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

BDNF levels are increased in peripheral blood of middle-aged amateur runners with no changes on histone H4 acetylation levels

Our aim was to compare the basal levels of plasma brain-derived neurotrophic factor (BDNF) and global histone H4 acetylation in peripheral blood mononuclear cells (PBMCs) of healthy amateur runners (EXE group) with sedentary individuals (SED group) as well as to investigate the acute effect of a running race on these markers in the EXE group. Five days before the race, all participants were submitted to a basal blood collection. On the race day, two blood samples were collected in the EXE group before the running started and immediately at the end. In the basal period, a significant increase of plasma BDNF levels in the EXE individuals when compared to the SED group (p = 0.036) was demonstrated, while no difference in global histone H4 acetylation levels was observed. These parameters were unaltered in the EXE group after the race. The increased levels of BDNF might be linked to healthy middle-aged runners' phenotype.

Association of serum BDNF levels with psychotic symptom in chronic patients with treatment-resistant depression in a Chinese Han population

The neurotrophic hypothesis of depression is supported by consistent findings of lower serum BDNF levels in depressed patients. Increasing evidence shows different clinical characteristics of patients with psychotic major depression versus nonpsychotic major depression. However, the possible association between BDNF and psychotic symptoms in depression has not been investigated. We recruited 90 treatment-resistant depression (TRD) patients and 90 gender- and age-matched healthy control subjects and examined serum BDNF in both groups. Patients' depressive symptoms were assessed using the 17-item Hamilton Depression Rating Scale (HDRS-17), and psychopathological symptoms by the 18-item Brief Psychiatric Rating Scale (BPRS-18). Our results showed that BDNF levels were significantly lower in patients than controls. Correlation analysis revealed a significantly positive correlation between BDNF and the thought disturbance subscale of BPRS-18 (p < 0.05), and a trend toward a significantly positive correlation between BDNF and the BPRS-18 total score (p = 0.06). Stepwise multiple regression analyses confirmed BDNF as the influencing factor for the thought disturbance subscales of the BPRS-18. Our findings suggest that BDNF may be involved in the pathophysiology of TRD, and its associated psychotic symptoms, especially thought disturbance.

Chronic administration of ellagic acid improved the cognition in middle-aged overweight men

This study aimed to investigate if ellagic acid has beneficial effects on cognitive deficits in middle-aged overweight individuals and to propose a possible mechanism. A total of 150 middle-aged male participants, including 76 normal-weight and 74 overweight men, aged between 45 to 55 years, were recruited for this study. Both normal-weight and overweight participants were administered either 50 mg ellagic acid or placebo cellulose daily for 12 weeks. Blood lipids, peripheral brain-derived neurotrophic factor (BDNF), and saliva cortisol were assessed on the last day of the procedure to investigate the effects induced by ellagic acid. The results revealed that ellagic acid treatment improved the levels of blood lipid metabolism with a 4.7% decline in total cholesterol, 7.3% decline in triglycerides, 26.5% increase in high-density lipoprotein, and 6.5% decline in low-density lipoprotein. Additionally, ellagic acid increased plasma BDNF by 21.2% in the overweight group and showed no effects on normal-weight participants. Moreover, the increased saliva cortisol level in overweight individuals was inhibited by 22.7% in a 12-week ellagic acid treatment. Also, compared with placebo, overweight individuals who consumed ellagic acid showed enhanced cognitive function as measured by the Wechsler Adult Intelligence Scale-Revised and the Montreal Cognitive Assessment. To the best of our knowledge, this is the first report showing that ellagic acid prevents cognitive deficits through normalization of lipid metabolism, increase in plasma BDNF level, and reduction of saliva cortisol concentration. These results indicate that ellagic acid has a potential to restore cognitive performance related to mild age-related declines.

The Effects of Aerobic Exercise on the Recovery of Walking Ability and Neuroplasticity in People with Multiple Sclerosis: A Systematic Review of Animal and Clinical Studies

INTRODUCTION

Walking is of high priority for people with multiple sclerosis (PwMS). It remains unclear whether aerobic exercise can improve walking ability and upregulate neurotrophins. This review aims to consolidate evidence to develop optimal aerobic training parameters to enhance walking outcomes and neuroplasticity in PwMS.

METHODS

Clinical studies examining aerobic exercise for ≥3 weeks, having outcomes on walking with or without neurotrophic markers, were included. Studies utilizing animal models of MS were included if they employed aerobic exercise with outcomes on neurological recovery and neurotrophins. From a total of 1783 articles, 12 clinical and 5 animal studies were included.

RESULTS

Eleven clinical studies reported improvements in walking ability. Only two clinical studies evaluated both walking and neurotrophins, and neither found an increase in neurotrophins despite improvements in walking. Patients with significant walking impairments were underrepresented. Long-term follow-up revealed mixed results. Two animal studies reported a positive change in both neurological recovery and neurotrophins.

CONCLUSION

Aerobic exercise improves walking ability in PwMS. Gains are not consistently maintained at 2- to 9-month follow-up. Studies examining levels of neurotrophins are inconclusive, necessitating further research. Aerobic exercise enhances both neurological recovery and neurotrophins in animal studies when started 2 weeks before induction of MS.

Short-Duration Maximal and Long-Duration Submaximal Effort Forearm Exercise Achieve Elevations in Serum Brain-Derived Neurotrophic Factor

Brain-derived neurotrophic factor (BDNF) is a major orchestrator of exercise-induced brain plasticity and circulating (peripheral) BDNF may have central effects. Approximately 99% of circulating BDNF is platelet-bound, and at rest ~30% of circulating platelets are stored in the spleen. Interestingly, forearm handgrip exercise significantly elevates sympathetic outflow and has been shown to induce splenic constriction, suggesting that small muscle mass exercise could stand as a viable strategy for increasing circulating BDNF; however, the BDNF response to handgrip exercise is currently unknown. Purpose: This study examined BDNF and platelet responses to short-duration maximal (ME) and prolonged submaximal (SE) effort handgrip exercise. Methods: Healthy males (n = 18; 21.4 ± 2.1 years, BMI 25.0 ± 1.0 kg/m²) performed 10 min of ME and 30 min of SE. Blood was sampled for the determination of serum BDNF and platelet count at rest and during the last minute of exercise. Results: Compared to rest, serum BDNF significantly increased during ME (21.2%) and SE (11.2%), which displayed a non-significant trend toward an intensity-dependent response. Platelets increased in an intensity-dependent fashion compared to rest with an 8.0% increase during ME and 3.1% during SE, and these responses were significantly correlated with diastolic blood pressure responses to handgrip exercise. Further, the amount of BDNF per platelet significantly increased compared to rest during ME (13.4%) and SE (8.7%). Conclusions: Handgrip exercise evokes significant increases in serum BDNF and platelets, implicating splenic constriction as a key mechanism and confirming efficacy of this exercise model for elevating circulating BDNF.

