State-dependent decrease in levels of brain-derived neurotrophic factor in bipolar disorder: A meta-analytic study

Evidence has suggested a role of brain-derived neurotrophic factor (BDNF) in the pathogenesis of bipolar disorder (BD). Recent studies have examined BDNF levels in BD patients, but showed inconsistent results. In current study, meta-analyses by random-effects model were performed to compare blood BDNF levels between BD patients and healthy controls, and examine patients based on different affective status (manic, depressed, or euthymic state). Fifteen studies from 10 citations were included into the analysis. Pooling of results from all studies indicated that, overall, patients with BD had a lower level of BDNF than healthy controls (p = 1 × 10⁻⁴). But when separating these studies based on different affective status, it showed that the significance existed only when comparing patients in manic (p = 0.0008) or depressed (p = 0.02) state with controls, but not in euthymic state (p = 0.25). In addition, BDNF level was significantly increased after pharmacological treatment of manic state (p = 0.01). These findings indicate that BDNF levels are abnormally reduced in manic and depressed states of BD, and the reduced level in manic state increases after treatment. They suggest a role of blood BDNF level as a state-dependent biomarker of bipolar disorder.     

Increased serum glial cell line-derived neurotrophic factor immunocontent during manic and depressive episodes in individuals with bipolar disorder

Glial cell line-derived neurotrophic factor (GDNF) is a neurotrophic factor from the transforming growth factor β family, which plays a role in the development and function of hippocampal cells. Preclinical studies suggest that changes in neurotrophic growth factor systems might be involved in the pathophysiology of mood disorders including bipolar disorder (BD) [E.J. Nestler, M. Barrot, R.J. DiLeone, A.J. Eisch, S.J. Gold, L.M. Monteggia, Neurobiology of depression, Neuron 34 (2002) 13–25]. This is the first study to analyze GDNF immunocontent in BD subjects across different mood states, including mania, depression, and remission (euthymia). Fourty-four bipolar patients (14 depressed, 15 manic, and 15 euthymic) and 14 healthy controls, diagnosed according to the Structural Clinical Interview for DSM-IV were studied. Serum GDNF immunocontent was measured using Western blotting. Serum GDNF immunocontent was increased in manic (F = 42.31; p = 0.001; one-way ANOVA) and depressed (F = 42.31; p = 0.004; one-way ANOVA) bipolar patients, but not in euthymic patients as compared with controls. Our results indicate that changes in GDNF immunocontent occur during acute major affective episodes in bipolar subjects. These results further support the role of neurotrophins in the pathophysiology of bipolar disorder. Whether the observed increase in GDNF immunocontent correspond to a pathological or an adaptive response remains to be determined.     

Serum levels of brain-derived neurotrophic factor in patients with schizophrenia and bipolar disorder

There is evidence that major psychiatric discords such as schizophrenia (SZ) and bipolar disorder (BD) are associated with dysregulation of synaptic plasticity with downstream alterations of neurotrophins. Brain-derived neurotrophic factor (BDNF) is the most widely distributed neurotrophin in the central nervous system (CNS), and performs many biological functions such as promoting the survival, differentiation, and plasticity of neurons. Variants in the BDNF gene increase the risk of SZ and bipolar disorder. Chronic administration of drugs used to treat SZ and BD, such as lithium, valproate, quetiapine, clozapine, and olanzapine, increases BDNF expression in rat brain. To examine serum BDNF, three groups of chronically medicated DSM-IV SZ patients, on treatment with clozapine (n = 27), typical (n = 14), and other atypical antipsychotics (n = 19), 30 euthymic BD patients, and 26 healthy control had 5 ml blood samples collected by venipuncture. Serum BDNF levels were significantly higher in SZ patients (p < 0.001) when compared to either controls or euthymic BD patients. Increased BDNF in SZ patients might be related to the course of illness or to treatment variables. Prospective studies are warranted.     

