Brain-Derived Neurotrophic Factor Predicts Mortality Risk in Older Women

Association between cognitive function and skeletal muscle in patients undergoing maintenance hemodialysis

Background

Patients on hemodialysis have a higher burden of cognitive impairment than individuals of the same age in the general population. Studies have found a link between cognition and skeletal muscle function. However, few studies have investigated these associations and the underlying mechanisms in patients on hemodialysis.

Methods

A total of 166 patients on hemodialysis were enrolled in this longitudinal study. Cognitive function was assessed by Montreal Cognitive Assessment (MoCA) scores. Skeletal muscle indicators were evaluated using Inbody S10. Plasma brain-derived neurotrophic factor (BDNF) concentrations were measured by enzyme-linked immunosorbent assay. The primary outcome was a change in the MoCA scores. A mediation analysis was performed to examine the indirect effect of skeletal muscle on cognitive decline through BDNF.

Results

Among the 166 patients, the average age was 49.9 ± 11.2 years. Of these patients with a median follow-up of 1,136 days, 133 participated in the study. We defined MoCA scores decreased by ≥2 points at 3 years from the baseline measurement as cognitive decline (CD). Compared to the cognitively unchanged group, patients with CD had significantly lower fat-free mass, soft lean mass, skeletal muscle mass, and skeletal muscle index (all P<0.05). After adjusting for potential confounders, skeletal muscle indicators were protective predictors of CD. A significant increase in plasma BDNF levels was observed in the CD group. Mediation analysis suggested that BDNF played a mediating role of 20-35% between cognitive impairment and skeletal muscle.

Conclusion

Skeletal muscle is a protective predictor of CD in patients undergoing dialysis. BDNF mediates the relationship between cognitive impairment and skeletal muscle function.

The intriguing role of platelets as custodians of brain-derived neurotrophic factor

A State of the Art lecture titled "Platelets and neurotrophins" was presented at the International Society on Thrombosis and Haemostasis Congress in 2023. Neurotrophins, a family of neuronal growth factors known to support cognitive function, are increasingly recognized as important players in vascular health. Indeed, along with their canonical receptors, neurotrophins are expressed in peripheral tissues, particularly in the vasculature. The better-characterized neurotrophin in vascular biology is the brain-derived neurotrophic factor (BDNF). Its largest extracerebral pool resides within platelets, partly inherited from megakaryocytes and also likely internalized from circulation. Activation of platelets releases vast amounts of BDNF into their milieu and interestingly leads to platelet aggregation through binding of its receptor, the tropomyosin-related kinase B, on the platelet surface. As BDNF is readily available in plasma, a mechanism to preclude excessive platelet activation and aggregation appears critical. As such, binding of BDNF to α2-macroglobulin hinders its ability to bind its receptor and limits its platelet-activating effects to the site of vascular injury. Altogether, addition of BDNF to a forming clot facilitates not only paracrine platelet activation but also binding to fibrinogen, rendering the resulting clot more porous and plasma-permeable. Importantly, release of BDNF into circulation also appears to be protective against adverse cardiovascular and cerebrovascular outcomes, which has been reported in both animal models and epidemiologic studies. This opens an avenue for platelet-based strategies to deliver BDNF to vascular lesions and facilitate wound healing through its regenerative properties. Finally, we summarize relevant new data on this topic presented during the 2023 International Society on Thrombosis and Haemostasis Congress.

Impact of low-dose Brain-Derived Neurotrophic Factor (BDNF) on atrial fibrillation recurrence

BACKGROUND

Atrial fibrillation is the most common arrhythmia worldwide and is associated with significant morbidity and mortality. Despite the effectiveness of catheter-based ablation, periprocedural complication and recurrences remain a concern. In this context, we aim to appraise the potential impact of brain-derived neurotrophic factor (BDNF) on reducing episodes of paroxysmal atrial fibrillation (PAF).

METHODS

22 patients with an established diagnosis of PAF and without structural heart disease were considered. Every patient received 20 drops of GUNA-BDNF administered in the morning. During the 24 months of follow-up, the arrhythmic burden was measured by the average monthly duration of PAF episodes.

RESULTS

At the end of the follow-up period (24 months), data from 22 patients, of whom 17 men and five women, were analyzed. The arrhythmic burden, measured in terms of average monthly duration of PAF episodes, was found significantly reduced after the administration of low dose BDNF (9.5 vs. 65.3 minutes per month, P<0.001). A total of 17 out of 22 patients saw their arrhythmic burden eliminated or consistently reduced, furthermore two patients underwent a drastic reduction of the average monthly duration of AF (more than 200 minutes compared to the baseline). Only four patients, despite the administration of BDNF, still experienced an arrhythmic burden of 20 minutes or more. Considering the age groups, the major reduction was observed in people aged 70 or more, who were also the most represented in the sample. These results are coherent with the poor literature currently available.

CONCLUSIONS

BDNF low dose therapy has shown to have an impacting role in reducing the arrhythmic burden and recurrences of AF, with a particular effectiveness in patients over 70 and without structural heart disease. We should welcome this work, despite it limitations. Further clinical and molecular studies are needed before-considering BDNF low dose as a tool against PAF.

Probiotics supplementation and brain-derived neurotrophic factor (BDNF): a systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIMS

An emerging body of evidence has demonstrated the beneficial effects of probiotics on various mental health conditions. In this systematic review and meta-analysis, we sought to examine the effects of probiotics supplementation on brain-derived neurotrophic factor (BDNF) in adults.

METHODS

PubMed, Scopus, ISI Web of Science, and the Cochrane Library were searched, from database inception to April 2021, for eligible randomized controlled trials (RCTs). We pooled mean differences and standard deviations from RCTs using random-effect models.

RESULTS

Overall, meta-analysis of 11 trials (n = 648 participants) showed no significant changes in serum level of BDNF following probiotics. However, subgroup analysis revealed that probiotics increased BDNF levels in individuals suffering from neurological disorders (n = 214 participants; WMD = 3.08 ng/mL, 95% CI: 1.83, 4.34; P = 0.001; I2 = 7.5%; P-heterogeneity 0.34), or depression (n = 268 participants; WMD = 0.77 ng/mL, 95% CI: 0.07, 1.47; P = 0.032; I2 = 88.4%; P-heterogeneity < 0.001). Furthermore, a significant increase in BDNF levels was found in studies that administered the mixture of Lactobacillus and Bifidobacterium genera, and were conducted in Asia .

CONCLUSION

Our main findings suggest that probiotics may be effective in elevating BDNF levels in patients with depression and neurological disorders, and a mixed of Lactobacillus and Bifidobacterium appear to show greater efficacy than the single genus supplement. The low quality of evidence reduces clinical advocacy, and indicates that more large-scale, high-quality, RCTs are needed to facilitate reliable conclusions.

Pathophysiological mechanisms explaining the association between low skeletal muscle mass and cognitive function

Low skeletal muscle mass is associated with cognitive impairment and dementia in older adults. This review describes the possible underlying pathophysiological mechanisms: systemic inflammation, insulin metabolism, protein metabolism, and mitochondrial function. We hypothesize that the central tenet in this pathophysiology is the dysfunctional myokine secretion consequent to minimal physical activity. Myokines, such as fibronectin type III domain containing 5/irisin and cathepsin B, are released by physically active muscle and cross the blood–brain barrier. These myokines upregulate local neurotrophin expression such as brain-derived neurotrophic factor (BDNF) in the brain microenvironment. BDNF exerts anti-inflammatory effects that may be responsible for neuroprotection. Altered myokine secretion due to physical inactivity exacerbates inflammation and impairs muscle glucose metabolism, potentially affecting the transport of insulin across the blood–brain barrier. Our working model also suggests other underlying mechanisms. A negative systemic protein balance, commonly observed in older adults, contributes to low skeletal muscle mass and may also reflect deficient protein metabolism in brain tissues. As a result of age-related loss in skeletal muscle mass, decrease in the abundance of mitochondria and detriments in their function lead to a decrease in tissue oxidative capacity. Dysfunctional mitochondria in skeletal muscle and brain result in the excessive production of reactive oxygen species, which drives tissue oxidative stress and further perpetuates the dysfunction in mitochondria. Both oxidative stress and accumulation of mitochondrial DNA mutations due to aging drive cellular senescence. A targeted approach in the pathophysiology of low muscle mass and cognition could be to restore myokine balance by physical activity.