Long-term heroin use was associated with the downregulation of systemic platelets, BDNF, and TGF-β1, and it contributed to the disruption of executive function in Taiwanese Han Chinese

BACKGROUND

Long-term heroin addicts have low plasma brain-derived neurotrophic factor (BDNF) levels. However, the mechanisms and effects of systemic disturbances of BDNF caused by heroin remain unclear.

OBJECTIVE

Blood platelet might be a source of neurotrophic factors like BDNF and transforming growth factor (TGF)-β1. Thus, we investigated the effects of heroin on platelets, BDNF and TGF-β1, the association between blood platelets, BDNF, TGF-β1, and executive function in long-term heroin addicts.

METHODS

We enrolled 170 heroin addicts and 141 healthy controls. We measured their plasma BDNF and TGF-β1 levels and counted their platelets, red and white blood cells. The Wisconsin Card Sorting Test (WCST) was used to assess their executive function.

RESULTS

Plasma BDNF and TGF-β1 levels were significantly downregulated in long-term heroin addicts. BDNF, TGF-β1, and platelet levels were lower in patients who had used heroin for more than 6 years than in those who had used it for less than 6 years. Lower plasma BDNF and TGF-β1 levels were highly correlated with the changes in platelet counts. In the WCST, the number of trials needed to complete the first category were negatively associated with platelet counts and BDNF levels.

CONCLUSIONS

In long-term heroin addicts, lower platelet counts contributed to lower plasma BDNF and TGF-β1 levels, which, in turn, contributed to the disruption of executive function after long-term heroin use. Neurotrophic- and platelet-protective agents might provide a useful research focus for heroin addiction therapy.

Brain-derived neurotrophic factor serum and plasma levels in the treatment of acute schizophrenia with olanzapine or risperidone: 6-week prospective study

Antipsychotics have been the mainstay of the treatment of schizophrenia, and their potential role in neuroprotection could be related to brain-derived neurotrophic factor (BDNF). So far different effects on both serum and plasma levels of BDNF were reported related to the various antipsychotic treatments. Aim of this study was to investigate the influence of olanzapine or risperidone on both plasma and serum levels of BDNF in patients with acute schizophrenia. For 50 participants with acute episode of schizophrenia both plasma and serum BDNF, along with the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression scale, were assessed pretreatment and post treatment - after 6 weeks of either risperidone or olanzapine. Results show that a weak correlation between pretreatment plasma and serum levels of BNDF was found no longer significant after 6 weeks of treatment. Antipsychotics, olanzapine and risperidone showed no significant effect on post treatment plasma and serum levels of BDNF. Pretreatment plasma level of BDNF and PANSS positive subscale were positively correlated. Post treatment serum level of BDNF and Clinical Global Impression were negatively correlated. In conclusion, plasma and serum BDNF levels could be different markers to some extent with regard to clinical symptoms, response to therapy and outcome. The interrelation between serum and plasma BDNF should be established in further studies.

Val66Met functional polymorphism and serum protein level of brain-derived neurotrophic factor (BDNF) in acute episode of schizophrenia and depression

BACKGROUND

Brain-derived neurotrophic factor (BDNF) influences neuron differentiation during development as well as the synaptic plasticity and neuron survival in adulthood. BDNF has been implicated in the pathogenesis of schizophrenia and depression. Val66Met polymorphism and BDNF serum level are potential biomarkers in neuropsychiatric disorders. The aim of this study was to determine the effect of BDNF gene Val66Met functional polymorphism on serum BDNF concentration in patients with schizophrenia, during depression episode and in healthy control group.

METHODS

183 participants were recruited (61 patients with depressive episode, 56 females with schizophrenia, 66 healthy controls) from Polish population. Serum BDNF levels were measured using ELISA method. Val66Met polymorphism was genotyped using PCR- RFLP method.

RESULTS

Serum BDNF levels were not associated with Val66Met polymorphism in either of the groups. A significant increase of BDNF level in schizophrenia (p = 0.0005) and depression (p = 0.026) comparing to the control group has been observed.

CONCLUSIONS

Our results suggest that the functional Val66Met BDNF polymorphism is not associated with BDNF serum levels, which is in line with previous findings. Replication studies on larger groups are needed.

Exercise during pregnancy and its impact on mothers and offspring in humans and mice

Exercise during pregnancy has beneficial effects on maternal and offspring’s health in humans and mice. The underlying mechanisms remain unclear. This comparative study aimed to determine the long-term effects of an exercise program on metabolism, weight gain, body composition and changes in hormones [insulin, leptin, brain-derived neurotrophic factor (BDNF)]. Pregnant women (n=34) and mouse dams (n=44) were subjected to an exercise program compared with matched controls (period I). Follow-up in the offspring was performed over 6 months in humans, corresponding to postnatal day (P) 21 in mice (period II). Half of the mouse offspring was challenged with a high-fat diet (HFD) for 6 weeks between P70 and P112 (period III). In period I, exercise during pregnancy led to 6% lower fat content, 40% lower leptin levels and an increase of 50% BDNF levels in humans compared with controls, which was not observed in mice. After period II in humans and mice, offspring body weight did not differ from that of the controls. Further differences were observed in period III. Offspring of exercising mouse dams had significantly lower fat mass and leptin levels compared with controls. In addition, at P112, BDNF levels in offspring were significantly higher from exercising mothers while this effect was completely blunted by HFD feeding. In this study, we found comparable effects on maternal and offspring’s weight gain in humans and mice but different effects in insulin, leptin and BDNF. The long-term potential protective effects of exercise on biomarkers should be examined in human studies.

Serum brain-derived neurotrophic factors in Taiwanese patients with drug-naïve first-episode schizophrenia: Effects of antipsychotics

OBJECTIVES

Brain-derived neurotrophic factors (BDNF) are known to be related to the psychopathology of schizophrenia. However, studies focussing on drug-naïve first-episode schizophrenia are still rare.

METHODS

Over a 5-year period, we investigated the serum BDNF levels in patients with first-episode drug-naïve schizophrenia and compared them to age- and sex-matched healthy controls. We also explored the association between antipsychotic doses, positive and negative syndrome scale (PANSS) scores, and serum BDNF levels before and after a 4-week antipsychotic treatment.

RESULTS

The baseline serum BDNF levels of 34 patients were significantly lower than those of the controls (df = 66, P = .001). Although the PANSS scores of 20 followed-up patients improved significantly after antipsychotic treatment, the elevation of the serum BDNF levels was not statistically significant (P = .386). In addition, Pearson's correlation test showed significant correlations between pre-treatment negative scale scores and percentage changes in BDNF (P = .002).

CONCLUSIONS

The peripheral BDNF levels in Taiwanese patients with drug-naïve first-episode schizophrenia, compared with healthy controls, did not elevate after antipsychotic treatment, and pre-treatment negative symptoms played a pivotal role in trajectories of serum BDNF levels. Large samples will be needed in future studies to verify these results.

Differences in biomarkers of crack-cocaine adolescent users before/after abstinence

AIMS

To measure the variation in Brain-Derived Neurotrophic Factor (BDNF), Thiobarbituric Acid Reactive Substances (TBARS) and interleukin (IL) levels in crack-cocaine dependent adolescents after 21days of abstinence, comparing to levels found in a group of healthy controls.