Brain-derived neurotrophic factor serum levels before and after treatment for acute mania

Accumulating evidence suggests that reduced levels of brain-derived neurotrophic factor (BDNF) in acute mood episodes may play an important role in the pathophysiology of bipolar disorder (BD). In order to assess changes in BDNF serum levels in BD patients before and after treatment for acute mania, ten bipolar patients were prospectively examined at inpatient unit admission and discharge. Diagnoses were made using the Structured Clinical Interview for DSM-IV, SCID-I. Serum BDNF levels were measured by sandwich ELISA. The results showed that BDNF levels were decreased in BD patients during mania when compared to controls (p = 0.013) but this difference was no longer significant after treatment (p = 0.126). A sharp increase in BDNF levels was found after treatment of the episode of acute mania (p = 0.010). These findings suggest that the changes in BDNF serum levels may be associated with treatment response in acute mania. Further studies designed to validate the use of BDNF as a marker of treatment response in bipolar disorder are warranted.     

Serum neurotrophin-3 is increased during manic and depressive episodes in bipolar disorder

Accumulating evidence suggest that neural changes and cognitive impairment may accompany the course of bipolar disorder. Such detrimental effects of cumulative mood episodes may be related to changes in neurotrophins that take place during mood episodes but not during euthymic phases. The present study investigated serum neurotrophin-3 (NT-3) levels in patients with bipolar disorder during manic, depressed, and euthymic states, using an enzyme-linked immunosorbent assay (sandwich-ELISA). Serum NT-3 levels were increased in manic (p<0.001) and depressed (p<0.001) BD patients, as compared with euthymic patients and normal controls. These findings suggest that the NT-3 signaling system may play a role in the pathophysiology of BD.     

Circulating levels of GDNF in bipolar disorder

Neurotrophic factors regulate the survival and growth of neurons, and influence synaptic efficiency and plasticity. Several studies suggest the existence of a relationship between changes in neurotrophic levels and bipolar disorder (BD). The glial cell-line derived neurotrophic factor (GDNF) influences monoaminergic neurons and glial cells, but its role in BD patients is controversial. In order to elucidate it we evaluated plasma levels of GDNF in a sample of 70 BD patients (35 in mania and 35 in euthymia) and compared with 50 healthy controls matched for age, gender and educational levels. GDNF plasma levels were measured by enzyme-linked immunosorbent assay (ELISA). Patients were assessed by a Mini-International Neuropsychiatric Interview (MINI-plus), Young Mania and Hamilton Depression Rating Scales. Plasma GDNF levels were significantly increased in BD patients in euthymia compared with BD patients in mania and healthy controls (p < 0.05). GDNF plasma levels were correlated with age (ρ = 0.30, p < 0.05) and negatively correlated with manic symptoms in BD patients (ρ = −0.54, p < 0.05). Our results provide evidence that peripheral levels of GDNF are related with different mood states in BD, reinforcing the involvement of neurotrophic factors in its physiopathology.     

Attention orienting and inhibitory control across the different mood states in bipolar disorder: An emotional antisaccade task

An antisaccade experiment, using happy, sad, and neutral faces, was conducted to examine the effect of mood-congruent information on inhibitory control (antisaccade task) and attentional orienting (prosaccade task) during the different episodes of bipolar disorder (BD) – manic (n = 22), depressive (n = 25), and euthymic (n = 24). A group of 28 healthy controls was also included. Results revealed that symptomatic patients committed more antisaccade errors than healthy individuals, especially with mood-congruent faces. The manic group committed more antisaccade errors in response to happy faces, while the depressed group tended to commit more antisaccade errors in response to sad faces. Additionally, antisaccade latencies were slower in BD patients than in healthy individuals, whereas prosaccade latencies were slower in symptomatic patients. Taken together, these findings revealed the following: (a) slow inhibitory control in BD patients, regardless of their episode (i.e., a trait), and (b) impaired inhibitory control restricted to symptomatic patients (i.e., a state)     

Anterior genu corpus callosum and impulsivity in suicidal patients with bipolar disorder

