Brain-derived neurotrophic factor levels in schizophrenia: a systematic review with meta-analysis

Decreased cortical thickness in drug naïve first episode schizophrenia: in relation to serum levels of BDNF

This study was to examine cortical thickness in drug naïve, first episode schizophrenia patients, and to explore its relationship with serum levels of brain-derived neurotrophic factor (BDNF). Forty-five drug naive schizophrenia patients and 28 healthy controls were enrolled in the study. Freesurfer was used to parcellate cortical regions, and vertex-wise group analysis was used for whole brain cortical thickness. The clusters for the brain regions that demonstrated group differences were extracted, and the mean values of thickness were calculated. Serum levels of BDNF were measured using enzyme-linked immunosorbent assay (ELISA). After controlling for age and gender, significantly thinner cortical thickness was found in left insula and superior temporal gyrus in the patient group compared with the healthy control group (HC group) (p's < 0.001). Lower serum levels of BDNF were also found in the patient group compared with the HC group (p = 0.001). Correlation analysis showed a significant positive relationship between thickness of left insula and serum levels of BDNF within the HC group (r = 0.396, p = 0.037) but there was no such relationship within the patient group (r = 0.035, p = 0.819). Cortical thinning is present in drug naïve, first episode schizophrenia patients, indicating neurodevelopmental abnormalities at the onset of schizophrenia. Left insula might be an imaging biomarker in detecting the impaired protective role of neurotrophic factor for the brain development in schizophrenia.

Aerobic fitness and body mass index in individuals with schizophrenia: Implications for neurocognition and daily functioning

Previous reports indicate that among healthy individuals low aerobic fitness (AF) and high body-mass index (BMI) predict poor neurocognition and daily-functioning. It is unknown whether these associations extend to disorders characterized by poor neurocognition, such as schizophrenia. Therefore, we compared AF and BMI in individuals with schizophrenia and non-clinical controls, and then within the schizophrenia group we examined the links between AF, BMI, neurocognition and daily-functioning. Thirty-two individuals with schizophrenia and 64 gender- and age-matched controls completed assessments of AF (indexed by VO2max) and BMI. The former also completed measures of neurocognition, daily-functioning and physical activity. The schizophrenia group displayed significantly lower AF and higher BMI. In the schizophrenia group, AF was significantly correlated with overall neurocognition (r=0.57), along with executive functioning, working memory, social cognition, and processing speed. A hierarchical regression analysis indicated that AF accounted for 22% of the neurocognition variance. Furthermore, AF was significantly correlated with overall daily-functioning (r=0.46). In contrast, BMI displayed significant inverse correlations with neurocognition, but no associations to daily-functioning. AF was significantly correlated physical activity. The authors discuss the potential use of AF-enhancing interventions to improve neurocognitive and daily-functioning in schizophrenia, along with putative neurobiological mechanisms underlying these links, including Brain-Derived Neurotrophic Factor.

Increase of circulating BDNF levels and its relation to improvement of physical fitness following 12 weeks of combined exercise in chronic patients with schizophrenia: a pilot study

Brain-derived neurotrophic factor (BDNF), the most abundant of neurotrophins in the brain, is known to be responsible for maintenance of neurons has been implicated in the pathology of schizophrenia. In the present pilot study, we investigated the effect of a combined exercise program on circulating BDNF expression and the relationship between BDNF and improvements in physical fitness. Twenty-four patients with schizophrenia participated in the exercise intervention, three nonconsecutive days per week for 12 weeks. The resistance exercise program used the elastic band for eight different exercises for 25 min, and the aerobic exercise consisted of moderate walking for 25 min. After the training program, there were positive improvements in body composition and blood pressure. Also, there was significant improvement in leg strength, cardiovascular fitness, balance, and jump. Serum BDNF values had significantly increased following the combined exercise program. The elevation in serum BDNF concentrations correlated significantly with improvements in cardiovascular fitness and leg strength. These results suggest that exercise induced modulation of BDNF may play an important role in developing non-pharmacological treatment for chronic schizophrenic patients. In addition, these preliminary results serve to generate further hypothesis and facilitate the planning the exercise training program and management of participants.

Diverse glial cell line-derived neurotrophic factor (GDNF) support between mania and schizophrenia: a comparative study in four major psychiatric disorders

BACKGROUND

Brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) have essential roles in synaptic plasticity which is involved in pathogenesis and treatment of psychiatric disorders. However, it is not clear whether they act simultaneously during illness states in major psychiatric disorders.

METHODS

BDNF and GDNF serum levels were measured concomitantly by enzyme-linked immunosorbent assay (ELISA) method in 171 patients diagnosed with schizophrenia (n=33), bipolar disorder-manic episode (n=39), bipolar/unipolar depression (n=64, 24/40) and obsessive-compulsive disorder (n=35) according to DSM-IV, and 78 healthy volunteers. SCID-I and SCID non-patient version were used for clinical evaluation of the patients and healthy volunteers, respectively. Correlations between the two trophic factor levels, and illness severity scores, duration of illness and medication dosages were studied across different illnesses.

RESULTS

While patients had equally lower BDNF levels in all diagnoses, GDNF levels were significantly higher in mania and lower in schizophrenia compared to healthy controls. BDNF levels were negatively correlated to illness severity scores in affective episodes (mania and depression). Longer duration of illness (>5 years) had an impact on lower GDNF levels in schizophrenia. BDNF levels and antipsychotic drug dosages in schizophrenia, and GDNF levels and antidepressant drug dosages in obsessive-compulsive disorder were positively correlated.

CONCLUSION

Our data confirmed the evidence of equally deficient neuronal support by BDNF in all major psychiatric illnesses, but suggested a diverse glial functioning between schizophrenia and mania.

Preanalysis storage conditions influence the measurement of brain-derived neurotrophic factor levels in peripheral blood

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is a neurotrophin that plays a pivotal role in regulating neuronal function throughout life, and this factor is regarded as a potential biomarker of mental disorders. However, previous studies have suggested that plasma BDNF levels are more variable than serum BDNF levels.

METHODS

We determined the influence of time and temperature on the measurement of peripheral blood BDNF levels. Blood samples were aliquoted into four types of tubes, including tubes containing heparin, ethylenediaminetetraacetic acid (EDTA), and citrate for plasma, and anticoagulant-free tubes for serum. The samples were stored at 4 or 25°C for 0, 1, 2, 4, 6, 24 or 48 h, and the plasma and serum BDNF levels were measured using enzyme-linked immunosorbent assay.

RESULTS

There were interindividual and interanticoagulant compound variability in the plasma BDNF levels. The measured plasma BDNF levels increased over time, whereas the serum BDNF levels remained unchanged. Furthermore, the BDNF levels detected in plasma stored in heparin tubes at 4°C and those for samples stored in EDTA tubes at 25°C were much higher than those of the other samples.

CONCLUSION

This study indicates that measurements of plasma BDNF levels are dependent not only on the anticoagulant compounds but also on the storage time and temperature conditions used after blood sampling.

Comparison of serum BDNF levels in deficit and nondeficit chronic schizophrenia and healthy controls

The aim of this study was to compare serum BDNF levels of chronic schizophrenic patients, with or without deficit syndrome, and healthy controls. A comparative study of serum BDNF levels, determined by ELISA, was performed in 47 chronic patients with schizophrenia matched with 47 healthy controls. A part of the chronic schizophrenic sample was further divided into patients with a deficit (n=14) and a nondeficit syndrome (n=20), according to the Proxy for the Deficit Syndrome Scale. A significant difference was observed in decreased serum BDNF levels between chronic schizophrenia and healthy controls. No statistical significant differences in BDNF levels between deficit and nondeficit chronic schizophrenic patients were found. Our study confirms differences of serum BDNF levels of chronic schizophrenia and healthy controls, which correspond to the clinical progression of the disease. Our results do not support a relation between deficit profile in chronic schizophrenia and lower serum BDNF levels.