DESIGN

Cross-sectional nested on a short follow-up study.

SETTING

Two inpatient treatment units for adolescents, and a low-income neighborhood.

PARTICIPANTS

90 adolescents, of both genders, with diagnosis of crack cocaine dependence, and 81 healthy adolescents.

MEASUREMENTS

Serum levels of IL-6, IL-10, TBARS and BDNF were assessed on admission and discharge. Drug addiction severity was assessed by the Addiction Severity Index - Teen Version (T-ASI) and Cocaine Craving Questionnaire - Brief version (CCQ-b). Psychiatric comorbidities were assessed by the Schedule for Affective Disorders and Schizophrenia for School-Age Children - Present and Lifetime Version (K-SADS-PL). Generalized Estimating Equations (GEE) were used to estimate the IL-6, IL-10, TBARS and BDNF levels, adjusted for confounders. Hedges' g was used to estimate effect size.

FINDINGS

TBARS (p=0.005, d=0.04), IL-6 (p=0.027, d=0.40) and IL-10 (p=0.025, d=0.41) were elevated and BDNF (p<0.001, d=0.62) was reduced (p<0.001), in patients, in comparison to controls, at admission time. Variation in those levels between admission and discharge were not significant.

CONCLUSIONS

Crack-cocaine use seems to be associated with inflammatory and oxidative imbalances in adolescents.

The brain, sirtuins, and ageing

In mammals, recent studies have demonstrated that the brain, the hypothalamus in particular, is a key bidirectional integrator of humoral and neural information from peripheral tissues, thus influencing ageing both in the brain and at the 'systemic' level. CNS decline drives the progressive impairment of cognitive, social and physical abilities, and the mechanisms underlying CNS regulation of the ageing process, such as microglia-neuron networks and the activities of sirtuins, a class of NAD⁺-dependent deacylases, are beginning to be understood. Such mechanisms are potential targets for the prevention or treatment of age-associated dysfunction and for the extension of a healthy lifespan.

Regulatory role of NGFs in neurocognitive functions

Nerve growth factors (NGFs), especially the prototype NGF and brain-derived neurotrophic factor (BDNF), have a diverse array of functions in the central nervous system through their peculiar set of receptors and intricate signaling. They are implicated not only in the development of the nervous system but also in regulation of neurocognitive functions like learning, memory, synaptic transmission, and plasticity. Evidence even suggests their role in continued neurogenesis and experience-dependent neural network remodeling in adult brain. They have also been associated extensively with brain disorders characterized by neurocognitive dysfunction. In the present article, we aimed to make an exhaustive review of literature to get a comprehensive view on the role of NGFs in neurocognitive functions in health and disease. Starting with historical perspective, distribution in adult brain, implied molecular mechanisms, and developmental basis, this article further provides a detailed account of NGFs’ role in specified neurocognitive functions. Furthermore, it discusses plausible NGF-based homeostatic and adaptation mechanisms operating in the pathogenesis of neurocognitive disorders and has presents a survey of such disorders. Finally, it elaborates on current evidence and future possibilities in therapeutic applications of NGFs with an emphasis on recent research updates in drug delivery mechanisms. Conclusive remarks of the article make a strong case for plausible role of NGFs in comprehensive regulation of the neurocognitive functions and pathogenesis of related disorders and advocate that future research should be directed to explore use of NGF-based mechanisms in the prevention of implicated diseases as well as to target these molecules pharmacologically.

The effect of childhood trauma on serum BDNF in bipolar depression is modulated by the serotonin promoter genotype

In healthy humans, both childhood trauma and the short form of the serotonin promoter transporter genotype (5-HTTLPR) are associated with lower levels of brain-derived neurotrophic factor (BDNF). In subjects with bipolar disorder (BD), lower levels of BDNF and a higher degree of childhood trauma were observed compared with healthy controls. However, is still unknown if the functional 5-HTTLPR polymorphisms exerts an effect on both abnormalities. In 40 inpatients affected by a major depressive episode in the course of BD, we genotyped 5-HTTLPR, measured serum BDNF with ELISA, and assessed early adversities by the childhood trauma questionnaire (CTQ). Data were analyzed in the context of the general linear model correcting for age, sex, ongoing lithium treatment, severity of current depression, and CTQ minimization/denial scores to investigate the effect of 5-HTTLPR polymorphism and childhood trauma on BDNF levels. Early trauma were negatively associated with BDNF serum levels (higher CTQ scores, lower BDNF; p=0.0019). 5-HTTLPR l/l homozygotes showed significantly higher BDNF levels than 5-HTTLPR*s carriers (30.57±6.13 vs 26.82±6.41; p=0.0309). A separate-slopes analysis showed that 5-HTTLPR significantly influenced the relationship between early trauma and adult BDNF (interaction of 5-HTTLPR with CTQ scores: p=0.0023), due to a significant relationship between trauma and BDNF in 5-HTTLPR*s carriers, but not among l/l homozygotes. Putatively detrimental effects of childhood trauma exposure on adult BDNF serum levels are influenced by 5-HTTLPR genotype in patients affected by BD. Possible mechanisms include epigenetic modulation of BDNF gene expression, due to different reactivity to stressors in 5-HTTLPR genotype groups.

BNDF methylation in mothers and newborns is associated with maternal exposure to war trauma

BACKGROUND

The BDNF gene codes for brain-derived neurotrophic factor, a growth factor involved in neural development, cell differentiation, and synaptic plasticity. Present in both the brain and periphery, BDNF plays critical roles throughout the body and is essential for placental and fetal development. Rodent studies show that early life stress, including prenatal stress, broadly alters BDNF methylation, with presumed changes in gene expression. No studies have assessed prenatal exposure to maternal traumatic stress and BDNF methylation in humans. This study examined associations of prenatal exposure to maternal stress and BDNF methylation at CpG sites across the BDNF gene.

RESULTS

Among 24 mothers and newborns in the eastern Democratic Republic of Congo, a region with extreme conflict and violence to women, maternal experiences of war trauma and chronic stress were associated with BDNF methylation in umbilical cord blood, placental tissue, and maternal venous blood. Associations of maternal stress and BDNF methylation showed high tissue specificity. The majority of significant associations were observed in putative transcription factor binding regions.

CONCLUSIONS

This is the first study in humans to examine BDNF methylation in relation to prenatal exposure to maternal stress in three tissues simultaneously and the first in any mammalian species to report associations of prenatal stress and BDNF methylation in placental tissue. The findings add to the growing body of evidence highlighting the importance of considering epigenetic effects when examining the impacts of trauma and stress, not only for adults but also for offspring exposed via effects transmitted before birth.

