Decreased BDNF levels in CSF of drug-naive first-episode psychotic subjects: correlation with plasma BDNF and psychopathology

Association between reduced plasma BDNF concentration and MMSE scores in both chronic schizophrenia and mild cognitive impairment

Reduced brain derived neurotrophic factor (BDNF) concentration is reported to be associated with a cognitive decline in schizophrenia, depending on the stage of the disease. Aim of the study was to examine the possible association between plasma BDNF and cognitive decline in chronic stable schizophrenia and mild cognitive impairment (MCI). The study included 123 inpatients of both sexes with schizophrenia, 123 patients with MCI and 208 healthy control subjects. Cognitive abilities were assessed using mini mental state examination (MMSE), Clock Drawing test (CDT) and cognitive subscale of the Positive and Negative Syndrome Scale (PANSS). Plasma BDNF concentration was determined using ELISA. BDNF concentration was lower in patients with schizophrenia and MCI compared to age-matched healthy controls and was similar in carriers of different BDNF Val/66Met genotypes. The MMSE and CDT scores were lower in patients with schizophrenia compared to healthy controls and subjects with MCI. Reduced plasma BDNF was significantly associated with lower MMSE scores in all subjects. BDNF concentration in patients with schizophrenia was not affected by clinical and demographic factors. BDNF Val66Met polymorphism was not associated with the MMSE scores in all participants. Further studies should include longitudinal follow-up and other cognitive scales to confirm these results and offer cognition-improving strategies to prevent cognitive decline in chronic schizophrenia.

Identifying the differentially expressed peripheral blood microRNAs in psychiatric disorders: a systematic review and meta-analysis

Background

Evidence has suggested that microRNAs (miRNAs) may play an important role in the pathogenesis of psychiatric disorders (PDs), but the results remain inconclusive. We aimed to identify specific differentially expressed miRNAs and their overlapping miRNA expression profiles in schizophrenia (SZ), major depression disorder (MDD), and bipolar disorder (BD), the three major PDs.

Methods

The literatures up to September 30, 2023 related to peripheral blood miRNAs and PDs were searched and screened from multiple databases. The differences in miRNA levels between groups were illustrated by the standardized mean difference (SMD) and 95% confidence interval (95% CI).

Results

In total, 30 peripheral blood miRNAs were included in the meta-analysis, including 16 for SZ, 12 for MDD, and 2 for BD, each was reported in more than 3 independent studies. Compared with the control group, miR-181b-5p, miR-34a-5p, miR-195-5p, miR-30e-5p, miR-7-5p, miR-132-3p, miR-212-3p, miR-206, miR-92a-3p and miR-137-3p were upregulated in SZ, while miR-134-5p, miR-107 and miR-99b-5p were downregulated. In MDD, miR-124-3p, miR-132-3p, miR-139-5p, miR-182-5p, miR-221-3p, miR-34a-5p and miR-93-5p were upregulated, while miR-144-5p and miR-135a-5p were downregulated. However, we failed to identify statistically differentially expressed miRNAs in BD. Interestingly, miR-132-3p and miR-34a-5p were upregulated in both SZ and MDD.

Conclusions

Our study identified 13 differentially expressed miRNAs in SZ and 9 in MDD, among which miR-132-3p and miR-34a-5p were upregulated in both SZ and MDD by systematically analyzing qualified studies. These miRNAs may be used as potential biomarkers for the diagnosis of SZ and MDD in the future.

Systematic Review Registration

http://www.crd.york.ac.uk/PROSPERO, identifier CRD42023486982.

Can neurocognition, brain neurotrophic factor, triglyceride, and total cholesterol predict suicidal ideation in first-episode Han Chinese patients with schizophrenia?

OBJECTIVE

Previous studies have suggested that the suicide rate of patients with schizophrenia is high. This study investigates factors influencing suicidal ideation in first-episode schizophrenia patients, focusing on cognitive function, brain-derived neurotrophic factor (BDNF), triglyceride (TG), and total cholesterol (TC) in patients with first-episode schizophrenia.

METHODS

A total of 123 patients with first-episode schizophrenia and 38 healthy controls were included in the study. The patients were divided into suicidal and nonsuicidal ideation groups based on the Beck Scale for Suicidal Ideation, and they were assessed with Positive and Negative Syndrome Scale (PANSS). Cognitive function was assessed using the Chinese version of the MATRICS consensus cognitive battery (MCCB) and the serum BDNF, TG, and TC were detected. The main statistical methods include t-test, χ2 test, multivariate logistic regression analysis, receiver operating characteristic (ROC) curve analysis, and the DeLong test.

RESULTS

26.02% of patients exhibited suicidal ideation. Higher PANSS and TC levels were risk factors, while higher MCCB scores and BDNF levels were protective factors. ROC analysis indicated AUCs of 0.630, 0.724, and 0.762 for serum BDNF, PANSS, and MCCB, respectively, with a combined AUC of 0.870.

CONCLUSION

Serum BDNF level, PANSS score, and MCCB score can be used as auxiliary predictors of suicidal ideation in schizophrenic patients. Combining these three indicators can effectively predict suicidal ideation in schizophrenic patients.

Brain-derived neurotrophic factor levels across psychiatric disorders: A systemic review and network meta-analysis

As an important neurotrophic factor in the central nervous system, Brain-derived Neurotrophic Factor (BDNF) has been implicated in the pathophysiology of psychiatric disorders in many studies. However, its value as a biomarker for the diagnosis and differential diagnosis of mental disorders is still controversial, and its change patterns among different mental disorders have not been compared. We conducted a network meta-analysis of BDNF levels in different psychiatric disorders including schizophrenia(SCZ), major depressive disorder(MDD), bipolar disorder(BD), panic disorder(PD), post-traumatic stress disorder(PTSD), obsessive-compulsive disorder(OCD), generalized anxiety disorder(GAD) and insomnia. Studies were identified by searching electronic databases through 31/05/2023. BDNF levels decreased in patients with BD, MDD, OCD, PD, SCZ compared with controls, while significantly increased in patients with PTSD. According to the network meta-analysis, BDNF levels were significantly decreased in MDD and SCZ compared with BD (-2.6, 95% CIs [-5.32 to -0.15] and - 2.68 95% CIs [-5.18 to -0.23] respectively). However, in the traditional meta-analysis, there was a trend towards lower BDNF levels in SCZ compared to BD, with no significant difference (SMD = -0.20, 95% CIs [-0.49 to 0.08]). In conclusion, abnormal BDNF levels have been found in psychiatric disorders, and the changes in peripheral BDNF levels in patients with psychiatric disorders were reconfirmed in this study, which suggests BDNF exhibits promising clinical utility and may hold diagnostic value in distinguishing between MDD and BD.

Symptomatic remission and recovery in major psychosis: Is there a role for BDNF? A secondary analysis of the LABSP cohort data

Remission, relapse prevention, and clinical recovery are crucial areas of interest in schizophrenia (SCZ) research. Although SCZ is a chronic disorder with poor overall outcomes, years of research demonstrated that recovery is possible. There are considerable data linking brain-derived neurotrophic factor (BDNF) to SCZ, however, evidence on the role of BDNF in remission in SCZ is scarce. This secondary analysis of the Longitudinal Assessment of BDNF in Sardinian patients (LABSP) data aimed to investigate the relationship between serum BDNF levels and symptomatic remission, simultaneous clinical and functional remission, and recovery in patients with SCZ. A total of 105 patients with SCZ or schizoaffective disorder were recruited for a longitudinal assessment of BDNF levels over 24 months. Longitudinal data were analyzed using mixed-effects linear regression models. The study found significant associations between use of long acting injectables (χ2 = 7.075, df = 1, p = 0.008), baseline serum BDNF levels (U = 701, z = -2.543, p = 0.011), and "childhood" (U = 475, z = -2.124, p = 0.034) and "general" (U = 55, z = -2.014, p = 0.044) subscales of the Premorbid Adjustment Scale (PAS) with patients maintaining remission and recovery. The diagnosis of SCZ was significantly associated with lower BDNF levels for patients with simultaneous clinical and functional remission (Z = 2.035, p = 0.0419) and recovery (Z = 2.009, p = 0.0445) compared to those without. There were no significant associations between remission in the entire sample and longitudinal serum BDNF levels or genetic variants within the BDNF gene. These findings provide further insight into the complex relationship between BDNF and SCZ.

Mendelian randomization study of the relationship between blood and urine biomarkers and schizophrenia in the UK Biobank cohort

BACKGROUND

The identification of suitable biomarkers is of crucial clinical importance for the early diagnosis of treatment-resistant schizophrenia (TRS). This study aims to comprehensively analyze the association between TRS and blood and urine biomarkers.

METHODS

Candidate TRS-related single nucleotide polymorphisms (SNPs) were obtained from a recent genome-wide association study. The UK Biobank cohort, comprising 376,807 subjects with blood and urine biomarker testing data, was used to calculate the polygenic risk score (PRS) for TRS. Pearson correlation analyses were performed to evaluate the correlation between TRS PRS and each of the biomarkers, using calculated TRS PRS as the instrumental variables. Bidirectional two-sample Mendelian randomization (MR) was used to assess potential causal associations between candidate biomarkers with TRS.

RESULTS

Here we identify a significant association between TRS PRS and phosphate (r = 0.007, P = 1.96 × 10-4). Sex subgroup analyses identify seven and three candidate biomarkers associated with TRS PRS in male and female participants, respectively. For example, total protein and phosphate for males, creatinine and phosphate for females. Bidirectional two-sample MR analyses indicate that TRS is negatively associated with cholesterol (estimate = -0.363, P  = 0.008). Conversely, TRS is positively associated with total protein (estimate = 0.137, P  = 0.027), mean corpuscular volume (estimate = 0.032, P  = 2.25 × 10-5), and mean corpuscular hemoglobin (estimate = 0.018, P  = 0.007).

CONCLUSIONS

Our findings provide insights into the roles of blood and urine biomarkers in the early detection and treatment of TRS.