Serum brain-derived neurotrophic factor (BDNF) and its association with remission status in Chinese patients with schizophrenia

The neurotrophin, brain-derived neurotrophic factor (BDNF), characterises a probable neurobiochemical explanation of maldevelopments in schizophrenia and is a candidate biomarker of the illness. A paucity of studies examining neurobiochemical predictors of remission in schizophrenia exists. In this study, we seek to examine if serum BDNF level is associated with remission status in a sample of Chinese patients with schizophrenia. This study did not find a significant relationship between serum BDNF and remission in patients with schizophrenia. Identification of a suitable biomarker for diagnosis, management, and prognostic outcome is crucial and warrants further study.

Relationships between brain-derived neurotrophic factor, clinical symptoms, and decision-making in chronic schizophrenia: data from the Iowa Gambling Task

The levels of brain-derived neurotrophic factor (BDNF) are significantly decreased in patients with schizophrenia and correlate with impairments in cognitive function. However, no study has investigated the relationship between the serum BDNF levels and decision-making. We compared patients with schizophrenia to healthy controls with respect to their decision-making ability and serum BDNF levels. Eighty-six chronic schizophrenia patients and 51 healthy controls participated in this study. We controlled for gender, age, and estimated intelligence quotient (IQ), and we investigated the differences in decision-making performance on the Iowa Gambling Task (IGT) between the schizophrenia patient and control groups. We also compared the IGT scores, the serum BDNF levels, and the clinical symptoms between the groups. The IGT scores of the schizophrenia patients were lower than those of the controls. A negative correlation was detected between the mean net scores on the trials in the final two blocks and the serum BDNF levels (p < 0.05). Multiple regression analysis revealed that depressive symptoms and the serum BDNF levels were significantly associated with the mean net scores on the trials in the final two blocks. Based on these results, impaired sensitivity to both reward and punishment is associated with depressive symptoms and reduced serum BDNF levels in chronic schizophrenia patients and may be related to their poor performance on the IGT.

How much do we know about schizophrenia and how well do we know it? Evidence from the Schizophrenia Library

BACKGROUND

True findings about schizophrenia remain elusive; many findings are not replicated and conflicting results are common. Well-conducted systematic reviews have the ability to make robust, generalizable conclusions, with good meta-analyses potentially providing the closest estimate of the true effect size. In this paper, we undertake a systematic approach to synthesising the available evidence from well-conducted systematic reviews on schizophrenia.

METHOD

Reviews were identified by searching Medline, EMBASE, CINAHL, Current Contents and PsycINFO. The decision to include or exclude reviews, data extraction and quality assessments were conducted in duplicate. Evidence was graded as high quality if reviews contained large samples and robust results; and as moderate quality if reviews contained imprecision, inconsistency, smaller samples or study designs that may be prone to bias.

RESULTS

High- and moderate-quality evidence shows that numerous psychosocial and biomedical treatments are effective. Patients have relatively poor cognitive functioning, and subtle, but diverse, structural brain alterations, altered electrophysiological functioning and sleep patterns, minor physical anomalies, neurological soft signs, and sensory alterations. There are markers of infection, inflammation or altered immunological parameters; and there is increased mortality from a range of causes. Risk for schizophrenia is increased with cannabis use, pregnancy and birth complications, prenatal exposure to Toxoplasma gondii, childhood central nervous system viral infections, childhood adversities, urbanicity and immigration (first and second generation), particularly in certain ethnic groups. Developmental motor delays and lower intelligence quotient in childhood and adolescence are apparent.

CONCLUSIONS

We conclude that while our knowledge of schizophrenia is very substantial, our understanding of it remains limited.

New insight in expression, transport, and secretion of brain-derived neurotrophic factor: Implications in brain-related diseases

Brain-derived neurotrophic factor (BDNF) attracts increasing attention from both research and clinical fields because of its important functions in the central nervous system. An adequate amount of BDNF is critical to develop and maintain normal neuronal circuits in the brain. Given that loss of BDNF function has been reported in the brains of patients with neurodegenerative or psychiatric diseases, understanding basic properties of BDNF and associated intracellular processes is imperative. In this review, we revisit the gene structure, transcription, translation, transport and secretion mechanisms of BDNF. We also introduce implications of BDNF in several brain-related diseases including Alzheimer’s disease, Huntington’s disease, depression and schizophrenia.

DNA methylation of BDNF as a biomarker of early-life adversity

Early-life adversity increases the risk for psychopathology in later life. The underlying mechanism(s) is unknown, but epigenetic variation represents a plausible candidate. Early-life exposures can disrupt epigenetic programming in the brain, with lasting consequences for gene expression and behavior. This evidence is primarily derived from animal studies, with limited study in humans due to inaccessibility of the target brain tissue. In humans, although there is evidence for DNA methylation changes in the peripheral blood of psychiatric patients, a fundamental question remains as to whether epigenetic markers in the blood can predict epigenetic changes occurring in the brain. We used in utero bisphenol A (BPA) exposure as a model environmental exposure shown to disrupt neurodevelopment and exert long-term effects on behavior in animals and humans. We show that prenatal BPA induces lasting DNA methylation changes in the transcriptionally relevant region of the Bdnf gene in the hippocampus and blood of BALB/c mice and that these changes are consistent with BDNF changes in the cord blood of humans exposed to high maternal BPA levels in utero. Our data suggest that BDNF DNA methylation in the blood may be used as a predictor of brain BDNF DNA methylation and gene expression as well as behavioral vulnerability induced by early-life environmental exposure. Because BDNF expression and DNA methylation are altered in several psychiatric disorders that are associated with early-life adversity, including depression, schizophrenia, bipolar disorder, and autism, BDNF DNA methylation in the blood may represent a novel biomarker for the early detection of psychopathology.

Microglial intracellular Ca(2+) signaling as a target of antipsychotic actions for the treatment of schizophrenia

Microglia are resident innate immune cells which release many factors including proinflammatory cytokines, nitric oxide (NO) and neurotrophic factors when they are activated in response to immunological stimuli. Recent reports show that pathophysiology of schizophrenia is related to the inflammatory responses mediated by microglia. Intracellular Ca²⁺ signaling, which is mainly controlled by the endoplasmic reticulum (ER), is important for microglial functions such as release of NO and cytokines, migration, ramification and deramification. In addition, alteration of intracellular Ca²⁺ signaling underlies the pathophysiology of schizophrenia, while it remains unclear how typical or atypical antipsychotics affect intracellular Ca²⁺ mobilization in microglial cells. This mini-review article summarizes recent findings on cellular mechanisms underlying the characteristic differences in the actions of antipsychotics on microglial intracellular Ca²⁺ signaling and reinforces the importance of the ER of microglial cells as a target of antipsychotics for the treatment of schizophrenia.

Effects of weekly one-hour Hatha yoga therapy on resilience and stress levels in patients with schizophrenia-spectrum disorders: an eight-week randomized controlled trial

OBJECTIVE

To examine the effects of Hatha yoga therapy on resilience, brain-derived neurotrophic factor (BDNF) levels, and salivary alpha amylase (SAA) activity in patients with schizophrenia-spectrum disorders.

DESIGN AND PARTICIPANTS

Single-blinded, randomized controlled study in which outpatients with schizophrenia or related psychotic disorders (according to International Classification of Diseases, 10th Revision) were randomly assigned to a yoga or a control group.

SETTING

November 2012-April 2013 at Yamanashi Prefectural Kita Hospital, Japan.

INTERVENTIONS

In the yoga group, patients received weekly 1-hour Hatha yoga sessions, in addition to regular treatment, for 8 weeks. Those in the control group underwent regular treatment, which included a daycare rehabilitation program.

