Abnormal age-related changes of plasma antioxidant proteins in schizophrenia

Albumin and bilirubin are metal-binding proteins, shown to possess free radical scavenging properties, and may thus be selective antioxidants. In the present study we examined whether individual plasma antioxidants such as albumin and bilirubin, which significantly contribute to total antioxidant status (TAS), are reduced in patients with schizophrenia. We prospectively studied plasma antioxidant proteins, i.e. albumin and bilirubin, in male veteran schizophrenic patients using a within-subject, repeated measures, on–off–on haloperidol treatment design, as well as age- and sex-matched healthy volunteers. Male patients with schizophrenia either during haloperidol treatment (n=46) or in a drug-free condition (n=35) had significantly lower levels of both plasma albumin and bilirubin compared with age- and sex-matched healthy volunteers (n=31). Such reductions of plasma antioxidant proteins in schizophrenic patients appear to be age-related changes, in contrast to those observed in healthy volunteers. On the other hand, levels of plasma albumin and bilirubin were not significantly affected by haloperidol treatment, haloperidol withdrawal, or length of drug-free period. Moreover, plasma TAS was not influenced significantly by cigarette smoking, even though it may selectively decrease plasma bilirubin but not albumin levels. The present findings, taken together with our previous results of reduced plasma TAS and uric acid, as well as an increased Red blood cell superoxide dismutase, lend further support to the hypothesis that a defect in the antioxidant defense system exists in schizophrenia that may lead to oxidative damage.     

Serum BDNF levels and weight gain in schizophrenic patients on long-term treatment with antipsychotics

Several lines of evidence suggest that central brain-derived neurotrophic factor (BDNF) modulates food intake, metabolism, and increases in body weight. Reports have also shown that serum BDNF is altered in schizophrenic patients treated with antipsychotics. This study aimed to determine if there was a relationship between BDNF and antipsychotic-induced weight gain in patients with chronic schizophrenia. Serum BDNF was measured in 124 schizophrenia patients chronically treated with clozapine (n = 57), risperidone (n = 23) or typical antipsychotics (n = 44) and 50 healthy control subjects. To further assess group differences in serum BDNF, additional analyses were performed in a subset of patients and controls individually matched for body mass index (BMI). BDNF levels were lower in patients with schizophrenia than normal controls. However, this difference was not present when controlling for current BMI. In the individually BMI-matched sample, no differences in serum BDNF levels were observed in schizophrenic patients compared to BMI-matched healthy controls. BDNF levels negatively correlated with BMI gain in female but not in male patients when gender was considered. Antipsychotic class exerted differential effects over BDNF levels and BMI gain. Our findings suggest that decreased BDNF levels may be associated with weight gain in female schizophrenic patients on long-term antipsychotic treatment.     

Reduced serum BDNF levels in patients with chronic schizophrenic disorder in relapse,who were treated with typical or atypical antipsychotics

Brain-derived neurotrophic factor signals and dopaminergic function in the brain are strongly associated, and research on BDNF in schizophrenia may enhance our insights on the pathophysiological mechanisms of this disease. In the present study we aimed to investigate the possible association between serum BDNF levels and schizophrenic relapses and the possible differential effects of treatment with typical and atypical antipsychotics on serum BDNF levels in the same group of patients. We measured serum BDNF levels in 47 patients with schizophrenia during a relapse and again 6 weeks after administration of antipsychotic treatment (14 on risperidone, 18 on haloperidol, 10 on olanzapine and five on amisulpride) and in 44 healthy volunteers. Patients with schizophrenia showed reduced serum BDNF levels in relation to healthy volunteers at study entry. No significant differences were revealed in BDNF serum levels after 6 weeks of antipsychotic treatment in the patients compared to their own levels at study entry. However, serum BDNF was significantly increased in the subgroup receiving olanzapine compared to the other antipsychotics. Our findings may indicate a differential effect of olanzapine on BDNF levels compared to haloperidol, risperidone, and amisulpride.     