Plasma levels of myokines and inflammatory markers are related with functional and respiratory performance in older adults with COPD and sarcopenia

This study investigated whether blood-based biomarkers were related to functional test performance and respiratory muscle strength in older adults with COPD and sarcopenia. The participants included in this cross-sectional study were from both sexes and sixty years or older. Based on clinical assessment, participants were categorized in COPD (n = 43) and non-COPD (NCOPD) (n = 43) groups. They were also assessed for body composition and muscular mass by dual-energy X-ray absorptiometry, using the relative skeletal muscle index for the diagnosis of sarcopenia. A series of functional tests, including short physical performance battery (SPPB), 6-minute walking test (6MWT), maximal inspiratory and expiratory pressures (MIP and MEP), were carried out. Plasma levels of myokines (Irisin and BDNF), and soluble TNF receptors (sTNFR1 and sTNFR2) were determined by ELISA. In the multivariate analysis, 6MWD was associated with age, COPD-related sarcopenia and BDNF (R² = 0.29; f² = 0.41). SPPB score was associated with COPD-related sarcopenia and sTNFR1 (R² = 0.25; f² = 0.33). MIP value was associated with sex, COPD-related sarcopenia, sTNFR2 and Irisin (R² = 0.24; f² = 0.31). Finally, MEP value was associated with sex COPD-related sarcopenia (R² = 0.18; f² = 0.22). Plasma levels of myokines and inflammatory markers are related with functional and respiratory performance in older adults with COPD and sarcopenia.

Efficacy of Whole-Body Vibration Training on Brain-Derived Neurotrophic Factor, Clinical and Functional Outcomes, and Quality of Life in Women with Fibromyalgia Syndrome: A Randomized Controlled Trial

This study aimed to investigate the efficacy of whole-body vibration training (WBVT) on blood brain-derived neurotrophic factor (BDNF) levels and determine the clinical and functional outcomes in patients with fibromyalgia syndrome (FMS). Thirty-two women with FMS were randomized into an intervention group (IG), receiving 6 weeks of WBVT, or a control group (CG) with no intervention. The outcomes at the baseline and follow-up in both groups included blood BDNF levels, sit-to-stand test (STS), 6-minute walk test (6MWT), Fibromyalgia Impact Questionnaire (FIQ), Pittsburgh Sleep Quality Index (PSQI), Beck Depression Inventory (BDI), and visual analogue scale (VAS). WBVT resulted in a group-by-time interaction effect. Thus, after the intervention time, the IG had increased blood BDNF levels (p=0.045), a higher number of repetitions on the STS test (p=0.011), and increased walking distance on the 6MWT (p=0.010), compared to CG. Moreover, there was a reduction in the scores of the FIQ (p=0.001), the PSQI (p=0.001), the BDI (p=0.017), and pain assessed using VAS (p=0.008) in IG. The results demonstrate that WBVT promotes an increase in blood BDNF levels, with concomitant improvement in lower limb muscle strength, aerobic capacity, clinical symptoms, and quality of life in women with FMS. This trial is registered with Brazilian Clinical Trials Registry (REBEC; RBR-38nbbx) (https://ensaiosclinicos.gov.br/rg/RBR-38nbbx).

Brain derived neurotrophic factor declines after complete curative resection in gastrointestinal cancer

Background

Brain derived neurotrophic factor (BDNF) is a neurotrophin involved in neural and metabolic diseases, but it is also one of the crucial factors in cancer development and metastases. In the current study, we investigated serum BDNF concentrations in patients that underwent surgical treatment for colorectal cancer or pancreatic cancer.

Methods

Serum BDNF concentrations were measured with standard enzyme-linked immunosorbent assays, before and on the third day after the operation, in 50 consecutive patients with colorectal cancer and 25 patients with pancreatic cancer (tumours in the head of pancreas). We compared pre- and postoperative BDNF levels, according to the subsequent TNM stage, histologic stage, lymph node involvement, neuro- or angio-invasion, and resection range.

Results

In the pancreatic cancer group, BDNF concentrations fell significantly postoperatively (p = 0.011). In patients that underwent resections, BDNF concentrations fell (p = 0.0098), but not in patients that did not undergo resections (i.e., laparotomy alone). There were significant pre- and postoperative differences in BDNF levels among patients with (p = 0.021) and without (p = 0.034) distant metastases. Significant reductions in BDNF were observed postoperatively in patients with small tumours (i.e., below the median size; p = 0.023), in patients with negative angio- or lymphatic invasion (p = 0.028, p = 0.011, respectively), and in patients with lymph node ratios above 0.17 (p = 0.043). In the colon cancer group, the serum BDNF concentrations significantly fell postoperatively in the entire group (p = 0.0076) and in subgroups of patients with or without resections (p = 0.034, p = 0.0179, respectively). Significant before-after differences were found in subgroups with angioinvasions (p = 0.050) and in those without neuroinvasions (p = 0.049). Considering the TNM stages, the postoperative BDNF concentration fell in groups with (p = 0.0218) and without (p = 0.034) distant metastases and in patients with tumours below the median size (p = 0.018).

Conclusion

Our results suggested that BDNF might play an important role in gastrointestinal cancer development. BDNF levels were correlated with tumour volume, and with neuro-, angio- and lymphatic invasions. In pancreatic cancer, BDNF concentrations varied according to the surgical procedure and they fell significantly after tumour resections. Thus, BDNF may serve as a potential marker of complete resections in underdiagnosed patients. However, this hypothesis requires further investigation. In contrast, no differences according to the procedure was made in patients with colon cancer.

Role of Adiponectin and Brain Derived Neurotrophic Factor in Metabolic Regulation Involved in Adiposity and Body Fat Browning

Obesity, characterized by excessive fat mass, has been emerging as a major global epidemic and contributes to the increased risk of morbidity around the world. Thus, the necessity to find effective therapy and specific regulatory mechanisms is increasing for controlling obesity. Lately, many researchers have been interested in the linkage between obesity and adipokines/myokines, particularly adiponectin and brain-derived neurotrophic factor (BDNF). However, the role of adiponectin and BDNF in adiposity has not been clearly defined yet. We examined the association of adiposity with adiponectin and BDNF through human study (observational study) with Korean women and in vitro experiments. In the human study, we found a negative relationship between adiposity and circulating adiponectins but irregular patterns in the relationship between adiposity and circulating BDNFs. In the in vitro study using 3T3-L1 adipocytes, adiponectin treatment strongly promoted adipocyte differentiation and the fat browning process, whereas BDNF treatment attenuated adipocyte differentiation and the fat browning process in differentiated adipocytes. Our results demonstrate that adiponectin and BDNF play an important role in regulating fat mass and the expression of fat-browning markers in different ways, and also suggest that circulating adiponectin may be used as an important monitoring index for obesity status.

Free Fatty Acids and Their Inflammatory Derivatives Affect BDNF in Stroke Patients

Objective

The neurotrophin brain-derived neurotrophic factor (BDNF) affects poststroke functional outcome, neurogenesis, neuroprotection, and neuroplasticity. Its level is related to the diet and nutritional status, and more specifically, it is free fatty acids (FFAs) and eicosanoids that can have an impact on the BDNF level. The aim of this study was to analyze the potential impact of FFAs and eicosanoids on the BDNF level in stroke patients. Material and Methods. Seventy-three ischemic stroke patients were prospectively enrolled in the study. Laboratory tests were performed in all subjects, including the levels of FFAs, eicosanoids, and BDNF. FFAs and inflammatory metabolites were determined by gas chromatography and liquid chromatography, while BDNF was evaluated by the immune-enzymatic method (ELISA).