OUTCOME MEASURES

Assessments included the 25-item Resilience Scale (RS), Positive and Negative Syndrome Scale (PANSS), plasma and salivary BDNF level, and SAA activity.

RESULTS

Fifty patients participated (25 in each group; mean age±standard deviation, 50.9±11.3 years; mean duration of illness, 25.0±10.3 years; mean total PANSS score, 78.2±17.3). No significant differences in changes in any variable from baseline to week 8 were found between the two groups (changes in the yoga group versus the control group: RS score, -1.6±19.9 versus 0.3±17.2; PANSS score, 0.5±12.0 versus 5.0±15.6; plasma BDNF, 41.6±377.0 pg/dl versus 73.4±346.0 pg/dl; SAA, -26.2±72.6 kU/l versus -13.8±68.0 kU/l, respectively).

CONCLUSIONS

Adjunct yoga therapy showed no positive changes in resilience level or stress markers. Duration and intensity of yoga sessions and the focus on patients with chronic illness may explain the negative observations in light of past positive evidence regarding yoga therapy.

Serum brain-derived neurotrophic factor (BDNF) levels in schizophrenia: A systematic review

Background

There is increasing interest in the role of brain-derived neurotrophic factor (BDNF) in the onset and course of schizophrenia, but there are conflicting reports about serum levels of BDNF in patients with schizophrenia.

Aim

Conduct a meta-analysis combining studies from China and other countries that have evaluated the relationship of serum BDNF levels to schizophrenia.

Method

We used Cochrane methodology and RevMan 5.1 software to identify and pool the results of studies. Electronic searches of western and Chinese registries and follow-up assessment of references located 268 potential articles. Twenty-five articles (20 in English and 5 in Chinese) published before December 2011 that used case-control methods, included patients with schizophrenia who had no concurrent disorders, and used ELISA technology to assess serum BDNF were included in the analysis. The main outcome was the pooled standardized mean difference (SMD) between cases and controls. The quality of the studies was independently assessed by two raters using the GRADE system. The heterogeneity, sensitivity and potential publication bias of the studies was evaluated using RevMan.

Results

The pooled sample included 1663 patients with schizophrenia and 1355 controls. Fifteen of the included studies were rated as ‘poor quality’ and 10 were rated as ‘very poor quality’. The results of the studies were quite heterogenous (I²=95%) but subgroup analyses found that the heterogeneity was not related to country of origin, sample size, age, gender, prior use of antipsychotic medication, or study quality. The pooled SMD (computed using a random-effect model because of study heterogeneity) was -0.74 (95% CI, -0.99∼-0.50; Z=5.99, p<0.001). Sensitivity analysis found that the result was stable and there was no evidence of publication bias.

Conclusion

Despite the robust statistical findings of lower serum BDNF in patients with schizophrenia than in controls, given the low quality of the available studies and the substantial heterogeneity between studies, the evidence of lower serum BDNF in patients with schizophrenia must be considered ‘weak’. The potential use of serum BDNF as a biomarker for schizophrenia must wait until higher-quality prospective studies that follow patients over time and that use uniform selection and monitoring procedures confirm these preliminary results.

Gender difference in association of cognition with BDNF in chronic schizophrenia

While numerous studies have reported that brain-derived neurotrophic factor (BDNF) may be involved in the pathophysiology of schizophrenia, very few studies have explored its association with cognitive impairment or gender differences in schizophrenia which we explored. We compared gender differences in 248 chronic schizophrenic patients (male/female=185/63) to 188 healthy controls (male/female=98/90) on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and serum BDNF. Schizophrenic symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). Our results showed that schizophrenic patients performed worse than normals on most of the cognitive tasks, and male patients had significantly lower immediate memory and delayed memory scores than female patients. BDNF levels were significantly lower in patients than controls, and male patients had significantly lower BDNF levels than female patients. For the patients, BDNF was positively associated with immediate memory and the RBANS total score. Furthermore, these associations were only observed in female not male patients. Among healthy controls, no gender difference was observed in cognitive domains and BDNF levels, or in the association between BDNF and cognition. Our results suggest gender differences in cognitive impairments, BDNF levels and their association in chronic patients with schizophrenia. However, the findings should be regarded as preliminary due to the cross-sectional design and our chronic patients, which need replication in a first-episode and drug naïve patients using a longitudinal study.

Serum Brain-derived neurotrophic factor levels in post-stroke depression

BACKGROUND

Depression is a frequent mood disorder that affects around a third of stroke patients and has been associated with poorer outcome. Our aim was to determine whether there is a relationship between serum Brain-derived neurotrophic factor (BDNF) levels and post-stroke depression (PSD).

METHODS

Two hundred and sixteen ischemic stroke patients admitted to the hospital within the first 24h after stroke onset were consecutively recruited and followed up for 3 months. Based on the symptoms, diagnoses of depression were made in accordance with DSM-IV criteria for post-stroke depression at day 90. Enzyme-linked immunosorbent assay (ELISA) was used to measure serum levels of BDNF at admission. Multivariate analyses were performed using logistic regression models.

RESULTS

In our study, 59 patients (27.3%) were diagnosed as having major depression at 3 months. Patients with major depression showed lower levels of serum BDNF [8.1 (5.6-9.4) vs. 13.7 (10.4-16.5)ng/ml, P<0.0001] at admission. In multivariate analyses, serum BDNF was an independent predictor of PSD at 3 months [odds ratio (OR): 0.79(0.72-0.87), P=0.003]. Serum levels of BDNF≤10.2ng/ml were independently associated with post-stroke (OR, 11.5; 95% CI, 5.6-23.4, P<0.0001), after adjustment for possible variables.

CONCLUSION

The present study demonstrates a strong relationship between serum BDNF levels at admission and the development of PSD within 3 months. Further studies are necessary to confirm this association, which may open the way to the proposal of new therapeutic options.

Oroxylin A enhances memory consolidation through the brain-derived neurotrophic factor in mice

Memory consolidation is a process by which acquired information is transformed from a labile into a more stable state that can be retrieved at a later time. In the present study, we investigated the role of oroxylin A on the memory consolidation process in mice. Oroxylin A improved the memory retention administered at 0 h, 1 h and 3 h after training in a passive avoidance task, suggesting that oroxylin A facilitates memory consolidation. Oroxylin A increased mature brain-derived neurotrophic factor (mBDNF) levels in the hippocampus from 6h to 24h after administration. Moreover, 3h post-training administration of oroxylin A enhanced the mBDNF level at 9h after the acquisition trial compared to the level at 6h after the acquisition trial. However, 6h post-training administration of oroxylin A did not increase the mBDNF level at 9h after the acquisition trial. Blocking mBDNF signaling with recombinant tropomyosin receptor kinase B (TrkB)-Fc or k252a at 9h after the acquisition trial obstructed the effect of oroxylin A on memory consolidation. Taken together, our data suggest that oroxylin A facilitates memory consolidation through BDNF-TrkB signaling and confirms that the increase of BDNF in a specific time window plays a crucial role in memory consolidation.

Alteration of imprinted Dlk1-Dio3 miRNA cluster expression in the entorhinal cortex induced by maternal immune activation and adolescent cannabinoid exposure

A significant feature of the cortical neuropathology of schizophrenia is a disturbance in the biogenesis of short non-coding microRNA (miRNA) that regulate translation and stability of mRNA. While the biological origin of this phenomenon has not been defined, it is plausible that it relates to major environmental risk factors associated with the disorder such as exposure to maternal immune activation (MIA) and adolescent cannabis use. To explore this hypothesis, we administered the viral mimic poly I:C to pregnant rats and further exposed some of their maturing offsprings to daily injections of the synthetic cannabinoid HU210 for 14 days starting on postnatal day 35. Whole-genome miRNA expression analysis was then performed on the left and right hemispheres of the entorhinal cortex (EC), a region strongly associated with schizophrenia. Animals exposed to either treatment alone or in combination exhibited significant differences in the expression of miRNA in the left hemisphere, whereas the right hemisphere was less responsive. Hemisphere-associated differences in miRNA expression were greatest in the combined treatment and highly over-represented in a single imprinted locus on chromosome 6q32. This observation was significant as the syntenic 14q32 locus in humans encodes a large proportion of miRNAs differentially expressed in peripheral blood lymphocytes from patients with schizophrenia, suggesting that interaction of early and late environmental insults may affect miRNA expression, in a manner that is relevant to schizophrenia.