The Role of the Brain-Derived Neurotrophic Factor in Chronic Pain: Links to Central Sensitization and Neuroinflammation

Chronic pain is sustained, in part, through the intricate process of central sensitization (CS), marked by maladaptive neuroplasticity and neuronal hyperexcitability within central pain pathways. Accumulating evidence suggests that CS is also driven by neuroinflammation in the peripheral and central nervous system. In any chronic disease, the search for perpetuating factors is crucial in identifying therapeutic targets and developing primary preventive strategies. The brain-derived neurotrophic factor (BDNF) emerges as a critical regulator of synaptic plasticity, serving as both a neurotransmitter and neuromodulator. Mounting evidence supports BDNF's pro-nociceptive role, spanning from its pain-sensitizing capacity across multiple levels of nociceptive pathways to its intricate involvement in CS and neuroinflammation. Moreover, consistently elevated BDNF levels are observed in various chronic pain disorders. To comprehensively understand the profound impact of BDNF in chronic pain, we delve into its key characteristics, focusing on its role in underlying molecular mechanisms contributing to chronic pain. Additionally, we also explore the potential utility of BDNF as an objective biomarker for chronic pain. This discussion encompasses emerging therapeutic approaches aimed at modulating BDNF expression, offering insights into addressing the intricate complexities of chronic pain.

Plasma BDNF/Irisin Ratio Associates with Cognitive Function in Older People

Background

Reliable blood biomarkers are crucial for early detection and treatment evaluation of cognitive impairment, including Alzheimer's disease and other dementias.

Objective

To examine whether plasma biomarkers and their combination are different between older people with mild cognitive impairment (MCI) and cognitively normal individuals, and to explore their relations with cognitive performance.

Methods

This cross-sectional study included 250 older adults, including 124 participants with MCI, and 126 cognitively normal participants. Plasma brain-derived neurotrophic factor (BDNF), irisin and clusterin were measured, and BDNF/irisin ratio was calculated. Global cognition was evaluated by the Montreal Cognitive Assessment.

Results

Plasma irisin levels, but not BDNF, were significantly different between MCI group and cognitively normal group. Higher irisin concentration was associated with an increased probability for MCI both before and after controlling covariates. By contrast, plasma BDNF concentration, but not irisin, was linearly correlated with cognitive performance after adjusting for covariates. Higher BDNF/irisin ratios were not only correlated with better cognitive performance, but also associated with lower risks of MCI, no matter whether we adjusted for covariates. Plasma BDNF and irisin concentrations increased with aging, whereas BDNF/irisin ratios remained stable. No significant results of clusterin were observed.

Conclusions

Plasma BDNF/irisin ratio may be a reliable indicator which not only reflects the odds of the presence of MCI but also directly associates with cognitive performance.

Relationship between thyroid-stimulating hormone, BDNF levels, and hippocampal volume in antipsychotic-naïve first-episode psychosis patients

Introduction

Thyroid hormones play an essential role in hippocampal development, a key structure in psychosis. However, the role of these hormones in first-episode psychosis (FEP) has received limited attention. It has been hypothesized that thyroid hormones could cause morphological modifications in the hippocampal structure through the upregulation of brain-derived neurotrophic factor (BDNF). In this study, we primarily aimed to determine the relationship between thyroid-stimulating hormone (TSH) levels, peripheral BDNF levels, and hippocampal volume in antipsychotic-naïve FEP patients. We also aimed to determine whether TSH levels were associated with clinical symptomatology.

Materials and methods

A total of 50 antipsychotic-naïve FEP patients were included in the study. At baseline, we collected fasting blood samples and registered sociodemographic and clinical variables (substance use, DUP, PANSS, GAF, and CDSS). Structural T1 MRI was performed at baseline to quantify brain volumes. No control group was used for this study.

Results

Of the 50 patients, more than one-third (36%) presented alterations in TSH levels, mainly elevated levels (32% of patients). The TSH levels were inversely correlated with both peripheral BDNF and hippocampal volume. On the multivariate analysis, the model that best predicted the relative hippocampal volume was a single variable model (TSH levels). No significant association was observed between TSH levels and clinical symptomatology.

Discussion

These results suggest that thyroid hormones could have a neuroprotective effect on the hippocampus in FEP patients, possibly through their effect by increasing BDNF concentrations, which could attenuate brain injury and neuroinflammation. Nevertheless, thyroid hormones could also affect hippocampal volume through other pathways.

Plasma biomarkers in adolescents with schizophrenia-spectrum disorder

AIM

Schizophrenia onset in the developmental age has a strong neurodevelopmental burden and is associated with a poorer prognosis. The approach to diagnosis is still based on symptomatic description without objective validation. In this study, we aimed to compare the peripheral blood levels of hypothesized biomarker proteins: brain-derived neurotrophic factor (BDNF), proBDNF, p75 neurotrophin receptor (p75NTR ) and S100B between early-onset schizophrenia-spectrum adolescents (n = 45) and healthy controls (n = 34).

METHODS

Clinical assessment of the participants encompassed symptomatic description with the use of structured interviews and executive function objective measurement. Plasma levels of BDNF protein were significantly lower in schizophrenia patients than in controls both at admission (p = .003) and 6-8 weeks follow-up (p = .007).

RESULTS

We observed significant correlations between BDNF, proBDNF and p75NTR levels and positive and negative symptoms scale (PANSS) scores, p75NTR and S100B levels and suicidal parameters, as well as a correlation of BDNF plasma level with the risky decision-making style in Iowa Gambling Task (IGT).

CONCLUSIONS

The results indicate a potential value of studied proteins as a biomarker in the diagnosis and monitoring of the disease's course.

Brain-Derived Neurotrophic Factor (BDNF) Concentration Levels in Cerebrospinal Fluid and Plasma in Patients With Glioblastoma: A Prospective, Observational, Controlled Study

Objective Glioblastomas (GBMs) are among the most frequent and most malignant of untreatable brain tumors. A GBM marker could accelerate diagnosis and facilitate therapeutic monitoring. This prospective, observational, controlled study compared brain-derived neurotrophic factor (BDNF) levels in cerebrospinal fluid (CSF) and plasma between patients with GBM and a control group. Materials and methods Patients in the observational group underwent elective GBM resection (n=24, 55.8%). Control patients (n=19, 44.2%) had elective brain surgery for an unrelated, non-neoplastic, non-traumatic pathology. We measured BDNF levels in tumors, CSF, and plasma with enzyme-linked immunosorbent assay (ELISA). Peripheral blood and CSF samples were collected before surgery, and tumors were sampled intraoperatively. We analyzed correlations between BDNF levels and patient sex, age, seizures, smoking, diabetes mellitus (DM), and the use of selected antiepileptic drug (AED) and antihypertensive drug groups. Results The mean CSF BDNF concentration was significantly lower in patients with GBM (6.5 pg/mL) than in controls (11.48 pg/mL) (p=0.002). Similarly, the mean plasma BDNF concentration was significantly lower in patients with GBM (288.59 pg/mL) than in controls (574.06 pg/mL) (p=0.0005). None of the examined factors influenced CSF, plasma, or tumor tissue BDNF concentrations (p>0.05). Conclusion Plasma and CSF BDNF levels were significantly lower in adults with GBM than in controls. Thus, CSF and plasma BDNF levels may aid in GBM diagnoses. Further prospective studies are required.

The relationship between the brain-derived neurotrophic factor and neurocognitive response to physical exercise in individuals with schizophrenia

OBJECTIVE

Physical exercise can improve neurocognition in individuals with schizophrenia, presumably by facilitating neuroplasticity. There is, however, large inter-individual variation in response. The brain-derived neurotrophic factor (BDNF) has been proposed to mediate these effects. The current aim was to investigate the sparsely studied relationship between peripheral resting BDNF and neurocognitive response to physical exercise in individuals with schizophrenia.

METHOD

The current study reports secondary analyses of data from a randomized controlled trial (RCT), ClinicalTrials.gov number 02205684, recently reported according to the CONSORT guidelines. Eighty-two individuals with schizophrenia (mean age 37 ± 14 years old, 61% men) were randomly allocated to high-intensity interval training (HIIT) or a comparison group performing low-intensity active video gaming (AVG). Both interventions consisted of 2 sessions/week for 12 weeks. In previously published primary RCT analyses, HIIT and AVG showed comparable small to moderate improvements in neurocognition. We now address the inter-individual variability in neurocognitive response. We apply mediation and moderation analyses for repeated measures designs (MEMORE) and mixed effects models.

RESULTS

Baseline neurocognition was not significantly correlated with baseline levels of mature BDNF (baseline-mBDNF) or the precursor proBDNF. Nonetheless, baseline-mBDNF, but not baseline proBDNF, moderated the effect of exercise on neurocognition (p = 0.025) and explained 7% of the variance. The neurocognitive improvement increased with increasing baseline-mBDNF values. The moderating effect of baseline-mBDNF remained significant in a more complex model adding the moderating effects of exercise mode, sex, age, duration of illness and baseline VO2max on the outcome (neurocognition). Mean baseline-mBDNF significantly decreased from baseline to post-intervention (p = 0.036), regardless of exercise mode, differing by sex and associated with improved VO2max but not with change in neurocognition. A mediating role of mBDNF on the effect of physical exercise on neurocognition was not supported. Values of proBDNF mainly remained stable from baseline to post-intervention.

CONCLUSION

We found that baseline-mBDNF moderated the effect of physical exercise on neurocognition in individuals with schizophrenia and explained a small part of the inter-individual variation in neurocognitive response. Mean mBDNF decreased from baseline to post-intervention, regardless of exercise mode. A mediating role of mBDNF on the effect of exercise on neurocognition was not supported. The inter-individual variation in neurocognitive response and the complex role of peripheral BDNF in physical exercise is still to be elucidated.