BDNF as a possible modulator of EEG oscillatory response at the parietal cortex during visuo-tactile integration processes using a rubber hand

Multisensory integration of visuo-tactile information presented on the body or a dummy body has a strong impact on body image. Previous researches show that alteration of body image induced by visuo-tactile integration is closely related to the activation of the parietal cortex, a sensory association area. The expression of brain-derived neurotrophic factor (BDNF) in the parietal area of macaque monkeys is thought to modulate the activation of the parietal cortex and alter the extension of body image during tool-use learning. However, the relationship between parietal cortex activation related to body image alterations and BDNF levels in humans remains unclear. We investigated the relationship between human serum BDNF levels and electroencephalography responses during a visuo-tactile integration task involving a rubber hand. We found cortical oscillatory components in the high frequency (gamma) band in the left parietal cortex. Moreover, the power values of these oscillations were positively correlated (p<0.05) with serum BDNF levels. Our results suggest that serum BDNF could play a role in modulating the cortical activity in response to visuo-tactile integration processes related to body image alteration in humans.

Yoga, Meditation and Mind-Body Health: Increased BDNF, Cortisol Awakening Response, and Altered Inflammatory Marker Expression after a 3-Month Yoga and Meditation Retreat

Thirty-eight individuals (mean age: 34.8 years old) participating in a 3-month yoga and meditation retreat were assessed before and after the intervention for psychometric measures, brain derived neurotrophic factor (BDNF), circadian salivary cortisol levels, and pro- and anti-inflammatory cytokines. Participation in the retreat was found to be associated with decreases in self-reported anxiety and depression as well as increases in mindfulness. As hypothesized, increases in the plasma levels of BDNF and increases in the magnitude of the cortisol awakening response (CAR) were also observed. The normalized change in BDNF levels was inversely correlated with BSI-18 anxiety scores at both the pre-retreat (r = 0.40, p < 0.05) and post-retreat (r = 0.52, p < 0.005) such that those with greater anxiety scores tended to exhibit smaller pre- to post-retreat increases in plasma BDNF levels. In line with a hypothesized decrease in inflammatory processes resulting from the yoga and meditation practices, we found that the plasma level of the anti-inflammatory cytokine Interleukin-10 was increased and the pro-inflammatory cytokine Interleukin-12 was reduced after the retreat. Contrary to our initial hypotheses, plasma levels of other pro-inflammatory cytokines, including Interferon Gamma (IFN-γ), Tumor Necrosis Factor (TNF-α), Interleukin-1β (IL-1β), Interleukin-6 (IL-6), and Interleukin-8 (IL-8) were increased after the retreat. Given evidence from previous studies of the positive effects of meditative practices on mental fitness, autonomic homeostasis and inflammatory status, we hypothesize that these findings are related to the meditative practices throughout the retreat; however, some of the observed changes may also be related to other aspects of the retreat such as physical exercise-related components of the yoga practice and diet. We hypothesize that the patterns of change observed here reflect mind-body integration and well-being. The increased BDNF levels observed is a potential mediator between meditative practices and brain health, the increased CAR is likely a reflection of increased dynamic physiological arousal, and the relationship of the dual enhancement of pro- and anti-inflammatory cytokine changes to healthy immunologic functioning is discussed.

The effect of acute exercise on blood concentrations of brain-derived neurotrophic factor in healthy adults: a meta-analysis

It has been hypothesized that one mechanism through which physical activity provides benefits to cognition and mood is via increasing brain-derived neurotrophic factor (BDNF) concentrations. Some studies have reported immediate benefits to mood and various cognitive domains after a single session of exercise. This meta-analysis sought to determine the effect of a single exercise session on concentrations of BDNF in peripheral blood, in order to evaluate the potential role of BDNF in mediating the beneficial effects of exercise on brain health. MEDLINE, Embase, PsycINFO, SPORTDiscus, Rehabilitation & Sports Medicine Source, and CINAHL databases were searched for original, peer-reviewed reports of peripheral blood BDNF concentrations before and after acute exercise interventions. Risk of bias within studies was assessed using standardized criteria. Standardized mean differences (SMDs) were generated from random effects models. Risk of publication bias was assessed using a funnel plot and Egger's test. Potential sources of heterogeneity were explored in subgroup analyses. In 55 studies that met inclusion criteria, concentrations of peripheral blood BDNF were higher after exercise (SMD = 0.59, 95% CI: 0.46-0.72, P < 0.001). In meta-regression analysis, greater duration of exercise was associated with greater increases in BDNF. Subgroup analyses revealed an effect in males but not in females, and a greater BDNF increase in plasma than serum. Acute exercise increased BDNF concentrations in the peripheral blood of healthy adults. This effect was influenced by exercise duration and may be different across genders.

Increased serum brain-derived neurotrophic factor in male schizophrenic patients with metabolic syndrome

Increased prevalence of metabolic syndrome was found in patients with schizophrenia. Brain-derived neurotrophic factor (BDNF) was involved in energy metabolism and the pathophysiology of schizophrenia, but differently in males and females. We aimed to investigate the serum BDNF levels in patients with schizophrenia with and without metabolic syndrome.Patients with schizophrenia were recruited. Their demographic data were collected. Metabolic profiles and serum BDNF levels were measured. Clinical symptoms were evaluated with Positive and Negative Syndrome Scale. Metabolic syndrome was determined with the criteria provided by Ministry of Health and Welfare of Taiwan. Framingham Risk Score (FRS) for estimate of 10-year risk for coronary heart disease was provided by National Institutes of Health.Of the 81 participants, 40.7% had metabolic syndrome. Those with metabolic syndrome had higher FRS. Using analysis of covariance adjusted for age and body mass index, male patients with schizophrenia with metabolic syndrome had higher serum BDNF levels than those without (4.6 ± 4.7 vs 3.3 ± 3.8 ng/mL, P = .022). No statistical difference was found between female patients with and without metabolic syndrome.Significant differences of serum BDNF levels were found between male patients with schizophrenia with and without metabolic syndrome, but not in females. This finding suggested the gender difference behind the mechanism of BDNF in metabolic syndrome in schizophrenia.

Associations between social relationship measures, serum brain-derived neurotrophic factor, and risk of stroke and dementia

INTRODUCTION

Mechanisms underlying social determinants of stroke and dementia are unclear and brain-derived neurotrophic factor (BDNF) may contribute as a molecular link.

METHODS

Using the Framingham Study, we examined social relationship measures as predictors of higher serum BDNF level and cumulative incidence of stroke and dementia.

RESULTS

Among 3294 participants, controlling for age and sex, isolation trended with lower BDNF (odds ratio = 0.69 [0.47-1.00]). Participants with more companionship had reduced risk for stroke (hazard ratio [HR] = 0.59 [0.41-0.83]) and dementia (HR = 0.67 [0.49-0.92]). Greater emotional support was associated with higher BDNF (odds ratio = 1.27 [1.04-1.54]), reduced dementia risk (HR = 0.69 [0.51-0.94], and among smokers, reduced stroke risk (HR = 0.23 [0.10-0.57]). Associations persisted after additional adjustments. BDNF partly mediated the total effect between emotional support and dementia risk.

CONCLUSIONS

Availability of social support appears to be associated with increased BDNF levels and, in certain subsets, reduce risk of subsequent dementia and stroke, thus warranting study of these pathways to understand their role in neuroprotection.

