Transport of brain-derived neurotrophic factor across the blood-brain barrier

Biological hypotheses and biomarkers of bipolar disorder

The most common mood disorders are major depressive disorders and bipolar disorders (BD). The pathophysiology of BD is complex, multifactorial, and not fully understood. Creation of new hypotheses in the field gives impetus for studies and for finding new biomarkers for BD. Conversely, new biomarkers facilitate not only diagnosis of a disorder and monitoring of biological effects of treatment, but also formulation of new hypotheses about the causes and pathophysiology of the BD. BD is characterized by multiple associations between disturbed brain development, neuroplasticity, and chronobiology, caused by: genetic and environmental factors; defects in apoptotic, immune-inflammatory, neurotransmitter, neurotrophin, and calcium-signaling pathways; oxidative and nitrosative stress; cellular bioenergetics; and membrane or vesicular transport. Current biological hypotheses of BD are summarized, including related pathophysiological processes and key biomarkers, which have been associated with changes in genetics, systems of neurotransmitter and neurotrophic factors, neuroinflammation, autoimmunity, cytokines, stress axis activity, chronobiology, oxidative stress, and mitochondrial dysfunctions. Here we also discuss the therapeutic hypotheses and mechanisms of the switch between depressive and manic state.

Epigenetic alterations of the BDNF gene in combat-related post-traumatic stress disorder

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) plays a crucial role in modulating resilience and vulnerability to stress. The aim of this study was to investigate whether epigenetic regulation of the BDNF gene is a biomarker of post-traumatic stress disorder (PTSD) development among veterans exposed to combat in the Vietnam War.

METHODS

Using the Clinician-Administered PTSD Scale, combat veterans were grouped into those with (n = 126) and without (n = 122) PTSD. DNA methylation levels at four CpG sites within the BDNF promoter I region were quantified in the peripheral blood using pyrosequencing. The effects of BDNF DNA methylation levels and clinical variables on the diagnosis of PTSD were tested using binary logistic regression analysis.

RESULTS

Subjects with PTSD showed a higher DNA methylation of four CpG sites at the BDNF promoter compared with those without PTSD. High methylation levels at the BDNF promoter CpG site, high combat exposure, and alcohol problems were significantly associated with PTSD diagnosis.

CONCLUSIONS

This study demonstrated an association between higher DNA methylation of the BDNF promoter and PTSD diagnosis in combat-exposed individuals. Our findings suggest that altered BDNF methylation may be a valuable biomarker of PTSD after trauma exposure.

Decreased peripheral brain-derived neurotrophic factor levels in Alzheimer's disease: a meta-analysis study (N=7277)

Studies suggest that dysfunction of brain-derived neurotrophic factor (BDNF) is a possible contributor to the pathology and symptoms of Alzheimer's disease (AD). Several studies report reduced peripheral blood levels of BDNF in AD, but findings are inconsistent. This study sought to quantitatively summarize the clinical BDNF data in patients with AD and mild cognitive impairment (MCI, a prodromal stage of AD) with a meta-analytical technique. A systematic search of Pubmed, PsycINFO and the Cochrane Library identified 29 articles for inclusion in the meta-analysis. Random-effects meta-analysis showed that patients with AD had significantly decreased baseline peripheral blood levels of BDNF compared with healthy control (HC) subjects (24 studies, Hedges' g=-0.339, 95% confidence interval (CI)=-0.572 to -0.106, P=0.004). MCI subjects showed a trend for decreased BDNF levels compared with HC subjects (14 studies, Hedges' g=-0.201, 95% CI=-0.413 to 0.010, P=0.062). No differences were found between AD and MCI subjects in BDNF levels (11 studies, Hedges' g=0.058, 95% CI=-0.120 to 0.236, P=0.522). Interestingly, the effective sizes and statistical significance improved after excluding studies with reported medication in patients (between AD and HC: 18 studies, Hedges' g=-0.492, P<0.001; between MCI and HC: 11 studies, Hedges' g=-0.339, P=0.003). These results strengthen the clinical evidence that AD or MCI is accompanied by reduced peripheral blood BDNF levels, supporting an association between the decreasing levels of BDNF and the progression of AD.

Affective alterations in patients with Cushing's syndrome in remission are associated with decreased BDNF and cortisone levels

OBJECTIVE

Affective alterations and poorer quality of life often persist in patients with Cushing's syndrome (CS) in remission. Brain-derived neurotrophic factor (BDNF) regulates the hypothalamic-pituitary-adrenal axis (HPA) and is highly expressed in brain areas controlling mood and response to stress. Our aims were to assess affective alterations after long-term remission of CS and evaluate whether they are associated with serum BDNF, salivary cortisol (SalF) and/or cortisone (SalE) concentrations.

SUBJECTS AND METHODS

Thirty-six CS patients in remission (32 females/4 males; mean age (±s.d.), 48.8 ± 11.8 years; median duration of remission, 72 months) and 36 gender-, age- and BMI-matched controls were included. Beck Depression Inventory-II (BDI-II), Center for Epidemiological Studies Depression Scale (CES-D), Positive Affect Negative Affect Scale (PANAS), State-Trait Anxiety Inventory (STAI), Perceived Stress Scale (PSS) and EuroQoL and CushingQoL questionnaires were completed and measured to evaluate anxiety, depression, stress perception and quality of life (QoL) respectively. Salivary cortisol was measured using liquid chromatography/tandem mass spectrometry (LC/TMS). BDNF was measured in serum using an ELISA.

RESULTS

Remitted CS patients showed worse scores in all questionnaires than controls: STAI (P < 0.001), BDI (P < 0.001), CES-D (P < 0.001), PANAS (P < 0.01), PSS (P < 0.01) and EuroQoL (P < 0.01). A decrease in BDNF was observed in CS vs controls (P = 0.038), and low BDNF was associated with more anxiety (r = -0.247, P = 0.037), depression (r = -0.249, P = 0.035), stress (r = -0.277, P = 0.019) and affective balance (r = 0.243, P = 0.04). Morning salivary cortisone was inversely associated with trait anxiety (r = -0.377, P = 0.040) and depressed affect (r = -0.392, P = 0.032) in CS patients. Delay to diagnosis was associated with depressive symptoms (BDI-II: r = 0.398, P = 0.036 and CES-D: r = 0.449, P = 0.017) and CushingQoL scoring (r = -0.460, P < 0.01).

CONCLUSIONS

Low BDNF levels are associated with affective alterations in 'cured' CS patients, including depression, anxiety and impaired stress perception. Elevated levels of SalE might also be related to poor affective status in these patients.

High-Intensity Locomotor Exercise Increases Brain-Derived Neurotrophic Factor in Individuals with Incomplete Spinal Cord Injury

High-intensity locomotor exercise is suggested to contribute to improved recovery of locomotor function after neurological injury. This may be secondary to exercise-intensity-dependent increases in neurotrophin expression demonstrated previously in control subjects. However, rigorous examination of intensity-dependent changes in neurotrophin levels is lacking in individuals with motor incomplete spinal cord injury (SCI). Therefore, the primary aim of this study was to evaluate the effect of locomotor exercise intensity on peripheral levels of brain-derived neurotrophic factor (BDNF) in individuals with incomplete SCI. We also explored the impact of the Val66Met single-nucleotide polymorphism (SNP) on the BDNF gene on intensity-dependent changes. Serum concentrations of BDNF and insulin-like growth factor-1 (IGF-1), as well as measures of cardiorespiratory dynamics, were evaluated across different levels of exercise intensity achieved during a graded-intensity, locomotor exercise paradigm in 11 individuals with incomplete SCI. Our results demonstrate a significant increase in serum BDNF at high, as compared to moderate, exercise intensities (p = 0.01) and 15 and 30 min post-exercise (p < 0.01 for both), with comparison to changes at low intensity approaching significance (p = 0.05). Serum IGF-1 demonstrated no intensity-dependent changes. Significant correlations were observed between changes in BDNF and specific indicators of exercise intensity (e.g., rating of perceived exertion; R = 0.43; p = 0.02). Additionally, the data suggest that Val66Met SNP carriers may not exhibit intensity-dependent changes in serum BDNF concentration. Given the known role of BDNF in experience-dependent neuroplasticity, these preliminary results suggest that exercise intensity modulates serum BDNF concentrations and may be an important parameter of physical rehabilitation interventions after neurological injury.