Reduced serum BDNF levels in schizophrenic patients on clozapine or typical antipsychotics

Neurotrophic factors regulate neuronal development and synaptic plasticity, possibly playing a role in the pathophysiology of schizophrenia and other psychiatric disorders. Decreased brain-derived neurotrophic factor (BDNF) levels have been found in brains and in the serum of schizophrenic patients, but results are inconsistent. Also, clozapine may upregulate brain BDNF expression. In the present study, we assessed serum BDNF immunoreactivity in 44 schizophrenic patients (20 on clozapine and 24 on typical antipsychotics) and in 25 healthy volunteers. Serum BDNF levels were measured using an enzyme immunoassay. Healthy controls showed significantly higher levels of BDNF compared to the whole group of schizophrenic patients (p<0.001) as well as to the subgroups on typical antipsychotics and clozapine (p<0.001). Serum BDNF values for controls were 168.8+/-26.3pg/ml, for the clozapine group were 125.4+/-44.5pg/ml and for the group on typicals were 101.3+/-51.6pg/ml. BDNF values from patients on clozapine were non-significantly higher than values from patients on typical antipsychotics (p=0.09). Serum BDNF was strongly and positively correlated with clozapine dose (r=0.643; p=0.002) but not with other demographic characteristics. These results reinforce previous findings of reduced serum BDNF levels in schizophrenic patients and suggest a differential effect of clozapine compared to typical antipsychotics on such levels.     

Associations of serum brain-derived neurotrophic factor with cognitive impairments and negative symptoms in schizophrenia

Brain-derived neurotrophic factor (BDNF) may be involved in the pathophysiology of schizophrenia. The aim of this study was to examine the associations of serum BDNF levels with the cognition and clinical characteristics in patients with schizophrenia. Sixty-three patients with schizophrenia and 52 age- and sex-matched healthy controls were examined with neuropsychological tests. Serum BDNF levels were determined by enzyme-linked immunosorbent assay (ELISA). There were no significant differences in serum BDNF levels between normal controls and patients with schizophrenia. Serum BDNF levels of normal controls showed negative correlations with verbal working memory, but this was not the case with schizophrenic patients. Meanwhile, serum BDNF levels of schizophrenic patients showed positive correlations with the scores of the Scale for the Assessment of Negative Symptoms (SANS) and the Information subtest scores of Wechsler Adult Intelligence Scale Revised (WAIS-R). Serum BDNF levels are related with the impairment of verbal working memory and negative symptoms in patients with schizophrenia.     

Abnormal expression of brain-derived neurotrophic factor and its receptor in the corticolimbic system of schizophrenic patients

Previous neuropathological studies have revealed that the corticolimbic system of schizophrenic patients expresses abnormal levels of various synaptic molecules, which are known to be influenced by the neuronal differentiation factors, neurotrophins. Therefore, we determined levels of neurotrophins and their receptors in the postmortem brains of schizophrenic patients and control subjects in relation to molecular impairments in schizophrenia. Among the neurotrophins examined, levels of brain-derived neurotrophic factor (BDNF) were elevated specifically in the anterior cingulate cortex and hippocampus of schizophrenic patients, but levels of nerve growth factors and neurotrophin-3 showed no change in any of the regions examined. In parallel, the expressions of TrkB receptor and calbindin-D, which are both influenced by BDNF, were reduced significantly in the hippocampus or the prefrontal cortex. However, neuroleptic treatment did not appear to mimic the neurotrophic change. Neither withdrawal of drug treatment in patients nor chronic administration of haloperidol to rats altered levels of BDNF. These findings suggest that neurotrophic abnormality is associated with the corticolimbic structures of schizophrenic patients and might provide the molecular substrate for pathological manifestations of the illness.     