Neurotrophins and psychiatric disorders

Increasing number of studies has during the last decade linked neurotrophic factors with the pathophysiology of neuropsychiatric disorders and with the mechanisms of action of drugs used for the treatment of these disorders. In particular, brain-derived neurotrophic factor BDNF and its receptor TrkB have been connected with the pathophysiology in mood disorders, and there is strong evidence that BDNF signaling is critically involved in the recovery from depression with both pharmacological and psychological means. Neurotrophins play a central role in neuronal plasticity and network connectivity in developing adult brain, and recent evidence links plasticity and network rewiring with mood disorders and their treatment. Therefore, neurotrophins should not be seen as happiness factors but as critical tools in the process where brain networks are optimally tuned to environment, and it is against this background that the effects of neurotrophins on neuropsychiatric disorders should be looked at.

Long-term effects of combined neonatal and adolescent stress on brain-derived neurotrophic factor and dopamine receptor expression in the rat forebrain

Altered brain-derived neurotrophic factor (BDNF) signalling and dopaminergic neurotransmission have been shown in the forebrain in schizophrenia. The 'two hit' hypothesis proposes that two major disruptions during development are involved in the pathophysiology of this illness. We therefore used a 'two hit' rat model of combined neonatal and young-adult stress to assess effects on BDNF signalling and dopamine receptor expression. Wistar rats were exposed to neonatal maternal separation (MS) stress and/or adolescent/young-adult corticosterone (CORT) treatment. At adulthood the medial prefrontal cortex (mPFC), caudate putamen (CPu) and nucleus accumbens (NAc) were analysed by qPCR and Western blot. The 'two hit' combination of MS and CORT treatment caused significant increases in BDNF mRNA and protein levels in the mPFC of male, but not female rats. BDNF mRNA expression was unchanged in the CPu but was significantly reduced by CORT in the NAc. DR3 and DR2 mRNA were significantly up-regulated in the mPFC of two-hit rats and a positive correlation was found between BDNF and DR3 expression in male, but not female rats. DR2 and DR3 expression were significantly increased following CORT treatment in the NAc and a significant negative correlation between BDNF and DR3 and DR2 mRNA levels was found. Our data demonstrate male-specific two-hit effects of developmental stress on BDNF and DR3 expression in the mPFC. Furthermore, following chronic adolescent CORT treatment, the relationship between BDNF and dopamine receptor expression was significantly altered in the NAc. These results elucidate the long-term effects of 'two hit' developmental stress on behaviour.

Changes in serum levels of brain derived neurotrophic factor and nerve growth factor-beta in schizophrenic patients before and after treatment

Schizophrenia is one of the most debilitating diseases among psychiatric disorders. Recent studies suggest the existence of effective immunological changes in the pathophysiology of this disease. The purpose of the current study was to determine the changes in serum levels of Brain Derived Neurotrophic Factor (BDNF) and Nerve Growth Factor-beta (NGF) in schizophrenic patients before treatment and 40 days after treatment. In this case-control study, serum levels of BDNF and NGF were measured by ELISA in 26 patients with schizophrenia and 26 healthy controls. All patients were treated with clozapine or risperidone for 40 days. A positive and negative syndrome scale (PANSS) questionnaire has been used to recognize the severity of the disease and to assess the response to treatment. Neurotrophin concentrations were compared before and after the treatment and with control groups using paired t-test and ANOVA test. BDNF and NGF levels in the case group were more than levels after treatment, but these differences were significant only for NGF. Concentrations in both neurotrophins were higher than the control group. The statistically significant difference was observed between changes in the NGF levels in the case and the control group, while no significant difference was seen in changes of BDNF. The main conclusion to be drawn from this study was that the increase in BDNF and particularly NGF may have an important role in causing schizophrenia. And possibly drugs clozapine and risperidone help to treat the disease by reducing the concentration of Neurotrophins.

BDNF and S100B in psychotic disorders: evidence for an association with treatment responsiveness

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) and S100B are involved in brain plasticity processes and their serum levels have been demonstrated to be altered in patients with psychoses. This study aimed to identify subgroups of patients with psychotic disorders across diagnostic boundaries that show a specific symptom profile or response to treatment with antipsychotics, by measuring serum levels of BDNF and S100B.

METHODS

The study sample consisted of 58 patients with DSM-IV psychotic disorders. Comprehensive Assessment of Symptoms and History (CASH), Positive and Negative Syndrome Scale (PANSS) and Clinical Global Impression scale for severity and improvement (CGI-S/CGI-I) were applied at baseline and after 6 weeks of antipsychotic treatment. At both time points, serum levels of BDNF and S100B were measured and compared with a matched control sample.

RESULTS

Baseline BDNF and S100B levels were significantly lower in patients as compared with controls and did not change significantly during treatment. Dividing the patient sample according to baseline biochemical parameters (low and high 25% and middle 50%), no differences in symptom profiles or outcome were found with respect to BDNF. However, the subgroups with low and high S100B levels had higher PANSS scores than the middle subgroup. In addition, the high subgroup still showed significantly more negative symptoms after treatment, whereas the low subgroup showed more positive symptoms compared with the other subgroups.

CONCLUSION

Serum levels of BDNF and S100B are lowered in patients with psychotic disorders across diagnostic boundaries. The differences between high and low S100B subgroups suggest a relationship between S100B, symptom dimensions and treatment response, irrespective of diagnostic categories.

The relationship between serum brain-derived neurotrophic factor (BDNF) and cardiometabolic indices in schizophrenia

Brain derived neurotrophic factor (BDNF), which has been implicated in the pathogenesis of schizophrenia, has been recently shown to be involved in the regulation of metabolism and energy homeostasis. This study seeks to examine the relationship between BDNF, metabolic indices and cardiovascular (CVD) risk in patients with schizophrenia. Medical histories, demographic information and anthropometric measurements were collected and analyzed from 61 participants with schizophrenia. Fasting glucose and lipids were measured in a central laboratory, and serum BDNF was analyzed using commercially available enzyme-linked immunosorbent assay (ELISA). The 10-year CVD risk for each participant was computed using the Framingham risk score (FRS). Linear regressions were performed to examine the relationships between serum BDNF with body mass index (BMI), blood pressure (BP), triglycerides (TG), total cholesterol, high-density lipoprotein cholesterol (HDL-C) and glucose. To examine the relationship between serum BDNF and FRS, serum BDNF was categorized into quartiles, and a multiple regression was performed. After adjusting for age, gender and current smoking status, diastolic BP (dBP) (p=0.045) and TG (p=0.015) were found to be significantly associated with serum BDNF. Participants in the highest quartile of serum BDNF had a 3.3 times increase in FRS over those in the lowest quartile. Our findings support the possible regulatory role of BDNF in metabolism and cardiovascular homeostasis among patients with schizophrenia similar to that observed among the non-mentally ill. Serum BDNF not only present itself as a candidate biomarker of schizophrenia but also might be a viable marker of metabolic co-morbidities associated with schizophrenia.