Role of brain-derived neurotrophic factor in the molecular neurobiology of major depressive disorder

Major depressive disorder (MDD) is one of the most common neuropsychiatric disorders, which affects up to 20% of people in their lifetime in the United States. The exact neurobiological mechanisms of MDD remain elusive, and the diagnostics are still uncertain. Basic and clinical research from recent years demonstrated that the etiology of MDD might be associated with genetic changes of neurotrophins, particularly brain-derived neurotrophic factor (BDNF). BDNF plays a key role in neuronal development and neurogenesis. However, the detailed mechanisms related to depression and antidepressant responses are not fully understood. This review summarizes the current knowledge of the causal relationship between BDNF and MDD, and describes the important role of BDNF in the progress of depression in animal models and patients with depressive disorders.

The effects of desipramine, fluoxetine, or tianeptine on changes in bulbar BDNF levels induced by chronic social instability stress and inflammation

BACKGROUND

Stress is a major predisposing factor in the development of psychiatric disorders and potential source of augmented inflammatory processes in the brain. Increasing body of evidence shows an important role of alterations in the olfactory bulbs (OBs) function in stress-related disorders. The aim of the present study was to investigate the impact of antidepressants on the alterations of brain-derived neurotrophic factor (BDNF) induced by lipopolysaccharide (LPS) in female rats subjected to chronic social instability stress (CSIS).

METHODS

9 weeks old female rats were subjected to CSIS and injected ip once daily with desipramine (10 mg/kg), fluoxetine (5 mg/kg), or tianeptine (10 mg/kg) for 4 weeks. On the last day of the experiment, rats being at the estrus phase of cycle were injected ip with LPS (1 mg/kg) or saline.

RESULTS

The BDNF mRNA and protein levels were evaluated in the olfactory bulbs. and the BDNF protein levels were measured in plasma. A single LPS administration in the stressed rats resulted in significant decrease in the bulbar BDNF mRNA, but not in the protein level. Chronic administration of desipramine, fluoxetine, or tianeptine increased the BDNF mRNA expression and protein levels in the LPS-injected stressed rats. There was no effect of the studied antidepressants on the reduction of the plasma BDNF protein level induced by CSIS and LPS.

CONCLUSIONS

These results suggest that studied antidepressants were effective in inhibiting the impact of LPS on BDNF expression in the stressed rats what may be significant for beneficial action of this drugs.

Neuroprotection and neurotoxicity in the developing brain: an update on the effects of dexmedetomidine and xenon

Growing and consistent preclinical evidence, combined with early clinical epidemiological observations, suggest potentially neurotoxic effects of commonly used anesthetic agents in the developing brain. This has prompted the FDA to issue a safety warning for all sedatives and anesthetics approved for use in children under three years of age. Recent studies have identified dexmedetomidine, the potent α2-adrenoceptor agonist, and xenon, the noble gas, as effective anesthetic adjuvants that are both less neurotoxic to the developing brain, and also possess neuroprotective properties in neonatal and other settings of acute ongoing neurologic injury. Dexmedetomidine and xenon are effective anesthetic adjuvants that appear to be less neurotoxic than other existing agents and have the potential to be neuroprotective in the neonatal and pediatric settings. Although results from recent clinical trials and case reports have indicated the neuroprotective potential of xenon and dexmedetomidine, additional randomized clinical trials corroborating these studies are necessary. By reviewing both the existing preclinical and clinical evidence on the neuroprotective effects of dexmedetomidine and xenon, we hope to provide insight into the potential clinical efficacy of these agents in the management of pediatric surgical patients.

Potential unfavorable impacts of BDNF Val66Met polymorphisms on metabolic risks in average population in a longevous area

Background

Brain-derived neurotrophic factor (BDNF) has been implicated in cognitive performance and the modulation of several metabolic parameters in some disease models, but its potential roles in successful aging remain unclear. We herein sought to define the putative correlation between BDNF Val66Met and several metabolic risk factors including BMI, blood pressure, fasting plasma glucose (FPG) and lipid levels in a long-lived population inhabiting Hongshui River Basin in Guangxi.

Methods

BDNF Val66Met was typed by ARMS-PCR for 487 Zhuang long-lived individuals (age ≥ 90, long-lived group, LG), 593 of their offspring (age 60–77, offspring group, OG) and 582 ethnic-matched healthy controls (aged 60–75, control group, CG) from Hongshui River Basin. The correlations of genotypes with metabolic risks were then determined.

Results

As a result, no statistical difference was observed on the distribution of allelic and genotypic frequencies of BDNF Val66Met among the three groups (all P > 0.05) except that AA genotype was dramatically higher in females than in males of CG. The HDL-C level of A allele (GA/AA genotype) carriers was profoundly lower than was non-A (GG genotype) carriers in the total population and the CG (P = 0.009 and 0.006, respectively), which maintained in females, hyperglycemic and normolipidemic subgroup of CG after stratification by gender, BMI, glucose and lipid status. Furthermore, allele A carriers, with a higher systolic blood pressure, exhibited 1.63 folds higher risk than non-A carriers to be overweight in CG (OR = 1.63, 95% CI: 1.05 - 2.55, P = 0.012). Multiple regression analysis displayed that the TC level of LG reversely associated with BDNF Val66Met genotype.

Conclusions

These data suggested that BDNF 66Met may play unfavorable roles in blood pressure and lipid profiles in the general population in Hongshui River area which might in part underscore their poorer survivorship versus the successful aging individuals and their offspring.

Electronic supplementary material

The online version of this article (doi:10.1186/s12877-016-0393-0) contains supplementary material, which is available to authorized users.

Brain-Derived Neurotrophic Factor and Major Depressive Disorder: Evidence from Meta-Analyses

Accumulating evidence suggests that brain-derived neurotrophic factor (BDNF) is associated with the pathophysiology of major depressive disorder (MDD). In this mini review, we explored the association between BDNF and MDD using meta-analytic evidence. Our findings indicated that the Val66Met polymorphism in the BDNF gene was not associated with MDD or hippocampal volume in patients with MDD. However, plasma/serum levels of BDNF were decreased in patients with acute MDD compared with healthy controls. Both antidepressant treatment and electroconvulsive therapy increased plasma and serum levels of BDNF in patients with MDD. Val66Met polymorphism in the BDNF gene was associated with an antidepressant response in patients with MDD. Taken together, we did not detect any plausible evidence regarding Val66Met polymorphism in the BDNF gene contributing to a risk of MDD. However, peripheral BDNF levels are decreased in patients with MDD, and the polymorphisms are associated with treatment response. In conclusion, BDNF is best understood to be a biomarker for the state of MDD and its treatment response rather than a risk factor for MDD.