伴发迟发性运动障碍的精神分裂症患者血清脑源性神经营养因子水平的对照研究

目的 探讨外周血清脑源性神经营养因子(brain derived neurotrophic factor,BDNF)浓度与精神分裂症伴发的迟发性运动障碍(tadrive dyskinesia,TD)的关系.方法 收集精神分裂症伴发TD患者61例、不伴发TD的患者78例,以及正常对照102名.用酶联免疫吸附法检测BDNF水平,采用不自主运动量表(abnormal involuntary movement scale,AIMS)评估TD的严重程度,阳性和阴性症状量表(positive and negative symptom scale,PANSS)评估患者精神症状.结果 TD组、非TD组和对照组的BDNF水平分别为(9.35±1.60)μg/L、(10.12±2.03)μg/L、(12.27±2.7)μg/L,3组的差异有统计学意义(F=37.8,P<0.01);两两比较显示,TD组和非TD组均低于对照组(P<0.01),而TD组又低于非TD组(P<0.05).使用典型和非典型抗精神病药物患者之间的BDNF水平差异无统计学意义(P>0.05).TD组BDNF水平与AIMS总分、年龄、总病程负相关(r分别为-0.24、-0.32、-0.22,P均小于0.05),而在非TD组BDNF水平与上述因素均无相关(P>0.05).结论 精神分裂症伴发TD患者外周BDNF浓度下降,且其水平与异常运动严重程度相关,提示BDNF可能在TD的病理生理中发挥作用.     

Associations between serum brain-derived neurotrophic factor levels and clinical phenotypes in schizophrenia patients

This study investigated serum brain-derived neurotrophic factor (BDNF) protein levels in schizophrenia patients and healthy control subjects and schizophrenia patients with various clinical phenotypes. During a 1-year period, 126 schizophrenic patients and 96 healthy control subjects were recruited. Serum BDNF protein levels were measured using an ELISA Kit. Psychiatric diagnoses were made according to DSM-IV criteria. One-way analysis of variance (ANOVA) showed no significant differences in serum BDNF protein levels between schizophrenia and healthy normals. Additionally, no significant differences existed in BDNF levels between schizophrenia patients for the following variables: with/without a suicide attempt; antipsychotic drug use, family tendency and disease onset before and after 25 years old. However, patients with catatonic schizophrenia had lower serum BDNF protein levels than patients with paranoid or residual schizophrenia. These analytical results suggested that BDNF might play an important role in the clinical subtypes of schizophrenia, but it needed further investigation in future.     

Low serum levels of brain-derived neurotrophic factor in patients with schizophrenia do not elevate after antipsychotic treatment

Brain-derived neurotrophic factor (BDNF) has been suggested to be involved in the etiology of schizophrenia. There is a line of evidence that disruption of neurotrophins could play a role in the etiology of schizophrenia, and antipsychotics show their effect by altering levels of neurotrophins. The aim of this study was to evaluate the effect of antipsychotics on serum BDNF levels and their relationship with the symptoms in patients with schizophrenia. Twenty-two schizophrenia patients were enrolled in the study. The control group consisted of 22 age- and sex-matched physically and mentally healthy volunteers (7 male, 15 female). Serum BDNF levels and the positive and negative syndrome scale (PANSS) scores were recorded at baseline and after 6 weeks of treatment. Serum BDNF levels were also recorded in the control group. Schizophrenia patients who failed to meet 30% improvement in PANSS score were excluded from the study. The baseline serum BDNF levels of schizophrenia patients were lower than those of controls (t = 4.56; df = 21; p < 0.001). There was no correlation between serum BDNF levels and PANSS scores in patients with schizophrenia (p > 0.05). Although PANSS (for positive symptoms p < 0.001, for negative symptoms p < 0.001) and general psychopathology (t = 20.9; df = 22; p < 0.001) scores improved significantly after 6 weeks of antipsychotic treatment; there was no change in BDNF levels in patients' serum (p > 0.05). Our results support the view that BDNF would be associated with schizophrenia. However, we could not conclude that treatment with antipsychotics alters serum BDNF levels in patients with schizophrenia.     

