A meta-analysis of cytokines in suicidal behavior

Higher levels of plasma Adrenocorticotropic hormone (ACTH) are associated with lower suicidal ideation in depressed patients compared to controls and suicide attempters, independently from depression severity

Introduction

Suicidal ideation, an important risk factor for suicide attempts, has an unclear neurobiological basis and is potentially linked to the dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and immune-inflammatory systems. While inflammatory markers have been associated with suicide attempts and, to a lower extent suicidal ideation, the data on the role of a stress-response system is less robust, with most studies carried out with cortisol showing inconsistent results. The present study extends on the previous studies implicating stress-response and immune-inflammatory systems in suicidal thoughts and behaviours, focusing on the associations of several stress-response (adrenocorticotropic hormone (ACTH), cortisol, and dehydroepiandrosterone (DHEA)) and immune-inflammatory (C-reactive protein (CRP),interle ukin-6 (IL-6), and tumour necrosis factor-alpha (TNF-alpha)) with suicidal ideation severity in recent suicide attempters, patients with major depressive disorder, and non-psychiatric controls.

Methods

This observational study included 156 adults from three Vilnius hospitals, recruited into one of the three groups in equal parts: recent suicide attempters, patients with major depressive disorder in current depressive episode, and non-psychiatric controls. Measures included the Hamilton Depression Rating Scale (HDRS-17) and the Beck Scale for Suicide Ideation/Suicide Severity Index (BSS/SSI), alongside sociodemographic data, alcohol, tobacco use, and morning blood samples, measuring plasma ACTH, cortisol, DHEA, CRP, and IL-6. Data were analysed with non-parametric tests, Kendall's tau correlation, and multivariate linear regression adjusted for confounders.

Results

We found a negative correlation between the plasma ACTH levels and suicidal ideation severity (tau = -0.130, p = 0.033), which was driven by the patients with major depressive disorder (tau = -0.237, p = 0.031). Suicidal ideation severity was also negatively correlated with TNF-alpha (tau = -0.231; p < 0.001), positively correlated with IL-6 (tau = 0.154, p = 0.015), and CRP levels (tau = 0.153, p = 0.015), but no differences were observed in group-stratified analyses. The association between plasma ACTH levels and suicidal ideation severity in patients with major depressive disorder remained robust to adjustment for major confounders (adjusted for age, sex, education years, body mass index, smoking status, plasma CRP and PEth concentration (measuring chronic alcohol exposure), and antidepressant use) in the linear regression model (t = -2.71, p = 0.011), as well as additionally adjusting for depression severity (t = -2.99, p = 0.006).

Discussion

The present study shows an association between plasma ACTH levels and suicidal ideation severity in patients with major depressive disorder, robust to adjustment for antidepressant use and depression severity. This finding highlights the potential role of ACTH, in elucidating the effects of stress and mental health disorders. Our findings underscore the importance of the HPA axis in the diagnosis and treatment of suicidal ideation in major depressive disorder and invite further research on interventions targeting this pathway.

Immunological alterations in patients with current and lifetime suicide ideation and attempts: Examining the relationship with depressive symptoms

Background

Suicidal ideation and attempt (SI/SA) have been associated with dysregulation of the immune response and inflammation. However, few studies have explored how innate and acquired cellular immunity impact on the peripheral immune response. Our study addresses this gap by examining the composition of peripheral immune cells and humoral markers among individuals with current SI/SA, individuals with a history of SI/SA, and healthy controls (HC). Additionally, we aim to explore whether depressive symptoms settle the relationship between inflammation and SI/SA.

Methods

This is a multicenter case-control study that included 105 participants. Clinical and demographic characterists together with hemogram parameters, soluble pro and anti-inflamatory factors, and specific innate and adaptive immune cell populations were compared among patients with current SI/SA (n = 21), a history of lifetime SI/SA (n = 42), and HC (n = 42).

Results

Patients with both current and lifetime SI/SA had a significant increase in the absolute count of monocytes and in the monocyte/lymphocyte ratio (MLR). Additionally, patients with current and lifetime SI/SA showed a significant increase in high-sensitivity C- reactive protein (hs-CRP), and patients with lifetime SI/SA also showed higher levels of Erythrocyte Sedimentation Rate (ESR). The cellular inflammatory status of patients with SI/SA was characterized by altered proportions of monocytes with higher levels of nonclassical and intermediate monocytes. No differences were observed in the number of lymphocytes and the proportion of CD4 and CD8 between patients and HC, but we found differences in markers of exhaustion of CD4 lymphocytes, with increased levels of Programmed cell death protein 1 (PD1) in Current SI/SA and Lymphocyte activation gene 3 (LAG3) in Current SI/SA and Lifetime SI/SA compared to HC. The plasmainflammatory status was marked by higher levels of soluble Triggering receptor expressed on myeloid cells 2 (sTREM2) in patients with lifetime SI/SA compared to HC. Finally, the multinomial analysis indicates that inflammation and depressive symptoms are independently associated with SI/SA.

Conclusion

This study highlights the association of immunological alterations with SI/SA. Furthremore, SI/SA is independently influenced by depressive symptoms and inflammation. This may have important therapeutic implications, as in these patients, it may be necessary to treat the inflammatory process beyond treating the depressive symptoms.

Association between peripheral plasma cytokine levels and suicidal ideation in first-episode, drug-naïve major depressive disorder

BACKGROUND

Inflammatory processes could potentially impact both mood and suicide risk, however, the relationship between cytokines and suicidal ideation remains unclear. This study aimed to investigate the association between plasma levels of cytokines and suicidal ideation in population with major depressive disorders (MDD).

METHODS

A cross-sectional study was performed to assess the peripheral plasma levels of interleukin-1β (IL-1β), IL-2, IL-6, IL-8, IL-10 and tumor necrosis factor-α (TNF-α) in 88 Chinese Han first-episode drug-naïve MDD patients. Suicidal ideation in the past week were identified using the Beck Scale for Suicide Ideation-Chinese Version (BSI-CV). The Hamilton Depression Rating Scale-17 (HAMD-17), the Hamilton Anxiety Rating Scale-14 (HAMA-14) and the Childhood Trauma Questionnaire (CTQ) was used to assess depression, anxiety and childhood trauma. Multivariable logistic regression models were used to estimate the association between cytokines and suicidal ideation. Interaction and stratified analyses were conducted according to age, sex, marital status, education, smoking status, BMI and physical activity.

RESULTS

Among the 88 participants, 42 individuals (47.7%) reported suicidal ideation within the past week. In the fully adjusted model, a statistically significant trend was observed in the association between IL-2 level and suicidal ideation (OR: 1.40, 95% CI: 1.00-1.97). The stratified analysis showed a statistically significant association between IL-6 level and suicidal ideation among younger people (OR: 1.17, 95% CI: 1.01-1.36) and a significant positive association between IL-8 (OR: 1.59, 95% CI: 1.03-2.44) and IL-10 (OR: 2.51, 95% CI: 1.27-4.96) levels and suicide ideation among higher educated populations.

LIMITATIONS

The cross-sectional design, residual confounding effects and small sample size CONCLUSION: Our findings indicate a significant positive association between plasma IL-2 level and suicidal ideation in MDD patients. IL-2 has the potential to be a biomarker of suicidal ideation in patients with depression.

Impacts of inflammatory cytokines on depression: a cohort study

BACKGROUND

Inflammatory factors are associated with depression. We seek to investigate the correlation between inflammatory cytokines and prognosis of depression or suicidal ideation and behavior at 3 months in depression patients.

METHODS

Eighty-two depressed outpatients were recruited and treated as usual. Plasma cytokines were measured at baseline. Patients were followed up with Patient Health Questionnaire-9 and suicidal ideation and behavior according to the item 3 of Hamilton depression scale for 3 months.

RESULTS

Compared to the depression patients with low level of interleukin-1β, the high one had severe depressive symptoms at month 2 and 3 (B 0.92, P < 0.01; B 0.86, P = 0.02; respectively). The incidence of suicidal ideation or behavior was 18.3% at 3 months. Depression patients with high levels of tumor necrosis factor-α showed high risk of suicidal ideation and behavior than the low one (OR 2.16, 95% CI 1.00-4.65, P = 0.04).

CONCLUSIONS

High levels of interleukin-1β and tumor necrosis factor-α were predictive of middle-term severe depressive symptoms and suicidal ideation and behavior respectively.

Grey matter abnormalities in major depressive disorder patients with suicide attempts: A systematic review of age-specific differences

Background

Previous studies have reported alterations in brain structure in major depressive disorder (MDD) patients with suicide attempts. However, age-related changes in suicidal MDD patients remain unclear.

Methods

We performed a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Embase, PubMed, and Web of Science were searched to identify relevant studies from inception to January 2023. All voxel-based and surface-based morphometry studies comparing suicidal MDD patients to MDD or healthy controls were included. Studies were then grouped by age range (old, middle-age, adolescent) and the commonalities and age-related structural brain alterations were summarized. The included studies were evaluated using the Newcastle-Ottawa Scale (NOS).