Suicidality is a life-threatening symptom in patients with bipolar disorder (BD). Impulsivity and mood instability are associated with suicidality in mood disorders. Evidence suggests that gray and white matter abnormalities are linked with impulsivity in mood disorders, but little is known about the association between corpus callosum (CC) and impulsivity in BD. We examined the relationship between CC areas, impulsivity and suicidality in BD patients. We studied 10 female BD patients with a history of suicide attempt (mean ± SD age 36.2 ± 10.1 years), 10 female BD patients without suicide attempt history (44.2 ± 12.5 years) and 27 female healthy subjects (36.9 ± 13.8 years). Impulsivity was evaluated by the Barratt Impulsivity Scale (BIS). We traced MR images to measure the areas of the CC genu, anterior body, posterior body, isthmus and splenium. The genu was divided into anterior, middle and posterior regions. The suicidal and non-suicidal BD patients had significantly higher BIS total, attention and non-planning scores than the healthy subjects (ps < 0.01), and the suicidal BD patients had significantly higher BIS motor scores than the non-suicidal BD and healthy subjects (ps < 0.01). There were no significant differences among the three groups on any regional CC areas, although the suicidal BD patients had the smallest areas. The suicidal BD patients showed a significant inverse correlation between anterior genu area and the BIS total (r = −0.75, p = 0.04), motor (r = −0.79, p = 0.02) and non-planning scores (r = −0.79, p = 0.02). These correlations were not found in the non-suicidal BD patients or healthy subjects. The results suggest that the anterior medial frontal region may be involved in the pathophysiology of impulsive and suicidal behaviors in BD.     

Decreased serum brain-derived neurotrophic factor levels in schizophrenic patients with tardive dyskinesia

The pathogenesis of tardive dyskinesia (TD) may involve neurodegeneration and associated dysfunction of brain-derived neurotrophic factor (BDNF) for the survival and maintenance of function in neurons. We therefore compared serum BDNF levels in schizophrenic patients with (n = 129) and without TD (n = 235), and normal controls (n = 323). Assessments included the abnormal involuntary movement scale (AIMS) and the positive and negative syndrome scale (PANSS). Our results were that patients with TD had lower serum BDNF levels than those without TD and normals. Lower serum BDNF levels were correlated with greater PANSS negative subscores, but not correlated with the AIMS scores. Serum BDNF levels did not differ between patients on typical and atypical antipsychotics and were not correlated with antipsychotic doses or years of exposure. We concluded that decreased BDNF levels might be associated with TD pathophysiology and more negative symptoms of schizophrenia.     

Increased plasma levels of brain-derived neurotrophic factor in patients with long-term bipolar disorder

Recent data indicate that neurotrophins may play a role in the physiopathology of bipolar disorder (BD) and may be useful as biomarkers of the disease. The aim of this study was to evaluate the plasma concentrations of brain-derived neurotrophic factor (BDNF) in BD patients, and to correlate their levels with clinical parameters. BDNF was measured in plasma from 53 BD type I subjects (34 during mania and 19 during euthymia) and 38 healthy controls by enzyme-linked immuno-sorbent assay (ELISA). Patients were assessed by a structured clinical interview (Mini-plus), Young mania and Hamilton depression rating scales. Plasma BDNF levels were significantly increased in patients with mania (P ≤ 0.001) and euthymia (P ≤ 0.001) when compared with controls, but did not correlate with any clinical parameters. BDNF concentration was higher in BD patients with 10 or more years of disease. BDNF plasma levels were increased in BD patients, mainly in those with a longer course of disease. In line with previous studies, it is conceivable that BDNF may play a role in the pathophysiology of BD.     

Changes in plasma brain-derived neurotrophic factor levels in smokers after smoking cessation

Several studies have reported that brain-derived neurotrophic factor (BDNF) might be associated with nicotine dependence. However, there are few studies on BDNF levels in humans with nicotine dependence. In the present study, we compared the differences in plasma BDNF levels in patients with nicotine dependence and in healthy nonsmokers, and we investigated serial changes in plasma BDNF levels in patients with nicotine dependence following smoking cessation. Forty-five voluntary smokers and 66 nonsmokers were recruited in this study. Of the 45 smokers, 12 were taking varenicline, 21 were using a nicotine patch, and 12 were unaided in their cessation effort by their own choice. Plasma BDNF levels were measured at baseline using an enzyme-linked immunosorbent assay (both smokers and nonsmokers) and at weeks 4 and 12 after smoking cessation (abstinent smokers only). A total of 19 smokers were able to remain abstinent during the entire study period. Baseline plasma BDNF levels were significantly lower in smokers compared to nonsmokers (F = 4.410, p = 0.002). The plasma BDNF levels in the abstinent smokers significantly increased from baseline after 4 weeks of smoking cessation (z = −2.86, p = 0.004) but had a tendency of decrease in the period between weeks 4 and 12. We could not find differences in the plasma BDNF levels among the three smoker subgroups at week 12 following cessation. Changes in plasma BDNF levels might be related to the process of abstinence and the pathophysiology of nicotine dependence.     