Effects of antipsychotics on the serum BDNF levels in schizophrenia

Brain-derived neurotrophic factor (BDNF) is active during a critical developmental period and likely influences the neuroplasticity of schizophrenia. This study longitudinally examined the effects of atypical antipsychotics on serum BDNF levels in schizophrenic patients. Specifically, this study measured serum BDNF levels in 53 patients with paranoid schizophrenia during a relapse and again 4 weeks following the administration of antipsychotic treatment (with risperidone in 32 cases, and clozapine in 21 cases). BDNF levels remained unchanged relative to study entry after 4 weeks of atypical antipsychotic treatment. However, serum BDNF was significantly increased in the subgroup receiving risperidone compared to that receiving clozapine, albeit only in the 15 male subjects and not in the 17 females. These results suggest that gender might significantly influence the antipsychotic treatment of schizophrenia from the perspective of BDNF. These findings may also indicate that the treatment with atypical antipsychotic agents differentially affects BDNF levels.     

Serum BDNF levels and weight gain in schizophrenic patients on long-term treatment with antipsychotics

Several lines of evidence suggest that central brain-derived neurotrophic factor (BDNF) modulates food intake, metabolism, and increases in body weight. Reports have also shown that serum BDNF is altered in schizophrenic patients treated with antipsychotics. This study aimed to determine if there was a relationship between BDNF and antipsychotic-induced weight gain in patients with chronic schizophrenia. Serum BDNF was measured in 124 schizophrenia patients chronically treated with clozapine (n = 57), risperidone (n = 23) or typical antipsychotics (n = 44) and 50 healthy control subjects. To further assess group differences in serum BDNF, additional analyses were performed in a subset of patients and controls individually matched for body mass index (BMI). BDNF levels were lower in patients with schizophrenia than normal controls. However, this difference was not present when controlling for current BMI. In the individually BMI-matched sample, no differences in serum BDNF levels were observed in schizophrenic patients compared to BMI-matched healthy controls. BDNF levels negatively correlated with BMI gain in female but not in male patients when gender was considered. Antipsychotic class exerted differential effects over BDNF levels and BMI gain. Our findings suggest that decreased BDNF levels may be associated with weight gain in female schizophrenic patients on long-term antipsychotic treatment.     

Brain-derived neurotrophic factor and electroconvulsive therapy in a schizophrenic patient with treatment-resistant paranoid-hallucinatory symptoms

It has been proposed that deficits in the production and the utilization of brain-derived neurotrophic factor (BDNF) may contribute to the pathogenesis of schizophrenia. At the same time, electroconvulsive shock, an experimental model of electroconvulsive therapy (ECT), has been shown to induce an increase of BDNF protein in brains of animal models. These findings suggest that one putative mechanism of action of ECT is the regulation of BDNF and/or related neurotrophins. In this case report, a 54-year-old man with severe treatment-resistant schizophrenic symptoms was treated with ECT. To evaluate the effect of ECT on BDNF serum levels, we collected a blood sample before each ECT session. During the course of ECT treatment, the paranoid and hallucinatory symptoms gradually improved, whereas BDNF levels increased over time. In addition, there was a general improvement of its positive and negative schizophrenic symptoms and depressive state. In conclusion, this case report further validates the therapeutic efficacy of ECT in schizophrenic patients with inadequate or poor response to traditional treatments. Moreover, ECT therapeutic effect is associated with an increase in BDNF serum levels. Further studies are needed to characterize the relationship between BDNF and ECT in schizophrenic patients.     

Investigation of serum BDNF levels in drug-naive patients with schizophrenia

The role of brain-derived neurotrophic factor (BDNF) is to promote and modulate the neuronal responses across neurotransmitter systems in the brain. Therefore, abnormal BDNF signaling may be associated with the pathophysiology of schizophrenia. Decreased BDNF levels in the brain and the serum of patients with psychotic disorders have been reported. In the present study, we assessed serum BDNF levels in a group of 14 drug-naive first-episode patients with schizophrenia (FEP), compared to 15 healthy controls. The serum BDNF levels in the sample of FEP patients was significantly reduced compared to normal controls (23.92+/-5.99 ng/ml vs. 30.0+/-8.43 ng/ml, F=5.01, df=1, p=.034). Negative correlations were shown between serum BDNF levels of the patients and the PANSS Positive and Negative subscale scores. Our findings indicate that BDNF levels at the onset of schizophrenia may reflect associated pathophysiological processes as well as the severity of positive and negative psychotic symptoms.     

