Suicidal Major Depressive Disorder Patients Research Articles

The relationship between event-related potential components and suicide risk in major depressive disorder

BackgroundSuicide is a serious global issue, with major depressive disorder (MDD) being a significant risk factor for suicidal thoughts and behaviors. There is an urgent need to determine whether event-related potential components (ERPs) could be used as an indicator to assess suicidal risk. MethodsFrom 2020 to 2023, 258 participants in total were recruited into the study. All participants were divided into four groups: MDD patients at high (n = 66), moderate (n = 66), and low risk (n = 56) of suicide, and healthy controls (HCs)(n = 70). Each participant provided socio-demographic information and underwent evaluations using clinical psychological scales such as 7-item Generalized Anxiety Disorder (GAD-7), Health Questionnaire-9 items (PHQ-9), and Nurses' Global Assessment of Suicide Risk (NGASR). The auditory brainstem response test and ERP examination were performed for all subjects. ResultsOur study found that the amplitude of P2–P3 and N2–P3 was significantly reduced in MDD patients at moderate and high risk of suicide, and these were negatively correlated with NGASR total score (all P < 0.05). Point B latency was positively correlated with NGASR total score (P < 0.05). Patients with MDD patients at low risk for suicide had a lower A-B amplitude compared to HCs (P < 0.05). No differences were found in MMN or P50 components between the four groups (all P > 0.05). ConclusionsMDD patients at higher risk of suicide exhibited severe impairment of cognitive function. ERP indices, such as the amplitude of P2–P3 and N2–P3, could be associated with the risk of suicide in MDD patients.

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

BackgroundPrevious 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. MethodsWe 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). ResultsA 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. ConclusionThis 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.

Investigation of the Relationship among Cortisol, Pro-inflammatory Cytokines, and the Degradation of Tryptophan into Kynurenine in Patients with Major Depression and Suicidal Behavior.

The increased degradation of tryptophan (Trp) along the kynurenine (Kyn) pathway due to inflammation and/or activation of the hypothalamic-pituitary-adrenal (HPA) axis has been reported among the biological factors involved in the pathophysiology of major depressive disorder (MDD) and suicide. However, the interaction among these multiple factors is not yet completely clarified. We studied plasma levels of Trp, Kyn, cortisol and proinflammatory cytokines (IL-1, IL- 6, IL-12, IL-20) and calculated the ratio Kyn/Trp as an index of the breakdown of Trp into Kyn in 31 suicidal MDD patients and 67 non-suicidal MDD patients. We confirmed that suicidal MDD patients have reduced plasma Trp, higher Kyn and Kyn/Trp ratio, and no difference in cortisol levels than non-suicidal MDD patients. IL-1 and IL-12 levels were significantly higher in suicidal MDD than in non-suicidal MDD (p=0.034 and p=0.023, respectively), whereas Il-6 and IL-20 levels were equal in the two groups. The Kyn/Trp ratio was positively correlated with a pro-inflammatory cytokines index (r=0.309, p=0.002) and cortisol (r=0.368, p=0.001). Notably, the variance in the Kyn/Trp ratio explained by the model including both cortisol and inflammatory parameters as dependent variables, substantially improved compared with the models in which the two parameters were considered separately. These findings show that both cortisol and proinflammatory cytokines are involved in the enhanced breakdown of Trp into Kyn occurring in suicidal MDD patients, thus adding new knowledge on the biological mechanisms leading to the activation of the Kyn pathway in MDD and suicide.

Association of short-term particulate matter exposure with suicide death among major depressive disorder patients: a time-stratified case-crossover analysis

There is growing evidence that suggests a potential association between particulate matter (PM) and suicide. However, it is unclear that PM exposure and suicide death among major depressive disorder (MDD) patients, a high-risk group for suicide. We aimed to assess the effect of short-term exposure to PM on the risk of suicide in MDD patients who are at high risk for suicide. We investigated the risk of suicide among 922,062 newly-diagnosed MDD patients from 2004 to 2017 within the Korean National Health Insurance Service (NHIS) database. We identified 3,051 suicide cases from January 1, 2015, to December 31, 2017, within the death statistics database of the Korean National Statistical Office. PMs with aerodynamic diameter less than 2.5 μm (PM2.5), less than 10 μm (PM10), and 2.5–10 μm (PM2.5–10) were considered, which were provided from the National Ambient Air Monitoring System in South Korea. Time-stratified case-crossover analysis was performed to investigate the association of particulate matter exposure to suicide events. The risk of suicide was significantly high upon the high level of exposure to PM2.5, PM2.5–10 (coarse particle) and PM10 on lag 1 (p for trend < 0.05). Short-term exposure to a high level of PM was associated with an elevated risk for suicide among MDD patients. There is a clear dose–response relationship between short-term PM exposures with suicide death among MDD patients. This result will be used as an essential basis for consideration when establishing an air pollution alarm system for reducing adverse health outcomes by PM.