The interrelationship of metabolic syndrome and neurodegenerative diseases with focus on brain-derived neurotrophic factor (BDNF): Kill two birds with one stone

The brain-derived neurotrophic factor (BDNF) is involved in metabolic syndrome (MetS) and neurodegenerative diseases (NDD) like Alzheimer's disease, Huntington's disease, Parkinson's disease and depression. If one factor plays an essential role in the pathogenesis of two diseases, it can be concluded that there might be a common root in these two diseases, as well. This review was aimed to highlight the crucial roles of BDNF in the pathogenesis of MetS and NDD and to introduce sole prophylactic or therapeutic applications, BDNF gene therapy and BDFN administration, in controlling MetS and NDD.

Kidney–brain axis inflammatory cross-talk: from bench to bedside

Epidemiologic data suggest that individuals at all stages of chronic kidney disease (CKD) have a higher risk of developing neuropsychiatric disorders, cognitive impairment, and dementia. This risk is generally explained by the high prevalence of both symptomatic and subclinical ischemic cerebrovascular lesions. However, other potential mechanisms, including cytokine/chemokine release, production of reactive oxygen species (ROS), circulating and local formation of trophic factors and of renin–angiotensin system (RAS) molecules, could also be involved, especially in the absence of obvious cerebrovascular disease. In this review, we discuss experimental and clinical evidence for the role of these mechanisms in kidney–brain cross-talk. In addition, we hypothesize potential pathways for the interactions between kidney and brain and their pathophysiological role in neuropsychiatric and cognitive changes found in patients with CKD. Understanding the pathophysiologic interactions between renal impairment and brain function is important in order to minimize the risk for future cognitive impairment and to develop new strategies for innovative pharmacological treatment.

Determinants of Blood Brain-Derived Neurotrophic Factor Blood Levels in Patients with Alcohol Use Disorder

BACKGROUND

Blood brain-derived neurotrophic factor (BDNF) levels are influenced by both addiction and mood disorders, as well as somatic conditions, gender, and genetic polymorphisms, leading to widely varying results. Depressive symptoms and episodes are frequently observed in patients with alcohol use disorder, and vary widely over time, making it a challenge to determine which aspects are specifically involved in variations of serum BDNF levels in this population.

METHODS

We assessed 227 patients with alcohol dependence involved in a detoxification program, at baseline and after a follow-up of 6 months, for the Alcohol Use Disorders Identification Test score, the length of alcohol dependence, and the number of past detoxification programs. The Beck Depression Inventory and information on current tobacco and alcohol use, suicidal ideation, body mass index, age, gender, and psychotropic treatments were also collected. Serum BDNF (ELISA) and 2 genetic polymorphisms of the BDNF gene (Val33Met and rs962369) were analyzed.

RESULTS

The presence of the Met allele, 2 markers of the history of alcohol dependence (gamma glutamyl transferase and the number of past treatments in detoxification programs), and the presence of a depressive episode (but not depressive score) were significantly associated with the 2 blood levels of BDNF at baseline and after 6 months. After controlling for baseline BDNF levels, the presence of the Met allele and an ongoing depressive episode were the only variables associated with changes in BNDF levels after 6 months.

CONCLUSIONS

Low serum BDNF levels are associated with characteristics related to alcohol consumption and mood disorders, and variants of the BDNF gene in alcohol use disorder patients. The factors that most strongly influenced changes in serum BDNF levels following treatment in an alcohol detoxification program were variants of the BDNF gene and ongoing depression.

Longitudinal assessment of brain-derived neurotrophic factor in Sardinian psychotic patients (LABSP): a protocol for a prospective observational study

INTRODUCTION

Brain-derived neurotrophic factor (BDNF) plays a crucial role in neurodevelopment, synaptic plasticity and neuronal function and survival. Serum and plasma BDNF levels are moderately, but consistently, decreased in patients with schizophrenia (SCZ) compared with healthy controls. There is a lack of knowledge, however, on the temporal manifestation of this decline. Clinical, illness course and treatment factors might influence the variation of BDNF serum levels in patients with psychosis. In this context, we propose a longitudinal study of a cohort of SCZ and schizophrenic and schizoaffective disorder (SAD) Sardinian patients with the aim of disentangling the relationship between peripheral BDNF serum levels and changes of psychopathology, cognition and drug treatments.

METHODS AND ANALYSIS

Longitudinal assessment of BDNF in Sardinian psychotic patients (LABSP) is a 24-month observational prospective cohort study. Patients with SAD will be recruited at the Psychiatry Research Unit of the Department of Medical Science and Public Health, University of Cagliari and University of Cagliari Health Agency, Cagliari, Italy. We will collect BDNF serum levels as well as sociodemographic, psychopathological and neurocognitive measures. Structured, semistructured and self-rating assessment tools, such as the Positive and Negative Syndrome Scale for psychopathological measures and the Brief Assessment of Cognition in Schizophrenia for cognitive function, will be used.

ETHICS AND DISSEMINATION

This study protocol was approved by the University of Cagliari Health Agency Ethics Committee (NP2016/5491). The study will be conducted in accordance with the principles of good clinical practice, in the Declaration of Helsinki in compliance with the regulations. Participation will be voluntary and written informed consent will be obtained for each participant upon entry into the study. We plan to disseminate the results of our study through conference presentations and publication in international peer-reviewed journals. Access to raw data will be available in anonymised form upon request to the corresponding author.

Neuroprotective Effects of Physical Activity: Evidence from Human and Animal Studies

In the present article, we provide a review of current knowledge regarding the role played by physical activity (PA) in preventing age-related cognitive decline and reducing risk of dementia. The cognitive benefits of PA are highlighted by epidemiological, neuroimaging and behavioral studies. Epidemiological studies identified PA as an influential lifestyle factor in predicting rates of cognitive decline. Individuals physically active from midlife show a reduced later risk of cognitive impairment. Neuroimaging studies documented attenuation of age-related brain atrophy, and also increase of gray matter and white matter of brain areas, including frontal and temporal lobes. These structural changes are often associated with improved cognitive performance. Importantly, the brain regions that benefit from PA are also those regions that are often reported to be severely affected in dementia. Animal model studies provided significant information about biomechanisms that support exercise-enhanced neuroplasticity, such as angiogenesis and upregulation of growth factors. Among the growth factors, the brain-derived neurotrophic factor seems to play a significant role. Another putative factor that might contribute to beneficial effects of exercise is the neuropeptide orexin-A. The beneficial effects of PA may represent an important resource to hinder the cognitive decline associated with aging.