Results

A total of 17 studies met the inclusion criteria, including 3 of late-life depression (LLD) patients, 11 of middle-aged depression (MAD) patients, and 3 of adolescent depression (AOD) patients. The majority of studies had moderate to high NOS scores, indicating good quality. Patients in all three age groups exhibited extensive alterations in the lateral, medial, and orbital regions of the frontal lobes. Furthermore, suicidal MAD patients showed a specific decrease in the gray matter volume of the dorsolateral prefrontal cortex compared to suicidal LLD patients. Cortical thickness and left angular gyrus volume were decreased in suicidal MAD and suicidal LLD patients, but increased in suicidal AOD patients.

Conclusion

This systematic review summarizes structural brain changes in suicidal MDD patients at three age groups: elderly, middle-aged, and adolescent. These findings help elucidate the common circuitry of MDD related to suicide over the lifespan and highlight unique circuitry associated with different ages. These findings may help predict the risk of suicide in MDD patients at different ages.

[Ketamine and suicidal behavior: Contribution of animal models of aggression-impulsivity to understanding its mechanism of action]

More than two-thirds of suicides occur during a major depressive episode. Acting out prevention measures and therapeutic options to manage the suicidal crisis are limited. The impulsive-aggressive dimensions are vulnerability factors associated with suicide in patients suffering from a characterized depressive episode: this can be a dimension involved in animals. Impulsive and aggressive rodent models can help analyze, at least in part, the neurobiology of suicide and the beneficial effects of treatments. Ketamine, a glutamatergic antagonist, by rapidly improving the symptoms of depressive episodes, would help reduce suicidal thoughts in the short term. Animal models share with humans impulsive and aggressive endophenotypes modulated by the serotonergic system (5-HTB receptor, MAO-A enzyme), neuroinflammation or the hypothalamic-pituitary-adrenal axis and stress. Significant effects of ketamine on these endophenotypes remain to be demonstrated.

[How can ketamine be used to manage suicidal risk?]

In France, suicidal behaviors remain a major public health issue. Depressed patients with suicidal ideation have more severe depressive symptoms, a more unfavorable disease course, and a greater number of suicide attempts than patients without suicidal ideation. Unfortunately, conventional antidepressants tend to be less effective in patients with suicidal tendencies than in those without. Nevertheless, promising advancements have emerged with the use of ketamine, which has shown significant and rapid efficacy in reducing the intensity of suicidal ideation in depressed patients within the first 72 h after its administration. Several mechanisms are potentially involved: (1) reduction of anhedonia. It has been demonstrated that ketamine reduces both anhedonia and suicidal ideation. In depressed patients, the reduction of anhedonia observed 2 h after ketamine administration is associated with metabolic changes in the anterior cingulate cortex involved in suicidal ideation; (2) activation of neuroplasticity cascades. The reduction in suicidal ideation within 24 h following ketamine administration is correlated with changes in plasma BDNF levels and is modulated by the Val66Met functional polymorphism of the BDNF gene. Moreover, preclinical and clinical studies have shown that ketamine induces functional and connectivity changes in the prefrontal and anterior cingulate regions, which are strongly implicated in suicidal behaviors; (3) reduction of inflammation. It is now widely accepted that suicidal behaviors are associated with low-grade inflammation, and with elevated quinolinic acid and reduced kynurenic acid levels. Interestingly, predictors of a reduction in suicidal ideation after ketamine infusion include initial severity of suicidal thoughts and depression, as well as baseline blood levels of kynurenic acid; (4) involvement of the opioidergic system. Post-mortem studies have indicated alterations in the opioidergic system related to suicidal behaviors. A recent study suggested that the antisuicidal effect of ketamine may depend on this system because naltrexone, an antagonist of mu opioid receptors, abolished the typical antidepressant effect and reduction in suicidal ideation observed following ketamine administration. In conclusion, ketamine exhibits promising potential in mitigating suicidal ideation - its effects are specific, rapid, albeit temporary. The suggested mechanisms driving its efficacy are multifaceted. Nevertheless, it is yet to be determined whether ketamine administration can effectively prevent suicidal behaviors.

Immune-related biomarkers and suicidal behaviors: A meta-analysis

Biomarkers that can differentiate between psychiatric disorders with and without suicidal behavior history from each other and from healthy volunteers may explain part of the pathogenesis of suicidal behavior. We conducted the hitherto largest meta-analysis comparing immune biomarkers between subjects with and without suicide attempt history or death by suicide. The study protocol was registered with PROSPERO, CRD42020212841. Standardized mean differences (SMD) were pooled with random-effects models. Heterogeneity between studies was assessed with the I2-statistic and publication bias was evaluated by the Egger test and funnel plots. Data were based on 36 studies including 2679 persons with suicidal behaviors and 6839 comparison subjects, and four immune-related biomarkers (CRP, IL-6, TNF-α and IL-1β). Suicidal behavior was associated with higher CRP blood levels compared with: healthy controls (SMD [95%CI] = 1.42[0.85-1.98]); patients with depression alone (SMD [95%CI] = 1.23[0.20-2.26]); and patients with any psychiatric disorders (SMD [95%CI] = 0.39[0.22-0.55]). IL-6 blood level was higher in patients with suicidal behaviors compared with healthy controls (SMD [95%CI] = 1.13[0.45-1.82]) and when compared with psychiatric patients without suicidal behaviors (SMD [95%CI] = 0.22 [0.11-0.33]). Meta-regression and subgroup analyses revealed that increased CRP in suicidal behavior is primarily driven by recent suicidal behavior. These results implicate the immune system and inflammatory response in suicidal behavior independent of a relationship to major psychiatric disorders, and that these biological measures are predominantly state-dependent markers. Future studies are needed to determine the cause-and-effect relationship of these immune system biomarkers with suicidal behavior, and their potential predictive properties.

Association of interleukin-6 with suicidal ideation in veterans: a longitudinal perspective

Introduction

Studies showing associations between inflammation in suicide are typically cross-sectional. Present study investigated how cytokine levels track with suicidal ideation and severity longitudinally.

Methods

Veterans with a diagnosis of major depressive disorder (MDD) with or without suicide attempt history (MDD/SA n = 38, MDD/NS n = 41) and non-psychiatric non-attempter controls (HC n = 33) were recruited, MDD/SA and HC groups were followed longitudinally at 3 months and 6 months. Blood plasma was collected and processed using Luminex Immunology Multiplex technology.

Results

Significant differences in depression severity (BDI) and suicidal ideation severity (SSI) were observed across all groups at study entry, wherein MDD/SA group had the highest scores followed by MDD/NS and HC, respectively. Cytokines IL-1β, IL-4, TNF-α, IFN-γ, and IL-6 were examined at study entry and longitudinally, with IL6 levels differing significantly across the groups (p = 0.0123) at study entry. Significant differences in changes in cytokine levels between depressed attempters and the control group were detected for IL-6 (interaction F1,91.77 = 5.58, p = 0.0203) and TNF-α (F1,101.73 = 4.69, p = 0.0327). However, only depressed attempters showed a significant change, in IL-6 and TNF-α levels, decreasing over time [IL-6: b = -0.04, 95% CI = (-0.08, -0.01), p = 0.0245 and TNF-α: b = -0.02, 95% CI = (-0.04, -0.01), p = 0.0196]. Although IL-6 levels were not predictive of suicidal ideation presence [OR = 1.34, 95% CI = (0.77, 2.33), p = 0.3067], IL-6 levels were significantly associated with suicidal ideation severity (b = 0.19, p = 0.0422).

Discussion

IL-6 was not associated with presence of suicidal ideation. IL-6 however, was associated with severity of ideation, suggesting that IL-6 may be useful in clinical practice, as an objective marker of heightened suicide risk.

Interpersonal Life Stress and Inflammatory Reactivity as Prospective Predictors of Suicide Attempts in Adolescent Females

Adolescents' suicidal behavior frequently is preceded by interpersonal stress, but not all who experience distress attempt to end their lives. Recent theories have posited individual differences in stress-related inflammatory reactivity may be associated with psychopathology risk; this study examined inflammatory reactivity as a moderator of the prospective association between interpersonal stress and adolescents' suicidal behavior. Participants included 157 at-risk adolescent females (ages 12 to 16 years) and assessed individual differences in proinflammatory cytokine responses to a brief laboratory-based social stressor, both interpersonal and non-interpersonal life events, and suicidal behavior over an 18-month follow-up period. Measuring levels of the key proinflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) before and after an experimentally-induced social stressor, results revealed that blunted cytokine reactivity heightened the effect of high interpersonal stress exposure on risk for suicidal behaviors over the subsequent 9 months. Significant effects were not revealed for non-interpersonally themed stress. Finding highlight the urgent need for more research examining inflammation reactivity among adolescents.

Comparison of oxidative stress parameters, thiol-disulfide homeostasis, and pro-inflammatory cytokines levels in patients with bipolar disorder and their first-degree relatives

BACKGROUND

In this study, we aimed to compare the oxidative stress parameters, thiol-disulfide homeostasis, and plasma pro-inflammatory cytokines levels of patients with bipolar disorder (BD), BD patients' first-degree relatives (FDRs), and the healthy controls (HCs).