Altered resting-state cerebral blood flow and functional connectivity mediate suicidal ideation in major depressive disorder

The relationships among cerebral blood flow (CBF), functional connectivity (FC) and suicidal ideation (SI) in major depressive disorder (MDD) patients have remained elusive. In this study, we characterized the changes in CBF and FC among 175 individuals including 47 MDD without SI (MDDNSI), 59 MDD with SI (MDDSI), and 69 healthy control (HC) who underwent arterial spin labeling and resting-state functional MRI scans. Then the voxel-wise CBF, seed-based FC and partial correlation analyses were measured. Mediation analysis was carried out to reveal the effects of FC on the association between CBF and behavioral performances in both subgroups. Results showed that CBF was higher in MDDSI patients in the bilateral precuneus compared to HC and MDDNSI participants. MDDSI patients exhibited enhanced FC in the prefrontal-limbic system and decreased FC in the sensorimotor cortex (SMC) relative to MDDNSI patients. CBF and FC were significantly correlated with clinical variables. More importantly, exploratory mediation analyses identified that abnormal FC can mediate the association between regional CBF and behavioral performances. These results highlight the potential role of precuneus gyrus, prefrontal-limbic system as well as SMC in the process of suicide and provide new insights into the neural mechanism underlying suicide in MDD patients.

Associations of serum cystatin C with depressive symptoms and suicidal ideation in major depressive disorder

BackgroundIndividuals with major depressive disorder (MDD) have high suicidal ideation. There is evidence that serum cystatin C (Cys C) may be involved in the pathophysiology of MDD. The present study aimed to investigate Cys C concentration in patients with MDD and clarify its possible association with depressive symptoms and suicidal ideation.MethodsAn online cross-sectional survey of 159 patients diagnosed with MDD was conducted. Serum Cys C levels were measured using ADVIA 2400 biochemical analyzer. The 24-item Hamilton Depression Scale (HAMD-24) was administered to evaluate the depressive symptoms. Generalized linear regression, logistic regression and restricted cubic spline models were used to examine the association of serum Cys C levels with depressive symptoms and suicidal ideation.ResultsSerum Cys C levels were higher in MDD patients than in controls (p = 0.001) and were positively associated with scores on HAMD-24 in unadjusted (gender distribution, age, smoking, alcohol consumption, family history of depression and traumatic life events; (p = 0.003) and fully adjusted linear regression model (p = 0.005). The fully adjusted regression coefficient with 95% confidence intervals for serum Cys C levels and HAMD-24 score was 30.339 (9.602 to 51.077). The level of Cys C in the suicidal ideation (SI) group was significantly higher than that in the non-suicide ideation (non-SI) group (p = 0.001). Serum Cys C levels were positively associated with suicidal ideation in each logistic regression model (all p < 0.05).ConclusionSerum Cys C levels were elevated in MDD patients and appeared to be positively correlated with depressive symptoms and suicidal ideation. These findings suggest that the dysfunction of Cys C may be involved in the severity of depression and in the pathophysiological process of MDD. Thus, regulation of serum Cys C could potentially be an effective predictor of the severity of depression and potentially, play a role in reducing the risk of suicide in MDD patients.

Association between serum lipid concentrations and attempted suicide in patients with major depressive disorder: A meta-analysis.