Decreased serum levels of α-synuclein in patients with schizophrenia and their unaffected siblings

AIM

The final common pathway in the etiopathogenesis of schizophrenia is suggested that there is a defect in the presynaptic terminal in dopaminergic transmission, in which α-synuclein has an important role. Peripheral biomarker studies in schizophrenia have become crucial for better diagnoses, early interventions, and personalized therapies. This study aims to compare α-synuclein levels in patients with schizophrenia and their unaffected siblings with healthy controls, as a potential peripheral biomarker for schizophrenia.

METHODS

The quantifications of α-synuclein serum concentrations were conducted by the ELISA method. PANSS and CGI-S were used to analyse the severity of the symptoms of the subjects. Data were analysed by nonparametric tests and the Receiver Operating Curve (ROC) analysis.

RESULTS

Sixty-two patients with schizophrenia (mean age: 34,8 ± 9,9, %64,5 male), their 56 unaffected siblings (mean age: 39,4 ± 11,5, %55,4 male) and 56 healthy controls (mean age: 36,2 ± 9,8, %64,3 male) were included. α-synuclein levels were significantly lower in the patient (27,65 (12,61-46,09) pg/ml) and the unaffected sibling groups (24,62 (15,60-57,87) pg/ml) compared with healthy controls (45,58 (11,25-108,30) pg/ml) (p < .001). According to the ROC analysis, the optimal cut-off value for α-synuclein levels in distinguishing the schizophrenia group from the control group was 42.20. The sensitivity of the measurement of serum α-synuclein at this point was 93.5%, and the specificity was 60.7%.

CONCLUSION

Our study demonstrates that decreased levels of serum α-synuclein may be utilized as a possible peripheral biomarker of familial risk for schizophrenia in both patients and their siblings.

Repeated methamphetamine exposure decreases plasma brain-derived neurotrophic factor levels in rhesus monkeys

Background

Brain-derived neurotrophic factor (BDNF) is known to prevent methamphetamine (METH)-induced neurotoxicity and plays a role in various stages of METH addiction. However, there is a lack of research with longitudinal design on changes in plasma BDNF levels in active METH-dependent individuals.

Aims

The aim of the study was to investigate changes in BDNF levels during METH self-administration in monkeys.

Methods

This study measured plasma BDNF levels in three male rhesus monkeys with continuous METH exposure and four male control rhesus monkeys without METH exposure. Changes in plasma BDNF levels were then assessed longitudinally during 40 sessions of METH self-administration in the three monkeys.

Results

Repeated METH exposure decreased plasma BDNF levels. Additionally, plasma BDNF decreased with long-term rather than short-term accumulation of METH during METH self-administration.

Conclusions

These findings may indicate that the changes in peripheral BDNF may reflect the quantity of accumulative METH intake during a frequent drug use period.

Long non-coding RNAs in schizophrenia: Genetic variations, treatment markers and potential targeted signaling pathways

Schizophrenia (SZ), a complex and debilitating spectrum of psychiatric disorders, is now mainly attributed to multifactorial etiology that includes genetic and environmental factors. Long non-coding RNAs (lncRNAs) are gaining popularity as a way to better understand the comprehensive mechanisms beneath the clinical manifestation of SZ. Only in recent years has it been elucidated that mammalian genomes encode thousands of lncRNAs. Strikingly, roughly 30-40% of these lncRNAs are extensively expressed in different regions across the brain, which may be closely associated with SZ. The therapeutic and adverse effects of atypical antipsychotic drugs (AAPDs) are partially reflected by their role in the regulation of lncRNAs. This begs the question directly, do any lncRNAs exist as biomarkers for AAPDs treatment? Furthermore, we comprehend a range of mechanistic investigations that have revealed the regulatory roles for lncRNAs both involved in the brain and the periphery of SZ. More crucially, we also combine insights from a variety of signaling pathways to argue that lncRNAs probably play critical roles in SZ via their interactive downstream factors. This review provides a thorough understanding regarding dysregulation of lncRNAs, corresponding genetic alternations, as well as their potential regulatory roles in the pathology of SZ, which might help reveal useful therapeutic targets in SZ.

Plasma Brain-Derived Neurotrophic Factor Levels in First-Episode and Recurrent Major Depression and before and after Bright Light Therapy in Treatment-Resistant Depression

Brain-derived neurotrophic factor (BDNF) is implicated in the etiology and treatment response in major depressive disorder (MDD). However, peripheral BDNF concentrations have not been compared across different MDD stages. Bright light therapy (BLT) offers some potential in treatment-resistant depression (TRD), but its effects on BDNF levels are unknown. This study included a cross-sectional analysis of plasma BDNF concentration in females with TRD, unmedicated MDD patients, and healthy controls (HC), and measurements of longitudinal BLT effects on plasma BDNF levels in TRD patients. The present study included 55 drug-naïve, first-episode patients, 25 drug-free recurrent-episode MDD patients, 71 HC participants, and 54 TRD patients. Patients were rated by Hamilton Depression Rating Scale (HAMD)-17 and the Montgomery-Åsberg Depression Rating Scale (MADRS). Patients with TRD received BLT during 4 weeks. The total HAMD-17 and MADRS scores decreased following BLT. All patient groups had lower plasma BDNF than HC, but BDNF levels did not differ between first- and recurrent-episode BDNF patients and TRD patients before or after BLT. However, responders and remitters to BLT had higher post-treatment plasma BDNF concentrations than patients who did not achieve response or remission. The changes in plasma BDNF levels may be candidates for biomarkers of treatment response to BLT in TRD patients.

Pimavanserin treatment increases plasma brain-derived neurotrophic factor levels in rats

Background

Pimavanserin, a serotonin 5HT-2A receptor inverse agonist is the first-line, FDA-approved treatment of hallucinations and delusions associated with Parkinson's Disease psychosis (PDP), which occurs in up to 50% of PD patients. The neurobiological mechanism underlying the therapeutic effectiveness of Pimavanserin in PDP remains unknown. Several earlier studies have shown that treatment with 5HT-2A antagonists and other drugs acting on the serotonergic system such as SSRIs increase Brain derived neurotrophic factor (BDNF) levels in rodents. BDNF is synthesized as the precursor proBDNF, that undergoes cleavage intra or extracellularly to produce a mature BDNF (mBDNF) protein. mBDNF is believed to play a key role in neuroplasticity and neurogenesis. The present study tested the hypothesis that treatment with Pimavanserin is associated with higher and sustained elevations of mBDNF.

Methods

Adult Sprague-Dawley male rats were treated with Pimavanserin, Fluoxetine or vehicle for 4 weeks (chronic) or 2 h (acute). BDNF levels were determined by enzyme-linked Immunosorbent assay (ELISA).

Results

We found significant increases in plasma mBDNF levels in rats following chronic Pimavanserin treatment, but not in Fluoxetine-treated rats. No significant changes in mBDNF levels were found in the prefrontal cortex or hippocampus following Pimavanserin or Fluoxetine treatment.

Conclusion

These findings suggest that increase in mBDNF levels could be a contributing mechanism for the neuroprotective potential of Pimavanserin.

BDNF and Cognitive Function in Chilean Schizophrenic Patients

Despite cognitive symptoms being very important in schizophrenia, not every schizophrenic patient has a significant cognitive deficit. The molecular mechanisms underlying the different degrees of cognitive functioning in schizophrenic patients are not sufficiently understood. We studied the relation between brain-derived neurotrophic factor (BDNF) and cognitive functioning in two groups of schizophrenic patients with different cognitive statuses. According to the Montreal Cognitive Assessment (MoCA) results, the schizophrenic patients were classified into two subgroups: normal cognition (26 or more) and cognitive deficit (25 or less). We measured their plasma BDNF levels using ELISAs. The statistical analyses were performed using Spearman's Rho and Kruskal-Wallis tests. We found a statistically significant positive correlation between the plasma BDNF levels and MoCA score (p = 0.04) in the subgroup of schizophrenic patients with a cognitive deficit (n = 29). However, this correlation was not observed in the patients with normal cognition (n = 11) and was not observed in the total patient group (n = 40). These results support a significant role for BDNF in the cognitive functioning of schizophrenics with some degree of cognitive deficit, but suggest that BDNF may not be crucial in patients with a normal cognitive status. These findings provide information about the molecular basis underlying cognitive deficits in this illness.

Biomarkers in the cerebrospinal fluid of patients with psychotic disorders compared to healthy controls: a systematic review and meta-analysis

Psychotic disorders are severe mental disorders with poorly understood etiology. Biomarkers in the cerebrospinal fluid (CSF) could provide etiological clues and diagnostic tools for psychosis; however, an unbiased overview of CSF alterations in individuals with psychotic disorders is lacking. The objective of this study was to summarize all quantifiable findings in CSF from individuals with psychotic disorders compared to healthy controls (HC). Studies published before January 25th, 2023 were identified searching PubMed, EMBASE, Cochrane Library, Web of Science, ClinicalTrials.gov, and PsycINFO. Screening, full-text review, data extraction, and risk of bias assessments were performed by two independent reviewers following PRISMA guidelines. Findings in patients and healthy controls were compared and summarized using random-effects analyses and assessment of publication bias, subgroup and sensitivity analyses were performed. 145 studies, covering 197 biomarkers, were included, of which 163 biomarkers have not previously been investigated in meta-analyses. All studies showed some degree of bias. 55 biomarkers measured in CSF were associated with psychosis and of these were 15 biomarkers measured in ≥2 studies. Patients showed increased levels of noradrenaline (standardized mean difference/SMD, 0.53; 95% confidence interval/CI, 0.16 to 0.90) and its metabolite 3-methoxy-4-hydroxyphenylglycol (SMD, 0.30; 95% CI: 0.05 to 0.55), the serotonin metabolite 5-hydroxyindoleacetic acid (SMD, 0.11; 95% CI: 0.01 to 0.21), the pro-inflammatory neurotransmitter kynurenic acid (SMD, 1.58; 95% CI: 0.34 to 2.81), its precursor kynurenine (SMD,0.99; 95% CI: 0.60 to 1.38), the cytokines interleukin-6 (SMD, 0.58; 95% CI: 0.39 to 0.77) and interleukin-8 (SMD, 0.43; 95% CI: 0.24 to 0.62), the endocannabinoid anandamide (SMD, 0.78; 95% CI: 0.53 to 1.02), albumin ratio (SMD, 0.40; 95% CI: 0.08 to 0.72), total protein (SMD, 0.29; 95% CI: 0.16 to 0.43), immunoglobulin ratio (SMD, 0.45; 95% CI: 0.06 to 0.85) and glucose (SMD, 0.48; 95% CI: 0.01 to 0.94). Neurotensin (SMD, -0.67; 95% CI: -0.89 to -0.46) and γ-aminobutyric acid (SMD, -0.29; 95% CI: -0.50 to -0.09) were decreased. Most biomarkers showed no significant differences, including the dopamine metabolites homovanillic acid and 3,4-dihydroxyphenylacetic acid. These findings suggest that dysregulation of the immune and adrenergic system as well as blood-brain barrier dysfunction are implicated in the pathophysiology of psychotic disorders.