METHODS

Thirty-five patients with BD, 35 FDRs of BD, and 35 healthy controls (HCs) were included. The individuals' ages varied from 28 to 58, and the groups were well-matched in terms of age and gender. The total thiol (TT), native thiol (NT), disulfide (DIS), total oxidant status (TOS), total antioxidant status (TAS), IL-1β, IL-6, and TNF-α concentrations were measured from serum samples. The oxidative stress index (OSI) was calculated using mathematical formulas.

RESULTS

TOS was significantly higher in both patients and FDRs than HCs (p < 0.01 for all pairwise comparisons). OSI, DIS, oxidized thiol, and the ratio of thiol oxidation-reduction levels were significantly higher in both patients with BD and FDRs than HCs (p < 0.01 for all pairwise comparisons). TAS, TT, NT, and reduced thiol levels were significantly lower in both patients with BD and FDRs than HCs (p < 0.01 for all pairwise comparisons). IL-1β, IL-6, and TNF-α were significantly higher in both patients and FDRs than HCs (p < 0.01 for all pairwise comparisons).

LIMITATIONS

Small sample size.

CONCLUSIONS

Early diagnosis is important for treating of bipolar disorder. TT, NT, DIS, TOS, TAS, OSI, IL1-β, IL-6, and TNF-α can be used as potential biomarkers in the early diagnosis and intervention of BD. Furthermore, oxidative/antioxidative markers and plasma pro-inflammatory cytokine parameters may guide the determination of the disease's activity and response to treatment.

Pharmacological Mechanism of Ketamine in Suicidal Behavior Based on Animal Models of Aggressiveness and Impulsivity: A Narrative Review

Around 700,000 people die from suicide each year in the world. Approximately 90% of suicides have a history of mental illness, and more than two-thirds occur during a major depressive episode. Specific therapeutic options to manage the suicidal crisis are limited and measures to prevent acting out also remain limited. Drugs shown to reduce the risk of suicide (antidepressants, lithium, or clozapine) necessitate a long delay of onset. To date, no treatment is indicated for the treatment of suicidality. Ketamine, a glutamate NMDA receptor antagonist, is a fast-acting antidepressant with significant effects on suicidal ideation in the short term, while its effects on suicidal acts still need to be demonstrated. In the present article, we reviewed the literature on preclinical studies in order to identify the potential anti-suicidal pharmacological targets of ketamine. Impulsive-aggressive traits are one of the vulnerability factors common to suicide in patients with unipolar and bipolar depression. Preclinical studies in rodent models with impulsivity, aggressiveness, and anhedonia may help to analyze, at least in part, suicide neurobiology, as well as the beneficial effects of ketamine/esketamine on reducing suicidal ideations and preventing suicidal acts. The present review focuses on disruptions in the serotonergic system (5-HT_B receptor, MAO-A enzyme), neuroinflammation, and/or the HPA axis in rodent models with an impulsive/aggressive phenotype, because these traits are critical risk factors for suicide in humans. Ketamine can modulate these endophenotypes of suicide in human as well as in animal models. The main pharmacological properties of ketamine are then summarized. Finally, numerous questions arose regarding the mechanisms by which ketamine may prevent an impulsive-aggressive phenotype in rodents and suicidal ideations in humans. Animal models of anxiety/depression are important tools to better understand the pathophysiology of depressed patients, and in helping develop novel and fast antidepressant drugs with anti-suicidal properties and clinical utility.

Impact of antidepressant treatment on complete blood count parameters and inflammatory ratios in adolescents with major depressive disorder

Neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) are novel biomarkers of systemic inflammation in depression. This study aims to examines the impact of selective serotonin reuptake inhibitor (SSRI) treatment on complete blood count (CBC) parameters and inflammatory ratios in major depressive disorder (MDD). CBC parameters and inflammatory ratios were examined in a total of 45 drug-naive adolescents with MDD and were compared before and after SSRI treatment for 12 weeks and between responders and nonresponders. Following SSRI treatment in MDD, the red blood cell (RBC) count, hematocrit, and red cell distribution width (RDW) significantly increased. Hemoglobin tended to increase. The MCV, MCH, and MCHC values decreased significantly. White blood cell count, neutrophil percentage, monocyte count, and monocyte and basophil percentages decreased significantly. The percentage of lymphocytes significantly increased. The MLR decreased, whereas the NLR tended to decrease. Platelet count and PLR did not change significantly. A higher platelet count at baseline has been associated with non-response to SSRI treatment in patients with MDD. SSRI treatment increased RBC count, hematocrit, RDW, and lymphocyte percentage, and reduced MLR, and neutrophil and monocyte percentages in responders MDD. We suggest higher platelet counts at baseline as a potential predictor of nonresponders.

Inflammation, cognitive dysfunction, and suicidal ideation among patients with major depression

BACKGROUND

Dysregulated proinflammatory cytokines have been shown to be associated with suicidal behavior. Cognitive deficits in working memory and inhibitory control have been demonstrated in depressed patients and people with suicidal ideation (SI). However, the association between proinflammatory cytokines, SI, and cognitive deficits in patients with major depressive disorder (MDD) remains unclear.

METHODS

A total of 77 patients with MDD and age-/sex-matched 60 healthy individuals were recruited. MDD patients were divided into two groups: with SI (n = 36) and no SI (n = 41). SI was defined by a score of ≥2 in item 3 of the 17-item Hamilton Rating Scale for Depression. Levels of proinflammatory cytokines, including soluble interleukin-6 receptor, soluble tumor necrosis factor-α receptor type 1, and C-reactive protein (CRP), were measured, and cognitive function was assessed using 2-back task and Go/No-Go task.

RESULTS

Patients with SI had higher levels of CRP than those without SI and controls (P = .007). CRP was positively associated with SI (β = 0.21, P = .037), independent of cognitive function and depressive symptoms. Furthermore, SI was associated with cognitive deficits in working memory and inhibitory control after adjusting for confounding factors (P < .05).

CONCLUSION

Our findings suggest that higher levels of serum CRP and deficits in working memory and inhibitory control may be associated with higher SI among patients with MDD.

Pro-inflammatory cytokines and suicidal behavior among patients with bipolar I disorder

OBJECTIVE

Suicidal behavior and different mood states of bipolar I disorder (BD) have been shown to be associated with dysregulated proinflammatory cytokines. Only a few studies have examined the association between inflammation and SB in BD, and the association between proinflammatory cytokines, SB, and cognitive deficits in patients with BD remains unclear.

METHODS

77 patients with BD and 61 age-/sex-matched healthy controls were recruited. Patients were divided into two groups: with suicidal ideation (SI; n = 21) and no SI (n = 56). SI was defined by a score of ≥1 in item 10 of Montgomery Åsberg Depression Rating Scale. Levels of proinflammatory cytokines, including soluble interleukin-6 receptor (sIL-6R), soluble tumor necrosis factor-α receptor type 1 (sTNF-αR1), and C-reactive protein (CRP), were measured, and cognitive function was assessed using 2-back task and Go/No-Go task.

RESULTS

Patients with SI had higher levels of sTNF-αR1 than those without SI and the controls (p = .004). BD patients with or without a history of suicide attempt had higher levels of CRP than the controls. SI was associated with serum levels of sTNF-αR1 and IL-6sR, even after additionally controlling for working memory and inhibitory control (p < .05).

CONCLUSION

This study indicates that serum levels of sTNF-αR1 have distinct differences between BD patients with or without SI, and our findings strengthen the hypothesis of a link between suicidal behavior and neuro-inflammation pathophysiology in BD.

Hyper/neuroinflammation in COVID-19 and suicide etiopathogenesis: Hypothesis for a nefarious collision?

Accumulating scientific and clinical evidence highlighted pathological hyperinflammation as a cardinal feature of SARS-CoV-2 infection and acute COVID-19 disease. With the emergence of long COVID-19 syndrome, several chronic health consequences, including neuropsychiatric sequelae, have gained attention from the public and medical communities. Since inflammatory mediators have also been accredited as putative biomarkers of suicidal ideations and behaviors, hyper- and neuroinflammation might share some colliding points, overlapping and being interconnected in the context of COVID-19. This review aims to provide a summary of current knowledge on the molecular and cellular mechanisms of COVID-19-associated hyper/neuroinflammation with focus on their relevance to the inflammatory hypothesis of suicide development. Subsequently, strategies to alleviate COVID-19 hyper/neuroinflammation by immunomodulatory agents (many of which at experimental stages) as well as psychopharmacologic/psychotherapeutic approaches are also mentioned. While suicide risk in COVID-19 survivors - until now little known - needs further analysis through longitudinal studies, current observations and mechanistic postulates warrant additional attention to this possibly emerging mental health concern.

Inflammation biomarkers in suicide attempts and their relation to abuse, global functioning and cognition

OBJECTIVES

To explore the link between cytokines and suicide attempts and their relationship with the psychological aspects of this complex multifactorial phenomenon.