Results

The plasma level of BDNF negatively correlated with C22:1n9 13 erucic acid, C18:3n3 linolenic acid (ALA), and lipoxin A4 15-epi-LxA4. A direct association was observed in relation to BDNF and C16:1 palmitoleic acid and C20:3n6 eicosatrienoic acid (dihomo-gamma-linolenic acid (DGLA)).

Conclusions

Saturated fatty acids and omega-3 and omega-9 erucic acids can affect signaling in the BDNF synthesis resulting in the decrease in BDNF. There is a beneficial effect of DGLA on the BDNF level, while the effect of ALA on BDNF can be inhibitory. Specialized proresolving lipid mediators can play a role in the BDNF metabolism. BDNF can interact with inflammation as the risk factor in the cardiovascular disorders, including stroke.

The BDNF rs6265 Polymorphism is a Modifier of Cardiomyocyte Contractility and Dilated Cardiomyopathy

Brain-derived neurotrophic factor (BDNF) is a neuronal growth and survival factor that harbors cardioprotective qualities that may attenuate dilated cardiomyopathy. In ~30% of the population, BDNF has a common, nonsynonymous single nucleotide polymorphism rs6265 (Val66Met), which might be correlated with increased risk of cardiovascular events. We previously showed that BDNF correlates with better cardiac function in Duchenne muscular dystrophy (DMD) patients. However, the effect of the Val66Met polymorphism on cardiac function has not been determined. The goal of the current study was to determine the effects of rs6265 on BDNF biomarker suitability and DMD cardiac functions more generally. We assessed cardiovascular and skeletal muscle function in human DMD patients segregated by polymorphic allele. We also compared echocardiographic, electrophysiologic, and cardiomyocyte contractility in C57/BL-6 wild-type mice with rs6265 polymorphism and in mdx/mTR (mDMD) mouse model of DMD. In human DMD patients, plasma BDNF levels had a positive correlation with left ventricular function, opposite to that seen in rs6265 carriers. There was also a substantial decrease in skeletal muscle function in carriers compared to the Val homozygotes. Surprisingly, the opposite was true when cardiac function of DMD carriers and non-carriers were compared. On the other hand, Val66Met wild-type mice had only subtle functional differences at baseline but significantly decreased cardiomyocyte contractility. Our results indicate that the Val66Met polymorphism alters myocyte contractility, conferring worse skeletal muscle function but better cardiac function in DMD patients. Moreover, these results suggest a mechanism for the relative preservation of cardiac tissues compared to skeletal muscle in DMD patients and underscores the complexity of BDNF signaling in response to mechanical workload.

The Effects of Exercise Training on the Brain-Derived Neurotrophic Factor (BDNF) in the Patients with Type 2 Diabetes: A Systematic Review of the Randomized Controlled Trials

Purpose

Glucose dysregulation is one of the distinctive features of type 2 diabetes that is associated with an increased risk of cognitive impairment and dementia. The low concentrations of brain-derived neurotrophic factor (BDNF) are reported in people with insulin resistance, metabolic syndrome, and type 2 diabetes. BDNF can be increased by an adjustment in lifestyle including caloric restriction and exercise training. Studies have reported controversial findings about physical activity and its association with BDNF, but there is no comprehensive conclusions on this issue. The aim of this study was to systematically review the effects of exercise training on BDNF levels in patients with type 2 diabetes.

Methods

The electronic databases of Embase, Pedro, PubMed, Medline, Cochrane Library, as well as the Google Scholar search engine were used to obtain the related data about the role of exercise training on BDNF levels in patients with type 2 diabetes. The search period was set from inception to August 2019. Keywords of "exercise", "training", "physical activity", "brain-derived neurotrophic factor", "type 2 diabetes", and "randomized clinical trials", were used in persian and English. The PEDro scale was used to evaluate the quality of the included articles. Results. Finally, 11 articles (four human and seven animal articles) with medium to high quality were included in the study which 5 articles reported elevation (one human and four animal articles), 4 articles reported a reduction (one human and three animal articles), and 2 articles reported no changes (both of them in human articles) in BDNF level following the exercise training.

Conclusion

Decreased energy intake and increased energy expenditure through exercise training may modulate BDNF levels in patients with type 2 diabetes.

Whole Body Vibration Training on Muscle Strength and Brain-Derived Neurotrophic Factor Levels in Elderly Woman With Knee Osteoarthritis: A Randomized Clinical Trial Study

Background: Osteoarthritis of the knee (kOA) is a chronic, progressive, degenerative health condition that contributes to the imbalance between the synthesis and destruction of articular cartilage. Recently, whole body vibration (WBV) training has been recommended as an effective alternative for strength training in elderly people, and various physiological effects are obtained in response to exercise performed on a vibratory platform, such as an increase in muscle activation and improved muscle performance. However, the effects of WBV particularly on the strength of the quadriceps muscle and neuronal plasticity are unknown.

Objective: The aim of this study was to evaluate the effects of adding WBV to squat training on the isometric quadriceps muscle strength (IQMS) and the plasma levels of brain-derived neurotrophic factor (BDNF) in elderly woman with kOA.

Methods: Fifteen elderly women ≥65 years of age with kOA were randomized into two interventions: (1) the vibration group (VG), in which participants performed squat exercise training in association with WBV or (2) the exercise group (EG), in which participants performed squat exercise training without vibration, for 12 weeks 3×/week.

Results: Compared to the EG group, the VG group demonstrated a significantly greater delta (Δ) in IQMS values (IC95% 0.43–7.06; p ≤ 0.05) and in Δ BDNF plasma levels (IC95% −32.51 to 4.217; p ≤ 0.05) after the intervention period. There was an association between increase of Δ BDNF plasma levels and increase of Δ IQMS (β = 0.57; R² = 0.32; p = 0.03).

Conclusion: The addition of WBV to squat exercise training improves lower limb muscle performance in elderly women with kOA. These findings suggest that the improvement in muscle performance is related to neuromuscular adaptations induced by WBV.

Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT03918291.

Acute Effects of High Intensity, Resistance, or Combined Protocol on the Increase of Level of Neurotrophic Factors in Physically Inactive Overweight Adults: The BrainFit Study

The purpose of this study was to compare the neurotrophic factor response following one session of high-intensity exercise, resistance training or both in a cohort of physically inactive overweight adults aged 18–30 years old. A randomized, parallel-group clinical trial of 51 men (23.6 ± 3.5 years; 83.5 ± 7.8 kg; 28.0 ± 1.9 kg/m²) who are physically inactive (i.e., < 150 min of moderate-intensity exercise per week or IPAQ score of <600 MET min/week for >6 months) and are either abdominally obese (waist circumference ≥90 cm) or have a body mass index, BMI ≥25 and ≤ 30 kg/m² were randomized to the following four exercise protocols: high-intensity exercise (4 × 4 min intervals at 85–95% maximum heart rate [HRmax] interspersed with 4 min of recovery at 75–85% HRmax) (n = 14), resistance training (12–15 repetitions per set, at 50–70% of one repetition maximum with 60 s of recovery) (n = 12), combined high-intensity and resistance exercise (n = 13), or non-exercising control (n = 12). The plasma levels of neurotrophin-3 (NT-3), neurotrophin-4 (also known as neurotrophin 4/5; NT-4 or NT-4/5), and brain-derived neurotrophic factor (BDNF) were determined before (pre-exercise) and 1-min post-exercise for each protocol session. Resistance training induced significant increases in NT-3 (+39.6 ng/mL [95% CI, 2.5–76.6; p = 0.004], and NT-4/5 (+1.3 ng/mL [95% CI, 0.3–2.3; p = 0.014]), respectively. Additionally, combined training results in favorable effects on BDNF (+22.0, 95% CI, 2.6–41.5; p = 0.029) and NT-3 (+32.9 ng/mL [95% CI, 12.3–53.4; p = 0.004]), respectively. The regression analysis revealed a significant positive relationship between changes in BDNF levels and changes in NT-4/5 levels from baseline to immediate post-exercise in the combined training group (R² = 0.345, p = 0.034) but not the other intervention groups. The findings indicate that acute resistance training and combined exercise increase neurotrophic factors in physically inactive overweight adults. Further studies are required to determine the biological importance of changes in neurotrophic responses in overweight men and chronic effects of these exercise protocols.

