Plasma cytokine and growth factor response to acute psychosocial stress in major depressive disorder.

BACKGROUND: Pro-inflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor (TNF)-α are elevated in response to psychosocial stress; however, less is known about other inflammatory markers. METHODS: We explored response to the Trier Social Stress Test (TSST) of 16 cytokines and growth factors in patients with major depressive disorder (MDD, n = 12) vs. healthy volunteers (HV, n = 16). Outcomes were baseline and post-stress levels estimated by area under the curve (AUCi) and peak change over 3 timepoints. We also explored correlations between biomarkers and clinical characteristics. RESULTS: Baseline concentrations were higher in MDD for platelet-derived growth factor (PDGF)-AB/BB (p = 0.037, d = 0.70), granulocyte-macrophage colony-stimulating factor (GM-CSF, p = 0.033, d = 0.52), and IL-8 (p = 0.046, d = 0.74). After TSST, AUCi was higher in MDD for GM-CSF (p = 0.003, d = 1.21), IL-5 (p = 0.014, d = 1.62), and IL-27 (p = 0.041, d = 0.74). In MDD, depression severity correlated positively with soluble CD40L (sCD40L) for AUCi (Spearman's ρ = 0.76, p = 0.004) and with baseline vascular endothelial growth factor A (VEGFA, r = 0.85, p < 0.001), but negatively with baseline monokine induced by gamma interferon (MIG, aka CXCL9; r = -0.77, p = 0.003). CONCLUSIONS: Effect sizes were robust in this exploratory study, although interpretation of the results must be cautious, given small sample size and multiple comparisons. Differential study of stress-induced biomarkers may have important ramifications for MDD treatment.

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-1ß). 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 adenosine triphosphate-related genes to major depression and suicidal behavior: Cognition as a potential mediator.

BACKGROUND: Soluble epoxide hydrolase (sEH, encoded by EPHX2) and P2X2 (a subtype of ATP receptors) may mediate the antidepressant-like effects of ATP. We sought to determine whether polymorphisms and mRNA expression of EPHX2 and P2X2 are associated with depression and suicidal behavior and how cognition may mediate such associations. METHOD: We examined 83 single nucleotide polymorphisms (SNPs) of EPHX2 and P2X2. Subjects were MDD suicide attempters (N = 143), MDD non-suicide attempters (N = 248), and healthy volunteers (HV, N = 110). Data on demographics, depression severity, and suicide attempts were collected. Participants completed a set of cognitive tasks. Polymorphisms were genotyped using MALDI-TOF MS within the MassARRAY system. The expression of mRNA was measured using real-time polymerase chain reaction (RT-PCR). RESULTS: Cognitive function was a significant mediator (p = 0.006) of the genetic effect on depression. Allele C of rs202059124 was associated with depression risk (OR = 11.57, 95%CI: 2.33-209.87, p = 0.0181). A significant relationship was found between P2X2 mRNA expression and depression (OR = 0.68, 95%CI: 0.49-0.94, p = 0.0199). One haploblock (rs9331942 and rs2279590) was associated with suicide attempts: subjects with haplotype GC (frequency = 19.8 %, p = 0.017) and AT (frequency = 35.2 %, p < 0.001) had a lower rate of suicide attempts. CONCLUSIONS: Our results confirmed that cognitive impairment plays a role in the effect of rs9331949 on depression. Moreover, we confirmed a relationship between P2X2, EPHX2, and MDD in humans and presented preliminary haplotype-based evidence that implicates EPHX2 in suicide. LIMITATIONS: The main limitation of this study is the limited sample size. More comprehensive and multi-domain cognition tasks and different assessment measures are required in further study.

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors.

BACKGROUND: Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. METHODS: We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. RESULTS: Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. CONCLUSIONS: Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.

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-1ß (IL-1ß) 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-1ß (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-1ß 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-1ß 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.

Oral Health-Related Quality of Life Among Publicly Insured Mental Health Service Outpatients With Serious Mental Illness.