Genetic variations of PIP4K2A confer vulnerability to poor antipsychotic response in severely ill schizophrenia patients

Literature suggests that disease severity and neurotransmitter signaling pathway genes can accurately identify antipsychotic response in schizophrenia patients. However, putative role of signaling molecules has not been tested in schizophrenia patients based on severity of illness, despite its biological plausibility. In the present study we investigated the possible association of polymorphisms from five candidate genes RGS4, SLC6A3, PIP4K2A, BDNF, PI4KA with response to antipsychotic in variably ill schizophrenia patients. Thus in present study, a total 53 SNPs on the basis of previous reports and functional grounds were examined for their association with antipsychotic response in 423 schizophrenia patients segregated into low and high severity groups. Additionally, haplotype, diplotype, multivariate logistic regression and multifactor-dimensionality reduction (MDR) analyses were performed. Furthermore, observed associations were investigated in atypical monotherapy (n = 355) and risperidone (n = 260) treated subgroups. All associations were estimated as odds ratio (OR) and 95% confidence interval (CI) and test for multiple corrections was applied. Single locus analysis showed significant association of nine variants from SLC6A3, PIP4K2A and BDNF genes with incomplete antipsychotic response in schizophrenia patients with high severity. We identified significant association of six marker diplotype ATTGCT/ATTGCT (rs746203-rs10828317-rs7094131-rs2296624-rs11013052-rs1409396) of PIP4K2A gene in incomplete responders (corrected p-value = 0.001; adjusted-OR = 3.19, 95%-CI = 1.46–6.98) with high severity. These associations were further observed in atypical monotherapy and risperidone sub-groups. MDR approach identified gene-gene interaction among BDNF_rs7103411-BDNF_rs1491851-SLC6A3_rs40184 in severely ill incomplete responders (OR = 7.91, 95%-CI = 4.08–15.36). While RGS4_rs2842026-SLC6A3_rs2975226 interacted synergistically in incomplete responders with low severity (OR = 4.09, 95%-CI = 2.09–8.02). Our findings provide strong evidence that diplotype ATTGCT/ATTGCT of PIP4K2A gene conferred approximately three-times higher incomplete responsiveness towards antipsychotics in severely ill patients. These results are consistent with the known role of phosphatidyl-inositol-signaling elements in antipsychotic action and outcome. Findings have implication for future molecular genetic studies as well as personalized medicine. However more work is warranted to elucidate underlying causal biological pathway.

Serum BDNF concentrations as peripheral manifestations of depression: evidence from a systematic review and meta-analyses on 179 associations (N=9484)

Meta-analyses, published in 2008-2010, have confirmed abnormally low serum brain-derived neurotrophic factor (BDNF) concentrations in depressed patients and normalization of this by antidepressant treatment. These findings are believed to reflect peripheral manifestations of the neurotrophin hypothesis, which states that depression is secondary to an altered expression of BDNF in the brain. Since the publication of these meta-analyses, the field has seen a huge increase in studies on these topics. This motivated us to update the evidence on the aforementioned associations and, in addition, to compile the data on serum BDNF concentrations in relation to the symptom severity of depression. Using a manifold of data as compared with earlier meta-analyses, we find low serum BDNF concentrations in 2384 antidepressant-free depressed patients relative to 2982 healthy controls and to 1249 antidepressant-treated depressed patients (Cohen's d=-0.71 and -0.56, P-values <0.0000001). When publication bias is accounted for, these effect-sizes become substantially smaller (d=-0.47 and -0.34, respectively, P-values<0.0001). We detect between-study heterogeneity in outcomes for which only year of publication and sample size are significant moderators, with more recent papers and larger samples sizes in general being associated with smaller between-group differences. Finally, the aggregated data negate consistent associations between serum BDNF concentrations and the symptom severity of depression. Our findings corroborate the claim that altered serum BDNF concentrations are peripheral manifestations of depression. However, here we highlight that the evidence for this claim is slimmer as was initially thought and amidst a lot of noise.

Identification of subgroups of schizophrenia patients with changes in either immune or growth factor and hormonal pathways

Schizophrenia is a heterogeneous disorder normally diagnosed using the Diagnostic and Statistical Manual of Mental Disorders criteria. However, these criteria do not necessarily reflect differences in underlying molecular abnormalities of the disorder. Here, we have used multiplexed immunoassay analyses to measure immune molecules, growth factors, and hormones important to schizophrenia in acutely ill antipsychotic-naive patients (n = 180) and matched controls (n = 398). We found that using the resulting molecular profiles, we were capable of separating schizophrenia patients into 2 significantly distinct subgroups with predominant molecular abnormalities in either immune molecules or growth factors and hormones. These molecular profiles were tested using an independent cohort, and this showed the same separation into 2 subgroups. This suggests that distinct abnormalities occur in specific molecular pathways in schizophrenia patients. This may be of relevance for intervention studies that specifically target particular molecular mechanisms and could be a first step to further define the complex schizophrenia syndrome based on molecular profiles.

Decreased BDNF and TrkB mRNA expression in multiple cortical areas of patients with schizophrenia and mood disorders

Abnormalities in brain-derived neurotrophic factor (BDNF)/trkB signaling have been implicated in the etiology of schizophrenia and mood disorders. Patients with schizophrenia, bipolar disorder (BPD) and major depression (MDD) have reduced levels of neurotrophins in their brains when compared with normal unaffected individuals; however, only a few brain areas have been examined to date. Owing to the broad range of symptoms manifested in these disorders, we hypothesized that multiple associative areas of the neocortex may be implicated and that the degree of change in BDNF and trkB-TK+ mRNA expression and the cortical region or layers involved may vary according to Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnosis. We compared BDNF and trkB-TK+ mRNA levels across all layers of the prefrontal cortex (dorsolateral prefrontal cortex, DLPFC), orbital frontal cortex (OFC), anterior cingulate cortex (ACC), inferior temporal gyrus (ITG) and superior temporal gyrus (STG) in four groups: schizophrenia, BPD, MDD and unaffected controls (n=60). BDNF mRNA levels were significantly decreased in layers IV and V of DLPFC in schizophrenia patients, in layer VI of ACC in schizophrenia and MDD and in layer VI of ITG in schizophrenia, BPD and MDD. BDNF mRNA levels were also significantly decreased in layer V and/or VI of STG in schizophrenia, BPD and MDD. TrkB-TK+ mRNA levels were only significantly decreased in the cortical layer VI of OFC in BPD. The shared and distinct patterns of neurotrophin transcript reductions, with some specific to each group, may compromise the function and plasticity of distinct cortical areas to various degrees in the different groups and contribute to the range and overlap of symptoms manifested across the diagnoses.

Level of thyroid-stimulating hormone (TSH) in patients with acute schizophrenia, unipolar depression or bipolar disorder

The aim of this study is to investigate differences in thyroid-stimulating hormone (TSH) level in patients with acute schizophrenia, unipolar depression, bipolar depression and bipolar mania. Serum level of TSH was measured in 1,685 Caucasian patients (1,064 women, 63.1%; mean age 46.4). Mean serum TSH concentration was: schizophrenia (n = 769) 1.71 μIU/mL, unipolar depression (n = 651) 1.63 μIU/mL, bipolar disorder (n = 264) 1.86 μIU/mL, bipolar depression (n = 203) 2.00 μIU/mL, bipolar mania (n = 61) 1.38 μIU/mL (H = 11.58, p = 0.009). Depending on the normal range used, the overall rate of being above or below the normal range was 7.9-22.3% for schizophrenia, 13.9-26.0% for unipolar depression, 10.8-27.6% for bipolar disorder, 12.2-28.5% for bipolar depression, and 11.4-24.5% for bipolar mania. We have also found differences in TSH levels between the age groups (≤20, >20 years and ≤40, >40 years and ≤60 years and >60 years). TSH level was negatively correlated with age (r = -0.23, p < 0.001). Weak correlations with age have been found in the schizophrenia (r = -0.21, p < 0.001), unipolar depression (r = -0.23, p < 0.001), bipolar depression (r = -0.25, p = 0.002) and bipolar disorder (r = -0.21, p = 0.005) groups. Our results confirm that there may be a higher prevalence of thyroid dysfunctions in patients with mood disorders (both unipolar and bipolar) and that these two diagnostic groups differ in terms of direction and frequency of thyroid dysfunctions.