DNA Methylation in Major Depressive Disorder

Epigenetic mechanisms regulate gene expression, influencing protein levels and ultimately shaping phenotypes during life. However, both stochastic epigenetic variations and environmental reprogramming of the epigenome might influence neurodevelopment and ageing, and this may contribute to the origins of mental ill-health. Studying the role of epigenetic mechanisms is challenging, as genotype-, tissue- and cell type-dependent epigenetic changes have to be taken into account, while the nature of mental disorders also poses significant challenges for linking them with biological profiles. In this chapter, we summarise the current evidence suggesting the role of DNA methylation as a key epigenetic mechanism in major depressive disorder.

BDNF Responses in Healthy Older Persons to 35 Minutes of Physical Exercise, Cognitive Training, and Mindfulness: Associations with Working Memory Function

Brain-derived neurotrophic factor (BDNF) has a central role in brain plasticity by mediating changes in cortical thickness and synaptic density in response to physical activity and environmental enrichment. Previous studies suggest that physical exercise can augment BDNF levels, both in serum and the brain, but no other study has examined how different types of activities compare with physical exercise in their ability to affect BDNF levels. By using a balanced cross over experimental design, we exposed nineteen healthy older adults to 35-minute sessions of physical exercise, cognitive training, and mindfulness practice, and compared the resulting changes in mature BDNF levels between the three activities. We show that a single bout of physical exercise has significantly larger impact on serum BDNF levels than either cognitive training or mindfulness practice in the same persons. This is the first study on immediate BDNF effects of physical activity in older healthy humans and also the first study to demonstrate an association between serum BDNF responsivity to acute physical exercise and working memory function. We conclude that the BDNF increase we found after physical exercise more probably has a peripheral than a central origin, but that the association between post-intervention BDNF levels and cognitive function could have implications for BDNF responsivity in serum as a potential marker of cognitive health.

Consequences of brain-derived neurotrophic factor withdrawal in CNS neurons and implications in disease

Growth factor withdrawal has been studied across different species and has been shown to have dramatic consequences on cell survival. In the nervous system, withdrawal of nerve growth factor (NGF) from sympathetic and sensory neurons results in substantial neuronal cell death, signifying a requirement for NGF for the survival of neurons in the peripheral nervous system (PNS). In contrast to the PNS, withdrawal of central nervous system (CNS) enriched brain-derived neurotrophic factor (BDNF) has little effect on cell survival but is indispensible for synaptic plasticity. Given that most early events in neuropsychiatric disorders are marked by a loss of synapses, lack of BDNF may thus be an important part of a cascade of events that leads to neuronal degeneration. Here we review reports on the effects of BDNF withdrawal on CNS neurons and discuss the relevance of the loss in disease.

Cross-sectional associations of objectively measured physical activity with brain-derived neurotrophic factor in adolescents

OBJECTIVE

The purpose of this study was to examine the associations between objectively measured physical activity and serum brain-derived neurotrophic factor (BDNF) in adolescents.

METHODS

Cross-sectional analyses were performed using data from 415 adolescents who participated in the 2015 follow-up of the Childhood Health Activity and Motor Performance School Study Denmark (the CHAMPS-study DK). Physical activity was objectively measured by accelerometry monitors. Serum BDNF levels were analyzed using the Enzyme-linked immunosorbent assay (ELISA). Anthropometrics and pubertal status were measured using standardized procedures.

RESULTS

With adjustment for age, pubertal status and body mass index, mean physical activity (counts per minute) was negatively associated with serum BDNF in boys (P=0.013). Similarly, moderate-to-vigorous physical activity (MVPA) was negatively associated with serum BDNF in boys (P=0.035). In girls, mean physical activity and MVPA were not associated with serum BDNF. Without adjustment for wear time, sedentary time was not associated with serum BDNF in either sex.

CONCLUSION

These findings indicate that higher physical activity is associated with lower serum BDNF in boys, but not in girls.

Cellular and molecular mechanisms of the brain-derived neurotrophic factor in physiological and pathological conditions

Brain-derived neurotrophic factor (BDNF) is a neurotrophin that plays a key role in the central nervous system, promoting synaptic plasticity, neurogenesis and neuroprotection. The BDNF gene structure is very complex and consists of multiple 5′-non-coding exons, which give rise to differently spliced transcripts, and one coding exon at the 3′-end. These multiple transcripts, together with the complex transcriptional regulatory machinery, lead to a complex and fine regulation of BDNF expression that can be tissue and stimulus specific. BDNF effects are mainly mediated by the high-affinity, tropomyosin-related, kinase B receptor and involve the activation of several downstream cascades, including the mitogen-activated protein kinase, phospholipase C-γ and phosphoinositide-3-kinase pathways. BDNF exerts a wide range of effects on neuronal function, including the modulation of activity-dependent synaptic plasticity and neurogenesis. Importantly, alterations in BDNF expression and function are involved in different brain disorders and represent a major downstream mechanism for stress response, which has important implications in psychiatric diseases, such as major depressive disorders and schizophrenia. In the present review, we have summarized the main features of BDNF in relation to neuronal plasticity, stress response and pathological conditions, and discussed the role of BDNF as a possible target for pharmacological and non-pharmacological treatments in the context of psychiatric illnesses.

The Role of DNA Methylation and Histone Modifications in Neurodegenerative Diseases: A Systematic Review

IMPORTANCE

Epigenetic modifications of the genome, such as DNA methylation and histone modifications, have been reported to play a role in neurodegenerative diseases (ND) such as Alzheimer's disease (AD) and Parkinson's disease (PD).

OBJECTIVE

To systematically review studies investigating epigenetic marks in AD or PD.

METHODS

Eleven bibliographic databases (Embase.com, Medline (Ovid), Web-of-Science, Scopus, PubMed, Cinahl (EBSCOhost), Cochrane Central, ProQuest, Lilacs, Scielo and Google Scholar) were searched until July 11th 2016 to identify relevant articles. We included all randomized controlled trials, cohort, case-control and cross-sectional studies in humans that examined associations between epigenetic marks and ND. Two independent reviewers, with a third reviewer available for disagreements, performed the abstract and full text selection. Data was extracted using a pre-designed data collection form.

RESULTS

Of 6,927 searched references, 73 unique case-control studies met our inclusion criteria. Overall, 11,453 individuals were included in this systematic review (2,640 AD and 2,368 PD outcomes). There was no consistent association between global DNA methylation pattern and any ND. Studies reported epigenetic regulation of 31 genes (including cell communication, apoptosis, and neurogenesis genes in blood and brain tissue) in relation to AD and PD. Methylation at the BDNF, SORBS3 and APP genes in AD were the most consistently reported associations. Methylation of α-synuclein gene (SNCA) was also found to be associated with PD. Seven studies reported histone protein alterations in AD and PD.

CONCLUSION

Many studies have investigated epigenetics and ND. Further research should include larger cohort or longitudinal studies, in order to identify clinically significant epigenetic changes. Identifying relevant epigenetic changes could lead to interventional strategies in ND.

Brain-Derived Neurotrophic Factor Serum Levels and Hippocampal Volume in Mild Cognitive Impairment and Dementia due to Alzheimer Disease

Background/Aims

Hippocampal atrophy is a recognized biomarker of Alzheimer disease (AD) pathology. Serum brain-derived neurotrophic factor (BDNF) reduction has been associated with neurodegeneration. We aimed to evaluate BDNF serum levels and hippocampal volume in clinical AD (dementia and mild cognitive impairment [MCI]).

Methods

Participants were 10 patients with MCI and 13 with dementia due to AD as well as 10 healthy controls. BDNF serum levels were determined by ELISA and volumetric measures with NeuroQuant®.