Systematic review and meta-analysis of the effect of adverse childhood experiences (ACEs) on brain-derived neurotrophic factor (BDNF) levels

There is continued interest in identifying dysregulated biomarkers that mediate associations between adverse childhood experiences (ACEs) and negative long-term health outcomes. However, little is known regarding how ACE exposure modulates neural biomarkers to influence poorer health outcomes in ACE-exposed children. To address this, we performed a systematic review and meta-analysis of the impact of ACE exposure on Brain Derived Neurotrophic Factor (BDNF) levels - a neural biomarker involved in childhood and adult neurogenesis and long-term memory formation. Twenty-two studies were selected for inclusion within the systematic review, ten of which were included in meta-analysis. Most included studies retrospectively assessed impacts of childhood maltreatment in clinical populations. Sample size, BDNF protein levels in ACE-exposed and unexposed subjects, and standard deviations were extracted from ten publications to estimate the BDNF ratio of means (ROM) across exposure categories. Overall, no significant difference was found in BDNF protein levels between ACE-exposed and unexposed groups (ROM: 1.08; 95 % CI: 0.93-1.26). Age at sampling, analyte type (e.g., sera, plasma, blood), and categories of ACE exposure contributed to high between-study heterogeneity, some of which was minimized in subset-based analyses. These results support continued investigation into the impact of ACE exposure on neural biomarkers and highlight the potential importance of analyte type and timing of sample collection on study results.

A consideration of the increased risk of schizophrenia due to prenatal maternal stress, and the possible role of microglia

Schizophrenia is caused by interaction of a combination of genetic and environmental factors. Of the latter, prenatal exposure to maternal stress is reportedly associated with elevated disease risk. The main orchestrators of inflammatory processes within the brain are microglia, and aberrant microglial activation/function has been proposed to contribute to the aetiology of schizophrenia. Here, we evaluate the epidemiological and preclinical evidence connecting prenatal stress to schizophrenia risk, and consider the possible mediating role of microglia in the prenatal stress-schizophrenia relationship. Epidemiological findings are rather consistent in supporting the association, albeit they are mitigated by effects of sex and gestational timing, while the evidence for microglial activation is more variable. Rodent models of prenatal stress generally report lasting effects on offspring neurobiology. However, many uncertainties remain as to the mechanisms underlying the influence of maternal stress on the developing foetal brain. Future studies should aim to characterise the exact processes mediating this aspect of schizophrenia risk, as well as focussing on how prenatal stress may interact with other risk factors.

BDNF as a biomarker for neuropathic pain: Consideration of mechanisms of action and associated measurement challenges

INTRODUCTION

The primary objective of this paper is to (1) provide a summary of human studies that have used brain derived neurotrophic factor (BDNF) as a biomarker, (2) review animal studies that help to elucidate the mechanistic involvement of BDNF in the development and maintenance of neuropathic pain (NP), and (3) provide a critique of the existing measurement techniques to highlight the limitations of the methods utilized to quantify BDNF in different biofluids in the blood (i.e., serum and plasma) with the intention of presenting a case for the most reliable and valid technique. Lastly, this review also explores potential moderators that can influence the measurement of BDNF and provides recommendations to standardize its quantification to reduce the inconsistencies across studies.

METHODS

In this manuscript we examined the literature on BDNF, focusing on its role as a biomarker, its mechanism of action in NP, and critically analyzed its measurement in serum and plasma to identify factors that contribute to the discrepancy in results between plasma and serum BDNF values.

RESULTS

A large heterogenous literature was reviewed that detailed BDNF's utility as a potential biomarker in healthy volunteers, patients with chronic pain, and patients with neuropsychiatric disorders but demonstrated inconsistent findings. The literature provides insight into the mechanism of action of BDNF at different levels of the central nervous system using animal studies. We identified multiple factors that influence the measurement of BDNF in serum and plasma and based on current evidence, we recommend assessing serum BDNF levels to quantify peripheral BDNF as they are more stable and sensitive to changes than plasma BDNF.

CONCLUSION

Although mechanistic studies clearly explain the role of BDNF, results from human studies are inconsistent. More studies are needed to evaluate the methodological challenges in using serum BDNF as a biomarker in NP.

Effects of neuronavigation-guided rTMS on serum BDNF, TrkB and VGF levels in depressive patients with suicidal ideation

BACKGROUND

Neuronavigation-guided high-dose repetitive transcranial magnetic stimulation (rTMS) could rapidly treat depressive patients with suicidal ideation. But the mechanism of rTMS still needs to be elucidated. This study aims to investigate if rTMS improves suicidal ideation and depressive symptoms by influencing brain-derived neurotrophic factor (BDNF), tropomysin receptor kinase B (TrkB) and VGF levels.

METHODS

In the present 1-week study, 59 treatment-naive depressive patients with suicidal ideation were randomly assigned to the active (n = 31) or sham (n = 28) rTMS group. The severity of suicidal ideation and depression were measured by the Beck Scale for Suicide Ideation, the Hamilton Depression Rating Scale and Montgomery-Asberg Depression Rating Scale. Fasting venous blood samples were collected at baseline and after treatment. Serum protein concentrations of BDNF, TrkB and VGF were measured by enzyme linked immunosorbent assay.

RESULTS

We found after treatment the levels of BDNF in the active rTMS group were higher than the sham group (p = 0.011), TrkB levels were decreased in the active group (p < 0.001), VGF levels were increased in the active group (p = 0.005). Post-treatment VGF levels in the active group were higher than the sham group (p = 0.008). However, there were no significant correlation between changes in BDNF, TrkB and VGF levels and the changes in clinical variables.

LIMITATIONS

Participants taking medication may affect the results.

CONCLUSIONS

Our results suggest that the BDNF-TrkB pathway and VGF may be implicated in the mechanisms underlying neuronavigation-guided rTMS for treating depressive patients with suicidal ideation.

Prospects for Neurotrophic Factor-Based Early Intervention in Schizophrenia: Lessons Learned from the Effects of Antipsychotic Drugs on Cognition, Neurogenesis, and Neurotrophic Factors

Although reducing psychotic symptoms in schizophrenia has been a major focus of therapeutic interventions for decades, improving cognition is considered a better predictor of functional outcomes. However, the most commonly prescribed antipsychotic drugs (APDs) show only marginal beneficial effects on cognition in patients with schizophrenia. The neural mechanisms underlying cognitive disturbances in schizophrenia remain unknown that making drug development efforts very challenging. Since neurotrophic factors are the primary architects of neurogenesis, synaptic plasticity, learning, and memory, the findings from preclinical and clinical studies that assess changes in neurogenesis and neurotrophic factors and their relationship to cognitive performance in schizophrenia, and how these mechanisms might be impacted by APD treatment, may provide valuable clues in developing therapies to combat cognitive deficit in schizophrenia. Numerous evidence produced over the years suggests a deficit in a wide spectrum of neurotrophic factors in schizophrenia. Since schizophrenia is considered a neurodevelopmental disorder, early intervention with neurotrophic factors may be more effective in ameliorating the cognitive deficits and psychopathological symptoms associated with this pathology. In this context, results from initial clinical trials with neurotrophic factors and their future potential to improve cognition and psychosocial functioning in schizophrenia are discussed.

Synaptic plasticity and mental health: methods, challenges and opportunities

Activity-dependent synaptic plasticity is a ubiquitous property of the nervous system that allows neurons to communicate and change their connections as a function of past experiences. Through reweighting of synaptic strengths, the nervous system can remodel itself, giving rise to durable memories that create the biological basis for mental function. In healthy individuals, synaptic plasticity undergoes characteristic developmental and aging trajectories. Dysfunctional plasticity, in turn, underlies a wide spectrum of neuropsychiatric disorders including depression, schizophrenia, addiction, and posttraumatic stress disorder. From a mechanistic standpoint, synaptic plasticity spans the gamut of spatial and temporal scales, from microseconds to the lifespan, from microns to the entire nervous system. With the numbers and strengths of synapses changing on such wide scales, there is an important need to develop measurement techniques with complimentary sensitivities and a growing number of approaches are now being harnessed for this purpose. Through hemodynamic measures, structural and tracer imaging, and noninvasive neuromodulation, it is possible to image structural and functional changes that underlie synaptic plasticity and associated behavioral learning. Here we review the mechanisms of neural plasticity and the historical and future trends in techniques that allow imaging of synaptic changes that accompany psychiatric disorders, highlighting emerging therapeutics and the challenges and opportunities accompanying this burgeoning area of study.