Trial Registration: ClinicalTrials.gov, NCT02915913 (Date: September 22, 2016).

Psychological and Physiological Biomarkers of Neuromuscular Fatigue after Two Bouts of Sprint Interval Exercise

The main aim of our study was to determinate whether a repeated bout (RB) (vs. first bout [FB]) of sprint interval cycling exercise (SIE) is sufficient to mitigate SIE-induced psychological and physiological biomarker kinetics within 48 h after the exercise. Ten physically active men (age, 22.6 ± 5.2 years; VO₂max, 44.3 ± 5.7 ml/kg/min) performed the FB of SIE (12 repeats of 5 s each) on one day and the RB 2 weeks later. The following parameters were measured: motor performance (voluntary, electrically induced and isokinetic skeletal muscle contraction torque, and central activation ratio [CAR]); stress markers [brain-derived neurotrophic factor (BDNF), cortisol, norepinephrine, and epinephrine]; inflammatory markers (IL-6, IL-10, and TNF-α); metabolic markers (glucose and lactate); muscle and rectal temperature; cycling power output; and psychological perceptions. The average cycling power output and neuromuscular fatigue after exercise did not differ between the FB and RB. There were significant decreases in cortisol and BDNF concentration at 12 h (P < 0.05) and 24 h (P < 0.001) after the FB, respectively. The decrease in cortisol concentration observed 12 h after exercise was significantly greater after the RB (P < 0.05) than after the FB. The immune-metabolic response to the RB (vs. FB) SIE was suppressed and accompanied by lower psychological exertion. Most of the changes in psychological and physiological biomarkers in the FB and RB were closely related to the response kinetics of changes in BDNF concentration.

Brain-derived neurotrophic factor levels and depression during methamphetamine withdrawal

BACKGROUND

Depression symptoms is highly comorbid with methamphetamine (METH) dependence. Except for the role in the pathophysiology of depression symptoms, brain-derived neurotrophic factor (BDNF) is also involved in the METH dependence. The present study aims to explore whether BDNF plays a role in the development of depression symptoms during METH withdrawal.

METHODS

We recruited 179 patients with METH dependence who were followed up for two weeks. Ultimately, 131 (73.2%) patients finished the follow-up. Besides, 90 healthy controls were also recruited. Serum BDNF levels were measured by DuoSet ELISA Development System upon admission. The short form (13 items) of the Beck Depression Inventory (BDI) and Amphetamine Withdrawal Questionnaire (AWQ) were used to measure the depression and withdrawal symptoms. Patients with BDI score ≥ 8 were identified to have depression symptoms.

RESULTS

Of the 131 patients, 64 (48.9%) were identified to have depression symptoms at the two-week endpoint. Patients with depression symptoms showed significantly lower BDNF levels than those with no depression symptoms. Serum BDNF levels (≤ 1251.0pg/ml) were independently associated with the development of depression symptoms during METH withdrawal (OR = 3.50, 95% CI, 1.14-10.73, p = 0.028).

LIMITATIONS

BDNF levels were tested in serum but not in brain and the baseline BDI and AWQ scores between the depression and non-depression groups were not matched. Besides, the follow-up time was relatively short.

CONCLUSIONS

Our study demonstrated that patients with serum BDNF levels ≤ 1251.0pg/ml had higher risk of depression symptoms during METH withdrawal.

New insights about the putative role of myokines in the context of cardiac rehabilitation and secondary cardiovascular prevention

Exercise training prevents the onset and the development of many chronic diseases, acting as an effective tool both for primary and for secondary prevention. Various mechanisms that may be the effectors of these beneficial effects have been proposed during the past decades: some of these are well recognized, others less. Muscular myokines, released during and after muscular contraction, have been proposed as key mediators of the systemic effects of the exercise. Nevertheless the availability of an impressive amount of evidence regarding the systemic effects of muscle-derived factors, few studies have examined key issues: (I) if skeletal muscle cells themselves are the main source of cytokine during exercise; (II) if the release of myokines into the systemic circulation reach an adequate concentration to provide significant effects in tissues far from skeletal muscle; (III) what may be the role carried out by muscular cytokine regarding the well-known benefits induced by regular exercise, first of all the anti-inflammatory effect of exercise. Furthermore, a greater part of our knowledge regarding myokines derives from the muscle of healthy subjects. This knowledge may not necessarily be transferred per se to subjects with chronic diseases implicating a direct or indirect muscular dysfunction and/or a chronic state of inflammation with persistent immune-inflammatory activation (and therefore increased circulating levels of some cytokines): cachexia, sarcopenia due to multiple factors, disability caused by neurological damage, chronic congestive heart failure (CHF) or coronary artery disease (CAD). A key point of future studies is to ascertain how is modified the muscular release of myokines in different categories of unhealthy subjects, both at baseline and after rehabilitation. The purpose of this review is to discuss the main findings on the role of myokines as putative mediators of the therapeutic benefits obtained through regular exercise in the context of secondary cardiovascular prevention.

BDNF - A key player in cardiovascular system

Neurotrophins (NTs) were first identified as target-derived survival factors for neurons of the central and peripheral nervous system (PNS). They are known to control neural cell fate, development and function. Independently of their neuronal properties, NTs exert unique cardiovascular activity. The heart is innervated by sensory, sympathetic and parasympathetic neurons, which require NTs during early development and in the establishment of mature properties, contributing to the maintenance of cardiovascular homeostasis. The identification of molecular mechanisms regulated by NTs and involved in the crosstalk between cardiac sympathetic nerves, cardiomyocytes, cardiac fibroblasts, and vascular cells, has a fundamental importance in both normal heart function and disease. The article aims to review the recent data on the effects of Brain-Derived Neurotrophic Factor (BDNF) on various cardiovascular neuronal and non-neuronal functions such as the modulation of synaptic properties of autonomic neurons, axonal outgrowth and sprouting, formation of the vascular and neural networks, smooth muscle migration, and control of endothelial cell survival and cardiomyocytes. Understanding these mechanisms may be crucial for developing novel therapeutic strategies, including stem cell-based therapies.

Plasma brain-derived neurotrophic factor concentration is a predictor of chronic kidney disease in patients with cardiovascular risk factors - Hyogo Sleep Cardio-Autonomic Atherosclerosis study

Background

Brain-derived neurotrophic factor (BDNF) has been shown to have protective effects against cardiovascular diseases and death through neural and non-neural pathways via tropomyosin-related kinase B signaling. However, it is not known whether plasma BDNF concentration is a predictor of chronic kidney disease (CKD).

Design

This study was conducted as a prospective cohort study as part of the Hyogo Sleep Cardio-Autonomic Atherosclerosis.

Methods

We measured plasma BDNF concentration in 324 patients without CKD, defined as an estimated glomerular filtration rate (eGFR) less than 60 ml/min/1.73m², and with cardiovascular risk factors. As potential confounders, sleep condition, nocturnal hypertension, and autonomic function were quantitatively examined. The patients were followed for a median 37 months (range 2–59 months) and occurrence of CKD was noted.

Results

Plasma BDNF concentration was significantly and independently associated with CKD development, which occurred in 38 patients (11.7%). Kaplan-Meier analysis revealed that patients with reduced plasma BDNF concentration exhibited a significantly (p = 0.029) greater number of CKD events as compared to those with a higher concentration. Moreover, comparisons of key subgroups showed that the risk of CKD in association with low plasma BDNF concentration was more prominent in patients with a greater reduction of nocturnal systolic blood pressure, better movement index, higher standard deviations of the NN(RR) interval or average NN(RR) interval for each 5-minute period, and without past cardiovascular disease events, smoking habit, or albuminuria.

Conclusions

Plasma BDNF concentration is an independent predictor for development of CKD in patients with cardiovascular risk factors.