Results

MCI and dementia patients presented lower BDNF serum levels than healthy participants; dementia patients presented a smaller hippocampal volume than MCI patients and healthy participants.

Discussion

The findings support that the decrease in BDNF might start before the establishment of neuronal injury expressed by the hippocampal reduction.

The correlation between plasma brain-derived neurotrophic factor and cognitive function in bipolar disorder is modulated by the BDNF Val66Met polymorphism

We explored the effect of the Brain-derived neurotrophic factor (BDNF) Val66Met polymorphism (rs6265) on correlation between changes in plasma BDNF levels with cognitive function and quality of life (QoL) after 12 weeks of treatment in bipolar disorder (BD). Symptom severity and plasma BDNF levels were assessed upon recruitment and during weeks 1, 2, 4, 8 and 12. QoL, the Wisconsin Card Sorting Test (WCST), and the Conners’ Continuous Performance Test (CPT) were assessed at baseline and endpoint. The BDNF Val66Met polymorphism was genotyped. Changes in cognitive function and QoL over 12 weeks were reduced using factor analysis for the evaluation of their correlations with changes in plasma BDNF. Five hundred forty-one BD patients were recruited and 65.6% of them completed the 12-week follow-up. Changes in plasma BDNF levels with factor 1 (WCST) were significantly negatively correlated (r = −0.25, p = 0.00037). After stratification of BD subtypes and BDNF genotypes, this correlation was significant only in BP-I and the Val/Met genotype (r = −0.54, p = 0.008). We concluded that changes in plasma BDNF levels significantly correlated with changes in WCST scores in BD and is moderated by the BDNF Val66Met polymorphism and the subtype of BD.

Relationships between serum BDNF and the antidepressant effect of acute exercise in depressed women

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) has recently emerged as one potential mechanism with which exercise improves mood in major depressive disorder (MDD). This study examined the relationship between changes in serum total BDNF and mood following acute exercise in MDD. It was hypothesized that acute exercise would increase BDNF in an intensity-dependent manner and that changes in BDNF would be significantly related to improvement in depressed mood post-exercise.

METHODS

Twenty-four women (age: 38.6±14.0years) with MDD exercised for 30min on a stationary bicycle at light, moderate and hard exercise intensities and performed a quiet rest session using a within-subjects, randomized and counter-balanced design. Before, 10 and 30min after each session, participants completed the profile of mood states (POMS). Blood was drawn before and within 10min after completion of each session and serum total BDNF (sBDNF) was measured by enzyme-linked immunosorbent assay. Acute exercise-induced changes in POMS Depression and sBDNF were analyzed via 4 session (quiet rest, light, moderate, hard) by 2 measurement (pre, post) ANOVA. Secondary analyses examined the effects of baseline mood and antidepressant usage on sBDNF.

RESULTS

Exercise resulted in an acute improvement in depressed mood that was not intensity dependent (p>0.05), resulting in significant acute increases in sBDNF (p=0.006) that were also not intensity-dependent (p>0.05). Acute changes in sBDNF were not significantly correlated to changes in POMS depression at 10m (r=-0.171, p=0.161) or 30m (r=-0.151, p=0.215) post-exercise. The fourteen participants taking antidepressant medications exhibited lower post-exercise sBDNF (p=0.015) than the participants not currently taking antidepressants, although mood responses were similar.

CONCLUSION

Acute exercise is an effective mood-enhancing stimulus, although sBDNF does not appear to play a role in this short-term response. Patients who are not currently taking antidepressant medications and those who have greater pre-exercise depression may experience a greater sBDNF response to exercise, but the clinical significance of this is currently unclear. Circulating BDNF levels are unlikely to be altered by steady-state acute exercise in a linear dose-dependent manner. This does not eliminate its potential relevance in the antidepressant response to chronic exercise training, but suggests that other mechanisms are involved in the acute affective response to exercise in depression.

Submandibular Glands Contribute to Increases in Plasma BDNF Levels

Brain-derived neurotrophic factor (BDNF) promotes survival and differentiation of neural cells in the central and peripheral nervous systems. BDNF has been detected in plasma, but its source has not yet been established. Expression of BDNF mRNA has been identified in the submandibular glands when male rats are exposed to acute immobilization stress. In the present study, we investigated whether plasma BDNF is influenced by the submandibular glands in this model. Acute immobilization stress for 60 min significantly increased the level of plasma BDNF. However, plasma BDNF elevation was markedly suppressed in bilaterally sialoadenectomized rats. There were no significant differences between stressed (60 min) and non-stressed rats with respect to the BDNF mRNA expression in the hippocampus, heart, lung, liver, pancreas, or spleen, as determined by real-time polymerase chain-reaction. These findings suggest that the submandibular glands may be the primary source of plasma BDNF in conditions of acute immobilization stress.

APOEε4 impacts up-regulation of brain-derived neurotrophic factor after a six-month stretch and aerobic exercise intervention in mild cognitively impaired elderly African Americans: A pilot study

Possession of the Apolipoprotein E (APOE) gene ε4 allele is the most prevalent genetic risk factor for late onset Alzheimer's disease (AD). Recent evidence suggests that APOE genotype differentially affects the expression of brain-derived neurotrophic factor (BDNF). Notably, aerobic exercise-induced upregulation of BDNF is well documented; and exercise has been shown to improve cognitive function. As BDNF is known for its role in neuroplasticity and survival, its upregulation is a proposed mechanism for the neuroprotective effects of physical exercise. In this pilot study designed to analyze exercise-induced BDNF upregulation in an understudied population, we examined the effects of APOEε4 (ε4) carrier status on changes in BDNF expression after a standardized exercise program. African Americans, age 55years and older, diagnosed with mild cognitive impairment participated in a six-month, supervised program of either stretch (control treatment) or aerobic (experimental treatment) exercise. An exercise-induced increase in VO₂Max was detected only in male participants. BDNF levels in serum were measured using ELISA. Age, screening MMSE scores and baseline measures of BMI, VO₂Max, and BDNF did not differ between ε4 carriers and non-ε4 carriers. A significant association between ε4 status and serum BDNF levels was detected. Non-ε4 carriers showed a significant increase in BDNF levels at the 6month time point while ε4 carriers did not. We believe we have identified a relationship between the ε4 allele and BDNF response to physiologic adaptation which likely impacts the extent of neuroprotective benefit gained from engagement in physical exercise. Replication of our results with inclusion of diverse racial cohorts, and a no-exercise control group will be necessary to determine the scope of this association in the general population.

Peripheral Brain-Derived Neurotrophic Factor Levels in Alzheimer's Disease and Mild Cognitive Impairment: a Comprehensive Systematic Review and Meta-analysis

Alzheimer's disease (AD) is becoming a growing global problem, and there is an urgent need to identify reliable blood biomarkers of the risk and progression of this condition. A potential candidate is the brain-derived neurotrophic factor (BDNF), which modulates major trophic effects in the brain. However, findings are apparently inconsistent regarding peripheral blood BDNF levels in AD patients vs. healthy people. We thus performed a systematic review and meta-analysis of the studies that have examined peripheral BDNF levels in patients with AD or mild cognitive impairment (MCI) and healthy controls. We searched articles through PubMed, EMBASE, and hand searching. Over a total pool of 2061 potential articles, 26 met all inclusion criteria (including a total of 1584 AD patients, 556 MCI patients, and 1294 controls). A meta-analysis of BDNF levels between early AD and controls showed statistically significantly higher levels (SMD [95 % CI]: 0.72 [0.31, 1.13]) with no heterogeneity. AD patients with a low (<20) mini-mental state examination (MMSE) score had lower peripheral BDNF levels compared with controls (SMD [95 % CI]: -0.33 [-0.60, -0.05]). However, we found no statistically significant difference in blood (serum/plasma) BDNF levels between all AD patients and controls (standard mean difference, SMD [95 % CI]: -0.16 [-0.4, 0.07]), and there was heterogeneity among studies (P < 0.0001, I ² = 85.8 %). There were no differences in blood BDNF levels among AD or MCI patients vs. controls by subgroup analyses according to age, sex, and drug use. In conclusion, this meta-analysis shows that peripheral blood BDNF levels seem to be increased in early AD and decreased in AD patients with low MMSE scores respectively compared with their age- and sex-matched healthy referents. At present, however, this could not be concluded from individual studies.