Assessing the expression of two post-transcriptional BDNF regulators, TTP and miR-16 in the peripheral blood of patients with Schizophrenia

Schizophrenia (SCZ) is a severe mental disorder with an unknown pathophysiology. Brain-Derived Neurotrophic Factor (BDNF) is a neurotrophin that has been associated with synapse plasticity, learning, and memory, as well as neurodevelopment and neuroprotection. The importance of neurodevelopmental and neurotoxicity-related components in the pathophysiology of SCZ has been highlighted in research on the neurobiology of this disease. The purpose of this research is to investigate the significant expression of two variables, tristetraprolin (TTP) and miR-16, which are known to be regulators of BDNF expression. Fifty Iranian Azeri SCZ patients were enrolled, and fifty healthy volunteers were age- and gender-matched as controls. A quantitative polymerase chain reaction measured the expression levels of the TTP and miR-16 in the peripheral blood (PB) of SCZ patients and healthy people. TTP expression levels in patients were higher than in controls, regardless of gender or age (posterior beta = 1.532, adjusted P-value = 0.012). TTP and miR-16 expression levels were found to be significantly correlated in both SCZ patients and healthy controls (r = 0.701, P < 0.001 and r = 0.777, P < 0.001, respectively). Due to the increased expression of TTP in SCZ and the existence of a significant correlation between TTP and miR-16, which helps to act on target mRNAs with AU-rich elements, this mechanism can be considered an influencing factor in SCZ.

Converging Evidence Points to BDNF as Biomarker of Depressive Symptoms in Schizophrenia-Spectrum Disorders

Brain-derived neurotrophic factor (BDNF) is a key modulator of neuroplasticity and has an important role in determining the susceptibility to severe psychiatric disorder with a significant neurodevelopmental component such as major psychoses. Indeed, a potential association between BDNF serum levels and schizophrenia (SCZ) and schizoaffective disorder (SAD) has been tested in diverse studies and a considerable amount of them found reduced BDNF levels in these disorders. Here, we aimed at testing the association of BDNF serum levels with several demographic, clinical, and psychometric measures in 105 patients with SCZ and SAD, assessing the moderating effect of genetic variants within the BDNF gene. We also verified whether peripheral BDNF levels differed between patients with SCZ and SAD. Our findings revealed that BDNF serum levels are significantly lower in patients affected by SCZ and SAD presenting more severe depressive symptomatology. This finding awaits replication in future independent studies and points to BDNF as a possible prognostic indicator in major psychoses.

Various BDNF administrations attenuate SPS-induced anxiety-like behaviors

Post-traumatic stress disorder (PTSD) has become epidemic following severely stressful incidents. Previous studies have shown that brain-derived neurotrophic factor (BDNF) has anxiolytic effects on various anxiety or depression disorders including PTSD. However, the detailed mechanisms of BDNF for treating PTSD were rarely investigated. In the current study, single-prolonged stress (SPS) was used as an animal model recapitulating specific aspects for a PTSD-like phenotype. The effects of BDNF on SPS-induced anxiety-like behaviors were investigated. We showed that the levels of BDNF in the cerebro-spinal fluid (CSF) were significantly reduced after the rats experienced SPS. The SPS-induced reductions of percentages of time spent in the central area to total time in the open field test, were dose-dependently mitigated after BDNF intracerebroventricular (i.c.v.) injections. BDNF i.c.v. administration also dose-dependently increased the preference of the light box in the light-dark box test. Both expressions of tyrosine kinase receptor B (TrkB) protein and mRNA in the prefrontal cortex (PFC) and amygdala were significantly increased after SPS challenges. BDNF i.c.v. administration attenuated these compensatory increases of TrkB. At last, the anxiolytic effects of BDNF on SPS model were also observed by using other two injection methods. These results inspired us to study that different administrations of BDNF were used in patients with PTSD in the future, in-depthly.

The mediating effect of brain-derived neurotrophic factor levels on childhood trauma and psychiatric symptoms in patients with first-episode schizophrenia

BACKGROUND

Previous studies have implicated childhood trauma and abnormal brain-derived neurotrophic factor in the pathogenesis of schizophrenia. Here, we explored whether brain-derived neurotrophic factor levels mediated the relationship between childhood trauma and psychopathological symptoms in patients with first-episode schizophrenia.

METHODS

Patients with first-episode schizophrenia (n = 192) and healthy controls (n = 136) were enrolled. Childhood traumatic experiences and psychopathology were assessed by Childhood Trauma Questionnaire and Positive and Negative Syndrome Scale, respectively. Enzyme-linked immunosorbent assay was used to quantify brain-derived neurotrophic factor levels.

RESULTS

The patients with first-episode schizophrenia experienced more severe childhood trauma and had lower serum brain-derived neurotrophic factor levels than healthy controls. Emotional abuse and Childhood Trauma Questionnaire total score showed positive correlation with Positive and Negative Syndrome Scale positive, general psychopathological subscore and total score. Emotional neglect showed positive correlation with Positive and Negative Syndrome Scale positive subscore. Physical neglect was positively associated with Positive and Negative Syndrome Scale negative subscore. Emotional neglect and Childhood Trauma Questionnaire total score were negatively correlated with serum brain-derived neurotrophic factor levels. The serum brain-derived neurotrophic factor levels mediated the relationship between both Childhood Trauma Questionnaire total score and Positive and Negative Syndrome Scale total score and negative symptoms in the patients. The brain-derived neurotrophic factor levels also mediated the relationship between emotional neglect and Positive and Negative Syndrome Scale total score in the patients.

CONCLUSION

Childhood trauma might contribute to the clinical symptoms of schizophrenia by affecting brain-derived neurotrophic factor levels. Perhaps we can prevent schizophrenia by reducing childhood traumatic experiences.

Ketogenic and Modified Mediterranean Diet as a Tool to Counteract Neuroinflammation in Multiple Sclerosis: Nutritional Suggestions

Ketogenic Diet is a nutritional pattern often used as dietotherapy in inflammatory diseases, including neurological disorders. Applied on epileptic children since 1920, in recent years it has been taken into account again as a tool to both reduce inflammatory burdens and ameliorate the nutritional status of patients affected by different pathologies. Multiple sclerosis (MS) is considered an immune-mediated neuro-inflammatory disease and diet is a possible factor in its pathogenesis. The aim of this work is to investigate the main potential targets of MS-related impairments, in particular the cognitive deficits, focusing on the alteration of biomarkers such as the Brain Derived-Neurotrophic Factor and the Tryptophan/Kynurenine ratio that could play a role on neuroprotection and thus on MS progression. Furthermore, we here propose nutritional suggestions which are useful in the development of a ketogenic diet protocol that takes advantage of the anti-inflammatory properties of low-carbohydrate foods from the Mediterranean diet to be applied to subjects with MS. In conclusion, this approach will allow one to develop the ketogenic diet combined with a modified Mediterranean diet as a possible tool to improve neuroinflammation in multiple sclerosis.

Serum BDNF levels, glycolipid metabolism in deficit schizophrenia: A case-control study

BACKGROUND

Few studies have compared serum BDNF and glycolipid profiles in patients with deficit schizophrenia (DS) and non-deficit schizophrenia (NDS). We aimed to compare BDNF and glycolipid profiles between DS and NDS patients and healthy controls, and to investigate the relationship between BDNF, glycolipid profiles in DS and NDS patients.

METHODS

A total of 591 patients with chronic schizophrenia (SZ) and 238 healthy controls participated in this study. According to Proxy for the Deficit Syndrome Scale, SZ patients were divided into DS (n = 158) and NDS (n = 273) patients. Psychiatric symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). Serum BDNF levels were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

BDNF levels were significantly lower in SZ patients than those in healthy controls (7.81 ± 2.98 ng/ml vs. 11.96 ± 2.29 ng/ml, P < 0.01). Furthermore, BDNF levels were lower in DS group than those in NDS group (P = 0.007, OR = 0.846, 95% CI = 0.750-0.955). Lower triglyceride levels were also an independent predictor for DS patients (P = 0.007, OR = 0.846, 95% CI = 0.750-0.955). Serum BDNF levels were negatively associated with the severity of deficit syndrome in SZ patients (β = -1.151, t = -2.559, P = 0.011). In DS group, triglycerides were associated with PANSS negative subscore (β = -0.262, t = -2.994, P = 0.003) and depressive factor subscore (β = 0.282, t = 2.146, P = 0.035).

CONCLUSION

Serum BDNF and triglycerides may be informative biomarkers of DS in SZ patients. The differences in glycolipid metabolism patterns between DS and NDS patients indicate that deficit syndrome is an independent endophenotype of SZ patients.

Association between brain-derived neurotropic factor (BDNF), high-sensitivity C-reactive protein (hs-CRP) and psychiatric symptoms in medicated and unmedicated patients

BACKGROUND

There is evidence that brain-derived neurotropic factor (BDNF) plays a protective role in the brain. Peripheral levels of BDNF correlate with its concentration in the brain. Previous studies have revealed lower serum BDNF levels in patients with mental illnesses. In most studies serum BDNF correlates negatively with psychiatric disorders and disease severity. Most studies in this field are on psychiatric diagnosis and personality traits. The aim of our study is to explore associations between general psychiatric symptoms, independent of diagnostic groups, and serum BDNF as well as the inflammatory biomarker high-sensitive CRP (hs-CRP). Comparison between the group regularly using psychotropic medication and those not using psychotropic medication is conducted.

METHODS

The study is a cross sectional study with 132 participants from a general open inpatient psychiatric ward at the Nordland Hospital Trust, Bodoe, Norway. Participants were assessed on serum levels of BDNF and hs-CRP. Psychiatric symptoms were assessed by a self-rating scale (Symptom check list, SCL-90- R). Multiple linear regression model was used for statistical analyses of associations between levels of BDNF, hs-CRP and symptoms.

RESULTS

We found a positive association (p < 0.05), for most SCL-90 symptom clusters with BDNF in the psychotropic medication-free group. No associations were found in the group of patients using psychotropic medication, except one, the paranoid ideation cluster (p 0.022). No associations were found between hs-CRP and symptom clusters.