BackgroundThere is growing evidence that serum lipid concentrations may be associated with attempted suicide in patients with major depressive disorder (MDD), but these findings remain controversial. Thus, we performed a comprehensive meta-analysis to quantitatively assess the associations between serum lipid concentrations and attempted suicide in MDD patients.Materials and methodsElectronic databases (PubMed, Embase, the Cochrane Library and the China National Knowledge Library) were searched for relevant literature up to 10 February 2020. We used a random-effects model based on heterogeneity amongst studies and generated pooled standardised mean differences (SMDs).ResultsThirty-two studies comprising 7,068 subjects met the inclusion criteria. A pooled analysis showed that compared with non-attempters, MDD patients who had attempted suicide had significantly lower serum concentrations of total cholesterol (TC) (SMD: -0.63, 95% CI: -0.83 to -0.44) and low-density lipoprotein cholesterol (LDL-C) (SMD: -0.69, 95% CI: -1.04 to -0.34), but the serum concentrations of high-density lipoprotein cholesterol (HDL-C) (SMD: -0.12, 95% CI: -0.33 to 0.10) and triglycerides (TGs) (SMD: 0.00, 95% CI: -0.20 to 0.20) were not significantly different between the two groups. Subgroup and meta-regression analysis indicated that heterogeneity with respect to TC concentrations may be due to different ages (p = 0.041) and sample sizes (p = 0.016) of studies, and that heterogeneity with respect to HDL-C concentrations may be partly due to different settings of studies (p = 0.017).ConclusionsThis meta-analysis demonstrated that lower concentrations of TC and LDL-C, but not of HDL-C and TGs, were associated with attempted suicide in MDD patients. This indicates that TC and LDL-C may be useful as biological markers for predicting whether MDD patients may attempt to commit suicide.

Association of thyroid dysfunction with suicide attempts in first-episode and drug naïve patients with major depressive disorder

BackgroundsThyroid dysfunction was reported to be associated with depression; however, its role in suicide risk in patients with major depressive disorder (MDD) remains unclear. The objective of this study was to compare thyroid function between suicide attempters and non-suicide attempters in a large sample of first episode drug naïve (FEDN) MDD patients, which received little systemic investigation. MethodsA total of 1718 outpatients with diagnosis of MDD at their first episode were recruited. Their socio-demographic, clinical data and thyroid function parameters were collected. The positive subscale of the Positive and Negative Syndrome Scale (PANSS), Hamilton Anxiety Rating Scale (HAMA) and Hamilton Depression Rating Scale (HAMD) were measured for psychotic, anxiety and depressive symptoms, respectively. ResultsOur results showed that compared with non-suicide attempters, suicide attempters had greater scores on HAMD, HAMA and PANSS psychotic symptoms and higher serum levels in thyroid stimulating hormone (TSH), anti-thyroglobulin (TgAb) and thyroid peroxidases antibody (TPOAb) (all p < 0.001). Further logistic regression analysis indicated that suicide attempts were associated with severe anxiety with an adjusted odds ratio (OR) of 2.704 and TPOAb with an adjusted OR of 2.188. LimitationsNo causal relationship could be drawn due to the cross-sectional design. ConclusionsOur results indicate TSH, TgAb and TPOAb may be promising biomarkers of suicide risk in MDD, suggesting the importance of regular assessment of thyroid function parameters for suicide prevention, and possible treatment for impaired thyroid function for intervention of suicide in MDD patients.

Cognitive Markers in Suicidal Major Depressive Disorder Patients

Introduction Cognitive impairment is a major factor influencing the severity and prognosis of major depression. On the other hand, the impossibility of finding solutions and support is characteristic for individuals with suicidal behavior. Therefore, the comparative investigation of cognitive functioning in suicidal and non-suicidal major depression disorder patients seems to be justified. Aim To evaluate weather suicidal major depressive disorder patients show a specific pattern of cognitive impairment as compared to non-suicidal major depressive disorder patients. Material and Methods 60 adult major depressive disorder patients (as diagnosed by using the ICD-10 criteria) were included, of which 30 were identified as having a significant suicide risk by using the Paykel Suicide Scale. Cognitive functioning (working memory and executive functions) was assessed by using the CogTest battery. Results Both working memory and executive function performance were lower in suicidal patients, with problem solving being the most prominent marker related to suicide risk. Conclusions Severe problem solving deficiency might be a marker of suicide risk in major depressive disorder patients.