Nano-particle delivery of brain derived neurotrophic factor after focal cerebral ischemia reduces tissue injury and enhances behavioral recovery

BACKGROUND

Low levels of brain-derived neurotrophic factor (BDNF) are linked to delayed neurological recovery, depression, and cognitive impairment following stroke. Supplementation with BDNF reverses these effects. Unfortunately, systemically administered BDNF in its native form has minimal therapeutic value due to its poor blood brain barrier permeability and short serum half-life. In this study, a novel nano-particle polyion complex formulation of BDNF (nano-BDNF) was administered to mice after experimental ischemic stroke.

METHODS

Male C57BL/6J (8-10weeks) mice were randomly assigned to receive nano-BDNF, native-BDNF, or saline treatment after being subjected to 60min of reversible middle cerebral artery occlusion (MCAo). Mice received the first dose at 3 (early treatment), 6 (intermediate treatment), or 12h (delayed treatment) following stroke onset; a second dose was given in all cohorts at 24h after stroke onset. Post-stroke outcome was evaluated by behavioral, histological, and molecular analysis for 15days after stroke.

RESULTS

Early and intermediate nano-BDNF treatment led to a significant reduction in cerebral tissue loss. Delayed treatment led to improved memory/cognition, reduced post-stroke depressive phenotypes, and maintained myelin basic protein and brain BDNF levels, but had no effect on tissue atrophy.

CONCLUSIONS

The results indicate that administration of a novel nano-particle formulation of BDNF leads to both neuroprotective and neuro-restorative effects after stroke.

The human BDNF gene: peripheral gene expression and protein levels as biomarkers for psychiatric disorders

Brain-derived neurotrophic factor (BDNF) regulates the survival and growth of neurons, and influences synaptic efficiency and plasticity. The human BDNF gene consists of 11 exons, and distinct BDNF transcripts are produced through the use of alternative promoters and splicing events. The majority of the BDNF transcripts can be detected not only in the brain but also in the blood cells, although no study has yet investigated the differential expression of BDNF transcripts at the peripheral level. This review provides a description of the human BDNF gene structure as well as a summary of clinical and preclinical evidence supporting the role of BDNF in the pathogenesis of psychiatric disorders. We will discuss several mechanisms as possibly underlying BDNF modulation, including epigenetic mechanisms. We will also discuss the potential use of peripheral BDNF as a biomarker for psychiatric disorders, focusing on the factors that can influence BDNF gene expression and protein levels. Within this context, we have also characterized, for we believe the first time, the expression of BDNF transcripts in the blood, with the aim to provide novel insights into the molecular mechanisms and signaling that may regulate peripheral BDNF gene expression levels.

High-flavonoid intake induces cognitive improvements linked to changes in serum brain-derived neurotrophic factor: Two randomised, controlled trials

BACKGROUND: Recent clinical studies have indicated the beneficial impact of dietary flavonoid intake on human cognitive performance. Although the mechanisms that mediate such improvements are currently unclear, animal and human trial data suggest that changes in neurotrophin expression, and related signalling apparatus, may be involved.

OBJECTIVE: To investigate the link between changes in serum brain-derived neurotrophic factor (BDNF) and changes in human cognitive performance following flavonoid intake.

METHODS: The relationship between serum levels of BDNF and age, gender, BMI, waist circumference, blood pressure and cognition at baseline, and following flavonoid intake, was investigated in two distinct randomised, controlled clinical trials. Trial 1 was conducted in men and women (aged 26–70 y; consuming an average of 3 portions of fruit and vegetables per day) and delivered high-flavonoid (>15 mg/100 g) or low-flavonoid (<5 mg/100 g) fruit and vegetables and increased intake by 2 portions every 6 weeks. The control arm was habitual diet over the same time frame. Trial 2 was conducted in an older males and female cohort (aged 62–75 y) intervening with a high-flavanol cocoa drink (494 mg total flavanols) and a low-flavanol cocoa drink (23 mg total flavanols) for 12 weeks.

RESULTS: Serum BDNF levels increased linearly to the age of 65, after which BDNF levels were found to decrease markedly. All other physiological and anthropometric measurements proved to not be significantly associated with serum BDNF levels (p > 0.05), although higher levels in males compared to females almost achieved significance (p = 0.056). At baseline, higher serum BDNF levels were associated with significantly better global cognition scores, relative to individuals with lower serum levels. In addition, following intervention for 18 weeks, high-flavonoid, but not low-flavonoid, fruit and vegetable intake induced significant improvements in cognitive performance and increases in serum BDNF levels (p = <0.001). Flavanol intervention for 12 weeks also resulted in significant increases in serum BDNF (p = <0.001), and such increases were correlated with improvements in global cognitive performance.

CONCLUSION: Increases in global cognition induced by high flavonoid fruit and vegetables, and cocoa flavanols were paralleled by concurrent changes in serum BDNF levels, suggesting a role for BDNF in flavonoid-induced cognitive improvements. Furthermore, we provide further data suggesting that serum BDNF levels may represent a biomarker of cognitive function.

MicroNeurotrophins Improve Survival in Motor Neuron-Astrocyte Co-Cultures but Do Not Improve Disease Phenotypes in a Mutant SOD1 Mouse Model of Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disease caused by loss of motor neurons. ALS patients experience rapid deterioration in muscle function with an average lifespan of 3–5 years after diagnosis. Currently, the most effective therapeutic only extends lifespan by a few months, thus highlighting the need for new and improved therapies. Neurotrophic factors (NTFs) are important for neuronal development, maintenance, and survival. NTF treatment has previously shown efficacy in pre-clinical ALS models. However, clinical trials using NTFs produced no major improvements in ALS patients, due in part to the limited blood brain barrier (BBB) penetration. In this study we assessed the potential neuroprotective effects of a novel class of compounds known as MicroNeurotrophins (MNTs). MNTs are derivatives of Dehydroepiandrosterone (DHEA), an endogenous neurosteroid that can cross the BBB and bind to tyrosine kinase receptors mimicking the pro-survival effects of NTFs. Here we sought to determine whether MNTs were neuroprotective in two different models of ALS. Our results demonstrate that BNN27 (10 μM) attenuated loss of motor neurons co-cultured with astrocytes derived from human ALS patients with SOD1 mutations via the reduction of oxidative stress. Additionally, in the G93A SOD1 mouse, BNN27 (10 mg/kg) treatment attenuated motor behavioral impairment in the paw grip endurance and rotarod tasks at postnatal day 95 in female but not male mice. In contrast, BNN27 (10 mg/kg and 50 mg/kg) treatment did not alter any other behavioral outcome or neuropathological marker in male or female mice. Lastly, BNN27 was not detected in post-mortem brain or spinal cord tissue of treated mice due to the rapid metabolism of BNN27 by mouse hepatocytes relative to human hepatocytes. Together, these findings demonstrate that BNN27 treatment failed to yield significant neuroprotective effects in the G93A SOD1 model likely due to its rapid rate of metabolism in mice.