CONCLUSION

We found no relation between symptom clusters and the inflammatory biomarker hs-CRP. Serum BDNF levels were positively associated with intensity of psychiatric symptoms in the group of patients not using psychotropic medication. Our findings are in conflict with several previous studies reporting increased hs-CRP as well as decreased rather than increased BDNF in mental suffering. Patients on psychotropic medication may not require the same upregulation because the medication is modulating the underlying biological pathology.

Inflammatory markers in type 2 diabetes with vs. without cognitive impairment; a systematic review and meta-analysis

People with type 2 diabetes mellitus (T2DM) are at increased risk of mild cognitive impairment and dementia. Systemic inflammation has been proposed as a common risk factor. This study aimed to summarize the clinical data pertaining to peripheral blood inflammatory markers. We identified original peer-reviewed articles reporting blood inflammatory marker concentrations in groups of people with a T2DM diagnosis who have cognitive impairment (CI; including mild cognitive impairment, Alzheimer's disease, vascular cognitive impairment) vs. normal cognition (NC). Between-group standardized mean differences (SMD) were summarized in random effects meta-analyses. From 2108 records, data were combined quantitatively from 40 studies. Concentrations of interleukin-6 (IL-6; N_CI/N_NC = 934/3154, SMD 0.74 95% confidence interval [0.07, 1.42], Z₅ = 2.15, p = 0.03; I² = 98.08%), C-reactive protein (CRP; N_CI/N_NC = 1610/4363, SMD 0.80 [0.50, 1.11], Z₁₄ = 5.25, p < 0.01; I² = 94.59%), soluble vascular cell adhesion molecule-1 (sVCAM-1; N_CI/N_NC = 104/1063, SMD 1.64 95% confidence interval [0.21, 3.07], Z₂ = 2.25, p = 0.02; I² = 95.19%), and advanced glycation end products (AGEs; N_CI/N_NC = 227/317, SMD 0.84 95% confidence interval [0.41, 1.27], Z₂ = 3.82, p < 0.01; I² = 81.07%) were higher among CI groups compared to NC. Brain derived neurotropic factor (BDNF) concentrations were significantly lower in CI compared to NC (N_CI/N_NC = 848/2063, SMD -0.67 95% confidence interval [-0.99, -0.35], Z₃ = -4.09, p < 0.01; I² = 89.20%). Cognitive impairment among people with T2DM was associated with systemic inflammation and lower BDNF concentrations. These inflammatory characteristics support an increased inflammatory-vascular interaction associated with cognitive impairment in T2DM. PROSPERO (CRD42020188625).

Association Between Depressive Symptoms and Serum Brain-Derived Neurotrophic Factor Levels in Patients With First-Episode and Drug-Naïve Schizophrenia

Previous studies have revealed that brain-derived neurotrophic factor (BDNF) levels are inversely associated with the severity of depressive symptoms. In addition, serum BDNF levels tend to increase with improvement in depressive symptoms. There is also evidence that BDNF has a possible role in the pathophysiology of schizophrenia. Therefore, the purpose of this study was to determine whether BDNF levels correlated with depressive symptoms in patients with first-episode and drug-naïve (FEDN) schizophrenia. In this study, 90 patients with FEDN schizophrenia and 60 healthy controls were recruited. The Positive and Negative Syndrome Scale (PANSS) and the 17-item Hamilton Depression Scale (HAMD-17) were used to gage psychopathological and depressive symptoms, respectively. All participants had their BDNF levels measured using a sandwich enzyme-linked immunosorbent test. Serum BDNF levels were lower in patients with FEDN schizophrenia compared with healthy controls. Moreover, patients with depressive symptoms exhibited a higher PANSS total score and a higher general psychopathology score than those without depressive symptoms (p < 0.05). For patients with depressive symptoms, serum BDNF levels were higher than in those without depressive symptoms (p < 0.05). An association between BDNF levels and the positive subscore was also observed (p < 0.01). However, there was no significant association between BDNF levels and HAMD scores (p > 0.05). In conclusion, BDNF levels were shown to be higher in the serum of patients with FEDN schizophrenia with depressive symptoms than in those without. Additionally, low levels of serum BDNF may contribute to the positive symptoms of FEDN schizophrenia but not to depressive symptoms.

BDNF controls GABAAR trafficking and related cognitive processes via autophagic regulation of p62

Reduced brain-derived neurotrophic factor (BDNF) and gamma-aminobutyric acid (GABA) neurotransmission co-occur in brain conditions (depression, schizophrenia and age-related disorders) and are associated with symptomatology. Rodent studies show they are causally linked, suggesting the presence of biological pathways mediating this link. Here we first show that reduced BDNF and GABA also co-occur with attenuated autophagy in human depression. Using mice, we then show that reducing Bdnf levels (Bdnf^+/-) leads to upregulated sequestosome-1/p62, a key autophagy-associated adaptor protein, whose levels are inversely correlated with autophagic activity. Reduced Bdnf levels also caused reduced surface presentation of α5 subunit-containing GABA_A receptor (α5-GABA_AR) in prefrontal cortex (PFC) pyramidal neurons. Reducing p62 gene dosage restored α5-GABA_AR surface expression and rescued PFC-relevant behavioral deficits of Bdnf^+/- mice, including cognitive inflexibility and reduced sensorimotor gating. Increasing p62 levels was sufficient to recreate the molecular and behavioral profiles of Bdnf^+/- mice. Collectively, the data reveal a novel mechanism by which deficient BDNF leads to targeted reduced GABAergic signaling through autophagic dysregulation of p62, potentially underlying cognitive impairment across brain conditions.

Exploring the association between brain-derived neurotrophic factor levels and longitudinal psychopathological and cognitive changes in Sardinian psychotic patients

Background and hypothesis

Schizophrenia spectrum disorders are among the most debilitating mental disorders and has complex pathophysiological underpinnings. There is growing evidence that brain-derived neurotrophic factor (BDNF) can play a role in its pathogenesis. The present study investigated the longitudinal variation of serum BDNF levels in a 24-month observational prospective cohort study of Sardinian psychotic patients and its relationship with psychopathological and cognitive changes. Furthermore, we examined whether genetic variation within the BDNF gene could moderate these relationships.

Study design

Every 6 months, 105 patients were assessed for their BDNF serum levels, as well as for a series of psychopathological, cognitive, and social measures. We performed a targeted analysis of four tag single nucleotide polymorphisms within the BDNF gene that were selected and analyzed using polymerase chain reaction. Longitudinal data were analyzed using mixed-effects linear regression models.

Study results

We observed a declining longitudinal trajectory of BDNF levels in psychotic patients in general, and in relation to the severity of depressive and negative symptoms. BDNF serum levels also declined in patients scoring lower in cognitive measures such as attention and speed of information processing and verbal fluency. The rs7934165 polymorphism moderated the significant association between verbal fluency and BDNF levels.

Conclusions

These findings in patients from real-world settings suggest a plausible role of peripheral BDNF levels as a marker of illness burden in schizophrenia spectrum disorders.

Brain Derived Neurotrophic Factor and Cognitive Dysfunction in the Schizophrenia-Bipolar Spectrum: A Systematic Review and Meta-Analysis

BACKGROUND

Cognitive impairment is a core feature of disorders on the schizophrenia-bipolar spectrum, i.e., schizophrenia, bipolar disorder, and schizoaffective disorder. Brain-derived neurotrophic factor (BDNF) has been proposed to be a biomarker of cognitive impairment in these disorders as it plays a critical role in neuroplasticity and proposed to mediate some of the psychotropic effects of medication. However, despite numerous studies investigating the association between circulating BDNF and these disorders, no solid conclusions have been drawn regarding its involvement in cognitive impairment.

OBJECTIVES

The current systematic review and meta-analysis aims to examine blood BDNF levels and cognitive dysfunction in patients on the schizophrenia-bipolar spectrum as well as to evaluate whether circulating BDNF measurements can act as a biomarker for cognitive dysfunction.

METHODS

Studies were identified by searching Embase and Medline databases for English language articles published in peer-reviewed journals between 2000 January and 2021 June according to the PRISMA guidelines. A total of 815 articles were identified of which 32 met the inclusion criteria for the systematic review - reporting on comparisons between blood BDNF levels and cognitive functions of schizophrenia or bipolar disorder patients versus healthy controls (no studies involving schizoaffective patients were specifically obtained for the time being). Twenty-four of these studies (19 with schizophrenia and 5 with bipolar disorder patients) were eligible to be included in the meta-analysis.

RESULTS

Our findings indicated that circulating BDNF levels were significantly reduced in patients experiencing an acute episode of schizophrenia or bipolar disorder compared to healthy controls. Cognitive function was also found to be significantly worse in patients, however, correlations between BDNF levels and cognitive impairment were not always detected. Interventions, especially pharmacotherapy seemed to improve certain aspects of cognition and increase circulating BDNF levels.

CONCLUSION

Circulating BDNF alone does not seem to be a valid biomarker of cognitive dysfunction in patients with disorders on the schizophrenia-bipolar spectrum, owing to several confounding factors. Changes of the circulating levels of BDNF should be evaluated in a wider context of other stress-, immune-, and inflammatory-related factors.

Peripheral BDNF levels in psychiatric patients with and without a history of suicide attempt: A systematic review and meta-analysis

OBJECTIVE

Psychiatric patients are at increased risk of attempting suicide. Several potential biomarkers of suicide risk have been proposed with inconsistent findings. The present paper aimed to evaluate differences in peripheral BDNF levels between psychiatric patients with and without a history of suicide attempts.

METHODS

We conducted a systematic review and meta-analysis following the PRISMA guidelines. Relevant papers published up to January 5, 2021 were identified searching the electronic databases Web of Knowledge^SM and PsycINFO. A random-effect meta-analysis was conducted using Stata 16.