Raised serum level of APRIL in patients with systemic lupus erythematosus: Correlations with disease activity indices

The aim of the present study is to assess serum APRIL levels in SLE patients versus rheumatoid arthritis (RA) patients and normal control and to correlate serum APRIL levels in SLE patients with disease activity indices. Serum APRIL levels was measured in 40 SLE patients, 20 patients with RA and 20 healthy volunteers who served as control group. Disease activity in SLE patients was assessed by the British Isles Lupus Assessment Group (BILAG) index and SLE disease activity index (SLEDAI), and results were correlated with serum APRIL levels. Significantly higher serum APRIL levels was observed in SLE patients compared to RA patients and normal controls (p = 0.003 and p ≤ 0.001, respectively). Positive correlations were found between serum APRIL levels and total BILAG index (r = 0.486 and p = 0.001), BILAG musculoskeletal score (r = 0.848 and p ≤ 0.001) and BILAG cardiorespiratory score (r = 0.326 and 0.04). Serum APRIL was higher in SLE patients compared to RA patients and normal control subjects and positively correlates with BILAG index and higher levels may be associated with musculoskeletal manifestations of the disease. APRIL antagonism could be a potential therapeutic target in SLE.     

Increased plasma brain-derived neurotrophic factor levels in chronic smokers following unaided smoking cessation

Recent animal studies have suggested an association between nicotine and alterations in brain-derived neurotrophic factor (BDNF) expression levels. However, the role of BDNF in humans with nicotine dependence has not yet been investigated. In this study, we explored the differences in the plasma BDNF levels of chronic smokers and healthy nonsmokers, and we investigated the changes in plasma BDNF levels in chronic smokers following unaided smoking cessation. Forty voluntary participants (20 smokers and 20 nonsmokers) were enrolled in this study. We measured the plasma BDNF levels at baseline (both groups) and at the end of the two-month study period (smoker group only) using an enzyme-linked immunosorbent assay. A total of 12 smokers (60.0%) completed the two-month study. ANCOVA with age and body mass index as covariates showed that the baseline plasma BDNF levels in smokers were significantly lower than those in nonsmokers (F = 4.626, p = 0.038). The plasma BDNF levels in the smokers significantly increased from baseline after the two-month smoking cessation period (Z = −3.059, p = 0.002). These findings suggest that BDNF may play a role in the pathophysiology of smoking behavior.     

Waist circumference and serum adiponectin levels in obese and non-obese postmenopausal women

Objectives

A proposed missing link between obesity and metabolic disturbances is adiponectin, an adipocyte-derived peptide. Adiponectin is a potent antidiabetic hormone and seems to have a beneficial influence on lipid profile as well. The need to explain the complex physiological roles of this hormone prompted the authors to study the relationship between adiponectin level and obesity – related abnormalities in a homogenous population of postmenopausal women.

Study design

The study involved 272 postmenopausal women aged 50–60 years. Invitations to participate in the study were sent to 4000 randomly chosen women from the Wroclaw city population fulfilling the age criterion. A telephone questionnaire was administered to the group of 1731 women who responded to the invitation and then subjects for the study were selected. Main outcome measures anthropometrical measurements of body fat tissue content and fat tissue distribution assessment were carried out in all the women. Moreover, serum concentrations of adiponectin, glucose, total cholesterol, HDL cholesterol, triglycerides and insulin were measured.