Association between norepinephrine transporter gene (SLC6A2) polymorphisms and suicide in patients with major depressive disorder

BackgroundAlthough several studies have investigated possible associations between norepinephrine neurotransmitter transporter gene (SLC6A2) polymorphisms and depression, few studies have examined associations between SLC6A2 polymorphisms and suicide. MethodsThree single-nucleotide polymorphisms (rs2242446, rs28386840, and rs5569) were measured in 550 patients: 201 with major depressive disorder (MDD) and suicide attempt/s, 160 with MDD without suicide attempts, and 189 healthy controls. Analysis of single-nucleotide polymorphisms (SNPs) and haplotype was conducted for the three groups. Subsequently, multivariate logistic regression analysis adjusting for age and gender was conducted to identify independent influences of each SNP. A possible association between suicide lethality and SLC6A2 polymorphisms was also investigated. ResultsIn the genotype and allele frequency analysis, there were significant differences in rs28386840 between suicidal MDD patients and healthy controls. In the haplotype analysis, TAA (rs2242446–rs28386840–rs5569, from left to right) was associated with suicide attempts in MDD, although the significance (p=0.043) disappeared after Bonferroni correction. There were no relationships between lethality scores and SLC6A2 polymorphisms in suicidal MDD. LimitationsModest sample size and a single type of neurotransmitter analyzed (norepinephrine) are the primary limitations. ConclusionOur results suggest that SLC6A2 polymorphisms were associated with suicide risk in patients with MDD. Future studies are warranted to elucidate possible mechanisms by which SLC6A2 polymorphisms influence suicide risk.

Peripheral metabolic abnormalities of lipids and amino acids implicated in increased risk of suicidal behavior in major depressive disorder

Suicide is the most serious consequence of major depressive disorder (MDD), yet a vast majority of MDD patients never attempt nor commit suicide. This discrepancy suggests a predisposition to suicidal behavior independent of MDD. However, the molecular basis of this predisposition remains largely unknown, hampering development of specific and targeted treatment of MDD patients at risk for suicide. A proton nuclear magnetic resonance (1H NMR)-based metabonomic approach was used to capture metabolic perturbations related to suicide predisposition in the context of MDD. 1H NMR spectra of plasma sampled from drug-naive depressed suicide attempters (n = 21), non-attempters (n = 35), and healthy controls (n = 35) were recorded and analyzed through a multivariate statistical approach. Multivariate statistical analysis demonstrated that the depressed suicide attempter group was significantly distinguishable from the depressed non-attempter group and controls group. Several key metabolites, including lipids (low-density lipoprotein, very low-density lipoprotein, cholesterol and unsaturated lipid), lipid metabolism-related molecules (glucose, pyruvate and lactate) and amino acids (alanine, glycine and taurine) responsible for discriminating depressed suicide attempters from the nonattempters and controls were identified. This study is the first to indicate that peripheral perturbations in lipid and amino acid metabolism may be implicated in the predisposition to suicide in MDD patients.

Transforming growth factor-β1 and major depressive disorder with and without attempted suicide: Preliminary study

A substantial body of evidence indicates that dysregulation of the immune system is associated with suicidal behavior in major depressive disorder (MDD). Transforming growth factor (TGF)-β1 is believed to be an important factor in regulating inflammatory responses and to have anti-inflammatory effects. We aimed to identify the role of TGF-β1 on suicidal depression. The TGF-β1 polymorphisms at codons 10 and 25 were analyzed in 122 suicidal MDD patients, 61 non-suicidal MDD patients, and 120 control subjects and, among them, in vitro TGF-β1 productions were measured in 48 suicidal MDD patients, 47 non-suicidal MDD patients, and 91 control subjects. There was no genetic polymorphism at codon 25 and three genotypes at codon 10. No significant difference in the distributions of the TGF-β1 genotypes was found among the three groups. The in vitro TGF-β1 productions were significantly higher in suicidal MDD patients (844.3 ± 329.7 pg/ml) and in non-suicidal MDD patients (853.0 ± 439.7 pg/ml) than in controls (683.0 ± 397.0 pg/ml) ( P = 0.01). In vitro TGF-β1 productions were not significantly different among patients with any of the TGF-β1 alleles or genotypes. Our findings suggest that in vitro TGF-β1 productions play an important role on MDD, but we found no associations between TGF-β1 and suicidal behavior.