RESULTS

Thirteen studies met inclusion criteria. Overall, no significant differences in BDNF levels between the two groups were found (13 studies, n = 1340, Hedge's g = -0.21, 95% CI -0.44 to 0.02). Heterogeneity was substantial (I² = 72.91%). Subgroup analyses revealed that BDNF levels were significantly reduced in plasma with medium effect size (5 studies, n = 363, Hedge's g = -0.44, 95% CI -0.86 to -0.02), but not in serum (8 studies, n = 977, Hedge's g = -0.09, 95% CI -0.33 to 0.15). No significant differences were found according to the type of diagnosis (major depressive disorder vs. other diagnoses) or the period of suicide attempt (lifetime vs. recent).

CONCLUSION

The utility of BDNF as a biomarker of suicide attempts in psychiatric patients appears limited to its plasma concentration. Although caution interpretation is needed, our findings may represent a starting point for the design of rigorous case-control studies exploring the association between neurotrophins and suicidal behaviors.

Brain-derived neurotrophic factor in patients with epilepsy: A systematic review and meta-analysis

INTRODUCTION

Epilepsy affects almost 1% of people and is characterized by sudden seizures. To date, no reliable biomarker has been found to diagnose or predict the outcomes of epilepsy. Brain-derived neurotrophic factor (BDNF) levels have recently been shown to differ between patients with certain neurologic disorders and normal population, and it is unknown whether this is the case for epilepsy. In this study, we mainly aim to answer this question.

METHODS

We searched three databases for studies comparing BDNF levels between patients with epilepsy and controls. Quality assessment of included studies was performed using the Newcastle-Ottawa scale and statistical analyses were carried out in STATA software version 16.

RESULTS

Final analyses included 10 studies involving 403 patients with epilepsy. BDNF levels were statistically similar between patients and controls (standardized mean difference (SMD) = - 0.30, 95% CI = - 1.32 to 0.71, p = 0.56). When categorized by epilepsy subtype, patients with partial epilepsy showed lower BDNF measures than controls (95% CI = - 1.42 to - 0.32, p < 0.01), while the difference was not significant in patients with generalized epilepsy (95% CI = - 2.81 to 1.65, p = 0.61). Subgroup analyses indicated that BDNF was lower in patients than controls when age or sex matching was not present. Patient samples acquired in the morning also showed significantly lower BDNF levels than controls, unlike afternoon samples. Meta-regression identified no predictor for the difference in BDNF levels.

CONCLUSION

Generally, patients with epilepsy had BDNF levels similar to general population, although patients with partial epilepsy showed lower BDNF levels. Taking into account the sub-group analyses, further studies with higher qualities are required to evaluate the role and utility of BDNF in epilepsy.

Expression of BDNF-Associated lncRNAs in Treatment-Resistant Schizophrenia Patients

Long non-coding RNAs (lncRNAs) play a decisive role in the development of the central nervous system and modulation, differentiation, and function of neurons. Thus, any abnormal pattern of expression of these transcripts might alter normal development leading to neuropsychiatric disorders. In this regard, transcripts of brain-derived neurotrophic factor (BDNF) and four BDNF-associated lncRNAs (BDNF-AS, MIR137HG, MIAT, and PNKY) were evaluated in the peripheral blood of schizophrenia (SCZ) patients as well as normal subjects. The results indicated that the relative expression (RE) of PNKY was higher in SCZ patients as compared with controls (posterior beta of RE = 2.605, P value = 0.006) and in female patients compared with female controls (posterior beta of RE = 2.831, P value < 0.0001). BDNF expression was also higher in SCZ patients when compared with controls (posterior beta of RE = 0.64, P value < 0.036). Finally, a correlation was detected between the disease status and gender in terms of BDNF-AS expression (P value = 0.026). An inverse correlation was also found between levels of PNKY and age in the control group (r = - 0.30, P value < 0.0001). Expressions of BDNF and all lncRNAs were correlated with each other in both patients and controls. PNKY had the best diagnostic power among all assessed genes in the identification of disease status (area under curve = 0.78). BDNF, BDNF-AS, MIR137HG, and MIAT genes could discriminate SCZ patients from normal subjects with diagnostic power of 71%, 72%, 67%, and 68%, respectively. The current investigation suggests the possibility of the application of transcript levels of lncRNAs as an SCZ diagnostic marker. However, it warrants further studies in larger sample sizes.

Increased telomerase activity in major depressive disorder with melancholic features: Possible role of pro-inflammatory cytokines and the brain-derived neurotrophic factor

The biological mechanisms responsible for depression symptoms are not yet understood. For this reason, it is important to reveal the etiopathogenetic mechanisms in this disease. This study aims to compare the levels of pro-inflammatory cytokines, Brain-Derived Neurotrophic Factor (BDNF), and telomerase activity in patients with major depressive disorder (MDD) and healthy controls. Plasma BDNF, interleukin-6 (IL-6), IL-1beta, and Tumor Necrosis Factor-alpha (TNF-alpha) levels, and telomerase activity were measured in 39 patients with major depression and 39 healthy controls matched with patients in terms of age, gender, and education year. Plasma concentration of BDNF, IL-6 levels, and telomerase activity was significantly different between patients with MDD and healthy controls. Correlation analysis showed a positive trend between plasma BDNF levels and plasma IL-6 levels in patients with MDD with melancholic features. Furthermore, the path analysis results showed that the telomerase activity was indirectly affected by gender, IL-1β, IL-6, BDNF, and BMI, via the severity of depression and anxiety and MDD status as the mediators. Further studies are needed to examine the molecular mechanism of the telomerase activity and the role of BDNF and pro-inflammatory cytokines in the telomerase activation in MDD.

Decreased brain-derived neurotrophic factor levels may predict early perioperative neurocognitive disorder in patients undergoing coronary artery bypass surgery: A prospective observational pilot study

STUDY OBJECTIVE

To determine the prognostic value of the change in intraoperative BDNF (Brain-derived neurotrophic factor) levels during cardiac surgery with cardiopulmonary bypass (CPB) on early perioperative neurocognitive disorder (PND).

DESIGN

Prospective observational pilot study.

SETTING

The study was performed in the Medical Faculty Hospital, from January 2020 to August 2020.

PATIENTS

45 adult patients undergoing elective coronary artery bypass surgery (CABG) with CPB.

INTERVENTIONS

None.

MEASUREMENTS

Cognitive function was evaluated 1 day before and 4 days after the surgery. Serum BDNF levels were measured at four time points (T1: after induction; T2: with aortic cross-clamp; T3: without aortic cross-clamp; T4: 4 days after surgery) by enzyme-linked immunosorbent assay.

MAIN RESULTS

The incidence of PND was 37.8% four days after surgery. Serum BDNF (T2 and T4) levels were significantly lower in PND group compared to non- PND group (p = 0.003 and p = 0.016, respectively). Moreover, lactate, rSO₂ (regional cerebral oxygen saturation), aortic cross-clamp time, CPB duration, and the amount of blood transfusion differed between the groups. Logistic regression analysis identified serum BDNF-T2, age, cross-clamp time, and rSO₂-T2 as independent risk factors for PND. Based on the ROC analysis, the area under curve (AUC) of BDNF-T2 concentration for prediction of PND was 0.759 with sensitivity of 71.4% and specificity of 64.7% (p < 0.01).

CONCLUSION

Intraoperative BDNF serum levels may be a useful biomarker in predicting PND in patients undergoing CABG surgery. More comprehensive studies is needed in order to confirm the effect of decreasing intraoperative BDNF serum levels on the development of PND.

TRIAL REGISTRATION NUMBER

NCT04250935 www.clinicaltrials.gov.

Association between hippocampal structure and serum Brain-Derived Neurotrophic Factor (BDNF) in healthy adults: A registered report

The hippocampus is a highly plastic brain structure supporting functions central to human cognition. Morphological changes in the hippocampus have been implicated in development, aging, as well as in a broad range of neurological and psychiatric disorders. A growing body of research suggests that hippocampal plasticity is closely linked to the actions of brain-derived neurotrophic factor (BDNF). However, evidence on the relationship between hippocampal volume (HCV) and peripheral BDNF levels is scarce and limited to elderly and patient populations. Further, despite evidence that BDNF expression differs throughout the hippocampus and is implicated in adult neurogenesis specifically in the dentate gyrus, no study has so far related peripheral BDNF levels to the volumes of individual hippocampal subfields. Besides its clinical implications, BDNF-facilitated hippocampal plasticity plays an important role in regulating cognitive and affective processes. In the current registered report, we investigated how serum BDNF (sBDNF) levels relate to volumes of the hippocampal formation and its subfields in a large sample of healthy adults (N = 279, 160 f) with a broad age range (20-55 years, mean 40.5) recruited in the context of the ReSource Project. We related HCV to basal sBDNF and, in a subsample (n = 103, 57 f), to acute stress-reactive change in sBDNF. We further tested the role of age as a moderator of both associations. Contrary to our hypotheses, neither basal sBDNF levels nor stress-reactive sBDNF change were associated with total HCV or volume of the dentate gyrus/cornu ammonis 4 (DG/CA4) subfield. We also found no evidence for a moderating effect of age on any of these associations. Our null results provide a first point of reference on the relationship between sBDNF and HCV in healthy mid-age, in contrast to patient or aging populations. We suggest that sBDNF levels have limited predictive value for morphological differences of the hippocampal structure when notable challenge to its neuronal integrity or to neurotrophic capacity is absent.

BDNF genotype Val66Met interacts with acute plasma BDNF levels to predict fear extinction and recall

Brain-derived neurotropic factor (BDNF) is a potent regulator of memory processes and is believed to influence the consolidation of fear extinction memories. No previous human study has tested the effect of unstimulated BDNF on fear extinction recall, and no study has tested the association between plasma BDNF levels and psychophysiological responding during an extinction paradigm. We tested the association between fear responses during a 2-day differential conditioning, extinction and extinction recall paradigm and Val66Met genotype in a group of healthy participants (N = 191). There were no group differences during habituation or acquisition. Met allele carriers compared to Val homozygotes displayed higher responses to the CS + compared to the CS- during extinction learning and had higher responding to both the CS+ and CS- during extinction recall. Plasma levels of BDNF protein that were collected in a sub-sample of the group (n = 56) moderated the effect of Met allele presence, such that lower BDNF level was associated with higher skin conductance response in the Met but not Val group to the CS+ during extinction learning and to both the CS+ and CS- during extinction recall. The current results extend previous observations of a Val66Met effect during fear extinction learning to extinction recall and show for the first time that these effects are moderated by plasma BDNF level.