Brain-derived neurotrophic factor (BDNF) plasma concentration in patients diagnosed with premature ovarian insufficiency (POI)

Premature ovarian insufficiency (POI) is defined as a cessation of function of ovaries in women younger than 40 years old. Brain-derived neurotrophic factor (BDNF) is a protein critically involved in neuronal growth and metabolism. BDNF also has been shown to be important regulator of oocyte maturation. Recent data show that BDNF can be potentially involved in POI pathology. The aim of the study was to assess the BDNF plasma concentrations in patients diagnosed with idiopathic POI. 23 women diagnosed with POI (age 31 ± 7 years) and 18 (age 31 ± 3) controls were included to the study, matched according to age and body mass index. The BDNF concentrations were measured using competitive enzyme-linked immunosorbent assay (ELISA). Hormonal and metabolic parameters were measured in all individuals, in controls in late follicular phase. The POI group demonstrated lower mean plasma concentrations of BDNF (429.25 ± 65.52 pg/ml) in comparison to healthy controls (479.75 ± 34.75 pg/ml, p = 0.0345). The BDNF plasma concentration correlated negatively (R = -0.79, p < 0.001) with number of months since last menstrual period. There was a positive correlation between BDNF and progesterone in controls. In conclusion, POI patients show significantly lower BDNF plasma concentration and it correlates with the duration of amenorrhea. This observation brings important potential insights to the pathology of POI.

Brain-derived neurotrophic factor (BDNF) serum basal levels is not affected by power training in mobility-limited older adults - A randomized controlled trial

Brain-derived neurotrophic factor (BDNF) is a potential important factor involved in neuroplasticity, and may be a mediator for eliciting adaptations in neuromuscular function and physical function in older individuals following physical training. As power training taxes the neural system to a very high extent, it may be particularly effective in terms of eliciting increases in systemic BDNF levels. We examined the effects of 12weeks of power training on mature BDNF (mBDNF) and total BDNF (tBDNF) in mobility-limited older adults from the Healthy Ageing Network of Competence (HANC) study. We included 47 older men and women: n=22 in the training group (TG: progressive high intensity power training, 2 sessions per week; age 82.7±5.4years, 55% women) and n=25 in the control group (CG: no interventions; age 82.2±4.5years, 76% women). Following overnight fasting, basal serum levels of mBDNF and tBDNF were assessed (human ELISA kits) at baseline and post-intervention. At baseline, mBDNF and tBDNF levels were comparable in the two groups, TG and CG. Post-intervention, no significant within-group or between-group changes were observed in mBDNF or tBDNF. Moreover, when divided into responder tertiles based upon changes in mBDNF and tBDNF (i.e. decliners, maintainers, improvers), respectively, comparable findings were observed for TG and CG. Altogether, basal systemic levels of serum mBDNF and tBDNF are not affected in mobility-limited older adults following 12-weeks of power training, and do not appear to be a major mechanistic factor mediating neuroplasticity in mobility-limited older adults.

Brain-derived neurotrophic factor plasma levels are increased in older women after an acute episode of low back pain

BACKGROUND

Low back pain (LBP) is a growing public health problem in old age, and it is associated with disabling pain and depressive disorders. We compared brain-derived neurotrophic factor (BDNF) plasma levels, a key neurotrophin in pain modulation, between older women after an acute episode of LBP and age-matched pain-free controls, and investigated potential differences in BDNF levels between controls and LBP subgroups based on pain severity, presence of depressive symptoms and use of analgesic and antidepressant drugs.

METHODS

A total of 221 participants (154 with LBP and 67 pain-free) were studied. A comprehensive assessment of sociodemographic and clinical variables was conducted including pain severity (11-point NRS), depressive symptoms (GDS-15), age, body mass index, physical activity and total number of comorbidities and medications in use.

RESULTS

BDNF levels in LBP group were significantly higher than controls (7515.9±3021.2; Md=7116.0 vs 6331.8±3364.0; Md=5897.5pg/mL, P=0.005). LBP subgroups exhibited higher BDNF levels than controls, regardless of pain severity, presence of depressive symptoms and use of analgesic drugs. BDNF levels were significantly higher in LBP subgroup without use of antidepressant drugs compared to both controls and LBP subgroup with use of antidepressant drugs.

DISCUSSION

This study provides evidence that older women with acute low back pain exhibit higher BDNF plasma levels compared to pain-free controls. Subgroup comparisons suggest that use of pain-relief drugs may influence BDNF levels. The study results offer a novel target for research on mechanisms of back pain in older adults.

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.

Metabolic Adaptation in Obesity and Type II Diabetes: Myokines, Adipokines and Hepatokines

Obesity and type II diabetes are characterized by insulin resistance in peripheral tissues. A high caloric intake combined with a sedentary lifestyle is the leading cause of these conditions. Whole-body insulin resistance and its improvement are the result of the combined actions of each insulin-sensitive organ. Among the fundamental molecular mechanisms by which each organ is able to communicate and engage in cross-talk are cytokines or peptides which stem from secretory organs. Recently, it was reported that several cytokines or peptides are secreted from muscle (myokines), adipose tissue (adipokines) and liver (hepatokines) in response to certain nutrition and/or physical activity conditions. Cytokines exert autocrine, paracrine or endocrine effects for the maintenance of energy homeostasis. The present review is focused on the relationship and cross-talk amongst muscle, adipose tissue and the liver as secretory organs in metabolic diseases.

Cognitive impairment and BDNF serum levels

BACKGROUND/AIMS

To investigate the alterations of brain-derived neurotrophic factor (BNDF) serum levels in subjects with different intensity of cognitive impairment and different neurodegenerative processes.

MATERIAL AND METHODS

Serum BDNF levels were analyzed by ELISA kit in 378 subjects: 134 Alzheimer's disease (AD) patients, 115 amnestic mild cognitive impairment (MCI) patients, and 129 controls divided into two groups: neurodegenerative control group (ND), consisting of 49 Parkinson's disease patients without any cognitive complaints, and cognitively normal control group (CN), consisting of 80 subjects without any neurological disorders.

RESULTS

AD patients had significantly lower (p<0.001) BDNF serum levels compared to MCI, CN and ND controls. Age and education had significant influence on BDNF serum levels regardless the diagnosis or group assignment. We have found no influence of depression on BDNF serum levels either in our group as a whole, or in each group assessed separately. We found significant correlation between BDNF serum levels and cognitive impairments. After multiple comparisons between the groups, we found that, after adjustment for confounding factors (age, gender, education, depression, cognitive impairment), BDNF serum levels were the lowest in AD group (p=0.05).

CONCLUSIONS

Advanced age and low educational level are associated with decreased BDNF serum levels. Decreased BDNF serum levels correspond to the severity of cognitive impairment. There is no correlation between BDNF serum levels and depressive symptoms.

Brain-derived neurotrophic factor and its clinical implications

Brain-derived neurotrophic factor (BDNF) plays an important role in neuronal survival and growth, serves as a neurotransmitter modulator, and participates in neuronal plasticity, which is essential for learning and memory. It is widely expressed in the CNS, gut and other tissues. BDNF binds to its high affinity receptor TrkB (tyrosine kinase B) and activates signal transduction cascades (IRS1/2, PI3K, Akt), crucial for CREB and CBP production, that encode proteins involved in β cell survival. BDNF and insulin-like growth factor-1 have similar downstream signaling mechanisms incorporating both p-CAMK and MAPK that increase the expression of pro-survival genes. Brain-derived neurotrophic factor regulates glucose and energy metabolism and prevents exhaustion of β cells. Decreased levels of BDNF are associated with neurodegenerative diseases with neuronal loss, such as Parkinson's disease, Alzheimer's disease, multiple sclerosis and Huntington's disease. Thus, BDNF may be useful in the prevention and management of several diseases including diabetes mellitus.

