributed largely to the enzyme N-acylphosphatidylethanolamine Phospholipase D (NAPE-PLD), one of three pathways capable of producing these bioactive lipids in the brain. In this report, we demonstrate that Nape-pld knockout (KO) mice displayed reduced sucrose preference and consumption, but other baseline anxiety-like or depression-like behaviors were unaltered. Additionally, we observed sex-dependent responses in thermal nociception and other baseline measures in wildtype (WT) mice that were absent in Nape-pld KO mice. In the Complete Freund's Adjuvant (CFA) model of inflammatory arthritis, WT mice exhibited sex-dependent changes in paw edema that were lost in Nape-pld KO mice. However, there was no effect of Nape-pld deletion on arthritic pain-like behaviors (grip force deficit and tactile allodynia) in either sex, indicating that while NAPE-PLD may alter local inflammation, it does not contribute to pain-like behaviors associated with inflammatory arthritis. Collectively, these findings indicate that chronic and systemic NAPE-PLD inactivation will likely be well-tolerated, warranting further pharmacological evaluation of this target in other disease indications.

Clinical pharmacological innovation in the treatment of depression

INTRODUCTION

Deficiencies in standard of care antidepressants are driving novel drug discovery. A new age of antidepressant medications has emerged with the introduction of rapid-acting antidepressants with efficacy in treatment-resistant patients.

AREAS COVERED

The newly approved medicines and those in clinical development for major depressive disorder (MDD) are documented in this scoping review of newly approved and emerging antidepressants. Compounds are evaluated for clinical efficacy, tolerability, and safety and compared to those of standard of care medicines.

EXPERT OPINION

A new age of antidepressant discovery relies heavily on glutamatergic mechanisms. New medicines based upon the model of ketamine have been delivered and are in clinical development. Rapid onset and the ability to impact treatment-resistant depression, raises the question of the best first-line medicines for patients. Drugs with improvements in tolerability are being investigated (e.g. mGlu_2/3 receptor antagonists, AMPA receptor potentiators, and novel NMDA receptor modulators). Multiple companies are working toward the identification of novel psychedelic drugs where the requirement for psychedelic activity is not fully known. Gaps still exist - methods for matching patients with specific medicines are needed, and medicines for the prevention of MDD and its disease progression need research attention.