Results

The most frequent (76%) phenotype among the investigated women was obesity (BMI >25) with abnormal (= 80 cm) waist circumference (OAW), Obesity with normal (<80 cm) waist (ONW) and normal weight with abnormal waist (NOAW) were observed in only 5% and 14% of the women, respectively. Non-obese women with normal waist (NONW) were noted in only 5% of the subjects. Serum adiponectin levels in both groups of non-obese women (NOAW and NONW) were significantly higher (p < 0.05) than in the women with obesity or overweight and abnormal waist circumference (OAW group). Adiponectin levels in the women with obesity or overweight and normal waist (ONW) were also higher than in the OAW group; however, this difference was not statistically significant (p = 0.05). In all the women, serum adiponectin level correlated negatively with BMI (r = −0.34, p = 0.0001), total fat (r = −0.28, p = 0.0001), android fat deposit (r = −0.23, p = 0.0001), waist circumference (r = −0.33, p = 0.0001), glucose (r = −0.27, p = 0.0001), triglycerides (r = −0.34, p = 0.0001), and FIRI (r = −0.34, p = 0.0001) and positively with the gynoid/android fat deposit ratio (r = 0.28, p = 0.0001) and HDL cholesterol (r = 0.36, p = 0.0001).

Conclusions

These results confirm that adiponectin could be a marker of the development of menopausal insulin resistance syndrome.     

Polymorphisms of interleukin 6 and interleukin 10 in Egyptian people with Behcet's disease

Cytokines play critical roles in the pathogenesis of Behçet's disease (BD). They mediated many of the effectors and regulatory functions of immune and inflammatory responses. Many studies have linked Interleukin-6 (IL-6) and Interleukin-10 (IL-10) pathologically to BD. Thus, this study aimed to investigate the associations between IL-6 and IL-10 promoter single-nucleotide polymorphisms (SNPs) and the susceptibility to BD and their implication on plasma levels. We genotyped IL-6 −174 G/C (rs1800795) using Mutagenically Separated Polymerase Chain Reaction PCR (MS-PCR) and IL-10 −1082 G/A (rs1800896) and −819 C/T (rs1800871) using Sequence Specific Primer PCR (SSP-PCR) in 87 Egyptian patients and 97 controls. The plasma levels of IL-6 and IL-10 were measured using Enzyme-linked Immunosorbent Assay (ELISA). Significant increase in the frequency of −1082 GG genotype (P < 0.05, OR = 2.25, 95%CI = 1.03–4.91) and significant decrease in the frequency of −1082 GA genotype (P < 0.05, OR = 0.53, 95%CI = 0.29–0.96) was demonstrated in BD patients compare to controls. Patients with genital ulcer had significantly lower frequency of −1082 GG (P < 0.05, OR 0.2, 95% CI = 0.04–0.99) and G allele (P < 0.05, OR = 0.28, 95%CI = 0.08–0.93), while patients with ocular manifestations had significantly higher frequency of −1082 G allele (P < 0.01, OR = 2.28, 95%CI = 1.19–4.36). BD patients had significantly higher level of IL-6 (P < 0.001) and significantly lower level of IL-10 (P < 0.001) compared to controls. The changes in the level of cytokines were independent of any genotype of IL-6 or any genotype/haplotype of IL-10. Patients with active disease state had significantly higher level of IL-6 compared to patients in remission (P < 0.05). In conclusion, our preliminary study indicates that the polymorphism at IL-10 −1082 G/A may play a role in BD susceptibility. The significant increase in IL-6 level and the significant decrease in IL-10 level in BD patients were independent of any particular genotype in IL-6 or any particular genotype/haplotype in IL-10.     

Cardio-respiratory fitness,habitual physical activity and serum brain derived neurotrophic factor (BDNF) in men and women

Short episodes of high intensity exercise transiently increase serum levels of BDNF in humans, but serum levels of BDNF at rest appear to be lower in more physically active humans with greater levels of energy expenditure. The relationship between serum BDNF concentration, cardio-respiratory fitness (Åstrand–Rhyming test estimated VO₂ max) and volume of long-term, regular exercise and sporting activity (Baecke Habitual Physical Activity Index) was investigated in 44 men and women between the age range of 18–57 years. In this group an inverse relationship between resting serum BDNF concentration and measures of both estimated VO₂ max (r = −0.352; P < 0.05) and long-term sporting activity (r = −0.428, P < 0.01) was found. These results indicate that increased levels of cardio-respiratory fitness and habitual exercise are associated with lower resting levels of serum BDNF in healthy humans. This is the first study to demonstrate an inverse relationship between a physiological estimate of cardio-respiratory fitness and serum BDNF.     