METHODS

96 participants, including 20 patients with a recent suicide attempt and diagnosis of Major Depression Disorder (MDD), 33 MDD patients with a lifetime history of suicide attempt, 23 non-attempter MDD patients, and 20 healthy controls underwent an assessment on depressive symptoms, global functioning, aggressive behaviour, presence of abuse and attention performance. Additionally, all participants had a blood extraction for IL-2, IL2-R, IL-4, IL-6, and TNF-α plasma levels analysis.

RESULTS

IL-6 levels were significantly different across groups (F(3,89)=3.690; p = 0.015), with higher concentrations in both recent (p = 0.04) and distant (p = 0.015) attempt in comparison to MDD non-attempters. IL-6 was associated with adult physical abuse (B = 2.591; p = 0.021), lower global functioning score (B = -0.512; p = 0.011), and poorer performance on attention (B = -0.897; p = 0.011).

CONCLUSIONS

Recent and distant suicidal behaviour is associated with elevated IL-6 levels, which may be influenced by stressful and traumatic experiences. Elevated concentrations of IL-6 could have a negative impact on attention, increasing suicide risk. More research is needed to clarify the role of cytokines in suicide-related features to explore novel treatments and more effective preventive interventions.

Inflammation and nitro-oxidative stress in current suicidal attempts and current suicidal ideation: a systematic review and meta-analysis

A meta-analysis showed a significant association between activated immune-inflammatory and nitro-oxidative (IO&NS) pathways and suicide attempts (SA). There is no data on whether recent suicidal ideation (SI) is accompanied by activated IO&NS pathways and whether there are differences between recent SA and SI. The current study searched PubMed, Google Scholar, and Web of Science, for articles published from inception until May 10, 2021, and systematically reviewed and meta-analysed the association between recent SA/SI (<3 months) and IO&NS biomarkers. We included studies which compared psychiatric patients with and without SA and SI and controls (either healthy controls or patients without SA/SI) and used meta-analysis (random-effect model with restricted maximum-likelihood) to delineate effect sizes with 95% confidence intervals (CI). Our search included 59 studies comprising 4.034 SA/SI cases and 12.377 controls. Patients with SA/SI showed activated IO&NS pathways (SMD: 0.299; CI: 0.200; 0.397) when compared to controls. The immune profiles were more strongly associated with SA than with SI, particularly when compared to healthy controls, as evidenced by activated IO&NS (SMD: 0.796; CI: 0.503; 1.089), immune (SMD: 1.409; CI: 0.637; 1.462), inflammatory (SMD: 1.200; CI: 0.584; 1.816), and neurotoxic (SMD: 0.904; CI: 0.431; 1.378) pathways. The effects sizes of the IO&NS, immune and inflammatory profiles were significantly greater in SA than in SI. In conclusion: activated IO&NS pathways are associated with recent SA and SI, and inflammation, T helper-1 activation, nitro-oxidative stress, lowered neuroprotection, and increased neurotoxicity explain at least in part why psychiatric patients show increased suicidal behaviours, especially SA.

Altered Levels of Plasma Inflammatory Cytokines and White Matter Integrity in Bipolar Disorder Patients With Suicide Attempts

OBJECTIVE

Bipolar disorder (BD) has a higher lifetime rate of suicide attempts (SA) than other psychiatric disorders. Furthermore, BD patients with SA (BD + S) are prone to a worse quality of life. However, the pathophysiology of BD + S is poorly understood. To further reveal the potential mechanisms of BD + S, abnormalities in peripheral plasma inflammatory cytokines and brain white matter (WM) in BD + S, as well as the correlation between them are investigated.

METHODS

We tested the levels of TNF-α, IL-1β, and IL-6 in peripheral plasma and collected the diffusion tensor imaging (DTI) data from 14 BD + S, 24 BD patients without SA (BD-S), and 26 healthy controls (HCs). The three groups were matched by age and gender. The levels of TNF-α, IL-1β, and IL-6 were detected by Luminex multifactor detection technology, and the fractional anisotropy (FA) values were employed to depict the alterations of WM. Partial correlation analyses were conducted to detect correlations between levels of TNF-α, IL-1β, and IL-6 and changes of WM, and the relationships between severity of clinical symptoms, including scores of HAMD-17 and YMRS, and cytokine levels or FA values in all groups.

RESULTS

For plasma inflammatory cytokines, there was no significant difference in their levels except for IL-6 among the three groups. Post-hoc analyses revealed that increased IL-6 level was only detected in BD + S (p < 0.05, Bonferroni correction). For DTI, BD + S showed specifically decreased FA in the bilateral middle cerebellar peduncle and the left superior corona radiata compared to BD-S and HCs (p < 0.05, Bonferroni correction). Additionally, both BD + S and BD-S groups revealed decreased FA in the bilateral body and genu of corpus callosum (CC) compared to HCs (p < 0.05, Bonferroni correction). No significant correlation between plasma inflammatory cytokines and WM integrity was found. In the BD + S group, we found negative correlation between the scores of YMRS and FA values of the left middle cerebellar peduncle (r = -0.74, p = 0.035).

CONCLUSION

The inflammation and impaired WM integrity may provide a scientific basis to understand the potential mechanisms of BD + S.

Genetic variations related to inflammation in suicidal ideation and behavior: A systematic review

BACKGROUND/OBJECTIVES

Immune-inflammatory changes have been found in all types of suicidal ideation and behavior (SIB), independently of associated mental disorders. Since several Single Nucleotide Polymorphisms (SNPs) affect the function of inflammation-related genes, we searched the literature for genetic variations potentially altering inflammatory processes in SIB.

METHODS

We included studies that looked for associations between SIB and SNPs in genes related to inflammatory processes. Case reports, literature reviews, and animal studies were excluded. Articles were retrieved from PubMed and PsycINFO databases, Google Scholar and GreySource Index until September 17th, 2022. Quality was assessed using Q-Genie.

RESULTS

We analyzed 32 studies. SIB has been associated with eighteen SNPs located in genes encoding for interleukin-8 (rs4073), C-reactive protein (rs1130864), tumor necrosis factor α (rs1800629, rs361525, and rs1099724), tumor necrosis factor receptor 2 (rs1061622), transforming growth factor β-1 (rs1982073), acid phosphatase 1 (rs7419262, rs300774), interleukin-10 (rs1800896), interferon γ (rs2430561), amino-carboxy muconate semialdehyde decarboxylase (rs2121337), interleukin 7 (rs10448044, rs10448042), macrophage migration inhibitory factor (rs755622), interleukin 1-α (rs1800587), and interleukin 1-β (rs1143634 and rs16944. A genome-wide association study reported one association at the threshold of significance with the rs300774 SNP, located in the 2p25 region containing ACP1 gene.

DISCUSSION

The studies included were methodologically and clinically diverse and of moderate quality. Their findings suggest that some inflammation-related SNPs could increase the likelihood of SIB but the evidence to date is insufficient. Further research using gene-gene (GxG) and gene-environment (GxE) approaches is warranted.

SYSTEMATIC REVIEW REGISTRATION

[https://www.crd.york.ac.uk], identifier [CRD42022296310].

Increased levels of neurofilament light chain in suicide attempters' serum

Background

A specific biological vulnerability underlies suicidal behavior. Recent findings have suggested a possible role of inflammation and neuroaxonal injury. However, the relationship between inflammation and clinical symptoms in this disorder is still unclear. The objective of this study is applying novel blood markers of neuroaxonal integrity such as neurofilament light chain (NfL) and comparing the results with the healthy control subjects.

Methods

In this cross-sectional study patients with suicide attempts were evaluated. The serum concentration of NfL on admission was measured by enzyme-linked immunosorbent assays.

Results

A total of 50 patients with a suicide attempts and 35 healthy controls were included in the study. The levels of NfL in attempted suicide patients were significantly higher in comparison with healthy controls (40.52 ± 33.54 vs 13.73 ± 5.11, P < 0.001). A significant association between serum levels of NfL and risk factors for suicide was not found.

Conclusion

These findings indicate that axonal damage may be an underlying neuropathological component of suicide attempt patients, although no correlation was observed with clinical features. This line of work could lead to new horizons in understanding the neurobiology of suicidal attempts and the development of better management strategies for these patients.

Allergies, infections, and psychiatric disorders among Black Americans: findings from the National Survey of American Life

Objectives: An emerging body of literature shows that allergies and infections are associated with psychiatric disorders, though there is little research to confirm these associations among Black Americans in the United States.Design: We analyzed data from the National Survey of American Life, and used multivariable logistic regression models to examine the associations between past 12-month allergies/infections and past 12-month psychiatric disorders, adjusting for socio-demographic characteristics, tobacco use, lifetime diabetes, and body mass index.Results: We found that allergies/infections were associated with mood, anxiety, and eating disorders, but not alcohol or substance use disorders. We detected effect modification by ethnicity, with stronger odds for mood, anxiety disorders, and alcohol use disorders, with no significant associations for substance use or eating disorders among Caribbean Blacks.Conclusions: Our findings underscore the importance of screening for psychiatric disorders among Black individuals complaining of allergies/infections, and the need to also treat allergies/infections among people with psychiatric disorders.