Relationship between body weight and the increment in serum brain-derived neurotrophic factor after oral glucose challenge in men with obesity and metabolic syndrome: A prospective study

Brain-derived neurotrophic factor (BDNF) plays a role in energy homeostasis. However, the postprandial BDNF change has not been well investigated. We hypothesized that the BDNF increment after oral glucose challenge is associated with body weight.To address this possibility, man adults with obesity in conjunction with metabolic syndrome were compared with normal weight controls at baseline in the initial cross-sectional protocol. The obese subjects then underwent a 12-week program for body-weight reduction in the prospective protocol. The area under the curve (AUC) of serum BDNF was recorded during a 75 g oral glucose tolerant test and the BDNF AUC index was defined as [(AUC of BDNF) - (fasting BDNF2 hours)]/(fasting BDNF2 hours).A total of 25 controls and 36 obese subjects completed the study assessments. In the cross-sectional protocol, the BDNF AUC index was significantly higher in the obese subjects than in the controls (9.0 ± 16.5% vs. - 8.0 ± 22.5%, P = 0.001). After weight reduction (from 97.0 ± 12.5 kg to 88.6 ± 12.9 kg, P < 0.001), the percentage change of body weight was significantly associated with the BDNF AUC index after the study (95% CI between 0.21 and 1.82, P = 0.015). Using 6% weight reduction as a cut-off value, a larger weight reduction was able to reliably predict a negative BDNF AUC index.In conclusion, a high BDNF AUC index was observed for obese men in this study, whereas the index value significantly decreased after body-weight reduction. These findings suggest that postprandial BDNF increment may be associated with obesity.

Insulin-Like Growth Factor 1 and Related Compounds in the Treatment of Childhood-Onset Neurodevelopmental Disorders

Insulin-Like Growth Factor 1 (IGF-1) is a neurotrophic polypeptide with crucial roles to play in Central Nervous System (CNS) growth, development and maturation. Following interrogation of the neurobiology underlying several neurodevelopmental disorders and Autism Spectrum Disorders (ASD), both recombinant IGF-1 (mecasermin) and related derivatives, such as (1-3)IGF-1, have emerged as potential therapeutic approaches. Clinical pilot studies and early reports have supported the safety/preliminary efficacy of IGF-1 and related compounds in the treatment of Rett Syndrome, with evidence mounting for its use in Phelan McDermid Syndrome and Fragile X Syndrome. In ASD, clinical trials are ongoing. Here, we review the role of IGF-1 in the molecular etiologies of these conditions in addition to the accumulating evidence from early clinical studies highlighting the possibility of IGF-1 and related compounds as potential treatments for these childhood-onset neurodevelopmental disorders.

Brain-derived neurotrophic factor protein and mRNA levels in patients with bipolar mania - A preliminary study

Background

Brain-derived neurotrophic factor (BDNF) protein or mRNA levels may be involved in the pathophysiology of bipolar disorder. However, the results were inconsistent. We aimed to simultaneously investigate the relationship of BDNF protein and mRNA levels in peripheral blood of patients with bipolar mania.

Methods

Patients with bipolar mania (n = 30) and healthy controls (n = 30) were recruited during our one-year study. Psychiatric diagnoses were made according to Diagnostic and Statistical Manual of Mental Disorders, 4th Edition criteria. The scores of the Young Mania Rating Scale (YMRS) of patients with bipolar mania were greater than 26. All participants had peripheral blood drawn to analyze the serum BDNF protein and mRNA levels.

Results

Using t-test, patients with bipolar mania had a lower BDNF protein and mRNA levels than did the healthy controls (p < 0.001 and 0.049, respectively), however, the statistical significances were lost after analysis of co-variance adjusted for age and body mass index. Twenty seven out of 30 patients with bipolar mania remained in the study after the 4 weeks of mood stabilizer treatment. Patients' BDNF protein and mRNA levels did not change significantly after 4-week treatment.

Conclusions

Our study found that serum BDNF protein and mRNA levels in patients with bipolar mania were lower than healthy controls, but a larger sample size will be needed to confirm this finding.

Brain-Derived Neurotrophic Factor Gene Val66Met Polymorphism Is a Risk Factor for Attention-Deficit Hyperactivity Disorder in a Turkish Sample

OBJECTIVE

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that negatively affects different areas of life. We aimed to evaluate the associations between the Val66Met polymorphism of brain-derived neurotrophic factor (BDNF) and ADHD and to assess the effect of the BDNF polymorphism on the neurocognitive profile and clinical symptomatology in ADHD.

METHODS

Two hundred one ADHD cases and 99 typically developing subjects (TD) between the ages of 8 and 15 years were involved in the study. All subjects were evaluated using a complete neuropsychological battery, Child Behavior Checklist, the Teacher's Report Form (TRF) and the DSM-IV Disruptive Behavior Disorders Rating Scale-teacher and parent forms.

RESULTS

The GG genotype was significantly more frequent in the patients with ADHD than in the TD controls, and the GG genotype was also significantly more frequent in the ADHD-combined (ADHD-C) subtype patients than in the TDs. However, there were no significant associations of the BDNF polymorphism with the ADHD subtypes or neurocognitive profiles of the patients. The teacher-assessed hyperactivity and inattention symptom count and the total score were higher, and the appropriately behaving subtest score of the TRF was lower in the GG genotypes than in the GA and AA (i.e., the A-containing) genotypes.

CONCLUSION

We found a positive association between the BDNF gene Val66Met polymorphism and ADHD, and this association was observed specifically in the ADHD-C subtype and not the ADHD-predominantly inattentive subtype. Our findings support that the Val66Met polymorphism of BDNF gene might be involved in the pathogenesis of ADHD. Furthermore Val66Met polymorphism of BDNF gene may be more closely associated with hyperactivity rather than inattention.

The role of growth factors as a therapeutic approach to demyelinating disease

A variety of growth factors are being explored as therapeutic agents relevant to the axonal and oligodendroglial deficits that occur as a result of demyelinating lesions such as are evident in Multiple Sclerosis (MS). This review focuses on five such proteins that are present in the lesion site and impact oligodendrocyte regeneration. It then presents approaches that are being exploited to manipulate the lesion environment affiliated with multiple neurodegenerative diseases and suggests that the utility of these approaches can extend to demyelination. Challenges are to further understand the roles of specific growth factors on a cellular and tissue level. Emerging technologies can then be employed to optimize the use of growth factors to ameliorate the deficits associated with demyelinating degenerative diseases.

Decreased Plasma BDNF Levels of Patients with Somatization Disorder

OBJECTIVE

Brain-derived neurotrophic factor (BDNF), one of the most abundant and important neurotrophins, is known to be involved in the development, survival, maintenance, and plasticity of neurons in the nervous system. Some studies have suggested that BDNF may play a role in the pathophysiology of several psychiatric illnesses such as depression and schizophrenia. Similarly, it is likely that the alteration of BDNF may be associated with the neuro-modulation that contributes to the development of somatization disorder.

METHODS

The purpose of this study was to determine whether there is an abnormality of plasma BDNF levels in patients with somatization disorder, and to analyze the nature of the alteration after pharmacotherapy using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

The plasma BDNF levels of the patients with a somatization disorder were significantly lower compared with those of the control volunteers (83.61±89.97 pg/mL vs. 771.36±562.14 pg/mL); moreover, the plasma BDNF levels of those patients who received an antidepressant were significantly increased after the treatment (118.13±91.45 pg/mL vs. 72.92±88.21 pg/mL).

CONCLUSION

These results suggest that BDNF may play a role in the pathophysiology of somatization disorder.