Brain-derived neurotrophic factor in bipolar disorder: Associations with age at onset and illness duration

Bipolar disorder (BD) is a heterogeneous disorder that contains neurodevelopmental differences. Defining homogeneous subgroups of BD patients by using age at onset (AAO) as a specifier may promote the classification of biomarkers. This study compares peripheral BDNF levels between pediatric and adult BD patients to investigate the associations between BDNF levels, AAO, and illness duration. We enrolled two groups of euthymic patients, those with pediatric BD (n = 39) and those with adult BD (n = 31), as well as a group of healthy controls (HCs) (n = 90). Participants were assessed using clinical measures and BDNF serum levels were obtained using ELISA. We observed that BDNF levels were comparable between adult BD and HCs, but were clearly lower in pediatric BD than in HCs. In adult BD with AAO ≥30 years, BDNF levels were significantly higher than in adult BD with AAO <30 years. In pediatric BD, patients with prepubertal-onset had higher BDNF levels than those with pubertal-onset. BDNF levels demonstrated the accuracy of being able to distinguish pediatric BD from healthy controls in a receiver operating characteristic (ROC) curve analysis (area under the curve [AUC] = 0.792). In adult BD, higher BDNF levels were associated with later disease onset, but this was not the case in pediatric BD. Finally, reduced BDNF levels were associated with illness duration in adult BD. The findings indicate that BDNF levels in BD patients are associated with AAO. BDNF may, therefore, potentially serve as a developmental marker in BD, when AAO is taken into account.

Sex differences in the association between serum BDNF and cognitive impairment in schizophrenia patients using various antipsychotics

BACKGROUND

Cognitive impairment is one of the core symptoms of schizophrenia patients. There are often various differences in the efficacy of different antipsychotics in the treatment of cognitive impairment by sex. The purpose of this study was to explore whether there are gender differences in the association between serum BDNF levels and cognitive performance in patients with schizophrenia taking different antipsychotics.

METHODS

We used Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to assess the cognitive function of three groups of schizophrenia patients (420 on clozapine, 183 on risperidone, 215 on typical antipsychotic drugs) and 467 healthy controls. Positive and Negative Syndrome Scale (PANSS) was used to assess schizophrenia symptoms of patients. Enzyme-Linked ImmunoSorbent Assay was used to measure serum brain-derived neurotrophic factor (BDNF) levels.

RESULTS

Among the patients taking clozapine and typical antipsychotic drugs, the RBANS total score, immediate memory, attention, and delayed memory subscores in females were higher than those in males (all p < 0.05). The RBANS total score and the delayed memory subscores in female patients taking risperidone were higher than those in male patients (all p < 0.05). Significant correlation between BDNF and cognition only existed in male patients taking clozapine, male patients taking risperidone, and male and female patients taking typical antipsychotic drugs (all p < 0.05).

CONCLUSION

Regardless of antipsychotic effect, the cognitive function of female patients is better compared to that of male patients. For male patients, the association between BDNF and cognitive performance exists in each medication group. For female patients, this significant association was only shown in the typical antipsychotic group, but not in the clozapine and risperidone groups.

Relationship between cytokines and brain-derived neurotrophic factor (BDNF) in trajectories of cancer-related cognitive impairment

Cytokines facilitate the peripheral immune and cerebral response, through their ability to modulate the expression of brain derived neurotrophic factor (BDNF). Cytokines and BDNF are implicated in cancer-related cognitive impairment (CRCI), but their relationship has not been clearly defined for this condition. The aim of this study was to evaluate the associations of cytokines and BDNF among early stage breast cancer (ESBC) patients with different CRCI trajectories. This was a multicenter longitudinal study involving 136 ESBC patients. CRCI was assessed using the FACT-Cog (V3) questionnaire. Plasma cytokines and BDNF levels were quantified at three time points throughout chemotherapy. The associations between cytokines and BDNF were analyzed using linear mixed models, with interaction terms for CRCI status. All cytokines analyzed showed inverse associations with BDNF levels. There was a significant interaction between IL-6 and the persistent impairment trajectory, which would impact on BDNF levels (p = 0.026). The inverse associations with BDNF were more pronounced for IFN-γ, IL-1β, IL-4, IL-8, and GM-CSF in patients with persistent CRCI. The coefficient values for IL-2, IL-4, and TNF-α also indicate that there was a greater magnitude of decrease in BDNF level for every unit of cytokine increase in patients with acute and persistent CRCI, compared to patients without CRCI. The differential associations between cytokines and BDNF may be indicative of probable susceptibility to the elevation of cytokines. Further research is required to elucidate the specific associations of cytokines and BDNF, along with their contributions to acute and persistent CRCI.

BDNF haploinsufficiency induces behavioral endophenotypes of schizophrenia in male mice that are rescued by enriched environment

Brain-derived neurotrophic factor (BDNF) is implicated in a number of processes that are crucial for healthy functioning of the brain. Schizophrenia is associated with low BDNF levels in the brain and blood, however, not much is known about BDNF's role in the different symptoms of schizophrenia. Here, we used BDNF-haploinsufficient (BDNF^+/-) mice to investigate the role of BDNF in different mouse behavioral endophenotypes of schizophrenia. Furthermore, we assessed if an enriched environment can prevent the observed changes. In this study, male mature adult wild-type and BDNF^+/- mice were tested in mouse paradigms for cognitive flexibility (attentional set shifting), sensorimotor gating (prepulse inhibition), and associative emotional learning (safety and fear conditioning). Before these tests, half of the mice had a 2-month exposure to an enriched environment, including running wheels. After the tests, BDNF brain levels were quantified. BDNF^+/- mice had general deficits in the attentional set-shifting task, increased startle magnitudes, and prepulse inhibition deficits. Contextual fear learning was not affected but safety learning was absent. Enriched environment housing completely prevented the observed behavioral deficits in BDNF^+/- mice. Notably, the behavioral performance of the mice was negatively correlated with BDNF protein levels. These novel findings strongly suggest that decreased BDNF levels are associated with several behavioral endophenotypes of schizophrenia. Furthermore, an enriched environment increases BDNF protein to wild-type levels and is thereby able to rescue these behavioral endophenotypes.

Plasma BDNF concentrations and the antidepressant effects of six ketamine infusions in unipolar and bipolar depression

Objectives

Accumulating evidence has implicated that brain derived neurotrophic factor (BDNF) is thought to be involved in the pathophysiology of depression, but its correlation with ketamine's antidepressant efficacy focusing on Chinese individuals with depression is not known. This study was aim to determine the correlation of plasma BDNF (pBDNF) concentrations and ketamine's antidepressant efficacy.

Methods

Ninety-four individuals with depression received six intravenous infusions ketamine (0.5 mg/kg). Remission and response were defined as Montgomery-Asberg Depression Rating Scale (MADRS) scores less than 10 and a reduction of 50% or more in MADRS scores, respectively. Plasma was collected at baseline and at 24 h and 2 weeks after completing six ketamine infusions (baseline, 13 d and 26 d).

Results

A significant improvement in MADRS scores and pBDNF concentrations was found after completing six ketamine infusions compared to baseline (all ps < 0.05). Higher baseline pBDNF concentrations were found in ketamine responders/remitters (11.0 ± 6.2/10.1 ± 5.8 ng/ml) than nonresponders/nonremitters (8.0 ± 5.5/9.2 ± 6.4 ng/ml) (all ps < 0.05). Baseline pBDNF concentrations were correlated with MADRS scores at 13 d (t =  - 2.011, p = 0.047) or 26 d (t =  - 2.398, p = 0.019) in depressed patients (all ps < 0.05). Subgroup analyses found similar results in individuals suffering from treatment refractory depression.

Conclusion

This preliminary study suggests that baseline pBDNF concentrations appeared to be correlated with ketamine's antidepressant efficacy in Chinese patients with depression.

The microRNA-195 - BDNF pathway and cognitive deficits in schizophrenia patients with minimal antipsychotic medication exposure

Cognitive impairment is a core characteristic of schizophrenia, but its underlying neural mechanisms remain poorly understood. Reduced brain-derived neurotrophic factor (BDNF), a protein critical for neural plasticity and synaptic signaling, is one of the few molecules consistently associated with cognitive deficits in schizophrenia although the etiological pathway leading to BDNF reduction in schizophrenia is unclear. We examined microRNA-195 (miR-195), a known modulator of BDNF protein expression, as a potential mechanistic component. One-hundred and eighteen first-episode patients with schizophrenia either antipsychotic medication-naïve or within two weeks of antipsychotic medication exposure and forty-seven age- and sex-matched healthy controls were enrolled. MiR-195 and BDNF mRNA and BDNF protein levels in peripheral blood were tested. Cognitive function was assessed using the MATRICS Consensus Cognitive Battery (MCCB). MiR-195 was significantly higher (p = 0.01) whereas BDNF mRNA (p < 0.001) and protein (p = 0.016) levels were significantly lower in patients compared with controls. Higher miR-195 expression was significantly correlated to lower BDNF protein levels in patients (partial r = -0.28, p = 0.003) and lower BDNF protein levels were significantly associated with poorer overall cognitive performance by MCCB and also in speed of processing, working memory, and attention/vigilance domains composite score (p = 0.002-0.004). The subgroup of patients with high miR-195 and low BDNF protein showed the lowest level of cognitive functions, and miR-195 showed significant mediation effects on cognitive functions through BDNF protein. Elevated miR-195 may play a role in regulating BDNF protein expression thereby influencing cognitive impairments in schizophrenia, suggesting that development of cognition enhancing treatment for schizophrenia may consider a micro-RNA based strategy.