History of Suicide Attempts and COVID-19 Infection in Veterans with Schizophrenia or Schizoaffective Disorder: Moderating Effects of Age and Body Mass Index

Introduction

Relative to the general population, patients with schizophrenia or schizoaffective disorder have higher rates of suicide attempts and mortality from COVID-19 infection. Therefore, determining whether a history of suicide attempt is associated with COVID-19 in patients with schizophrenia or schizoaffective disorder has implications for COVID-19 vulnerability stratification in this patient population.

Methods

We carried out cross-sectional analyses of electronic health records of veterans with a diagnosis of schizophrenia or schizoaffective disorder that received treatment at any United States Veterans Affairs Medical Center between January 1, 2020, and January 31, 2021. We used logistic regression to estimate unadjusted and adjusted (including age, sex, race, marital status, body mass index (BMI), and a medical comorbidity score) odds ratios (ORs) for COVID-19 positivity in suicide attempters relative to nonattempters.

Results

A total of 101,032 veterans (mean age 56.67 ± 13.13 years; males 91,715 [90.8%]) were included in the analyses. There were 2,703 (2.7%) suicide attempters and 719 (0.7%) patients were positive for COVID-19. The association between history of suicide attempt and COVID-19 positivity was modified by age and BMI, such that the relationship was only significant in patients younger than 59 years, and in obese (BMI ≥30) patients (adjusted OR 3.42, 95% CI 2.02–5.79 and OR 2.85, 95% CI 1.65–4.94, respectively).

Conclusions

Higher rates of COVID-19 in young or obese suicide attempters with a diagnosis of schizophrenia or schizoaffective disorder might be due to the elevated risk for the infection in this subgroup of patients.

Suicide attempts are associated with activated immune-inflammatory, nitro-oxidative, and neurotoxic pathways: A systematic review and meta-analysis

BACKGROUND

Suicide attempts (SA) frequently occur in patients with mood disorders and schizophrenia, which are both accompanied by activated immune-inflammatory and nitro-oxidative (IO&NS) pathways.

METHODS

We searched PubMed, Google Scholar, and Web of Science, for articles published from inception until February 1, 2021. We included studies that compared blood biomarkers in psychiatric patients with (SA+) and without SA (SA-) and heathy controls and we combined different IO&NS biomarkers into immune, inflammatory, and neurotoxic profiles and used meta-analysis (random-effect model with restricted maximum-likelihood) to delineate effect sizes with 95% confidence interval (CI).

FINDINGS

Our search included 51 studies comprising 4.945 SA+ patients and 24.148 controls. We stratified the control group into healthy controls and SA- patients. SA+ patients showed significantly (p<0.001) increased immune activation (SMD: 1.044; CI: 0.599, 1.489), inflammation (SMD: 1.109; CI: 0.505, 1.714), neurotoxicity (SMD: 0.879; CI: 0.465, 1.293), and lowered neuroprotection (SMD: 0.648; CI: 0.354, 0.941) as compared with healthy controls. When compared with SA- patients, those with SA+ showed significant (p<0.001) immune activation (SMD: 0.290; CI: 0.183, 0.397), inflammation (SMD: 0.311; CI: 0.191, 0.432), and neurotoxicity (SMD: 0.315; CI: 0.198, 0.432), and lowered neuroprotection (SMD: 0.341; CI: 0.167, 0.515). Patients with current, but not lifetime, SA showed significant (p<0.001) levels of inflammation and neurotoxicity as compared with controls.

CONCLUSIONS

Patients with immune activation are at a higher risk of SA which may be explained by increased neurotoxicity due to inflammation and nitro-oxidative stress. This meta-analysis discovered new biomarkers of SA and therapeutic targets to treat individuals with SA.

Increased C-reactive protein concentration and suicidal behavior in people with psychiatric disorders: A systematic review and meta-analysis

OBJECTIVE

Suicide is a leading cause of death worldwide. Identifying factors associated with suicidality (suicidal ideation [SI]/suicidal behavior) could increase our understanding of the pathophysiological underpinnings of suicide and improve its prevention.

METHODS

We conducted a systematic review (PubMed/PsycInfo/Cochrane databases, up to September 2020) and random-effect meta-analysis including observational studies comparing peripheral C-reactive protein (CRP) levels in suicidal versus non-suicidal patients affected by any psychiatric disorder and healthy controls (HC). Primary outcome was the CRP standardized mean difference (SMD) between patients with high suicidality versus those with absent or low suicidality. Secondary outcomes were SMD of CRP levels between those with suicide attempt versus no suicide attempt, as well as between those with (high) versus low or absent SI. Quality of included studies was measured with Newcastle-Ottawa scale.

RESULTS

Out of initial 550 references, 21 observational studies involving 7682 subjects (7445 with mood disorders or first-episode psychosis, 237 HC) were included. A significant association of CRP levels with suicidality (SMD 0.688, 95% CI 0.476-0.9, p < 0.001) emerged. CRP levels were higher in individuals with high SI (SMD 1.145, 95% CI 0.273-2.018, p = 0.010) and in those with suicide attempt (SMD 0.549, 95%CI 0.363-0.735, p < 0.001) than non-suicidal individuals (either patients or HC). Main analyses were confirmed in sensitivity analysis (removing HC), and after adjusting for publication bias. The cross-sectional design of included studies, and the high heterogeneity of diagnosis and treatment limit the generalizability of these results. Median quality of included studies was high.

CONCLUSION

CRP is associated with higher suicidality in patients with mental disorders. Large cohort studies longitudinally monitoring CRP levels are needed to explore its longitudinal association with suicidality.

Potential usefulness of complete blood count parameters and inflammatory ratios as simple biomarkers of depression and suicide risk in drug-naive, adolescents with major depressive disorder

We determined whether an elevated neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) were associated with depression in major depressive disorder (MDD), or suicide risk in MDD patients. A total of 137 adolescents with MDD who were antidepressant-naïve and 56 healthy controls (HC) were included. Recent suicidal behaviors were assessed. The NLR, PLR, and MLR were calculated from parameters obtained from a routine complete blood cell count parameters and compared between the MDD subgroups and HC. Cohen's d was calculated as a measure of effect size. The linear relationship between biomarkers with depression severity or suicidality severity was also analysed. Changes in CBC parameters and inflammatory ratios appeared to be more closely related to the suicidality severity than depressive severity. As compared with HC, the WBC count, neutrophil percentage, platelet count, NLR, and PLR were higher in MDD, whereas the lymphocyte percentage was lower. As compared to non-suicidal ideation (non-SI) MDD and HC, the lymphocyte percentage was decreased in MDD with suicidal attempts (SA), whereas monocyte count and MLR were increased. Suicidal attempts in MDD patients were associated with the lower lymphocytes percentage, as well as the elevated monocyte count and MLR.

Psychoneuroimmunology: The new frontier in suicide research

Elucidating complex, multifactorial phenomena like suicide and suicidal behaviors (SSB) require multidisciplinary fields such as Psychoneuroimmunology (PNI). Indeed, our appreciation of the bidirectional communication channels between the brain and the rest of the body with its immune arsenal as the key player has positioned PNI as a promising field of research. We now know that major psychiatric, behavioral, and somatic disorders related to SSB accompany neuroimmune dysregulation. These disorders range from depression, emotional dysregulation, atopy, and epilepsy to certain viral and parasitic infections. By utilizing epidemiological, genetic, microbial, and molecular approaches, the PNI research community has excogitated novel biomarker candidates and pathways in support of SSB risk stratification at individual level. This remarkable progress in just two previous decades shall, if successful, help implement personalized prevention and treatment strategies, using PNI-assisted tools. The aims of this narrative review and opinion piece are to summarize important discoveries concerning the role of neuroimmune activation in SSB and to highlight important future directions for the field. Major caveats of the findings concerning methodological approaches, clinical reality of frequent comorbid psychopathology, and novel molecular targets are presented. Finally, this review calls on the PNI research community for increased attention towards factors that promote resilience to suicide, while accepting "consciousness" under its wing. Thus, PNI represents the new frontier in suicide research. Future breakthroughs in this discipline shall bring us closer to understanding the biological substrates of qualia i.e., subjective, and experiential meanings of life and death.

A network meta-analysis of stress mediators in suicide behaviour

Stress homeostatic mediators are the most consistently anomalous biomarkers observed in suicide and may therefore point to a common 'core biology' of stress susceptibility, and suicidal behaviour. Previously reported meta-analyses have demonstrated aberrant levels of stress cortisol and inflammatory cytokines in suicide patients compared to controls, and significant associations between the stress regulator FK506-binding protein 51 (FKBP5) gene and suicidal behaviour. Although these independent studies were investigated as separate entities in suicide, stress mediators interact in a dynamic system, collectively giving rise to system changes physiologically, and ultimately psychologically and behaviourally. It is therefore important to study the dynamic network these stress mediators. Network meta-analysis allows for the simultaneous comparison of more than two biological mediators, and for comparisons to be made between mediators that have not been directly compared before, using previously reported, pooled meta data. Such network approaches may help study the complex biological phenomena of suicide and may provide better prediction of biological risk of suicidal states.

