Dokyung Yoon

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.

Prevalence and trends of metabolic syndrome in Korea: Korean National Health and Nutrition Survey 1998–2001

Background:  Metabolic syndrome (MetS) is a major international health problem. Limited information is available about the prevalence of MetS in Asia, especially in Korea.

Increased plasma nitric oxide metabolites in suicide attempters.

Objective: To evaluate any correlation between plasma levels of nitric oxide metabolites (NOx) and suicide attempt. Method: Plasma NOx levels were measured in 53 patients who had recently attempted suicide, 58 nonsuicidal psychiatric patients, and 75 normal controls. The severity of suicidal behaviors was evaluated using Weisman and Worden’s Risk-Rescue Rating Scale. Results: Plasma NOx levels were significantly higher in suicidal patients than nonsuicidal psychiatric patients or normal control subjects (F = 11.029, d.f. = 2, 183, p < 0.001). Among the patients with a diagnosis of major depression, suicidal depressive patients had significantly higher plasma NOx levels than nonsuicidal depressive patients (t = –3.090, d.f. = 84, p = 0.003). Conclusion: Our study suggests that increased NO production in plasma is associated with suicide attempt, especially in depressive patients.

Reply to Comments on “Low Plasma BDNF is associated with Suicidal Behavior in Major Depression”, Progress in Neuro-Psychopharmacology and Biological Psychiatry 2006

We thank Chi-Un Pae for his interest in our paper and for his comments. He addressed several issues regarding BDNF in patients diagnosed with major depressive disorder (MDD), especially regarding methodological limitations. We also agree with those limitations and already described them in our paper. First, Dr. Pae indicated the possibility that the BDNF levels of drug-free subjects could be higher than those of drug-naïve subjects among non-suicidal MDD patients in our study. Some previous studies have shown evidence of a reversal of reduced BDNF levels after antidepressant treatment in MDD patients (Aydemir et al., 2005; Gervasoni et al., 2005; Gonul et al., 2005). Non-suicidal MDD patients in our study included 1 patient drug-free for 2 weeks, 7 patients drug free for more than 2 months, and 24 drug-naïve patients. Plasma BDNF levels had no significant difference between the 8 drug-free patients (868.20±422.22 pg/mL) and the 24 drug-naïve patients (703.25±391.01 pg/mL) in our non-suicidal MDD group (df=30, t=1.218, p=0.225). This data was not included in our paper. Based on those findings, we excluded the effect of antidepressant treatments on BDNF level. We had diagnosed both non-suicidal and suicidal patients with DSM-IV criteria using a Structured Clinical Interview for DSM-IV. Thus, we excluded suicidal patients who were not able to complete an interview because of various problems, such as drowsiness or serious medical conditions. Because of this, our study could not include suicide attempters who had used more fatal means of attempted suicide. Dr. Pae pointed out the wide variations in the plasma BDNF levels in our data, which might weaken the statistical outcomes. As we commented in the published paper, recent reports onwhole blood, serum, and plasma BDNF indicated that measured BDNF levels vary among different laboratories (Karege et al., 2005). Further studies would be required to decide on a more stable, more accurate, and more reliable method for measuring BDNF. Suicidal behavior is a wide spectrum of behaviors including suicidal ideation, suicidal attempt, from low to high lethality, and completed suicide. Clinical features that increase the risk of suicidal behavior include psychiatric disorders, aggressive/ impulsive traits, hopelessness or pessimism, substance abuse and alcoholism, a history of physical or sexual abuse during childhood, and a history of head injury or neurological disorder (Mann, 2003). The pathogenesis of suicidal behavior is suggested to involve the serotonergic system, the hypothalamic-pituitary-adrenal axis, and norepinephrine (Mann, 2003). Mann also proposed the stress-diathesis model of suicide behavior (Mann et al., 1999). Moreover, BDNF is reported to be associated with stress (Duman, 2004; Duman and Monteggia, 2006), depressive disorder (Gervasoni et al., 2005; Gonul et al., 2005), and the serotonergic system (Djalali et al., 2005; RenPatterson et al., 2005). Taken together, many animal, clinical, and genetic findings have implicated the functions or the regulation of BDNF in the pathogenesis of suicidal behavior; these studies are probably just the tip of an iceberg. Our findings suggested that plasma BDNF levels were associated with attempted suicide as well as major depression (Kim et al., in press). However, further replication by studies with large samples and longitudinal follow-up will be needed to overcome various limitations and to confirm our findings.