Brain-derived neurotrophic factor correlates with functional and cognitive impairment in non-disabled older individuals

We used a complete battery of geriatric and psychometric tests to evaluate whether plasma-borne brain-derived neurotrophic factor (BDNF), a master molecule in neuroplasticity, is associated with the severity of functional and cognitive impairment in non-disabled older individuals. There was a significant positive correlation between BDNF plasma concentrations and the Barthel index, a measurement of the ability of individuals to perform the activities of daily living (p=0.03) and the concentration subcategory measured with the mini mental state examination (MMSE) test (p = 0.01). Furthermore, plasma BDNF inversely and significantly correlated with the blood eosinophil count (p = 0.01), the total cholesterol concentration (p = 0.04), and high-density lipoprotein cholesterol (p=0.04). However, BDNF did not correlate with any other socio-demographic or clinical characteristics, other analytical parameters measured in the blood, or any other geriatric assessment scales. Our results suggest that BDNF may play a role in the pathophysiology of functional impairment in the elderly and in some aspects of cognitive function. However, more studies are needed to understand the relationship between circulating BDNF and functional impairment to determine if BDNF represents a candidate biomarker for this type of cognitive impairment.

Protective Effects of BDNF against C-Reactive Protein-Induced Inflammation in Women

Background. Since high sensitivity C-reactive protein (hsCRP) is predictive of cardiovascular events, it is important to examine the relationship between hsCRP and other inflammatory and oxidative stress markers linked to cardiovascular disease (CVD) etiology. Previously, we reported that hsCRP induces the oxidative stress adduct 8-oxo-7,8-dihydro-2′deoxyguanosine (8-oxodG) and that these markers are significantly associated in women. Recent data indicates that brain-derived neurotrophic factor (BDNF) may have a role in CVD. Methods and Results. We examined BDNF levels in 3 groups of women that were age- and race-matched with low (<3 mg/L), mid (>3–20 mg/L), and high (>20 mg/L) hsCRP (n = 39 per group) and found a significant association between hsCRP, BDNF, and 8-oxodG. In African American females with high hsCRP, increases in BDNF were associated with decreased serum 8-oxodG. This was not the case in white women where high hsCRP was associated with high levels of BDNF and high levels of 8-oxodG. BDNF treatment of cells reduced CRP levels and inhibited CRP-induced DNA damage. Conclusion. We discovered an important relationship between hsCRP, 8-oxodG, and BDNF in women at hsCRP levels >3 mg/L. These data suggest that BDNF may have a protective role in counteracting the inflammatory effects of hsCRP.

Brain-Derived Neurotrophic Factor (BDNF) in Traumatic Brain Injury-Related Mortality: Interrelationships Between Genetics and Acute Systemic and Central Nervous System BDNF Profiles

BACKGROUND

Older adults have higher mortality rates after severe traumatic brain injury (TBI) compared to younger adults. Brain-derived neurotrophic factor (BDNF) signaling is altered in aging and is important to TBI given its role in neuronal survival/plasticity and autonomic function. Following experimental TBI, acute BDNF administration has not been efficacious. Clinically, genetic variation in BDNF (reduced signaling alleles: rs6265, Met-carriers; rs7124442, C-carriers) can be protective against acute mortality. Postacutely, these genotypes carry lower mortality risk in older adults and greater mortality risk among younger adults.

OBJECTIVE

Investigate BDNF levels in mortality/outcome following severe TBI in the context of age and genetic risk.

METHODS

Cerebrospinal fluid (CSF) and serum BDNF were assessed prospectively during the first week following severe TBI (n = 203) and in controls (n = 10). Age, BDNF genotype, and BDNF levels were assessed as mortality/outcome predictors.

RESULTS

CSF BDNF levels tended to be higher post-TBI (P = .061) versus controls and were associated with time until death (P = .042). In contrast, serum BDNF levels were reduced post-TBI versus controls (P < .0001). Both gene * BDNF serum and gene * age interactions were mortality predictors post-TBI in the same multivariate model. CSF and serum BDNF tended to be negatively correlated post-TBI (P = .07).

CONCLUSIONS

BDNF levels predicted mortality, in addition to gene * age interactions, suggesting levels capture additional mortality risk. Higher CSF BDNF post-TBI may be detrimental due to injury and age-related increases in pro-apoptotic BDNF target receptors. Negative CSF and serum BDNF correlations post-TBI suggest blood-brain barrier transit alterations. Understanding BDNF signaling in neuronal survival, plasticity, and autonomic function may inform treatment.

Brain-derived neurotrophic factor correlated with muscle strength in subjects undergoing stationary bicycle exercise training

AIMS

Several central nervous disorders are associated with metabolic syndrome (MetS) and type 2 diabetes. Reduction in brain-derived neurotrophic factor (BDNF) is involved in the mechanism of central nervous dysfunction. BDNF is up-regulated after exercise, but it is not known whether increased BDNF is related to increases in muscle strength.

METHODS

In the present study, subjects with MetS or type 2 diabetes were enrolled in an exercise program. All participants underwent an indoor bicycle exercise program for twelve weeks. Serum BDNF was determined after overnight fasting. Muscle strength was assessed by extension of the dominant lower extremity.

RESULTS

A total of 33 subjects were enrolled in this study. The body mass index did not change significantly (from 30.4±6.0 to 30.2±5.8kg/m(2), P=0.436), but serum BDNF increased significantly (from 17.1±9.1 to 24.2±10.7ng/mL, P<0.001) after the study. The exercise-associated BDNF was significantly correlated with the increased strength in lower-extremity extension test (r=0.54, P=0.001). Using multivariate regression analysis, muscle-strength increment, but not body-weight change, was an independent factor for serum BDNF (95% CI=0.009-0.044, P=0.005).

CONCLUSIONS

After a twelve-week program of stationary bicycle exercise, serum BDNF concentration increased, and this change was positively correlated with muscle strength of lower-extremity extension, but not body weight. (

TRIAL REGISTRATION

NCT02268292, ClinicalTrials.gov).

Circulating brain-derived neurotrophic factor concentrations and the risk of cardiovascular disease in the community

Background

Brain‐derived neurotrophic factor (BDNF) is a pleiotropic peptide involved in maintaining endothelial integrity. It is unknown if circulating BDNF levels are associated with risk of cardiovascular disease (CVD).

Methods and Results

We prospectively investigated the association of circulating BDNF levels with cardiovascular events and mortality in 3687 participants (mean age 65 years, 2068 women) from the Framingham Heart Study (FHS). Using a common nonsynonomous single nucleotide polymorphism (SNP) in the BDNF gene (rs6265), we then performed a Mendelian randomization experiment in the CARDIoGRAM (Coronary ARtery DIsease Genome‐Wide Replication And Meta‐Analysis) consortium (>22 000 coronary artery disease [CAD] cases, >60 000 controls) to investigate whether SNP rs6265 was associated with CAD in CARDIoGRAM and, if so, whether the effect estimate differed from that predicted based on FHS data. On follow‐up (median 8.9 years), 467 individuals (261 women) in FHS experienced a CVD event, and 835 (430 women) died. In multivariable‐adjusted Cox regression, serum BDNF was associated inversely with CVD risk (hazard ratio [HR] per 1‐SD increase 0.88, 95% CI 0.80 to 0.97, P=0.01) and with mortality (HR 0.87, 95% CI 0.80 to 0.93, P=0.0002). SNP rs6265 was associated with BDNF concentrations (0.772 ng/mL increase per minor allele copy) in FHS. In CARDIoGRAM, SNP rs6265 was associated with CAD (odds ratio 0.957, 95% CI 0.923 to 0.992), a magnitude consistent with the predicted effect (HR per minor allele copy 0.99, 95% CI 0.98 to 1.0; P=0.06 for difference between predicted and observed effect).

Conclusion

Higher serum BDNF is associated with a decreased risk of CVD and mortality. Mendelian randomization suggests a causal protective role of BDNF in the pathogenesis of CVD.

Correlation of plasma brain-derived neurotrophic factor and metabolic profiles in drug-naïve patients with bipolar II disorder after a twelve-week pharmacological intervention

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) is thought to be involved in the pathophysiology of bipolar disorder (BD) and metabolic syndrome. We investigated the correlation between plasma BDNF with mood symptoms and metabolic indices in patients with BD-II over a 12-week pharmacological intervention.

METHOD

Drug-naïve patients with BD-II (n=117) were recruited. Metabolic profiles [cholesterol, triglyceride, HbA1C, fasting serum glucose, body mass index (BMI)] and plasma BDNF wtrun "tblautotrun "tblsctrun "tbl_contere measured at baseline and 2, 8, and 12 weeks after beginning medication. To adjust within-subject dependence over repeated assessments, multiple linear regressions with generalized estimating equation methods were used.