The positive cognitive impact of aerobic fitness is associated with peripheral inflammatory and brain-derived neurotrophic biomarkers in young adults

There is ample evidence for supporting the positive impact of aerobic fitness on cognitive function, but little is known about the physiological mechanisms. The objective of this study was to investigate whether the positive cognitive impact of aerobic fitness is associated with inflammatory and neurotrophic peripheral biomarkers in young adults aged 18 to 29years (n=87). For the objective assessment of aerobic fitness, we measured maximal oxygen uptake (VO₂max) as a parametric measure of cardiorespiratory capacity. We demonstrated that young adults with the higher levels of VO₂max performed better on computerized cognitive tasks assessing sustained attention and working memory. This positive VO₂max-cognitive performance association existed independently of confounders (e.g., years of education, intelligence scores) but was significantly dependent on resting peripheral blood levels of inflammatory (C-reactive protein, CRP) and neurotrophic (brain-derived neurotrophic factor, BDNF) biomarkers. Statistical models showed that CRP was a mediator of the effect of VO₂max on working memory. Further, BDNF was a moderator of the effect of VO₂max on working memory. These mediating and moderating effects occurred in individuals with higher levels of aerobic fitness. The results suggest that higher aerobic fitness, as measured by VO₂max, is associated with enhanced cognitive functioning and favorable resting peripheral levels of inflammatory and brain-derived neurotrophic biomarkers in young adults.

Plasma but not serum brain-derived neurotrophic factor concentration is decreased by oral glucose tolerance test-induced hyperglycemia in children

BACKGROUND

Little is known regarding the relationships among circulating brain-derived neurotrophic factor (BDNF) levels and glucose or insulin in children and adolescents. The objective of this study was to investigate whether circulating BDNF levels would change during the oral glucose tolerance test (OGTT).

METHODS

We performed the OGTT and measured the serial changes in BDNF levels in both plasma and serum.

RESULTS

There were 22 subjects in the normal type (N) group and 20 in the borderline/diabetic type (B/D) group, defined by the results of the OGTT. Serum levels of BDNF were almost five times higher and plasma levels gradually decreased during the OGTT, whereas serum levels showed no significant change. The reduction of plasma BDNF level changes from baseline to 120 min were significantly different between the N and B/D groups (36.3% vs. 20.8%, p=0.023).

CONCLUSIONS

Our results showed that plasma levels of BDNF are more sensitive to acute changes in glucose or insulin levels than serum.

Supplementation of docosahexaenoic acid (DHA), vitamin D3 and uridine in combination with six weeks of cognitive and motor training in prepubescent children: a pilot study

Background

Learning and memory have been shown to be influenced by combination of dietary supplements and exercise in animal models, but there is little available evidence from human subjects. The aim of this pilot study was to investigate the effect of combining a motor- and cognitive exercise program with dietary supplementation consisting of 500 mg docosahexaenoic acid (DHA), 10 μg vitamin D₃ and 1000 mg uridine (DDU-supplement) in 16 prepubescent children (age 8–11 years).

Methods

We designed a randomized, placebo-controlled, double-blinded study lasting 6 weeks in which DDU-supplement or placebo was ingested daily. During the intervention period, all children trained approximately 30 min 3 days/week using an internet-based cognitive and motor training program (Mitii). Prior to and post the intervention period dietary record, blood sampling, physical exercise tests and motor and cognitive tests were performed.

Results

Fourteen of the 16 children completed the intervention and ingested the supplement as required. 6 weeks DDU-supplementation resulted in a significant increase in the blood concentration of vitamin D₂₊₃ and DHA (p = 0.023 and p < 0.001, respectively). Power calculation based on one of the cognitive tasks revealed a proper sample size of 26 children.

Conclusion

All children showed improved performance in the trained motor- and cognitive tasks, but it was not possible to demonstrate any significant effects on the cognitive tests from the dietary supplementation. However, DDU-supplementation did result in increased blood concentration of DHA and vitamin D₂₊₃.

Trial registration

Clinical registration ID: NCT02426554 (clinical Trial.gov). January 2015 retrospectively registered.

Theranostic Biomarkers for Schizophrenia

Schizophrenia is a highly heritable, chronic, severe, disabling neurodevelopmental brain disorder with a heterogeneous genetic and neurobiological background, which is still poorly understood. To allow better diagnostic procedures and therapeutic strategies in schizophrenia patients, use of easy accessible biomarkers is suggested. The most frequently used biomarkers in schizophrenia are those associated with the neuroimmune and neuroendocrine system, metabolism, different neurotransmitter systems and neurotrophic factors. However, there are still no validated and reliable biomarkers in clinical use for schizophrenia. This review will address potential biomarkers in schizophrenia. It will discuss biomarkers in schizophrenia and propose the use of specific blood-based panels that will include a set of markers associated with immune processes, metabolic disorders, and neuroendocrine/neurotrophin/neurotransmitter alterations. The combination of different markers, or complex multi-marker panels, might help in the discrimination of patients with different underlying pathologies and in the better classification of the more homogenous groups. Therefore, the development of the diagnostic, prognostic and theranostic biomarkers is an urgent and an unmet need in psychiatry, with the aim of improving diagnosis, therapy monitoring, prediction of treatment outcome and focus on the personal medicine approach in order to improve the quality of life in patients with schizophrenia and decrease health costs worldwide.

Intense resistance exercise increases peripheral brain-derived neurotrophic factor

OBJECTIVES

Brain-derived neurotrophic factor (BDNF) has been shown to increase in an intensity dependent manner in response to aerobic exercise. However, previous research investigating the use of resistance exercise to increase BDNF levels has been less conclusive, likely due to the low intensity nature of traditional resistance exercise programs. This study examined the influence of acute resistance exercise to-fatigue on serum BDNF levels and blood lactate.

DESIGN

Acute crossover study.

METHODS

Eleven untrained to intermediately trained males (age: 25.0±1.3 year) and five untrained females (age: 23.2±1.1 year) were recruited to undertake two bouts of resistance exercise. Strength (five sets of five repetitions, 180s recovery) and hypertrophy (three sets of ten repetitions, 60s recovery) based resistance exercise was implemented to-fatigue to examine the effect on serum BDNF and blood lactate levels immediately post-, and 30min post-exercise.

RESULTS

An interaction (p<0.01; ES=0.52) was observed between conditions immediately post-exercise, with hypertrophy resulting in significantly greater BDNF levels when compared with strength exercise. Changes in lactate and BDNF from baseline to post- exercise were positively correlated following hypertrophy exercise (r=0.70; p<0.01), but not correlated following strength exercise (r=0.18; p=0.56).

CONCLUSIONS

The use of a to-fatigue hypertrophy based resistance exercise protocol provides the necessary stimulus to increase peripheral serum BDNF. Mechanistically, the presence of lactate does not appear to drive the BDNF response during resistance exercise.