OBJECTIVE: The study investigated factors associated with unmet need for dental care and oral health-related quality of life (OHQoL) among individuals with serious mental illness receiving outpatient care in a public mental health program serving a largely low-income population, mostly from racial-ethnic minority groups. METHODS: Cross-sectional interview data were collected from a convenience sample (N=150) of outpatients. Adjusted risk ratios (ARRs) and adjusted risk differences (ARDs) were estimated by logistic regression models to examine the independent contribution of sociodemographic and clinical factors to low OHQoL and past-year unmet dental need, defined as inability to obtain all needed dental care. RESULTS: More than half of participants reported low OHQoL (54%) and a past-year dental visit (61%). Over one-third (39%) had past-year unmet dental need. Financial barriers (ARR=3.16) and nonfinancial barriers (ARR=2.18) were associated with greater risk for past-year unmet dental need after control for age, gender, high dental anxiety, and limited English proficiency. ARDs for financial and nonfinancial barriers indicated absolute differences of 40 and 27 percentage points, respectively. Unmet dental need (ARR=1.31), xerostomia severity (ARR=1.20), and a schizophrenia spectrum diagnosis (ARR=1.33) were associated with low OHQoL, after control for age and current smoking, with ARDs ranging from 11 to 15 percentage points. CONCLUSIONS: Improving oral health promotion, oral health service access, and the integration of the mental and oral health systems may help reduce the high prevalence of low OHQoL in this population, given that low OHQoL is partly driven by unmet dental need.

Plasma kynurenine levels are elevated in suicide attempters with major depressive disorder.

BACKGROUND: Inflammation has been linked to depression and suicide risk. One inflammatory process that has been minimally investigated in this regard is cytokine-stimulated production of kynurenine (KYN) from tryptophan (TRP). Recent data suggest that KYN increases in cerebrospinal fluid (CSF) are associated with depressive symptoms secondary to immune activation. KYN may alter dopaminergic and glutamatergic tone, thereby contributing to increased arousal, agitation and impulsivity - important risk factors in suicide. We hypothesized that patients with major depressive disorder (MDD) and a history of suicide attempt would have higher levels of KYN than depressed nonattempters, who in turn would have higher levels than healthy volunteers. METHODS: Plasma KYN, TRP, and neopterin were assayed by high performance liquid chromatography in three groups: healthy volunteers (n=31) and patients with MDD with (n=14) and without (n=16) history of suicide attempt. Analysis of variance tested for group differences in KYN levels. RESULTS: KYN levels differed across groups (F=4.03, df=(2,58), and p=0.023): a priori planned contrasts showed that KYN was higher in the MDD suicide attempter subgroup compared with MDD non-attempters (t=2.105, df=58, and p=0.040), who did not differ from healthy volunteers (t=0.418, df=58, and p=0.677). In post hoc testing, KYN but not TRP was associated with attempt status, and only suicide attempters exhibited a positive correlation of the cytokine activation marker neopterin with the KYN:TRP ratio, suggesting that KYN production may be influenced by inflammatory processes among suicide attempters. CONCLUSION: These preliminary results suggest that KYN and related molecular pathways may be implicated in the pathophysiology of suicidal behavior.

Lower CSF MHPG predicts short-term risk for suicide attempt.

Post-mortem studies document alterations in the central noradrenergic system in suicide. However, studies of non-fatal suicide attempts have, thus far, found no consistent relationship to the noradrenaline metabolite 3-methoxy-4-hydroxphenylglycol (MHPG) in cerebrospinal fluid (CSF). We therefore conducted a prospective study of CSF MHPG and suicidal acts in major depression and bipolar depression. CSF MHPG was assayed in 184 drug-free patients with DSM-IV major depressive disorder or bipolar disorder, presenting for treatment of a current depressive episode, who were then followed-up for up to 12 months. Survival analysis was conducted using Cox proportional hazards modelling to test association of CSF MHPG and future suicidal behaviour, and potential clinical mediators. Twenty-seven individuals made a suicide attempt (two fatal) in the follow-up period. Lower CSF MHPG predicted future suicide attempt or suicide (22% increase in hazard for each 10 pmol/ml lower MHPG, p=0.045). Lower CSF MHPG also correlated with higher medical lethality of future suicidal act (mean MHPG: 49+/-18 vs. 32+/-12 pmol/ml for low- vs. high-lethality, t=2.8, d.f.=25, p=0.009). Smoking and self-rated depression severity were also associated with lower CSF MHPG and with future suicide attempt, but were not statistically significant mediators in multivariate models. In conclusion, lower CSF MHPG is associated with short-term risk for future suicidal behaviour in the 12 months following a major depressive episode. Psychopathology that mediates the relationship between lower CSF MHPG and future suicidal behaviour needs to be identified.

Sex differences in clinical predictors of suicidal acts after major depression: a prospective study.