RESULTS

Seventy-six (65.0%) patients completed the intervention. Plasma BDNF levels were significantly associated with BMI (P=9.6E-5), low-density lipoprotein (P=0.034) and total (P=0.001) cholesterol, but not with the Hamilton Depression Rating Scale-17 and Young Mania Rating Scale scores over the 12-week treatment.

CONCLUSION

We found initial evidence of a positive correlation between plasma BDNF levels and BMI, low-density lipoprotein and total cholesterol in drug-naïve patients with BD-II. The specific function of BDNF in regulating and maintaining peripheral metabolic health requires additional investigation.

Elevated levels of plasma brain derived neurotrophic factor in rapid cycling bipolar disorder patients

Impaired neuroplasticity may be implicated in the pathophysiology of bipolar disorder, involving peripheral alterations of the neurotrophins brain derived neurotrophic factor (BDNF) and neurotrophin 3 (NT-3). Evidence is limited by methodological issues and is based primarily on case-control designs. The aim of this study was to investigate whether BDNF and NT-3 levels differ between patients with rapid cycling bipolar disorder and healthy control subjects and whether BDNF and NT-3 levels alter with affective states in rapid cycling bipolar disorder patients. Plasma levels of BDNF and NT-3 were measured in 37 rapid cycling bipolar disorder patients and in 40 age- and gender matched healthy control subjects using enzyme-linked immunosorbent assay (ELISA). In a longitudinal design, repeated measurements of BDNF and NT-3 were evaluated in various affective states in bipolar disorder patients during a 6-12 months period and compared with repeated measurements in healthy control subjects. Careful attention was given to standardization of all procedures and adjustment for potential confounders of BDNF and NT-3. In linear mixed models, adjusting for demographical and lifestyle factors, levels of BDNF were significantly elevated in bipolar disorder patients in euthymic- (p<0.05), depressed- (p<0.005) and manic/hypomanic (p<0.005) states compared with healthy control subjects. Within bipolar disorder patients, adjusting for medication, there was no significant difference in BDNF levels between affective states, with equally elevated levels present in euthymic-, depressive- and manic/hypomanic patients. Levels of BDNF were higher in patients with longer duration of illness compared with patients with shorter duration of illness. We found no difference in NT-3 levels between bipolar disorder patients in any affective state compared with healthy control subjects and no difference in NT-3 levels between affective states in bipolar disorder patients. The results suggest that BDNF may be a marker related to illness stage in bipolar disorder, not varying with affective states in rapid cycling bipolar disorder patients. Due to the nature of comparison, it cannot be excluded that the finding of elevated BDNF levels in bipolar disorder patients compared with healthy controls could be influenced by medication.

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

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

Variation in the BDNF gene interacts with age to predict mortality in a prospective, longitudinal cohort with severe TBI

BACKGROUND

Mortality predictions following traumatic brain injury (TBI), and our understanding of TBI pathology, may be improved by including genetic risk in addition to traditional prognostic variables. One promising target is the gene coding for brain-derived neurotrophic factor (BDNF), a ubiquitous neurotrophin important for neuronal survival and neurogenesis.

OBJECTIVE

We hypothesized the addition of BDNF genetic variation would improve mortality prediction models and that BDNF Met-carriers (rs6265) and C-carriers (rs7124442) would have the highest mortality rates post-TBI.

METHODS

This study examined BDNF functional single nucleotide polymorphisms rs6265 (val66met) and rs7124442 (T>C) in relation to mortality in a prospective, longitudinal cohort with severe TBI. We examined 315 individuals receiving care for a closed head injury within the University of Pittsburgh Medical Center, aged 16 to 74 years. Mortality was examined acutely (0-7 days postinjury) and postacutely (8-365 days postinjury). A gene risk score (GRS) was developed to examine both BDNF loci. Cox proportional hazards models were used to calculate hazard ratios for survivability post-TBI while controlling for covariates.

RESULTS

BDNF GRS was significantly associated with acute mortality, regardless of age. Interestingly, subjects in the hypothesized no-risk allele group had the lowest survival probability. Postacutely, BDNF-GRS interacted with age such that younger participants in the no-risk group had the highest survival probability, while older participants in the hypothesized no-risk group had the lowest probability of survival.

CONCLUSIONS

These data suggest complex relationships between BDNF and TBI mortality that interact with age to influence survival predictions beyond clinical variables alone. Evidence supporting dynamic, temporal balances of pro-survival/pro-apoptotic target receptors may explain injury and age-related gene associations.

Brain-derived neurotrophic factor, but not body weight, correlated with a reduction in depression scale scores in men with metabolic syndrome: a prospective weight-reduction study

BACKGROUND

Obesity, a critical component of metabolic syndrome (MetS), is associated with depression. Deficiency of brain-derived neurotrophic factor (BDNF) is involved in the mechanism of depression. We hypothesized that weight reduction would improve depressive symptoms via increasing BDNF levels in obese men.

METHODS

Male adults with obesity were enrolled in a weight-reduction program for twelve weeks. All subjects underwent daily caloric restriction and an exercise program which was regularly assessed in group classes. Fasting blood samples and Zung Self-Rating Depression Scale (Zung SDS) scores were collected for assessments before and after the study.

RESULTS

A total of 36 subjects completed this program. The average reduction in body weight was 8.4 ± 5.1 kg (8.8 ± 5.1%, P < 0.001). Fasting serum BDNF significantly increased after the study (from 40.4 ± 7.8 to 46.9 ± 8.9 ng/ml, P < 0.001). However, the depression symptoms, as assessed by the Zung Self-Rating Depression Scale (Zung SDS), did not reduce significantly (P = 0.486). Divided into subgroups based on changes in BDNF, Zung SDS scores were significantly reduced in subjects with greater BDNF increase than in those with minor BDNF change (-3.9 ± 6.2 vs. 2.3 ± 6.7, P = 0.009). The increased percentage of BDNF was inversely correlated with the change in Zung SDS (r = -0.380, P = 0.022). Multivariate regression analysis showed that reduction in BDNF was independently associated with change in Zung SDS (95% confidence interval -0.315 to -0.052, P = 0.008).

CONCLUSION

Zung SDS only significantly improved in men with increased fasting BDNF levels after a lifestyle intervention.

TRIAL REGISTRATION

(NCT01065753, ClinicalTrials.gov).

Chronic depression as a model disease for cerebral aging

Conceptualizations of the underlying neurobiology of major depression have changed their focus from dysfunctions of neurotransmission to dysfunctions of neurogenesis and neuroprotection. The “neurogenesis hypothesis of depression” posits that changes in the rate of neurogenesis are the underlying mechanism in the pathology and treatment of major depression. Stress, neuroinflammation, dysfunctional insulin regulation, oxidative stress, and alterations in neurotrophic factors possibly contribute to the development of depression. The influence of antidepressant therapies, namely pharmacotherapy and neuroprotectants, on cellular plasticity are summarized. A dysfunction of complex neuronal networks as a consequence of neural degeneration in neuropsychiatric diseases has led to the application of deep brain stimulation. We discuss the way depression seen in the light of the neurogenesis hypothesis can be used as a model disease for cerebral aging. A common pathological mechanism in depression and cerebral aging—a dysfunction of neuroprotection and neurogenesis—is discussed. This has implications for new treatment methods.

An update on frailty diagnosis and management

Frailty as a clinical syndrome is becoming more widely recognized and current evidence shows the importance of early detection of pre-frail states with a potential for reversibility of poor outcomes. The purpose of this review is to present the latest literature on frailty since the last review in this journal in 2007, with a particular focus on interventions aimed at reversing the processes of frailty.

The effect of exercise training modality on serum brain derived neurotrophic factor levels in individuals with type 2 diabetes

Introduction

Brain derived neurotrophic factor (BDNF) has been implicated in memory, learning, and neurodegenerative diseases. However, the relationship of BDNF with cardiometabolic risk factors is unclear, and the effect of exercise training on BDNF has not been previously explored in individuals with type 2 diabetes.