BDNF mRNA expression of peripheral blood mononuclear cells was decreased in depressive patients who had or had not recently attempted suicide

BackgroundRecent reports have suggested a pathophysiological role for brain-derived neurotrophic factor (BDNF) in major depression and suicide. We evaluate BDNF mRNA in peripheral blood mononuclear cells (PBMCs) of patients with major depression who had or had not recently attempted suicide. MethodsBDNF mRNA expression was examined in PBMCs of 30 major depressed patients without recent suicide attempts, 30 major depressed patients with recent suicide attempts, and 30 healthy controls. All patients were diagnosed with major depressive disorder (MDD) and they were either medication-naïve or medication-free. BDNF mRNA expression was measured using real-time quantitative PCR. ResultsBDNF mRNA expression was significantly decreased in PBMCs of MDD patients, with or without a history of suicide attempts, when compared with healthy controls (Z=−5.233, p<0.001). Suicidal MDD patients had more decrease in BDNF mRNA expression (χ2=45.881, df=2, p<0.001). LimitationsThe sample size of the present study was relatively small. Although suicidal MDD patients had higher HDRS scores than non-suicidal patients, the comparison of BDNF mRNA between them could not be adjusted for HDRS score. ConclusionsOur study suggests that the BDNF mRNA expression is reduced in PBMCs of patients with major depression. This alteration of BDNF mRNA expression was noteworthy in recent suicide attempters. Such a decrease in BDNF mRNA might be associated with BDNF decrease in serum or plasma, and might also correspond to a BDNF decline in the brains of MDD patients.

Reduced platelet BDNF level in patients with major depression

Serum and plasma brain-derived neurotrophic factor (BDNF) levels as well as brain BDNF have previously been shown to be decreased in patients with major depressive disorder (MDD). We explored whether platelet BDNF levels, circulating stored BDNF, would be lower in MDD patients than in normal controls. BDNF levels were examined in platelet-rich plasma (PRP) and platelet-poor plasma (PPP) in 20 hospitalized non-suicidal MDD patients, 20 recent-suicidal MDD patients, and 20 normal controls. Platelet BDNF content was calculated by subtracting PPP BDNF level from PRP BDNF level, and dividing the result by the total platelet count, and it was expressed as pg/10 6 platelets. Individuals were evaluated using a Structured Clinical Interview for DSM-IV and a Hamilton Depression Rating Scale. Platelet BDNF contents were significantly lower in non-suicidal patients (3.09 ± 2.53 pg/10 6 platelets) and recent-suicidal MDD patients (3.16 ± 1.99 pg/10 6 platelets) than in healthy controls (6.17 ± 2.64 pg/10 6 platelets) ( p < 0.01). However, platelet BDNF contents had no significant differences between non-suicidal and recent-suicidal patients. PRP BDNF levels were also significantly lower in non-suicidal and suicidal MDD patients than in healthy controls ( p = 0.029), while PPP BDNF had no significant difference between 3 groups ( p = 0.971). Our findings suggest that there is a decrease in the platelet BDNF of patients with major depression. Reduced platelet BDNF contents as circulating stored BDNF could be associated with lower serum BDNF level in patients with major depression.

Differences in cytokines between non-suicidal patients and suicidal patients in major depression

Several studies have shown that there is an imbalance between pro-inflammatory and anti-inflammatory cytokines in major depressive disorder (MDD). However, little is known about the role of cytokines in suicide. In the present study, amounts of IL-6, IL-2, IFN-γ, IL-4, and TGF-β1 produced by mitogen-stimulated whole blood were measured in 36 MDD patients who had recently attempted suicide, 33 non-suicidal MDD patients, and 40 normal controls. The severity of depression symptoms and suicidal behaviors was evaluated using Hamilton's depression rating scale (HDRS), the Lethality Suicide Attempt Rating Scale (LSARS), and the Risk-Rescue Rating (RRR). Non-suicidal MDD patients had significantly higher IL-6 production than suicidal MDD patients and normal controls ( p < 0.001). Suicidal MDD patients had significantly lower IL-2 compared with non-suicidal patients and normal controls ( p < 0.001). Both MDD groups, with or without attempted suicide, had significantly lower IFN-γ and IL-4 and higher TGF-β1 production. HDRS scores had significant positive correlations with IL-6, IFN-γ, and the Th1/Th2 ratio and significant negative correlations with IL-4 in non-suicidal depression patients ( p < 0.005); however, these correlations did not hold true for suicidal patients. Suicidal MDD patients had no significant correlations between the LSARS or RRR scores and cytokine release. Our findings suggest that the immune response has distinct differences between non-suicidal patients and suicidal patients. Non-suicidal MDD may be associated with increased IL-6 production and a Th1/Th2 imbalance with a shift to Th1, while suicidal MDD may be associated with decreased IL-2.