METHODS

This study aimed to establish the comparative relationships between key stress mediators in suicidal patients compared to non-suicidal controls using a random-effects network meta-analysis approach.. The key stress mediators included cortisol, six inflammatory markers (interleukin-6 (IL-6), interleukin-4 (IL-4), interleukin-2 (IL-2), tumour necrosis factor-a (TNF-α), interferon (IFN-y) and transforming growth factor β (TGF-β), and the FKBP5 single nucleotide polymorphism (SNP) allele. Data was derived from three previously published meta-analysis. The study population comprised of 1348 suicidal patients, defined as suicide attempters, completers, or patients with severe suicidal ideation, and 1750 non-suicidal controls, defined as healthy controls and psychiatric patients without suicidal ideation or previous attempts.

RESULTS

Pair-wise indirect effects of stress mediators in suicide compared to controls demonstrated that relative to the effect of the FKBP5 risk SNP allele on suicide risk, the magnitude of differences (suicide vs control) for the levels of IL-2 (SMD -0.72; 95% CI, -0.135 to -0.09 and IL-4 (SMD -0.71; 95% CI, -1.34 to -0.08) were significantly smaller (with 95% confidence intervals not crossing the null). The comparative relationships between stress mediators in suicidal behaviour demonstrates that the dynamic stress network relationship is dysregulated in suicide patients when compared to controls.

CONCLUSIONS

This model suggests that a genetic stress susceptibility with downstream abnormal cortisol stress axis functioning, together with anomalous interactions between the inflammatory system, may be one of the neurobiological correlates of suicide behaviour. This biological state may leave the individual physiologically susceptible and unable to cope with environmental stressors, which is consistent with the stress-diathesis hypothesis of suicide behaviour.

Suicidal ideation and suicide attempts: associations with sleep duration, insomnia, and inflammation

BACKGROUND

Sleep disturbance has been consistently identified as an independent contributor to suicide risk. Inflammation has emerged as a potential mechanism linked to both sleep disturbance and suicide risk. This study tested associations between sleep duration, insomnia, and inflammation on suicidal ideation (SI) and history of a suicide attempt (SA).

METHODS

Participants included 2329 adults with current or remitted depression and/or anxiety enrolled in the Netherlands Study of Depression and Anxiety. Sleep duration, insomnia, past week SI, and SA were assessed with self-report measures. Plasma levels of C-reactive protein, interleukin-6, and tumor necrosis factor-α were obtained.

RESULTS

Short sleep duration (⩽6 h) compared to normal sleep duration (7-9 h) was associated with reporting a prior SA, adjusting for covariates [adjusted odds ratio (AOR) 1.68, 95% CI 1.13-2.51]. A higher likelihood of SI during the past week was observed for participants with long sleep duration (⩾10 h) compared to normal sleep duration (AOR 2.22, 95% CI 1.02-4.82), more insomnia symptoms (AOR 1.44, 95% CI 1.14-1.83), and higher IL-6 (AOR 1.31, 95% CI 1.02-1.68). Mediation analyses indicated that the association between long sleep duration and SI was partially explained by IL-6 (AOR 1.02, 95% CI 1.00-1.05).

CONCLUSIONS

These findings from a large sample of adults with depression and/or anxiety provide evidence that both short and long sleep duration, insomnia symptoms, and IL-6 are associated with the indicators of suicide risk. Furthermore, the association between long sleep duration and SI may operate through IL-6.

Neutrophil-to-lymphocyte ratio and C-reactive protein in non-fatal suicidal attempts: A cross-sectional pilot study in Bangladesh

BACKGROUND

Precise identification of risk factors for suicide has been found as fundamentally challenging for the stakeholders. In search of that, the determination of potential biological markers of suicide has been scrutinizing in recent days. However, replicative studies across the culture and time are warranted to utilize the biomarkers in decision-making while considering suicide prevention.

OBJECTIVES

We aimed to measure the neutrophil-to-lymphocyte ratio (NLR) and C-reactive protein (CRP) in non-fatal suicidal attempts.

METHODS

This cross-sectional study was conducted from August 2020 to May 2021. Data were collected from 26 hospitalized patients after an immediate non-fatal suicidal attempt. We collected blood samples and assessed the complete blood count, NLR, and CRP. Data were analyzed by Statistical Package for the Social Science version 24.0 and Microsoft Excel software. We performed the independent Mann-Whitney U test to determine the variations between the groups. A value <.05 was considered as the level of significance.

RESULTS

The mean age of the study population was 24.1 (±7.3), more than half of them (n = 19, 73.1%) were female. The mode of attempt was either hanging (n = 13, 50.0%) or poisoning (n = 13, 50.0%). The previous attempt was noted in 12 (46.2%) cases. The mean CRP level was 16.8 (±30.2) mg/L and the mean NLR level was 8.3 (±6.8) for the total sample. Both the CRP and NLR were significantly higher among those who attempted hanging (P = .019 and .001).

CONCLUSIONS

The current study revealed preliminary findings on CRP and NLR among non-fatal suicides in Bangladesh where both of the parameters were significantly higher in non-fatal hanging.

Periodontal Pathogens and Neuropsychiatric Health

Increasing evidence incriminates low-grade inflammation in cardiovascular, metabolic diseases, and neuropsychiatric clinical conditions, all important causes of morbidity and mortality. One of the upstream and modifiable precipitants and perpetrators of inflammation is chronic periodontitis, a polymicrobial infection with Porphyromonas gingivalis (P. gingivalis) playing a central role in the disease pathogenesis. We review the association between P. gingivalis and cardiovascular, metabolic, and neuropsychiatric illness, and the molecular mechanisms potentially implicated in immune upregulation as well as downregulation induced by the pathogen. In addition to inflammation, translocation of the pathogens to the coronary and peripheral arteries, including brain vasculature, and gut and liver vasculature has important pathophysiological consequences. Distant effects via translocation rely on virulence factors of P. gingivalis such as gingipains, on its synergistic interactions with other pathogens, and on its capability to manipulate the immune system via several mechanisms, including its capacity to induce production of immune-downregulating micro-RNAs. Possible targets for intervention and drug development to manage distal consequences of infection with P. gingivalis are also reviewed.

Relationships between inflammatory markers and suicide risk status in major depression

Pro-inflammatory status has been implicated in depression and suicidal behaviors. Polyunsaturated fatty acids (PUFAs) and cytokines, two types of inflammatory biomarkers, have been associated with suicide, independent of depression severity. How these biomarkers relate to each other is less clear. We measured plasma phospholipid levels of arachidonic acid (AA%), docosahexaenoic acid (DHA%), and eicosapentaenoic acid (EPA%) as a percentage of total phospholipids, as well as serum interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α), in 80 patients with major depressive disorder (MDD) and 24 healthy controls (HC). Individual PUFA and cytokine species were compared using ANOVA across four suicide risk-stratified groups: 1) highest-risk, recent (within 5 years) suicide attempters (n = 20); 2) high-risk, severe current suicidal ideators (having intent or plan) with no recent attempt history (n = 22); 3) low-risk, current non-ideators who were also lifetime non-attempters (n = 38); and 4) HC (n = 24). None of the participants were enrolled following an acute suicide attempt. Of biomarkers studied, only DHA% (p = 0.012) and IL-1β (p = 0.002) differed between groups. In post-hoc testing, DHA% was lower in attempters than ideators (p = 0.018) or MDD non-ideators (trend level, p = 0.073). IL-1β was lowest in attempters, differentiating them from ideators (p = 0.009) and HC (p = 0.004). Recent suicide attempt, one of the most powerful predictors of suicide risk, was also most closely tied to inflammatory indices in this study. Low DHA% as an indicator of suicide risk is consistent with previous reports; however, lower IL-1β was unexpected and may relate to acuity/chronicity of inflammation. There is a need for prospective studies of immune status with respect to suicidal behaviors.

The role of gene polymorphisms, and analysis of peripheral and central levels of interleukins in suicidal behavior: A systematic review

In terms of the physiological characteristics of suicidal behavior (SB) disorder, an increase inflammation response has been reported in these individuals. Therefore, the pro-inflammatory and anti-inflammatory activities of interleukins are adequate markers to research in order to understand the pathogenesis of SB. For that reason, the aim of this systematic review was to evaluate the role of interleukins in individuals with suicidal behavior disorder. A systematic search was performed in PubMed, Scopus and EBSCO databases up to July 2019. We used the words "interleukin" AND "suicide", "interleukin" AND "suicidal", and "IL-". Articles where interleukins concentrations were measured in individuals with SB and/or genetic studies addressing interleukins genes variants as possible markers to SB were included. A total of 54 articles were included. Articles that measured interleukin levels comprised 1111 cases and 1588 controls; whereas the genetic studies comprised 3082 cases and 5148 controls. These studies evaluated the concentrations of IL-1β, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8, IL-10, sIL-2R in serum, plasma. The pro-inflammatory interleukins concentrations were higher in cases than in controls; however, we observed heterogeneity in the measurements and sample sources. Whereas, 9 polymorphisms of IL-1α, IL-1β, IL-6, IL-1β-8 genes were analyzed in association with suicide behavior disorder, though no conclusive outcomes were attained. Our results suggest that individuals with suicide risk undergo continuous stress that could trigger the release and circulation of pro-inflammatory interleukins and therefore their concentration in plasma. However, more studies are necessary in order to reach conclusively outcomes.