Association between -G308A tumor necrosis factor alpha gene polymorphism and schizophrenia

Dysregulation of the inflammatory response system has been linked to pathophysiology of schizophrenia. Evidence of immune activation has derived from the detection of abnormal levels of proinflammatory cytokines and their receptors in peripheral blood and cerebrospinal fluid from schizophrenic patients. Cytokines are involved in normal CNS development as well as in the pathogenesis of many neuro-psychiatric disorders, acting directly on neural cells or modulating neurotransmitter and neuropeptide systems. In particular tumor necrosis factor alpha (TNFalpha), depending on its concentration, can exert both neurotrophic and neurotoxic effects and influence neural cell growth and proliferation. Moreover, TNFalpha gene is located on the small arm of chromosome 6 (6p21.1-21.3), a locus associated with genetic susceptibility to schizophrenia. We studied the distribution of -G308A TNFalpha gene polymorphism in 84 schizophrenic patients and in 138 healthy volunteers. This biallelic base exchange polymorphism directly affects TNFalpha plasma levels. Frequency of the TNF2(A) allele is significantly increased in schizophrenic patients as compared to controls (P = 0.0042). Genotype distribution is also significantly different (P = 0.0024). TNF2 homozygotes are represented only in the patient group (P = 0.002). These data suggest a potential role of TNFalpha as a candidate gene for susceptibility to schizophrenia and suggest that immune dysregulation in schizophrenic patients could also have a genetic component.     

Cortical gray matter deficit in patients with bipolar disorder

Background: cortical gray matter volume deficit and ventricular enlargement are well documented in schizophrenia, but their presence in bipolar disorder is less well established.

Methods: global cortical gray matter, white matter and sulcal CSF, as well as lateral and third ventricular volume measures, were derived from axial MRI brain images obtained on age-matched bipolar (n=9), schizophrenic (n=9), and control (n=16) subjects. All subjects were free of history of alcohol or other substance dependence.

Results: relative to controls, bipolar patients had widespread volume deficits of cortical gray matter but not of cortical white matter. Schizophrenic patients had an even more severe cortical gray matter deficit and greater sulcal and lateral ventricular enlargement than the bipolar patients.

Conclusions: this group of patients with bipolar disorder had a widespread deficit of cortical gray matter similar to, but less pronounced than, that observed in patients with schizophrenia.     

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.     

精神分裂症患者脑源性营养因子与临床特征的关系

目的：探讨精神分裂症患者脑源性营养因子（BDNF）与临床特征的相关性。方法：符合美国精神障碍诊断与统计手册第4版（DSM-IV）诊断标准的精神分裂症患者173例,并选择年龄、性别相匹配的健康居民作为对照,以阳性和阴性症状量表（PANSS）评估精神症状,用酶联免疫吸附法检测血清BDNF水平。结果：患者组血清BDNF水平（9．8±1．9）μg／L显著低于正常对照组（11．8±2．5）μg／L,（t=-7．6．v=322,P〈0．01）;女性患者血清BDNF水平（10．4±2．1）μg／L显著高于男性组（9．6±1．8）μg／L,（t=2．3,v=154,P〈0．05）;氯氮平治疗的患者BDNF（10．1±1．6）μg／L显著高于利醅酮治疗者（8．9±2．6）μg／L,（F=3．1,v=2．P〈0．05）;患者BDNF水平与年龄、总病程、PANSS量表中阴性症状分呈显著负相关（r=-0．2,-0．16,-0．14,P〈0．05）,结论：精神分裂症患者血清BDNF水平显著下降;BDNF存在着性别差异,年龄越大、病程越长、阴性症状越重BDNF越低,接受氯氮平治疗患者BDNF高于利酪酮组.     