Cognitive Impairment in Schizophrenia: Interplay of BDNF and Childhood Trauma? A Review of Literature

Cognitive impairment is a core feature of schizophrenia. These deficits can also serve as an endophenotype for the illness in genetic studies. There is evidence that suggests that cognition can be considered a reasonable target for intervention in both schizophrenia and bipolar disorder. One of the most studied genetic phenotypes for psychosis is brain-derived neurotrophic factor (BDNF) Val66Met polymorphisms. BDNF has an established role in neuronal development and cell survival in response to stress and is abnormally expressed in schizophrenia. Studies have shown that childhood trauma is associated with poor prognosis of schizophrenic patients. BDNF-Val66Met polymorphism has been shown to moderate the impact of childhood adversity on later expression of affective symptoms, suggesting the possibility of gene environment interactions. Considering the recent advances of neuroscience an up to date review of relevant literature is warranted in this field. This article reviews the current literature available regarding associations between the Val66Met polymorphism, childhood trauma and cognitive dysfunction in schizophrenia.

A prospective, longitudinal study of platelet serotonin and plasma brain-derived neurotrophic factor concentrations in major depression: effects of vortioxetine treatment

BACKGROUND

Various antidepressants occupy brain serotonin transporter (SERT), decrease platelet serotonin (5-HT) concentration, and normalize reduced plasma brain-derived neurotrophic factor (BDNF) concentrations in depressed patients. Vortioxetine is a recently introduced antidepressant with a multimodal mechanism of action. In addition to SERT inhibition, vortioxetine acts via different 5-HT receptors. To further elucidate its mechanism of action, we have investigated the effects of vortioxetine on platelet 5-HT and plasma BDNF concentrations in patients with major depression.

METHODS

Platelet 5-HT and plasma BDNF concentrations were determined in 44 healthy subjects at baseline and in 44 depressed patients before and after 4 weeks of treatment with vortioxetine (5-15 mg daily). Platelet 5-HT concentration was determined using the ortho-phthalaldehyde-enhanced fluorometric method, and plasma BDNF concentration using a commercial enzyme-linked immunosorbent assay (Quantikine ELISA, R&D Systems).

RESULTS

At baseline, platelet 5-HT concentrations did not differ between depressed and control subjects, but plasma BDNF values were lower (p = 0.011; ω = 0.80) in depressed patients than in healthy subjects. Vortioxetine treatment significantly (p < 0.0001; ω = 0.80) decreased platelet 5-HT concentration and significantly (p = 0.004; ω = 0.80) increased plasma BDNF concentration in depressed patients compared to their baseline values. Age, gender, and smoking were not significantly associated with platelet 5-HT and plasma BDNF concentrations.

CONCLUSION

Despite a novel mechanism of action, vortioxetine shares some common effects with other antidepressants. This study is the first to show that, in addition to clinical improvement, 4 weeks of treatment with vortioxetine (5-15 mg daily), decreased platelet 5-HT and increased plasma BDNF concentrations in depressed patients.

BDNF serum levels in schizophrenic patients during treatment augmentation with sarcosine (results of the PULSAR study)

AIM

Finding a relationship between schizophrenia symptoms severity and initial level of BDNF and its changes during augmentation of antipsychotic treatment with sarcosine.

METHOD

57 individuals with schizophrenia with predominantly negative symptoms completed a 6-month RCT prospective study. The patients received 2g of sarcosine (n=27) or placebo (n=30) daily. At the beginning, after 6 weeks and 6 months BDNF levels were measured. Severity of symptoms was assessed using the Positive and Negative Syndrome Scale (PANSS) and Calgary Depression Scale for Schizophrenia (CDSS).

RESULTS

BDNF serum levels were stable after 6 weeks and 6 months in both groups. We noted improvement in negative symptoms, general psychopathology and total PANSS score in sarcosine group comparing to placebo, however there was no correlations between serum BDNF concentrations and PANSS scores in all assessments. Initial serum BDNF concentrations cannot be used as a predictor of the improvement resulting from adding sarcosine.

CONCLUSIONS

Our results indicate that either BDNF is not involved in the NMDA-dependent mechanism of sarcosine action or global changes in BDNF concentrations induced by amino-acid cannot be detected in blood assessments.

The Differential Levels of Inflammatory Cytokines and BDNF among Bipolar Spectrum Disorders

OBJECTIVE

Emerging evidence suggests that inflammation and neurodegeneration underlies bipolar disorder. To investigate biological markers of cytokines and brain-derived neurotrophic factor between bipolar I, bipolar II, and other specified bipolar disorder with short duration hypomania may support the association with inflammatory dysregulation and bipolar disorder and, more specifically, provide evidence for other specified bipolar disorder with short duration hypomania patients were similar to bipolar II disorder patients from a biological marker perspective.

METHODS

We enrolled patients with bipolar I disorder (n=234), bipolar II disorder (n=260), other specified bipolar disorder with short duration hypomania (n=243), and healthy controls (n=140). Their clinical symptoms were rated using the Hamilton Depression Rating Scale and Young Mania Rating Scale. Inflammatory cytokine (tumor necrosis factor-α, C-reactive protein, transforming growth factor-β1, and interleukin-8) and brain-derived neurotrophic factor levels were measured in each group. Multivariate analysis of covariance and linear regression controlled for possible confounders were used to compare cytokine and brain-derived neurotrophic factor levels among the groups.

RESULTS

Multivariate analysis of covariance adjusted for age and sex and a main effect of diagnosis was significant (P<.001). Three of the 5 measured biomarkers (tumor necrosis factor-α, transforming growth factor-β1, and interleukin-8) were significantly (P=.006, .01, and <.001) higher in all bipolar disorder patients than in controls. Moreover, covarying for multiple associated confounders showed that bipolar I disorder patients had significantly higher IL-8 levels than did bipolar II disorder and other specified bipolar disorder with short duration hypomania patients in multivariate analysis of covariance (P=.03) and linear regression (P=.02) analyses. Biomarkers differences between bipolar II disorder and other specified bipolar disorder with short duration hypomania patients were nonsignificant.

CONCLUSION

The immunological disturbance along the bipolar spectrum was most severe in bipolar I disorder patients. Other specified bipolar disorder with short duration hypomania patients and bipolar II disorder patients did not differ in these biological markers.

Brain-derived neurotrophic factor delivered to the brain using poly (lactide-co-glycolide) nanoparticles improves neurological and cognitive outcome in mice with traumatic brain injury

Currently, traumatic brain injury (TBI) is the leading cause of death or disabilities in young individuals worldwide. The multi-complexity of its pathogenesis as well as impermeability of the blood-brain barrier (BBB) makes the drug choice and delivery very challenging. The brain-derived neurotrophic factor (BDNF) regulates neuronal plasticity, neuronal cell growth, proliferation, cell survival and long-term memory. However, its short half-life and low BBB permeability are the main hurdles to be an effective therapeutic for TBI. Poly (lactic-co-glycolic acid) (PLGA) nanoparticles coated by surfactant can enable the delivery of a variety of molecules across the BBB by receptor-mediated transcytosis. This study examines the ability of PLGA nanoparticles coated with poloxamer 188 (PX) to deliver BDNF into the brain and neuroprotective effects of BNDF in mice with TBI. C57bl/6 mice were subjected to weight-drop closed head injuries under anesthesia. Using enzyme-linked immunosorbent assay, we demonstrated that the intravenous (IV) injection of nanoparticle-bound BDNF coated by PX (NP-BDNF-PX) significantly increased BDNF levels in the brain of sham-operated mice (p < 0.001) and in both ipsi- (p < 0.001) and contralateral (p < 0.001) parts of brain in TBI mice compared to controls. This study also showed using the passive avoidance (PA) test, that IV injection of NP-BDNF-PX 3 h post-injury prolonged the latent time in mice with TBI thereby reversing cognitive deficits caused by brain trauma. Finally, neurological severity score test demonstrated that our compound efficiently reduced the scores at day 7 after the injury indicating the improvement of neurological deficit in animals with TBI. This study shows that PLGA nanoparticles coated with PX effectively delivered BDNF into the brain, and improved neurological and cognitive deficits in TBI mice, thereby providing a neuroprotective effect.