IL10 polymorphisms associated with Behçet’s disease in Chinese Han

Objective

IL-10 is a potent anti-inflammatory cytokine that plays important roles in the pathogenesis of Behçet’s disease (BD). Two genome-wide association studies have identified IL10 as a potential risk factor for BD. Here, we investigated the association between IL10 polymorphisms and BD in Chinese Han.

Methods

407 BD patients and 679 healthy controls were enrolled, and genotyped by Sequenom MassArray system (Sequenom iPLEX assay, San Diego, CA).

Results

The frequency of risk allele of rs1800871 was notably higher in BD patients than in controls (71.9% vs. 66.2%, OR: 1.30, 95%CI: 1.08–1.58, p_c = 0.024). Similarly, rs1518111, which showed strong linkage disequilibrium (r² = 1) with allele rs1800871, was also associated with BD (p_c = 0.026). Rs3021094 was in association with BD in a dominant model (p_c = 0.035), and the haplotype (GACC) formed by rs1518111, rs3021094, rs3790622, and rs1800871 was associated with BD (p_c = 0.023). Results obtained from meta-analysis combined with our data showed that rs1800871 and rs1518111 were associated with BD.

Conclusion

IL10 may be the susceptibility gene for BD in Chinese Han population.     

CXC chemokine expression profiles in aqueous humor of patients with different clinical entities of endogenous uveitis

Aqueous humor (AH) samples from patients with Behçet's disease (BD) (n = 29), Vogt-Koyanagi-Harada (VKH) disease (n = 21), and HLA-B27-associated uveitis (n = 8), and 42 control patients were assayed for the neutrophil chemoattractants CXCL1/GRO-α and CXCL8/IL-8 and the lymphocyte chemoattractants CXCL9/MIG, CXCL10/IP-10 and CXCL12/SDF-1 with the use of a multiplex chemokine assay. Chemokine levels except SDF-1 were significantly higher in the 3 disease groups than in normal controls. Considering all patients, mean GRO-α levels were 15-fold higher than IL-8 levels and mean IP-10 levels were 22-fold higher than MIG levels. In patients with the same disease activity, AH levels of GRO-α and IP-10 were significantly higher in patients with BD than in patients with VKH disease and HLA-B27-associated uveitis (p = 0.0474; p < 0.001, respectively). These data suggest that GRO-α and IP-10 are the predominant CXC chemokines involved in neutrophil and activated T lymphocyte chemoattraction in endogenous uveitis, particularly in BD.     

Riluzole effect on occipital cortex: A structural and spectroscopy pilot study

Background

To investigate the mechanism underlying the anxiolytic properties of riluzole, a glutamate-modulating agent, we previously studied the effect of this drug on hippocampal N-acetylaspartate (NAA) and volume in patients with generalized anxiety disorder (GAD). In the same cohort, we now extend our investigation to the occipital cortex, a brain region that was recently implicated in the antidepressant effect of riluzole.

Methods

Fourteen medication-free adult patients with GAD received 8-week of open-label riluzole. Ten healthy subjects served as a comparison group. The healthy group did not receive riluzole treatment. Both groups underwent magnetic resonance imaging and spectroscopy at baseline and at the end of Week 8. Hamilton Anxiety Rating Scale (HAM-A) and Penn State Worry Questionnaire (PSWQ) were used as the primary and secondary outcome measures, respectively.

Results

At baseline, we found clusters of increased cortical thickness in the occipital region in GAD compared to healthy subjects. In the right hemisphere, 8 weeks of treatment reduced occipital cortical thickness in the GAD group (t = 3.67, p = 0.004). In addition, the improvement in HAM-A scores was negatively correlated with post-treatment right occipital NAA (r = −0.68, p = 0.008), and with changes in NAA levels (r = −0.53, p = 0.051). In the left hemisphere, we found positive associations between changes in occipital cortical thickness and improvement in HAM-A (r = 0.60, p = 0.04) and PSWQ (r = 0.62, p = 0.03).

Conclusion

These pilot findings implicate the occipital cortex as a brain region associated with pathology and clinical improvement in GAD. In addition, the region specific effect of riluzole implies a distinct pathophysiology in the occipital cortex – compared to other, previously studied, frontolimbic brain structures.