Brain-derived neurotrophic factor blood levels are decreased in schizophrenia patients and associate with rs6265 genotypes

OBJECTIVES

A growing number of studies implicate brain-derived neurotrophic factor (BDNF), an important promoter of synaptic transmission and neural plasticity, in the pathogenesis of schizophrenia. However, the existing data are controversial, that may reflect population differences between studied groups.

DESIGN AND METHODS

In the present study we performed a comparative analysis of BDNF plasma levels and its relation with rs6265 (G196A; Val66Met) polymorphism of BDNF gene (BDNF) in schizophrenia-affected and healthy subjects (controls) of the Armenian population. To check the influence of antipsychotics on BDNF plasma levels both medicated and non-medicated patients were involved in this study. Patients with paranoid form of schizophrenia chronically treated with typical antipsychotics (n=103), age- and sex-matched controls (n=105), and 25 antipsychotic-naive first-episode schizophrenia patients were involved. The levels of BDNF in the blood plasma were measured with a solid-phase enzyme-linked immunosorbent assay.

RESULTS

Decreased plasma levels of BDNF in both medicated and non-medicated schizophrenia patients compared to controls were observed. No significant difference in BDNF levels between medicated and non-medicated patients was detected. It was also detected that, compared to individuals homozygous for the standard allele (G/G) of rs6265, carriers of the rs6265 minor allele (A/G+A/A), which is significantly more frequent in schizophrenia patients than in controls, had decreased BDNF levels.

CONCLUSIONS

The data obtained suggested that the pathogenesis of schizophrenia is characterized by genetically predetermined decreased blood levels of BDNF. These results indicated that genetically determined alterations of neuroimmune modulators may be among the risk factors of schizophrenia and contribute to disease-specific pathologic changes in functional activity of both the neuronal synaptic plasticity and the immune system.

Serum brain-derived neurotrophic factor (BDNF) levels in attention deficit-hyperactivity disorder (ADHD)

It has been proposed that the neurotrophin brain-derived neurotrophic factor (BDNF) may be involved in attention deficit-hyperactivity disorder (ADHD) etiopathogenesis. Alterations in BDNF serum levels have been observed in childhood/adulthood neurodevelopmental pathologies, but no evidence is available for BDNF serum concentrations in ADHD. The study includes 45 drug-naïve ADHD children and 45 age-sex matched healthy subjects. Concentration of serum BDNF was determined by the ELISA method. BDNF serum levels in patients with ADHD were not different from those of controls (mean ± SD; ADHD: 39.33 ± 10.41 ng/ml; controls: 38.82 ± 8.29 ng/ml, t = -0.26, p = 0.80). Our findings indicate no alteration of serum BDNF levels in untreated patients with ADHD. A further stratification for cognitive, neuropsychological and psychopathological assessment in a larger sample could be useful to clarify the role of BDNF in the endophenotype characterization of ADHD.

Transcriptional consequences of schizophrenia candidate miR-137 manipulation in human neural progenitor cells

MIR137, transcribed as the microRNA miR-137, is one of the leading candidate schizophrenia susceptibility genes to arise from large genome-wide association studies (GWAS) of the disorder. Recent data suggest that miR-137 modulates the expression of other schizophrenia susceptibility genes. Although bioinformatic resources are available with which to predict genes regulated by individual microRNA, there has been a lack of empirical data on genome-wide gene expression changes following miR-137 manipulation. We have therefore performed a genome-wide assessment of transcriptional changes in a human neural progenitor cell line after miR-137 over-expression and inhibition in order to elucidate molecular pathways by which genetic perturbation of miR-137 could promote susceptibility to schizophrenia. Bioinformatically-predicted miR-137 targets showed a small but highly significant down-regulation following miR-137 over-expression. Genes that were significantly down-regulated in association with miR-137 over-expression were enriched for involvement in neuronal differentiation. Differentially expressed genes that were confirmed by qPCR included others at genome-wide significant risk loci for schizophrenia (MAD1L1 and DPYD) and BDNF. These data point to molecular pathways through which genetic variation at the MIR137 locus could confer risk for schizophrenia.

A positive correlation between serum levels of mature brain-derived neurotrophic factor and negative symptoms in schizophrenia

A meta-analysis study reported serum brain-derived neurotrophic factor (BDNF) levels as a potential biomarker for schizophrenia. However, at the time, commercially available human ELISA kits were unable to distinguish between pro-BDNF (precursor BDNF) and mature BDNF, because of limited antibody specificity. Here, we used new ELISA kits, to examine serum levels of mature BDNF and matrix metalloproteinase-9 (MMP-9), which converts pro-BDNF to mature BDNF in schizophrenia. Sixty-three patients with chronic schizophrenia and 52 age- and sex-matched healthy controls were enrolled. Patients were evaluated using the Brief Psychiatry Rating Scale, the Scale for the Assessment of Negative Symptoms (SANS) and neuropsychological tests. Neither serum mature BDNF nor MMP-9 levels differed between patients and controls. In male subgroups, serum MMP-9 levels of smoking patients were higher than those of non-smoking patients, but this was not observed in male controls or the female subgroup. In patients, serum mature BDNF levels were associated with SANS total scores and the Information subtest scores of the Wechsler Adult Intelligence Scale Revised (WAIS-R), while serum MMP-9 levels were associated with smoking and category fluency scores. These findings suggest that neither mature BDNF nor MMP-9 is a suitable biomarker for schizophrenia, although further studies using large samples are needed.

Chemokines and chemokine receptors in mood disorders, schizophrenia, and cognitive impairment: a systematic review of biomarker studies

The search for immune biomarkers in psychiatric disorders has primarily focused on pro-inflammatory cytokines. Other immune proteins including chemokines have been relatively neglected in such studies. Recent evidence has implicated chemokines in many neurobiological processes potentially relevant to psychiatric disorders, beyond their classical chemotactic functions. These may include neuromodulator effects, neurotransmitter-like effects, and direct/indirect regulation of neurogenesis. This systematic review presents the existing early evidence which supports an association of many chemokines with the psychiatric disorders: depression, bipolar disorder, schizophrenia, mild cognitive impairment and Alzheimer's disease. The non-specific association of chemokines including CXCL8 (IL-8), CCL2 (MCP-1), CCL3 (MIP-1α) and CCL5 (RANTES) with these disorders across diagnostic categories implies a generalised involvement of many chemokine systemic with psychiatric disease. Additional chemokines with great mechanistic relevance including CXCL12 (SDF-1) and CX3CL1 (fractalkine) have been rarely reported in the existing human literature and should be included in future clinical studies. The potential utility of these proteins as pathologically relevant biomarkers or therapeutic targets should be considered by future clinical and translational research.

Vascular endothelial growth factor and brain-derived neurotrophic factor in quetiapine treated first-episode psychosis

Objective. It has been suggested that atypical antipsychotics confer their effects via brain-derived neurotrophic factor (BDNF). We investigated the effect of quetiapine on serum levels of BDNF and vascular endothelial growth factor (VEGF) in drug-naive first-episode psychosis subjects. Methods. Fifteen patients drawn from a larger study received quetiapine treatment for twelve weeks. Baseline levels of serum BDNF and VEGF were compared to age- and sex-matched healthy controls and to levels following treatment. Linear regression analyses were performed to determine the relationship of BDNF and VEGF levels with outcome measures at baseline and week 12. Results. The mean serum BDNF level was significantly higher at week 12 compared to baseline and correlated with reductions in Brief Psychiatric Rating Scale (BPRS) and general psychopathology scores. Changes in serum VEGF levels also correlated significantly with a reduction in BPRS scores, a significant improvement in PANNS positive symptoms scores, and displayed a positive relationship with changes in BDNF levels. Conclusions. Our findings suggest that BDNF and VEGF are potential biomarkers for gauging improvement of psychotic symptoms. This suggests a novel neurotrophic-based mechanism of the drug effects of quetiapine on psychosis. This is the first report of VEGF perturbation in psychosis.