OBJECTIVE: Whether sex differences exist in clinical risk factors associated with suicidal behavior is unknown. The authors postulated that among men with a major depressive episode, aggression, hostility, and history of substance misuse increase risk for future suicidal behavior, while depressive symptoms, childhood history of abuse, fewer reasons for living, and borderline personality disorder do so in depressed women. METHOD: Patients with DSM-III-R major depression or bipolar disorder seeking treatment for a major depressive episode (N=314) were followed for 2 years. Putative predictors were tested with Cox proportional hazards regression analysis. RESULTS: During follow-up, 16.6% of the patients attempted or committed suicide. Family history of suicidal acts, past drug use, cigarette smoking, borderline personality disorder, and early parental separation each more than tripled the risk of future suicidal acts in men. For women, the risk for future suicidal acts was sixfold greater for prior suicide attempters; each past attempt increased future risk threefold. Suicidal ideation, lethality of past attempts, hostility, subjective depressive symptoms, fewer reasons for living, comorbid borderline personality disorder, and cigarette smoking also increased the risk of future suicidal acts for women. CONCLUSIONS: These findings suggest that the importance of risk factors for suicidal acts differs in depressed men and women. This knowledge may improve suicide risk evaluation and guide future research on suicide assessment and prevention.

The relationship of aggression to suicidal behavior in depressed patients with a history of alcoholism.

BACKGROUND: Alcoholism and depression are often comorbid. Studies suggest that depressed subjects with alcoholism have more chronic impairment and suicidal behavior than individuals with either diagnosis alone. The reason for higher rate of suicide and suicide attempts in comorbid subjects is uncertain. We explored clinical characteristics that may be associated with this increased suicidality. METHODS: In all, 219 depressed subjects (n=62 males and n=157 females) without a history of any alcohol or substance use disorder and 129 (n=49 males and n=80 females) depressed individuals with a prior history of alcohol use disorder participated in the study. Demographic and clinical parameters were assessed and recorded. RESULTS: Depressed subjects with a history of alcoholism had higher lifetime aggression and impulsivity, and were more likely to report a history of childhood abuse, suicide attempts, and tobacco smoking. Depressed suicide ideators with a history of alcoholism had higher suicide ideation scores than depressed suicide ideators without a history of alcoholism. Subjects with a history of alcoholism were younger at the time of the first depressive episode and first hospitalization than those without a history of alcoholism. Logistic regression analysis indicated that alcoholism was significantly associated with smoking and aggression. Suicidal behavior and higher suicidal ideation in depressed subjects with a history of alcoholism might be attributed to higher aggression scores in this group. CONCLUSION: The greater frequency of suicidal behavior and severity of suicidal ideation in major depression with comorbid alcoholism appears related to associated aggressive traits. Alcoholism, aggression, smoking, and suicide may have a common biological causal substrate.

Prospective study of clinical predictors of suicidal acts after a major depressive episode in patients with major depressive disorder or bipolar disorder.

OBJECTIVE: The authors investigated the predictive potential of a stress-diathesis model for suicidal behavior based on correlates of past suicidal acts. In this model, suicidal acts are precipitated by stressors such as life events or a major depressive episode in the setting of a propensity for acting on suicidal urges. This diathesis is expressed as the tendency to develop more pessimism in response to a stressor and/or the presence of aggressive/impulsive traits. The predictive potential of the diathesis was tested by determining whether clinical correlates of past suicidal behavior predict suicidal acts during a 2-year follow-up of patients with a major depressive episode. METHOD: Patients with DSM-III-R major depressive disorder or bipolar disorder (N=308) were assessed at presentation for treatment of a major depressive episode. Potential predictors of suicidal acts in the 2 years after study enrollment were identified on the basis of an association with previous suicidal behavior and were tested by using Cox proportional hazards regression analysis. In addition, pessimism and aggression/impulsivity factors were generated, and their predictive ability was tested by using Cox proportional hazards regression analysis. RESULTS: The three most powerful predictors of future suicidal acts were a history of suicide attempt, subjective rating of the severity of depression, and cigarette smoking, each of which had an additive effect on future risk. The pessimism and aggression/impulsivity factors both predicted suicidal acts, and each factor showed an additive effect. CONCLUSIONS: In addition to obtaining a history of suicidal behavior, clinicians may find it useful to assess patients' current level of pessimism, aggressive/impulsive traits, and comorbidity with substance use disorders, including nicotine-related disorders, to help identify patients at risk for suicidal behavior after major depression. Interventions such as aggressive pharmacotherapeutic prophylaxis to prevent relapse or recurrence of depressive symptoms may protect such at-risk individuals from future suicidal behavior.