The role of brain-derived neurotrophic factor and its single nucleotide polymorphisms in stroke patients

Stroke is the main cause of motoric and neuropsychological disability in adults. Recent advances in research into the role of the brain-derived neurotrophic factor in neuroplasticity, neuroprotection and neurogenesis might provide important information for the development of new poststroke-rehabilitation strategies. It plays a role as a mediator in motor learning and rehabilitation after stroke. Concentrations of BDNF are lower in acute ischemic-stroke patients compared to controls. Lower levels of BDNF are correlated with an increased risk of stroke, worse functional outcomes and higher mortality. BDNF signalling is dependent on the genetic variation which could affect an individual's response to recovery after stroke. Several single nucleotide polymorphisms of the BDNF gene have been studied with regard to stroke patients, but most papers analyse the rs6265 which results in a change from valine to methionine in the precursor protein. Subsequently a reduction in BDNF activity is observed. There are studies indicating the role of this polymorphism in brain plasticity, functional and morphological changes in the brain. It may affect the risk of ischemic stroke, post-stroke outcomes and the efficacy of the rehabilitation process within physical exercise and transcranial magnetic stimulation. There is a consistent trend of Met alleles' being connected with worse outcomes and prognoses after stroke. However, there is no satisfactory data confirming the importance of Met allele in stroke epidemiology and the post-stroke rehabilitation process. We present the current data on the role of BDNF and polymorphisms of the BDNF gene in stroke patients, concentrating on human studies.

Burnout and cognitive impairment: Associated with serum BDNF in a Chinese Han population

BACKGROUND

Some studies have demonstrated that subjects with chronic burnout showed cognitive impairments; however, cognitive performance in burnout has been under-investigated. Increasing evidence show that brain-derived neurotrophic factor (BDNF) plays a critical role in cognitive function. We hypothesized that decreased BDNF may be associated with cognitive impairments in burnout, which has not been investigated yet. The aim of the present study was to examine the association of BDNF with cognitive impairment in burnout.

METHOD

Using a cross-sectional design, 712 healthy subjects were recruited from a general hospital and they were all measured with the Maslach Burnout Inventory (MBI). We assessed part of subjects on the repeatable battery for the assessment of neuropsychological status (RBANS) (n=192) and serum BDNF levels (n=127).

RESULTS

30.5% of the subjects had burnout. Compared to those non-burnout subjects, the burnout subjects were younger, had significant lower BDNF levels (p=0.003) and scored lower on immediate memory, RBANS total score and attention (all p<0.05). Interestingly, after the Bonferroni correction, there were negative correlations between BDNF and MBI total score or reduced professional accomplishment (PA). Moreover, BDNF was positively associated with immediate memory, attention and RBANS total score. Further multiple regression analysis showed that BDNF was an independent contributor to the RBANS total score and attention, and BDNF and MBI depersonalization (DP) were independent contributors to immediate memory. In addition, there was mediating effect of BDNF in the relation between burnout and cognitive impairments.

CONCLUSIONS

Our results suggest that burnout is associated with significant cognitive impairments and decreased BDNF. Moreover, decreased BDNF is associated with cognitive impairments in burnout.

Serum brain-derived neurotrophic factor, glial-derived neurotrophic factor, nerve growth factor, and neurotrophin-3 levels in children with attention-deficit/hyperactivity disorder

It has been suggested that neurotrophins are involved in the etiopathogenesis of attention-deficit/hyperactivity disorder (ADHD). This study aimed to investigate whether there are differences in serum brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF), nerve growth factor (NGF), and neurotrophin-3 (NTF3) levels between children with ADHD and healthy controls. A total of 110 treatment-naive children with the combined presentation of ADHD and 44 healthy controls aged 8-18 years were enrolled in this study. The severity of ADHD symptoms was determined by scores on the Conners' Parent Rating Scale-Revised Short and Conners' Teacher Rating Scale-Revised Short. The severity of depression and anxiety symptoms of the children were evaluated by the self-report inventories. Serum levels of neurotrophins were measured using commercial enzyme-linked immunosorbent assay kits. The multivariate analysis of covariance (MANCOVA) revealed a significant main effect of groups in the levels of serum neurotrophins, an effect that was independent of age, sex, and the severity of the depression and anxiety. The analysis of covariance (ANCOVA) indicated that the mean serum GDNF and NTF3 levels of ADHD patients were significantly higher than that of controls. However, serum BDNF and NGF levels did not show any significant differences between groups. No correlations between the levels of serum neurotrophins and the severity of ADHD were observed. These results suggest that elevated serum GDNF and NTF3 levels may be related to ADHD in children.

Female gender and gastrointestinal symptoms, not brain-derived neurotrophic factor, are associated with depression and anxiety in cirrhosis

AIM

Cirrhosis places a substantial burden on the psychological status of affected individuals. The aim of our study was to identify the associated factors of psychological distress in cirrhosis.

METHODS

A total of 208 patients with cirrhosis were recruited. Each patient received validated questionnaires to assess gastrointestinal (GI) symptoms, depression, and anxiety. Serum brain-derived neurotrophic factor (BDNF) levels were measured by enzyme-linked immunosorbent assay.

RESULTS

A total of 16.35% of patients (n = 34) were diagnosed with depression and 10.58% (n = 22) with anxiety. The percentages of female patients among those diagnosed with depression and anxiety were 58.8% and 77.3%, respectively, which were significantly higher than that in non-depressed (35.1%) and non-anxious patients (34.4%). The patients who showed more GI symptoms had higher depression and anxiety scores. The GI symptom scores of patients with depression and anxiety were 4 (2.75, 7) and 4 (2.75, 7.25), respectively, which were significantly higher than that of patients without depression (2 [0, 4]) and anxiety (2 [1, 4]). Significantly higher depression and anxiety scores were detected in patients who suffered from abdominal bloating, belching, anorexia, abdominal pain, nausea/vomiting, and constipation. Cirrhotic patients had higher serum levels of BDNF than healthy controls (159.33 [96.64, 243.30] pg/mL vs. 70.74 [56.58, 93.52] pg/mL). In the cirrhosis group, there was no significant difference in BDNF levels between depressed and non-depressed patients. Multiple linear regression analysis revealed that depression and anxiety were each independently associated with female gender and GI symptom scores.

CONCLUSIONS

Female gender and GI symptoms are closely associated with depression and anxiety in cirrhosis. There is no significant correlation between BDNF level and psychological distress in cirrhosis.

Serum brain-derived neurotrophic factor and stability of depressive symptoms in coronary heart disease patients: A prospective study

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) supports neurogenesis, angiogenesis, and promotes the survival of various cell types in the brain and the coronary system. Moreover, BDNF is associated with both coronary heart disease (CHD) and depression. The current study aims to investigate whether serum BDNF levels are associated with the course of depressive symptoms in CHD patients.

METHODS

At baseline, N=225 CHD patients were enrolled while hospitalized. Of these, N=190 (84%) could be followed up 6 months later. Depressive symptoms were assessed both at baseline and at the 6-months follow-up using the Patient Health Questionnaire (PHQ-9). Serum BDNF concentrations were measured using fluorometric Enzyme-linked immunosorbent assays (ELISA).

RESULTS

Logistic regression models showed that lower BDNF levels were associated with persistent depressive symptoms, even after adjustment for age, sex, smoking and potential medical confounders. The incidence of depressive symptoms was not related to lower BDNF levels. However, somatic comorbidity (as measured by the Charlson Comorbidity Index) was significantly associated with the incidence of depressive symptoms.