No association of the brain-derived neurotrophic factor (BDNF) gene C-270T polymorphism with schizophrenia

Brain-derived neurotrophic factor (BDNF) regulates a variety of neuromodulatory processes during development, as well as in adulthood. It has been proposed as a risk factor for schizophrenia. We have investigated a possible association between schizophrenia and the C-270T polymorphism in the brain-derived neurotrophic factor (BDNF) gene in 397 schizophrenic patients and 380 control subjects. The diagnosis of schizophrenia was made for each patient by at least two psychiatrists, using DSM-IV and ICD-10 criteria in structured clinical interviews for DSM-IV Axis I disorders (SCID). No association was found between schizophrenia and the analyzed polymorphism, for either genotype or allele distribution (for genotype: p=0.513, for alleles: p=0.812). Differences were not statistically significant when analyzed separately by sex. For males, the differences for genotype distribution and allele frequency were p=0.078 and p=0.162 respectively and for females: p=0.441 and p=0.315. Thus, our data indicate that variations in the BDNF gene are unlikely to be an important factor in susceptibility to schizophrenia.     

Prevalence of obesity in adolescent and young adult patients with and without schizophrenia and in relationship to antipsychotic medication

The prevalence of obesity in inpatients of a German psychiatric rehabilitation center for adolescents and young adults (mean age 19.5 years) is assessed and set into relationship to diagnosis and medication regimen. In a cross-sectional naturalistic study body weights and heights of 151 inpatients, 109 of whom presented with ICD-10 schizophrenia spectrum disorders, were measured for the calculation of body mass indices (BMI, kg/m²); current medication regimen including the duration of treatment was assessed from medical records. BMIs were plotted into gender- and age-specific BMI-percentiles representative for the German population. Among the whole study population, obesity (BMI 90th percentile) was apparent in 44/98 (45%) of the male and in 31/53 (59%) of the female inpatients (overall: 50%). With respect to schizophrenia spectrum disorders, 36/70 (51%) males and 25/39 (64%) females (overall: 56%) were obese in contrast to 14/42 (33%) among the individuals without schizophrenia. Set into relationship to the treatment groups, the prevalence rates of obesity were 64% in patients treated with clozapine (n=69), 56% for other atypical antipsychotics (olanzapine, sulpiride, risperidone; n=27), 30% for classic antipsychotics (haloperidol, flupentixol, perazine; n=20) and 28% for the currently drug-free group (n=25). Together with other published findings in adults, these results suggest an increased prevalence of obesity among young patients with schizophrenia and especially among patients chronically treated with atypical antipsychotics.     

Abnormal expression of epidermal growth factor and its receptor in the forebrain and serum of schizophrenic patients

Epidermal growth factor (EGF) comprises a structurally related family of proteins containing heparin-binding EGF-like growth factor (HB-EGF) and transforming growth factor alpha (TGFalpha) that regulates the development of dopaminergic neurons as well as monoamine metabolism. We assessed the contribution of EGF to schizophrenia by measuring EGF family protein levels in postmortem brains and in fresh serum of schizophrenic patients and control subjects. EGF protein levels were decreased in the prefrontal cortex and striatum of schizophrenic patients, whereas the levels of HB-EGF and TGFalpha were not significantly different in any of the regions examined. Conversely, EGF receptor expression was elevated in the prefrontal cortex. Serum EGF levels were markedly reduced in schizophrenic patients, even in young, drug-free patients. Chronic treatment of animals with the antipsychotic drug haloperidol had no influence on EGF levels in the brain or serum. These findings suggest that there is abnormal EGF production in various central and peripheral tissues of patients with both acute and chronic schizophrenia. EGF might thus provide a molecular substrate for the pathologic manifestation of the illness, although additional studies are required to determine a potential link between impaired EGF signaling and the pathology/etiology of schizophrenia.