Influence of Aerobic Training and Combinations of Interventions on Cognition and Neuroplasticity after Stroke

Stroke often aggravated age-related cognitive impairments that strongly affect several aspects of quality of life. However, few studies are, to date, focused on rehabilitation strategies that could improve cognition. Among possible interventions, aerobic training is well known to enhance cardiovascular and motor functions but may also induce beneficial effects on cognitive functions. To assess the effectiveness of aerobic training on cognition, it seems necessary to know whether training promotes the neuroplasticity in brain areas involved in cognitive functions. In the present review, we first explore in both human and animal how aerobic training could improve cognition after stroke by highlighting the neuroplasticity mechanisms. Then, we address the potential effect of combinations between aerobic training with other interventions, including resistance exercises and pharmacological treatments. In addition, we postulate that classic recommendations for aerobic training need to be reconsidered to target both cognition and motor recovery because the current guidelines are only focused on cardiovascular and motor recovery. Finally, methodological limitations of training programs and cognitive function assessment are also developed in this review to clarify their effectiveness in stroke patients.

The Effects of Acute Physical Exercise on Memory, Peripheral BDNF, and Cortisol in Young Adults

In animals, physical activity has been shown to induce functional and structural changes especially in the hippocampus and to improve memory, probably by upregulating the release of neurotrophic factors. In humans, results on the effect of acute exercise on memory are inconsistent so far. Therefore, the aim of the present study was to assess the effects of a single bout of physical exercise on memory consolidation and the underlying neuroendocrinological mechanisms in young adults. Participants encoded a list of German-Polish vocabulary before exercising for 30 minutes with either high intensity or low intensity or before a relaxing phase. Retention of the vocabulary was assessed 20 minutes after the intervention as well as 24 hours later. Serum BDNF and salivary cortisol were measured at baseline, after learning, and after the intervention. The high-intensity exercise group showed an increase in BDNF and cortisol after exercising compared to baseline. Exercise after learning did not enhance the absolute number of recalled words. Participants of the high-intensity exercise group, however, forgot less vocabulary than the relaxing group 24 hours after learning. There was no robust relationship between memory scores and the increase in BDNF and cortisol, respectively, suggesting that further parameters have to be taken into account to explain the effects of exercise on memory in humans.

Comparing clinical responses and the biomarkers of BDNF and cytokines between subthreshold bipolar disorder and bipolar II disorder

Patients with subthreshold hypomania (SBP; subthreshold bipolar disorder) were indistinguishable from those with bipolar disorder (BP)-II on clinical bipolar validators, but their analyses lacked biological and pharmacological treatment data. Because inflammation and neuroprogression underlies BP, we hypothesized that cytokines and brain-derived neurotrophic factor (BDNF) are biomarkers for BP. We enrolled 41 drug-naïve patients with SBP and 48 with BP-II undergoing 12 weeks of pharmacological treatment (valproic acid, fluoxetine, risperidone, lorazepam). The Hamilton Depression Rating Scale (HDRS) and Young Mania Rating Scale (YMRS) were used to evaluate clinical responses at baseline and at weeks 0, 1, 2, 4, 8, and 12. Inflammatory cytokines (tumour necrosis factor [TNF]-α, transforming growth factor [TGF]-β1, interleukin [IL]-6, IL-8 and IL-1β) and BDNF levels were also measured. Mixed models repeated measurement was used to examine the therapeutic effect and changes in BDNF and cytokine levels between the groups. HDRS and YMRS scores significantly (P < 0.001) declined in both groups, the SBP group had significantly lower levels of BDNF (P = 0.005) and TGF-β1 (P = 0.02). Patients with SBP and BP-II respond similarly to treatment, but SBP patients may have different neuroinflammation marker expression.

BDNF DNA methylation changes as a biomarker of psychiatric disorders: literature review and open access database analysis

Brain-derived neurotrophic factor (BDNF) plays an important role in nervous system development and function and it is well established that BDNF is involved in the pathogenesis of a wide range of psychiatric disorders. Recently, numerous studies have associated the DNA methylation level of BDNF promoters with certain psychiatric phenotypes. In this review, we summarize data from current literature as well as from our own analysis with respect to the correlation of BDNF methylation changes with psychiatric disorders and address questions about whether DNA methylation related to the BDNF can be useful as biomarker for specific neuropsychiatric disorders.

Interictal serum brain-derived neurotrophic factor level reflects white matter integrity, epilepsy severity, and cognitive dysfunction in chronic temporal lobe epilepsy

OBJECTIVE

Most patients with temporal lobe epilepsy (TLE) have epileptic foci originating from the medial temporal lobe, particularly the hippocampus. Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin growth factor mainly expressed in the hippocampus, though it is not known whether the circulating level of BDNF reflects cognitive performance or white matter structural changes in chronic TLE.

METHODS

Thirty-four patients with TLE and 22 healthy controls were enrolled for standardized cognitive tests, diffusion tensor imaging, and serum BDNF measurement. The patients were further divided into a subgroup with unilateral TLE (n=23) and a subgroup with bilateral TLE (n=11) for clinical and neuroimaging comparisons.

RESULTS

There were significantly lower BDNF levels in the patients with TLE compared with the controls, with significance contributed mainly from the subgroup with bilateral TLE, which also had more frequent seizures. The BDNF levels correlated with epilepsy duration (σ=-0.355; p=0.040) and fractional anisotropy (FA) in the left temporal lobe, left thalamus, and right hippocampus. Using a regression model, BDNF level predicted verbal memory score. Further, design fluency scores were predicted by serum BDNF level via the interactions with left temporal FA.

CONCLUSIONS

Serum BDNF levels reflected longer epilepsy duration, impaired white matter integrity, and poor cognitive function in patients with chronic TLE.

Serum cortisol and BDNF in patients with major depression-effect of yoga

Depression is associated with low serum Brain Derived Neurotrophic Factor (BDNF) and elevated levels of serum cortisol. Yoga practices have been associated with antidepressant effects, increase in serum BDNF, and reduction in serum cortisol. This study examined the association between serum BDNF and cortisol levels in drug-naïve patients with depression treated with antidepressants, yoga therapy, and both. Fifty-four drug-naïve consenting adult outpatients with Major Depression (32 males) received antidepressants only (n = 16), yoga therapy only (n = 19), or yoga with antidepressants (n = 19). Serum BDNF andcortisol levels were obtained before and after 3 months using a sandwich ELISA method. One-way ANOVA, Chi-square test, and Pearson's correlation tests were used for analysis. The groups were comparable at baseline on most parameters. Significant improvement in depression scores and serum BDNF levels, and reduction in serum cortisol in the yoga groups, have been described in previous reports. A significant negative correlation was observed between change in BDNF (pre-post) and cortisol (pre-post) levels in the yoga-only group (r = -0.59, p = 0.008). In conclusion, yoga may facilitate neuroplasticity through stress reduction in depressed patients. Further studies are needed to confirm the findings and delineate the pathways for these effects.