CONCLUSIONS

Our findings suggest a role of BDNF in the link between CHD and depressive symptoms. Particularly, low serum BDNF levels could be considered as a valuable biomarker for the persistence of depressive symptoms among depressed CHD patients.

Meta-analyses of comparative efficacy of antidepressant medications on peripheral BDNF concentration in patients with depression

Background

Brain derived neurotrophic factor (BDNF) is one of the most important regulatory proteins in the pathophysiology of major depressive disorder (MDD). Increasing numbers of studies have reported the relationship between serum/plasma BDNF and antidepressants (ADs). However, the potential effects of several classes of antidepressants on BDNF concentrations are not well known. Hence, our meta-analyses aims to review the effects of differential antidepressant drugs on peripheral BDNF levels in MDD and make some recommendations for future research.

Methods

Electronic databases including PubMed, EMBASE, the Cochrane Library, Web of Science, and PsycINFO were searched from 1980 to June 2016. The change in BDNF levels were compared between baseline and post-antidepressants treatment by use of the standardized mean difference (SMD) with 95% confidence intervals (CIs). All statistical tests were two-sided.

Results

We identified 20 eligible trials of antidepressants treatments for BDNF in MDD. The overall effect size for all drug classes showed that BDNF levels were elevated following a course of antidepressants use. For between-study heterogeneity by stratification analyses, we detect that length of treatment and blood samples are significant effect modifiers for BDNF levels during antidepressants treatment. While both SSRIs and SNRIs could increase the BDNF levels after a period of antidepressant medication treatment, sertraline was superior to other three drugs (venlafaxine, paroxetine or escitalopram) in the early increase of BDNF concentrations with SMD 0.53(95% CI = 0.13–0.93; P = 0.009).

Conclusions

There is some evidence that treatment of antidepressants appears to be effective in the increase of peripheral BDNF levels. More robust evidence indicates that different types of antidepressants appear to induce differential effects on the BDNF levels. Since sertraline makes a particular effect on BDNF concentration within a short amount of time, there is potential value in exploring its relationship with BDNF and its pharmacological mechanism concerning peripheral blood BDNF. Further confirmatory trials are required for both observations.

Circadian Rhythms in Plasma Brain-derived Neurotrophic Factor Differ in Men and Women

The measurement of circulating levels of brain-derived neurotrophic factor (BDNF) has been proposed to be a marker of disease and an indicator of recovery. Thus, knowing the temporal pattern and influence of potential circadian rhythms is important. Although several studies have measured BDNF at different times of day, no studies have done so while controlling for potential masking influences such as sleep and activity. Further, no previous study has examined circadian rhythms within individuals. We examined circadian rhythms in plasma BDNF while minimizing masking from behavioral and environmental factors using a 30-h constant routine (CR) protocol. In a sample of 39 healthy adults, we found significant circadian rhythms in 75% of women and 52% of men. The timing of the acrophase of the BDNF rhythm, however, was unrelated to clock time in women, while it was related to clock time in men. These results indicate that the use of single-sample measures of plasma BDNF as a marker of disease will be unreliable, especially in women. Repeated plasma BDNF samples over a 24-h period within individuals would be needed to reveal abnormalities related to disease states.

Plasma Brain-Derived Neurotrophic Factor and Psychopathology in Attempted Suicide

BACKGROUND/AIMS

Increasing evidence suggests a link between brain-derived neurotrophic factor (BDNF) and suicidal behaviour (SB). Furthermore, decreased peripheral BDNF levels have been associated with clinical symptoms in various psychiatric disorders as well as with personality dimensions in healthy individuals. However, the relationship between BDNF and psychopathology is poorly investigated regarding SB.

METHODS

Plasma BDNF concentrations were analysed in 61 recent suicide attempters. Clinical symptoms were evaluated using the Comprehensive Psychopathological Rating Scale. Personality dimensions were assessed using the Marke-Nyman Temperament Scale.

RESULTS

Plasma BDNF correlated positively and significantly with the personality dimension Solidity but not with the other personality dimensions or with clinical symptoms.

CONCLUSION

BDNF plays an important role in the regulation of neuroplasticity and neurogenesis in humans. Our results indicate that lower BDNF concentrations are associated with higher levels of impulsiveness and changeability (low scores on the Solidity scale). Furthermore, low plasma BDNF levels may be proposed as a trait marker rather than a state marker for attempted suicide.

The Association of Serum Levels of Brain-Derived Neurotrophic Factor with the Occurrence of and Recovery from Delirium in Older Medical Inpatients

Limited studies of the association between BDNF levels and delirium have given inconclusive results. This prospective, longitudinal study examined the relationship between BDNF levels and the occurrence of and recovery from delirium. Participants were assessed twice weekly using MoCA, DRS-R98, and APACHE II scales. BDNF levels were estimated using an ELISA method. Delirium was defined with DRS-R98 (score > 16) and recovery from delirium as ≥2 consecutive assessments without delirium prior to discharge. We identified no difference in BDNF levels between those with and without delirium. Excluding those who never developed delirium (n = 140), we examined the association of BDNF levels and other variables with delirium recovery. Of 58 who experienced delirium, 39 remained delirious while 19 recovered. Using Generalized Estimating Equations models we found that BDNF levels (Wald χ² = 7.155; df: 1, p = 0.007) and MoCA (Wald χ² = 4.933; df: 1, p = 0.026) were associated with recovery. No significant association was found for APACHE II, dementia, age, or gender. BDNF levels do not appear to be directly linked to the occurrence of delirium but recovery was less likely in those with continuously lower levels. No previous study has investigated the role of BDNF in delirium recovery and these findings warrant replication in other populations.

Brain-derived Neurotrophic Factor Is Associated With Disease Severity and Clinical Outcome in Ugandan Children Admitted to Hospital With Severe Malaria

BACKGROUND

Malaria remains a leading cause of childhood death and neurologic disability in sub-Saharan Africa. Here, we test the hypothesis that malaria-induced alterations to circulating brain-derived neurotrophic factor (BDNF) are associated with poor clinical outcomes in children with severe malaria.

METHODS

We quantified BDNF (by enzyme-linked immunosorbent assay) in plasma samples collected [at presentation (day 1), day 3 and day 14], during a prospective study of Ugandan children admitted to hospital with severe malaria (n = 179).

RESULTS

BDNF concentration at presentation (day 1) was lower in children with cerebral malaria (P < 0.01), coma (P < 0.01), Lambaréné Organ Dysfunction Score >1 (P < 0.05) and respiratory distress (P < 0.01). Higher BDNF concentration at presentation was associated with shorter time to coma recovery [hazard ratio = 1.655 (1.194-2.293); P = 0.002] and a reduced odds ratio of disability [0.50 (0.27-0.94); P = 0.047] and death [0.45 (0.22-0.92); P = 0.035]. BDNF concentration was lower on day 1 and increased in children surviving severe malaria (day 14; P < 0.0001).

CONCLUSIONS

Our findings provide the new evidence linking circulating BDNF with disease severity, coma recovery and clinical outcome in children with severe malaria.