Gender identity disorder and schizophrenia: neurodevelopmental disorders with common causal mechanisms?

Gender identity disorder (GID), recently renamed gender dysphoria (GD), is a rare condition characterized by an incongruity between gender identity and biological sex. Clinical evidence suggests that schizophrenia occurs in patients with GID at rates higher than in the general population and that patients with GID may have schizophrenia-like personality traits. Conversely, patients with schizophrenia may experience alterations in gender identity and gender role perception. Neurobiological research, including brain imaging and studies of finger length ratio and handedness, suggests that both these disorders are associated with altered cerebral sexual dimorphism and changes in cerebral lateralization. Various mechanisms, such as Toxoplasma infection, reduced levels of brain-derived neurotrophic factor (BDNF), early childhood adversity, and links with autism spectrum disorders, may account for some of this overlap. The implications of this association for further research are discussed.

Dominant negative DISC1 mutant mice display specific social behaviour deficits and aberration in BDNF and cannabinoid receptor expression

OBJECTIVES. Disrupted in schizophrenia 1 (DISC1) is considered the most prominent candidate gene for schizophrenia. In this study, we aimed to characterize behavioural and brain biochemical traits in a mouse expressing a dominant negative DISC1mutant (DN-DISC1).

METHODS

DN-DISC1 mice underwent behavioural tests to evaluate object recognition, social preference and social novelty seeking. ELISA was conducted on brain tissue to evaluate BDNF levels. Western blot was employed to measure BDNF receptor (TrkB) and cannabinoid receptor CB1.

RESULTS

The mutant DISC1 mice displayed deficits in preference to social novelty while both social preference and object recognition were intact. Biochemical analysis of prefrontal cortex and hippocampus revealed a modest reduction in cortical TrkB protein levels of male mice while no differences in BDNF levels were observed. We found sex dependent differences in the expression of cannabinoid-1 receptors.

CONCLUSIONS

We describe novel behavioural and biochemical abnormalities in the DN-DISC1 mouse model of schizophrenia. The data shows for the first time a possible link between DISC1 mutation and the cannabinoid system.

Serum proBDNF/BDNF and response to fluvoxamine in drug-naïve first-episode major depressive disorder patients

BACKGROUND

We investigated the association between serum proBDNF, a precursor of brain-derived neurotrophic factor (BDNF), and response to fluvoxamine in patients with major depressive disorder (MDD) using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR): physically healthy and free of current alcohol or drug abuse, comorbid anxiety, or personality disorders.

METHODS

Fifty-one patients with MDD (M/F, 19:32; age, 38 ± 19 years) and 51 healthy controls (M/F, 22:29; age, 34 ± 17 years) were studied using DSM-IV-TR: physically healthy and free of current alcohol or drug abuse, comorbid anxiety, or personality disorders. Serum levels of proBDNF and MDNF were measured by sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

Serum mature BDNF levels in the MDD patients were significantly lower than those in the healthy controls (t = 3.046, p = 0.0018). On the other hand, no difference was found in serum proBDNF between the MDD patients and the healthy controls (t = -0.979, p = 0.833). A trend of negative correlation was found between baseline serum BDNF and baseline scores of the 17 items of the Hamilton Rating Scale for Depression (HAMD17) (r = -0.183, p = 0.071). No correlation was however found between HAMD17 scores and proBDNF at baseline (r = 0.092, p = 0.421). Furthermore, no correlation was observed between baseline HAMD17 scores and baseline proBDNF/BDNF (r = -0.130, p = 0.190). No changes were observed in serum levels of proBDNF and BDNF during the treatment periods.

CONCLUSIONS

These results suggest that there is no association between serum proBDNF/BDNF and fluvoxamine response in MDD patients at least within 4 weeks of the treatment.

Brain-derived neurotrophic factor as a potential biomarker of cognitive recovery in schizophrenia

Brain-derived neurotrophic factor (BDNF) has been proposed as a biomarker of schizophrenia and, more specifically, as a biomarker of cognitive recovery. Evidence collected in this review indicates that BDNF is relevant in the pathophysiology of schizophrenia and could play a role as a marker of clinical response. BDNF has been shown to play a positive role as a marker in antipsychotic treatment, and it has been demonstrated that typical antipsychotics decrease BDNF levels while atypical antipsychotics maintain or increase serum BDNF levels. Furthermore, BDNF levels have been associated with severe cognitive impairments in patients with schizophrenia. Consequently, BDNF has been proposed as a candidate target of strategies to aid the cognitive recovery process. There is some evidence suggesting that BDNF could be mediating neurobiological processes underlying cognitive recovery. Thus, serum BDNF levels seem to be involved in some synaptic plasticity and neurotransmission processes. Additionally, serum BDNF levels significantly increased in schizophrenia subjects after neuroplasticity-based cognitive training. If positive replications of those findings are published in the future then serum BDNF levels could be definitely postulated as a peripheral biomarker for the effects of intensive cognitive training or any sort of cognitive recovery in schizophrenia. All in all, the current consideration of BDNF as a biomarker of cognitive recovery in schizophrenia is promising but still premature.

Neurotrophins in mesial temporal lobe epilepsy with and without psychiatric comorbidities

Despite the strong association between epilepsy and psychiatric comorbidities, data on clinicopathologic correlations are scant. We previously reported differential mossy fiber sprouting (MFS) in mesial temporal lobe epilepsy (MTLE) patients with psychosis (MTLE + P) and major depression (MTLE + D). Because neurotrophins (NTs) can promote MFS, here, we investigated MFS, neuronal density and immunoreactivity for the NT nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin 3 (NT3) in hippocampi of 14 MTLE patients without a psychiatric history, 13 MTLE + D, 13 MTLE + P, and 10 control necropsies. Mossy fiber sprouting correlated with granular layer NGF immunoreactivity and seizure frequency. Patients with secondarily generalized seizures exhibited less NGF immunoreactivity versus patients with complex partial seizures. There was greater NT immunoreactivity in MTLE versus control groups but lesser NT immunoreactivity in MTLE + P versus MTLE patients; these findings correlated with neuropsychologic scores. Patients with MTLE + D taking fluoxetine showed greater BDNF immunoreactivity than those not taking fluoxetine; MTLE + P patients taking haloperidol had decreased neuronal density and immunoreactivity for NGF and BDNF in specific subfields versus those not taking haloperidol. There were no differences in NT3 immunoreactivity among the groups. These findings support a close association between MFS and NT expression in the hippocampi of MTLE patients and suggest that distinct structural and neurochemical milieu may contribute to the genesis or maintenance of psychiatric comorbidities in MTLE.

Modulating neural plasticity with non-invasive brain stimulation in schizophrenia

Schizophrenia is a severe mental disorder characterised by a complex phenotype including positive, negative, affective and cognitive symptoms. Various theories have been developed to integrate the clinical phenotype into a strong neurobiological framework. One theory describes schizophrenia as a disorder of impaired neural plasticity. Recently, non-invasive brain stimulation techniques have garnered much attention to their ability to modulate plasticity and treat schizophrenia. The aim of this review is to introduce the basic physiological principles of conventional non-invasive brain stimulation techniques and to review the available evidence for schizophrenia. Despite promising evidence for efficacy in a large number of clinical trials, we continue to have a rudimentary understanding of the underlying neurobiology. Additional investigation is required to improve the response rates to non-invasive brain stimulation, to reduce the interindividual variability and to improve the understanding of non-invasive brain stimulation in schizophrenia.