How Does COVID-19 Affect the Neurobiology of Suicide?

PURPOSE OF REVIEW

The aim of this review was to analyze COVID-19 effect on the biological features of suicidal vulnerability and its interaction with suicide-related biological pathways. We carried out a narrative review of international publications on the interactions of COVID-19 with the biological bases of suicide.

RECENT FINDINGS

We hypothesize that SARS-CoV-2 interacts with multiple biological processes that underlie suicidal behavior, such as the renin-angiotensin system, nicotinic receptors, and central and systemic inflammation. Social distancing measures may also worsen subjective or objective social disconnection, thus increasing the risk of suicide. Interestingly, the drugs used to prevent suicide could be promising options to counteract brain damage caused by this coronavirus. SARS-CoV-2 interacts with multiple biological pathways involved in suicide and opens a new window for understanding the suicidal process. The development of suicide prevention treatments in the context of a pandemic may benefit from knowledge on these interactions.

Time-Specific Associations of Tumor Necrosis Factor-α Levels and Polymorphisms (-850 C/T or -308 G/A) With Suicidal Ideation in Acute Coronary Syndrome Patients

Background: Considering the association of inflammation with suicide and acute coronary syndrome (ACS), we investigated the individual and interactive effects of serum tumor necrosis factor-alpha (sTNFα) levels and two polymorphisms (-850 C/T and -308 G/A) on suicidal ideation (SI) after ACS. Methods: The SI status using items on the Montgomery-Åsberg Depression Rating Scale (MADRS), related covariates including sociodemographic and clinical characteristics, sTNFα levels, and tumor necrosis factor-alpha (TNF-α) polymorphisms were evaluated in 969 patients within 2 weeks after ACS. Of the patients, 711 were evaluated 1 year later for SI. Multivariate logistic regression models were used to calculate individual and interactive associations after adjusting for the covariates. Results: Higher (vs. lower) sTNFα levels and the -850 C/T or T/T (vs. C/C) polymorphism were significantly associated with SI 2 weeks after ACS, while only higher sTNFα levels were significantly associated with SI after 1 year. Significant interactive effects were detected between sTNFα (higher) levels and the -850 C/T (C/C or C/T) polymorphism on SI 2 weeks after ACS and between the two (-850 CC or CT and -308 G/A or AA) polymorphisms on SI 1 year after ACS. Conclusions: The sTNFα level and two polymorphisms (-850C/T and -308 G/A), separately or in combination, could be time-specific biomarkers for SI in ACS. Focused interventions for ACS patients at risk of SI might reduce the suicidal burden in patients with ACS.

An increase in IL-6 levels at 6-month follow-up visit is associated with SSRI-emergent suicidality in high-risk children and adolescents treated with fluoxetine

Major depressive disorder (MDD) is associated with alterations in circulatory cytokines, in adults as well as in children and adolescents. Administration of selective serotonin reuptake inhibitors (SSRIs) to MDD pediatric patients modifies cytokine levels. However, most studies only assessed changes over a short time period. In this study, we evaluated long-term effects of the SSRI fluoxetine (FLX) in children and adolescents treated for anxiety and/or MDD, including a high-risk group with pre-treatment suicidality. The study group included ninety-two patients (35 boys and 57 girls) with MDD and/or anxiety disorders, aged 13.90 ± 2.41 years. All patients were treated with FLX and followed for 6 months. The study group included children with pretreatment suicidality (high-risk group;N = 62) and without pretreatment suicidality (N = 30) according to the Columbia Suicide Severity Rating Scale. Plasma concentrations of TNFα, IL-6, and IL-1β were measured by enzyme linked immunosorbent assays before and after six months of treatment. IL-6 and IL-1β significantly increased as a factor of time after 6 months of treatment. The elevation was statistically significant confined to children with pretreatment suicidality. Within the children with pretreatment suicidality, IL-6 levels increased significantly after 6 months only in the children who developed SSRI-associated suicidality. To summarize, an increase in IL-6 levels after 6 months of treatment may be associated with SSRI-emergent suicidality in children with pretreatment suicidality. Further studies are needed to clarify the role and mechanism(s) of IL-6 in the pathogenesis of this life-threatening adverse event.

Increased C-reactive protein concentrations were associated with suicidal behavior in patients with depressive disorders: a meta-analysis

Suicide is devastating with a high incidence in patients with depressive disorder (PDDs). Although some studies have explored underlying associations between C-reactive protein (CRP) levels and suicidal behavior in PDDs, consistent results have not been reached. Therefore, the aim of this meta-analysis was to explore the differences of peripheral blood CRP concentrations between suicidal and non-suicidal PDDs, and between suicidal PDDs and healthy controls (HCs). To this end, PubMed, Embase, and Web of science were searched for eligible studies, and pooled effect sizes from eligible studies were calculated by random-effect models. Furthermore, sensitivity and meta-regression analyses were performed to explain the causes of heterogeneity. Eventually, 7 studies with 2,108 participants were included. Our statistical results suggested that the concentrations of peripheral CRP may be significantly increased for suicidal PDDs, both compared with non-suicidal PDDs and HCs, respectively. The differences of detection methods may be linked with the sources of heterogeneity. In short, our findings showed both compared with non-suicidal PDDs and HCs, peripheral blood CRP levels may be significantly increased in suicidal PDDs, while more studies with large sample sizes are needed to validate our findings.

Increased circulatory IL-6 during 8-week fluoxetine treatment is a risk factor for suicidal behaviors in youth

OBJECTIVE

Selective serotonin reuptake inhibitors (SSRIs) are commonly used to treat anxiety and/or depression in pediatric populations. However, the response rates are low (approximately 50%). Moreover, SSRI use is frequently associated with adverse events (AE). Currently there are no available biomarkers for treatment response/AE. Identification of biomarkers predicting early response and/or AE could help maximize the benefit-risk ratio for the use of SSRIs, and accelerate matching of treatments to patients. Pro-inflammatory cytokines were proposed as potential biomarkers.

METHOD

Ninety-two patients (35 boys and 57 girls) with major depressive disorder and/or anxiety disorders, aged 13.90 ± 2.41 years, were treated with fluoxetine (FLX) for 8 weeks. Plasma concentrations of TNFα, IL-6, and IL-1β were measured by enzyme linked immunosorbent assays before and after FLX treatment. Clinical response and AE were measured using several clinical scales, including the Clinical Global Impression - improvement, Children's Depression Rating Scale-Revised, the Beck Depression Inventory, the Screen for Child Anxiety Related Emotional Disorders, the Columbia suicide severity rating scale, and the Suicide Ideation Questionnaire.

RESULTS

IL-6 levels increased after treatment only in the group of children who developed FLX-associated suicidality.

CONCLUSION

An increase in IL-6 levels during treatment may be a risk factor for the emergence of FLX-associated suicidality (OR = 1.70). Further studies are necessary to clarify the role and mechanism(s) of this cytokine in the pathogenesis of this life-threatening AE.

Psycho-Neuroendocrine-Immune Interactions in COVID-19: Potential Impacts on Mental Health

Coronavirus disease 2019 (COVID-19) is caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The impacts of the disease may be beyond the respiratory system, also affecting mental health. Several factors may be involved in the association between COVID-19 and psychiatric outcomes, such as fear inherent in the pandemic, adverse effects of treatments, as well as financial stress, and social isolation. Herein we discuss the growing evidence suggesting that the relationship between SARS-CoV-2 and host may also trigger changes in brain and behavior. Based on the similarity of SARS-CoV-2 with other coronaviruses, it is conceivable that changes in endocrine and immune response in the periphery or in the central nervous system may be involved in the association between SARS-CoV-2 infection and impaired mental health. This is likely to be further enhanced, since millions of people worldwide are isolated in quarantine to minimize the transmission of SARS-CoV-2 and social isolation can also lead to neuroendocrine-immune changes. Accordingly, we highlight here the hypothesis that neuroendocrine-immune interactions may be involved in negative impacts of SARS-CoV-2 infection and social isolation on psychiatric issues.

[Suicidal behavior in light of COVID-19 outbreak: Clinical challenges and treatment perspectives]

OBJECTIVE

The COVID-19 pandemic affected today more than 3,000,000 worldwide, and more than half of humanity has been placed in quarantine. The scientific community and the political authorities fear an epidemic of suicide secondary to this crisis. The aim of this review is to analyze the impact of the COVID-19 pandemic on the dimensions of the suicidal process and its interaction with the various risk factors. We also propose innovative strategies to manage suicidal behavior in the context of pandemic.

METHODS

We carried out a narrative review of international publications dealing with major pandemics (COVID-19, SARS) and their influence on suicidal vulnerability.