Decreased plasma BDNF level in depressive patients

Background Recent reports have suggested a pathophysiological role for brain-derived neurotrophic factor (BDNF) in major depressive disorder (MDD). We evaluated plasma levels of BDNF in patients with MDD. Methods Plasma BDNF levels were measured in 77 MDD patients and 95 normal controls. The severity of psychiatric symptoms was measured with the Hamilton Depression Rating Scale and the Brief Psychiatric Rating Scale. Results Plasma BDNF levels were significantly lower in MDD patients than in normal control subjects ( p < 0.001). Plasma BDNF levels were significantly lower in MDD patients with recurrent episodes than in MDD patients with the first episode or normal controls ( p < 0.001). Plasma BDNF levels were significantly lower in non-psychotic MDD patients than in psychotic MDD patients or normal controls ( p < 0.001). Plasma BDNF in suicidal MDD patients were significantly lower than those in non-suicidal MDD patients ( p < 0.001). Limitations We measured only plasma levels of BDNF. However, the cellular sources of BDNF in human plasma are not yet clearly defined. Conclusions Our study suggests that there is a decrease in plasma BDNF levels in untreated MDD patients. However, relapsed or recurrent episodes, suicidal behavior, and psychotic features could also affect the plasma levels of BDNF. Further studies are required to understand the source and role of the circulating BDNF in depression.

Low plasma BDNF is associated with suicidal behavior in major depression

Brain-derived neurotrophic factor (BDNF), the most abundant neurotrophin in the brain, has a known association with the pathophysiology of anxiety and depression. However, the role of BDNF in suicide has not been well investigated to date. This study examined plasma BDNF levels in 32 major depressive disorder (MDD) patients who had recently attempted suicide, 32 non-suicidal MDD patients, and 30 normal controls. The lethality of the suicide attempt was measured using the Risk-Rescue Rating (RRR) and Lethality Suicide Attempt Rating Scale (LSARS). The severity of depression was measured with the Hamilton Depression Rating Scale (HDRS). Plasma BDNF levels were measured by enzyme linked immunosorbent assay. BDNF levels were significantly lower in suicidal MDD patients (430.5 ± 397.0 pg/ml) than non-suicidal MDD patients (875.80 ± 663.02 pg/ml) or normal controls (889.4 ± 611.3 pg/ml) ( F = 6.682, p = 0.002). The most suitable cut-off point of BDNF level between suicidal depression and non-suicidal depression groups was 444.58 pg/ml. At this cut-off point, the sensitivity = 68.7%, specificity = 78.1%, positive predictive value = 75.9%, and negative predictive value = 71.4%. However, there was no significant difference in BDNF levels between the depressive control and normal control groups ( p = 0.996). LSARS and RRR did not reveal any significant correlations with BDNF levels in suicidal patients. In addition, BDNF levels were not different between fatal and non-fatal suicide attempts. These results suggest that reduction of plasma BDNF level is related to suicidal behavior in major depression and that BDNF level may be a biological marker of suicidal depression.

High delta sleep-inducing peptide-like immunoreactivity in plasma in suicidal patients with major depressive disorder

Delta sleep-inducing peptide (DSIP) supposedly involves the hypothalamus-pituitary-adrenal (HPA) axis. Previous studies have shown deviated plasma DSIP-like immunoreactivity (DSIP-LI) levels, as well as abnormal DSIP-LI responses to corticotropin-releasing hormone in patients with major depressive disorder (MDD). This study was performed to investigate plasma-DSIP-LI and its association with the dexamethasone suppression test (DST) in suicide attempters. Plasma-DSIP and serum cortisol were measured before and after dexamethasone intake in 34 suicide attempters and in healthy age- and sex-matched controls. We found significantly elevated DSIP-LI levels in MDD patients (p < .005), and a significant correlation between predexamethasone cortisol and predexamethasone DSIP-LI levels in healthy controls. Postdexamethasone DSIP-LI levels increased in subjects with low predexamethasone DSIP-LI levels, whereas they decreased in subjects with high predexamethasone DSIP-LI levels. Results give some support to the theory of glucocorticoid involvement in the regulation of DSIP, and suggest altered DSIP-LI levels in suicidal MDD patients.