Scutellarin and caffeic acid ester fraction, active components of Dengzhanxixin injection, upregulate neurotrophins synthesis and release in hypoxia/reoxygenation rat astrocytes

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellarin (Scu) and caffeic acid ester fraction (Caf), the extracts from the traditional Chinese herb, Erigeron breviscapus, are known to ameliorate post ischemic neuronal dysfunction.

AIM OF THE STUDY

Neurotrophic factors (NTFs) are essential for neuronal growth and survival. We explored the neuroprotective effect of Scu and Caf by synthesis and release of NGF, BDNF and GDNF in rat astrocytes exposed to hypoxia/reoxygenation and MACO rats. And the neuroprotection of Scu and Caf was also explored.

MATERIALS AND METHODS

The primary rat astrocytes were cultured in vitro. The temporal mRNA and protein expression profile during hypoxia/reoxygenation were analyzed using real-time RT-PCR and ELISA. The expression of p-CREB, p-Akt, p-MAPKs and Bax were analyzed by western blotting. Cell viability of neuro-2A was measured using CCK-8 and cell cytotoxicity was measured with LDH release.

RESULTS

During hypoxia/reoxygenation a similar decrease pattern of NTFs (NGF, BDNF and GDNF) was observed in both mRNA and protein; Scu and Caf enhanced the expressions of NGF, BDNF and GDNF mRNA and protein in astrocytes under hypoxia/reoxygenation condition. CREB and Akt, but not MAPKs ( p-JNK, p-ERK1/2 and p-38) may be involved in the expression of NTFs. Concomitantly, conditioned medium from astrocytes which was treated by Scu or Caf after hypo3h/Reox24h significantly reduced neurotoxicity compared with conditioned medium from hypo3h/Reox24h astrocytes alone, and they show the tendency of increased neurons viability accompanied with Bax changes.

CONCLUSIONS

These results indicate that the neuroprotective effect of Scu and Caf might be mediated, at least in part, via a stimulation of the production and release of NTFs through p-CREB and p-Akt signaling. Furthermore, Scu and Caf could antagonistic the hypoxia induced toxicity through astrocytes conditioned medium. Those results suggested that Scu and Caf might have therapeutic potential for stroke.

Plasma levels of mature brain-derived neurotrophic factor (BDNF) and matrix metalloproteinase-9 (MMP-9) in treatment-resistant schizophrenia treated with clozapine

Brain-derived neurotrophic factor (BDNF) regulates the survival and growth of neurons, and influences synaptic efficiency and plasticity. Peripheral BDNF levels in patients with schizophrenia have been widely reported in the literature. However, it is still controversial whether peripheral levels of BDNF are altered in patients with schizophrenia. The peripheral BDNF levels previously reported in patients with schizophrenia were total BDNF (proBDNF and mature BDNF) as it was unable to specifically measure mature BDNF due to limited BDNF antibody specificity. In this study, we examined whether peripheral levels of mature BDNF were altered in patients with treatment-resistant schizophrenia. Matrix metalloproteinase-9 (MMP-9) levels were also measured, as MMP-9 plays a role in the conversion of proBDNF to mature BDNF. Twenty-two patients with treatment-resistant schizophrenia treated with clozapine and 22 age- and sex-matched healthy controls were enrolled. The plasma levels of mature BDNF and MMP-9 were measured using ELISA kits. No significant difference was observed for mature BDNF however, MMP-9 was significantly increased in patients with schizophrenia. The significant correlation was observed between mature BDNF and MMP-9 plasma levels. Neither mature BDNF nor MMP-9 plasma levels were associated clinical variables. Our results do not support the view that peripheral BDNF levels are associated with schizophrenia. MMP-9 may play a role in the pathophysiology of schizophrenia and serve as a biomarker for schizophrenia.

Analysis of schizophrenia and hepatocellular carcinoma genetic network with corresponding modularity and pathways: novel insights to the immune system

Background

Schizophrenic patients show lower incidences of cancer, implicating schizophrenia may be a protective factor against cancer. To study the genetic correlation between the two diseases, a specific PPI network was constructed with candidate genes of both schizophrenia and hepatocellular carcinoma. The network, designated schizophrenia-hepatocellular carcinoma network (SHCN), was analysed and cliques were identified as potential functional modules or complexes. The findings were compared with information from pathway databases such as KEGG, Reactome, PID and ConsensusPathDB.

Results

The functions of mediator genes from SHCN show immune system and cell cycle regulation have important roles in the eitology mechanism of schizophrenia. For example, the over-expressing schizophrenia candidate genes, SIRPB1, SYK and LCK, are responsible for signal transduction in cytokine production; immune responses involving IL-2 and TREM-1/DAP12 pathways are relevant for the etiology mechanism of schizophrenia. Novel treatments were proposed by searching the target genes of FDA approved drugs with genes in potential protein complexes and pathways. It was found that Vitamin A, retinoid acid and a few other immune response agents modulated by RARA and LCK genes may be potential treatments for both schizophrenia and hepatocellular carcinoma.

Conclusions

This is the first study showing specific mediator genes in the SHCN which may suppress tumors. We also show that the schizophrenic protein interactions and modulation with cancer implicates the importance of immune system for etiology of schizophrenia.

Maternal generalized anxiety disorder during pregnancy and fetal brain development: a comparative study on cord blood brain-derived neurotrophic factor levels

OBJECTIVES

The study aimed to investigate whether maternal GAD during pregnancy affects fetal circulating brain-derived neurotrophic factor (BDNF), which plays important roles in neuronal development, by comparing cord blood BDNF levels in newborn infants of women with and without GAD.

METHODS

Study sample included 19 women with GAD and 25 women without any psychiatric disorder. GAD and other psychiatric diagnoses were screened by means of the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. The blood sample for the determination of BDNF level was obtained from the umbilical cord during delivery.

RESULTS

Cord blood BDNF levels in newborn infants of healthy women were approximately two-fold compared to newborn infants of women with GAD, and the difference was statistically significant. The duration of GAD during pregnancy was the only variable correlating with cord blood BDNF levels.

CONCLUSIONS

The study results imply that prolonged maternal GAD during pregnancy may negatively influence neurodevelopment of the fetus through lower levels of circulating BDNF.

Association of BDNF gene polymorphisms with schizophrenia and clinical symptoms in a Chinese population

The neurodevelopmental hypothesis is well established in schizophrenia. Accumulating evidence has shown that BDNF may be involved in the pathogenesis of schizophrenia. This study aimed to investigate the potential association of BDNF gene polymorphisms with susceptibility to schizophrenia and with the psychopathological symptoms in patients with schizophrenia in a Han Chinese population. Three polymorphisms (rs6265, rs12273539, and rs10835210) of the BDNF gene were analyzed in a case-control study of 709 Han Chinese individuals (375 patients and 334 controls). The patients' psychopathology was assessed using the positive and negative syndrome scale (PANSS). We found no significant differences in the genotype and allele distributions of all three polymorphisms between the patient and control groups; however, we found a trend toward to significant overall difference in the estimated haplotype frequencies, with more frequent haplotype ATC of rs6265-rs12273539-rs10835210 in the schizophrenic patients than in controls (P = 0.027). The quantitative trait analysis by the UNPHASED program showed significant associations between the rs6265 (A)-rs12273539 (C)-rs10835210 (A) haplotype and negative symptom scores from the PANSS (x(2)  = 5.79, P = 0.016). Our findings suggest that the BDNF gene polymorphisms may play a small effect on susceptibility to schizophrenia, but may contribute to the negative symptoms of the disease.