Methods

Men and women (N = 150) with type 2 diabetes were randomized to an aerobic exercise (aerobic), resistance exercise (resistance), or a combination of both (combination) for 9 months. Serum BDNF levels were evaluated at baseline and follow-up from archived blood samples.

Results

Baseline serum BDNF was not associated with fitness, body composition, anthropometry, glucose control, or strength measures (all, p>0.05). Similarly, no significant change in serum BDNF levels was observed following exercise training in the aerobic (−1649.4 pg/ml, CI: −4768.9 to 1470.2), resistance (−2351.2 pg/ml, CI:−5290.7 to 588.3), or combination groups (−827.4 pg/ml, CI: −3533.3 to1878.5) compared to the control group (−2320.0 pg/ml, CI: −5750.8 to 1110.8). However, reductions in waist circumference were directly associated with changes in serum BDNF following training (r = 0.25, p = 0.005).

Conclusions

Serum BDNF was not associated with fitness, body composition, anthropometry, glucose control, or strength measures at baseline. Likewise, serum BDNF measures were not altered by 9 months of aerobic, resistance, or combination training. However, reductions in waist circumference were associated with decreased serum BDNF levels. Future studies should investigate the relevance of BDNF with measures of cognitive function specifically in individuals with type-2 diabetes.

Plasma concentrations but not serum concentrations of brain-derived neurotrophic factor are related to pro-inflammatory cytokines in patients undergoing major abdominal surgery

OBJECTIVES

To investigate peripheral brain-derived neurotrophic factor (BDNF) concentrations in the perioperative period, their relationship with transforming growth factor-β1 (TGF-β1 tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-6 genetics.

DESIGN AND METHODS

Prospective, observational study. BDNF, TGF-β1, IL-6 and TNF-α were analysed at baseline (T0), 5 h (T1), 24 h (T2) and 5 days (T3) after surgery, in 21 patients. The IL-6 -174 G/C polymorphism was genotyped.

RESULTS

Serum BDNF concentrations decreased (P=0.048), correlated with TGF-β1 (r=0.610 at T1, r=0.493 at T2, r=0.554 at T3). Plasma BDNF concentrations raised (P=0.049), correlated with IL-6 and TNF-α at T1 (r=0.495 and r=0.441, respectively). BDNF response was predictable from TNF-α and IL-6 concentrations and the IL-6 -174 G/C genotype.

CONCLUSION

Serum and plasma BDNF concentrations could relate to platelet activation and inflammatory response, respectively. IL-6 genetics played a role in the BDNF acute response.

Association of plasma brain-derived neurotrophic factor and cardiovascular risk factors and prognosis in angina pectoris

BACKGROUND

Collateral circulation can protect and preserve the myocardium against episodes of ischemia and reduce cardiovascular events. Brain-derived neurotrophic factor (BDNF) is an angiogenic regulator promoting angiogenesis. We compared the association of plasma levels of BDNF and C-reactive protein, an established marker, and risk factors of cardiovascular dysfunction and prognosis in patients with angina pectoris.

METHODS

We enrolled 885 patients with angina pectoris. Plasma BDNF and CRP were measured by ELISA. Patients were prospectively followed for a median of 48 months (interquartile range 37-59 months), and information on further coronary events and mortality was collected.

RESULTS

Multiple risk factors for cardiovascular disease were independent determinants of low plasma BDNF level in patients with angina pectoris. Plasma BDNF was inversely associated with levels of triglycerides and low-density lipoprotein cholesterol, presence of diabetes mellitus, fibrinogen level, male sex and age and positively with high-density lipoprotein cholesterol level and platelet count. During follow-up, 15.2% of patients experienced a major coronary event (MCE), and 10.5% died. The plasma BDNF level was an independent predictor of 4-year MCE (adjusted hazard ratio=1.25 with 95% confidence interval 1.10-1.41, P<0.01 for each unit increase in the natural logarithm of the BDNF level) and of 4-year mortality (adjusted hazard ratio=1.29, 95% confidence interval 1.11-1.47, P<0.01).

CONCLUSION

Multiple cardiovascular risk factors are associated with plasma BDNF level in patients with angina pectoris, and low plasma BDNF may be associated with future coronary events and mortality in these patients.

Exercise-induced myokines and their role in chronic diseases

Physical inactivity has recently been identified as a major and independent risk factor for the development of dementia and cognitive decline. In addition to the effect of exercise with regard to protection against neurodegenerative diseases, it is well-established that physical inactivity increases the risk of type 2 diabetes, cardiovascular diseases (CVD), colon cancer and postmenopausal breast cancer. These diseases constitute a network of related diseases, also called "the diseasome of physical inactivity". In this review, physical inactivity is given the central role as an independent and strong risk factor for accumulation of visceral fat and consequently the activation of a network of systemic inflammatory pathways, which promote development of neurodegeneration as well as insulin resistance, atherosclerosis, and tumour growth. The recent finding that muscles produce and release myokines provides a conceptual basis for understanding some of the molecular mechanisms underlying organ cross talk, including muscle-fat cross talk. Accumulating data suggest that contracting skeletal muscles release myokines, which may work in a hormone-like fashion, exerting specific endocrine effects on visceral fat or mediating direct anti-inflammatory effects. Other myokines work locally within the muscle via paracrine mechanisms, exerting their effects on signalling pathways involved in fat oxidation.

Physical therapy intervention (PTI) increases plasma brain-derived neurotrophic factor (BDNF) levels in non-frail and pre-frail elderly women

Biomarkers are important factors in the identification of the frail elderly (higher risk of developing disease) and in assessing the impact of PTI. On the other hand, BDNF has been related to neuroprotection in a series of central nervous system diseases in older age. The levels of BDNF in groups of elderly women classified according to Fried phenotype (non-frail and pre-frail) were compared. We assessed the impact of a PTI on BDNF levels. A convenience sample of 48 elderly women was randomly selected. The PTI group was composed by 20 elderly women selected from this group. Plasma neurotrophic factors, such as BDNF, glial-derived neutrophic factor (GDNF), and nerve growth factor (NGF) were measured by enzyme-linked immunosorbent assay (ELISA). Timed-up-and-go (TUG) test, hand-grip and work/body weight were evaluated before and after the intervention. Plasma concentrations of BDNF were significantly higher in non-frail in comparison to pre-frail elderly women. After the PTI, higher levels of BDNF were found in elderly women (before 351±68 pg/ml and after 593±79 pg/ml; p<0.001). Both groups had an increase in BDNF levels after the PTI. The low levels of BDNF in pre-frail elderly women suggest that this neurotrophic factor may be a key pathophysiological mediator in the syndrome of frailty. The fact that PTI increased BDNF levels in both groups suggests that it may be possible to modify this phenotype.

Decreased serum brain-derived neurotrophic factor concentration in young nonobese subjects with low insulin sensitivity

OBJECTIVE

Insulin resistance and type 2 diabetes are associated with an increased risk of neurodegenerative diseases. Decreased brain-derived neurotrophic factor (BDNF) levels might play a role in the pathogenesis of neuropsychiatric disorders. The aim of our study was to estimate serum BDNF concentration in nonobese women divided into subgroups according to their insulin sensitivity.

DESIGN AND METHODS

We studied 46 young, healthy, nonobese women. Insulin sensitivity was estimated with the euglycemic-hyperinsulinemic clamp technique. Then, participants were divided into subgroups of high (mean, 12.79±2.01mg/kg fat-free mass/min) and low insulin sensitivity (mean, 7.33±1.66mg/kg fat-free mass/min).

RESULTS

We observed decreased serum BDNF concentration in women with low insulin sensitivity in comparison to high insulin sensitivity group (3306.11±603.10 vs 4141.91±755.37pg/mL, p=0.001). Serum BDNF was positively related to insulin sensitivity (r=0.43, p=0.003). This correlation remained significant after adjustment for other estimated parameters.

CONCLUSIONS

Serum BDNF is decreased in young nonobese women with low insulin sensitivity. Early detection and prevention of insulin resistance might be useful in the prevention of neurodegenerative disorders.