RESULTS

Many factors are likely to increase the emergence of suicidal ideation and suicide attempts during this crisis. Social distancing and quarantine could increase the feeling of disconnection and the perception of social pain in vulnerable individuals. Some populations at high suicidal risk could be further impacted by the current pandemic: the elderly, medical staff and individuals exposed to economic insecurity. Several innovative tools adapted to the constraints of social distancing and quarantine may prevent suicide risk: e-health, VigilanS, buddhist-derived practices and art engagement.

CONCLUSIONS

This unprecedented crisis may interact with certain dimensions of the suicidal process. However, it is time to innovate. Several suicide prevention tools all have their place in new modes of care and should be tested on a large scale.

La sensibilité aux stress sociaux chez les suicidants. Observation écologique

La démonstration de l’efficacité des soins basés sur le recontact, comme l’observation qu’un geste suicidaire suit régulièrement un événement de vie stressant, notamment dans le domaine social, suggèrent que les stress sociaux conduisant à l’exclusion sociale occupent un rôle central dans la survenue des conduites suicidaires. Les nouvelles technologies de la communication, à l’aide de Smartphones, permettent l’évaluation in vivo des patients à risque suicidaire. Non seulement, l’évaluation répétée du risque suicidaire dans l’environnement naturel du sujet n’est pas délétère pour les sujets, mais en outre, ce type d’innovation apporte des informations de grand intérêt pour suivre les séquences environnementales conduisant à la génération des idées de suicide. Ainsi, nous avons observé dans une étude d’évaluation écologique instantanée que les stress sociaux et eux-seuls, prédisent la survenue ultérieure d’idées de suicide. Ainsi, les individus vulnérables au suicide pourraient être particulièrement sensibles au stress sociaux. À ce titre, les études d’imagerie cérébrale démontrent l’existence d’anomalies cérébrales chez les suicidants lors de paradigmes d’exclusion sociale. Par ailleurs, les études récentes avancent la possibilité d’une inflammation chronique modérée dans les conduites suicidaires. Ainsi, divers marqueurs de l’inflammation, dont la CRP plasmatique et les taux de cytokines centraux et périphériques ont été associés aux conduites suicidaires. Il se trouve que les stress sociaux sont des inducteurs particulièrement puissants de cytokines pro-inflammatoires, en faisant intervenir des régions cérébrales également impliquées dans la vulnérabilité suicidaire (insula antérieure, cortex cingulaire antérieur). Nous formulons l’hypothèse que les sujets vulnérables aux conduites suicidaires présenteraient une réponse inflammatoire et algique exagérée aux stress sociaux.

Prospective study on cytokine levels in medication-naïve adolescents with first-episode major depressive disorder

BACKGROUND

Evidence suggests that depression is correlated with immune-inflammatory responses, and efforts have been made to identify the relationships between depression and inflammatory markers. This study investigated the level of cytokines before and after treatment for major depressive disorder (MDD) in medication-naïve adolescents with first-episode MDD and compared them with the levels in healthy adolescents. The relationship between cytokine levels and the severity of depressive symptoms was also examined.

METHODS

Twenty-five adolescents with MDD and 25 healthy controls aged 13 to 18 years were included in the study. Blood samples were obtained, and depression severity was assessed twice in the MDD group before and after treatment and once in the healthy group.

RESULTS

When compared with healthy controls, adolescents with MDD had lower levels of interleukin 2 (IL-2), interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) and IL-10 before treatment and higher levels of IL-2, IFN-γ, and IL-10 after treatment. In addition, the IFN-γ levels correlated with depressive severity scores in both the Children's Depression Inventory (CDI) and Hamilton Depression Rating Scale (HDRS). The IL-10 level correlated with depressive severity only on the HDRS.

LIMITATIONS

The sample size was small, and the 12-week follow-up time after treatment was relatively short.

CONCLUSION

IL-2, IFN-γ, TNF-α, and IL-10 levels in medication-naïve adolescents with first-episode MDD differed from those in healthy controls. The levels of IL-2, IFN-γ, and IL-10 were altered after antidepressant treatment. Further, the IFN-γ and IL-10 levels correlated with the severity of depressive symptoms.

A Specific Inflammatory Profile Underlying Suicide Risk? Systematic Review of the Main Literature Findings

Consistent evidence indicates the association between inflammatory markers and suicidal behavior. The burden related to immunological differences have been widely documented in both major affective disorders and suicidal behavior. Importantly, abnormally elevated pro-inflammatory cytokines levels have been reported to correlate with suicidal behavior but whether and to what extent specific inflammatory cytokines abnormalities may contribute to our understanding of the complex pathophysiology of suicide is unknown. The present manuscript aimed to systematically review the current literature about the role of pro-inflammatory cytokines in suicidal behavior. Most studies showed a link between abnormally higher interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β1, vascular endothelial growth factor (VEGF), kynurenic acid (KYN), and lower IL-2, IL-4, and interferon (IFN)-γ levels in specific brain regions and suicidal behavior. Unfortunately, most studies are not able to exclude the exact contribution of major depressive disorder (MDD) as a mediator/moderator of the link between inflammatory cytokines abnormalities and suicidal behavior. The association between suicidal patients (both suicide attempters or those with suicidal ideation) and the altered immune system was documented by most studies, but this does not reflect the existence of a specific causal link. Additional studies are needed to clarify the immune pathways underlying suicidal behavior.

Suicide epigenetics, a review of recent progress

BACKGROUND

Suicide results in over 800,000 deaths every year, making it a major public health concern worldwide. It is highly complex, with genetic and environmental influences. Epigenetic mechanisms, including DNA methylation, miRNA, and histone modifications, could explain the complex interplay of environmental risk factors with genetic risk factors in the emergence of suicidal behavior.

METHODS

Here, we review the literature on suicide epigenetics over the past 10 years.

RESULTS

There has been significant progress in the field of suicide epigenetics, with emerging findings in the brain-derived neurotrophic factor and hypothalamic-pituitary-adrenal axis genes.

LIMITATIONS

Studying patient subgroups is needed in order to extract more comparable and reproducible epigenetic findings in suicide.

CONCLUSIONS

It is crucial to consider suicidal patients or suicide victims' distal and proximal past history e.g., early-life adversity and psychiatric disorder in epigenetic studies of suicidality.

Potential application of helminth therapy for resolution of neuroinflammation in neuropsychiatric disorders

Neuropsychiatric disorders (NPDs) are among the major debilitating disorders worldwide with multiple etiological factors. However, in recent years, psychoneuroimmunology uncovered the role of inflammatory condition and autoimmune disorders in the etiopathogenesis of different NPDs. Hence, resolution of inflammation is a new therapeutic target of NPDs. On the other hand, Helminth infections are among the most prevalent infectious diseases in underdeveloped countries, which usually caused chronic infections with minor clinical symptoms. Remarkably, helminths are among the master regulator of inflammatory reactions and epidemiological studies have shown an inverse association between prevalence of autoimmune disorders with these infections. As such, changes of intestinal microbiota are known to be associated with inflammatory conditions in various NPDs. Conversely, helminth colonization alters the intestinal microbiota composition that leads to suppression of intestinal inflammation. In animal models and human studies, helminths or their antigens have shown to be protected against severe autoimmune and allergic disorders, decline the intensity of inflammatory reactions and improved clinical symptoms of the patients. Therefore, "helminthic therapy" have been used for modulation of immune disturbances in different autoimmunity illnesses, such as Multiple Sclerosis (MS) and Inflammatory Bowel Disease (IBD). Here, it is proposed that "helminthic therapy" is able to ameliorate neuroinflammation of NPDs through immunomodulation of inflammatory reactions and alteration of microbiota composition. This review discusses the potential application of "helminthic therapy" for resolution of neuroinflammation in NPDs.

Chemokine alterations in the postmortem brains of suicide completers

Suicide is a major health problem in the modern world. However, its physiological mechanisms have not been well elucidated yet. Immunological disturbances have been reported in psychiatric disorders such as major depressive disorder (MDD), bipolar disorder (BP), and schizophrenia. Some studies have also suggested an association between immunological alterations especially neuroinflammation, and suicide. Chemokines play important roles in inflammation, and studies investigating chemokines in psychiatric diseases such as schizophrenia, MDD, and BP have reported chemokine dysregulations. However, there have been very few studies on the association between chemokines and suicide. We studied chemokine alterations in the postmortem brains of suicide completers and compared them to those of controls. We obtained brain tissue samples of the dorsolateral prefrontal cortex from 16 suicide completers and 23 controls. We examined the concentrations of chemokines and related substances in the brain tissue from these two groups using the Bio-Plex Pro™ Human Chemokine Panel 40-Plex. We performed multiple regression analysis with covariates. The levels of CCL1, CCL8, CCL13, CCL15, CCL17, CCL19, CCL20, CXCL11, and IL-10 were significantly decreased, whereas the IL-16 levels were significantly increased in the suicide completers after adjustment with the Benjamini-Hochberg method to control for type Ⅰ errors (Q < 0.05). The observed chemokine alterations might suggest the presence of suicide-specific immunological mechanisms.