Plasma BDNF levels vary in relation to body weight in females

Effects of psychoplastogens on blood levels of brain-derived neurotrophic factor (BDNF) in humans: a systematic review and meta-analysis

BACKGROUND

Peripheral levels of brain-derived neurotrophic factor (BDNF) are often used as a biomarker for the rapid plasticity-promoting effects of ketamine, psychedelics, and other psychoplastogens in humans. However, studies analyzing peripheral BDNF after psychoplastogen exposure show mixed results. In this meta-analysis, we aimed to test whether the rapid upregulation of neuroplasticity seen in preclinical studies is detectable using peripheral BDNF in humans.

METHODS

This analysis was pre-registered (PROSPERO ID: CRD42022333096) and funded by the University of Fribourg. We systematically searched PubMed, Web of Science, and PsycINFO to meta-analyze the effects of all available psychoplastogens on peripheral BDNF levels in humans, including ketamine, esketamine, LSD, psilocybin, ayahuasca, DMT, MDMA, scopolamine, and rapastinel. Risk of bias was assessed using Cochrane Risk of Bias Tools. Using meta-regressions and mixed effects models, we additionally analyzed the impact of several potential moderators.

RESULTS

We included 29 studies and found no evidence that psychoplastogens elevate peripheral BDNF levels in humans (SMD = 0.024, p = 0.64). This result was not affected by drug, dose, blood fraction, participant age, or psychiatric diagnoses. In general, studies with better-controlled designs and fewer missing values reported smaller effect sizes. Later measurement timepoints showed minimally larger effects on BDNF.

CONCLUSION

These data suggest that peripheral BDNF levels do not change after psychoplastogen administration in humans. It is possible that peripheral BDNF is not an informative marker of rapid changes in neuroplasticity, or that preclinical findings on psychoplastogens and neuroplasticity may not translate to human subjects. Limitations of this analysis include the reliability and validity of BDNF measurement and low variation in some potential moderators. More precise methods of measuring rapid changes in neuroplasticity, including neuroimaging and stimulation-based methods, are recommended for future studies attempting to translate preclinical findings to humans.

The race-based stress reduction intervention (RiSE) study on African American women in NYC and Chicago: Design and methods for complex genomic analysis

RiSE study aims to evaluate a race-based stress-reduction intervention as an effective strategy to improve coping and decrease stress-related symptoms, inflammatory burden, and modify DNA methylation of stress response-related genes in older AA women. This article will describe genomic analytic methods to be utilized in this longitudinal, randomized clinical trial of older adult AA women in Chicago and NYC that examines the effect of the RiSE intervention on DNAm pre- and post-intervention, and its overall influence on inflammatory burden. Salivary DNAm will be measured at baseline and 6 months following the intervention, using the Oragene-DNA kit. Measures of perceived stress, depressive symptoms, fatigue, sleep, inflammatory burden, and coping strategies will be assessed at 4 time points including at baseline, 4 weeks, 8 weeks, and 6 months. Genomic data analysis will include the use of pre-processed and quality-controlled methylation data expressed as beta (β) values. Association analyses will be performed to detect differentially methylated sites on the targeted candidate genes between the intervention and non-intervention groups using the Δβ (changes in methylation) with adjustment for age, health behaviors, early life adversity, hybridization batch, and top principal components of the probes as covariates. To account for multiple testing, we will use FDR adjustment with a corrected p-value of <0.05 regarded as statistically significant. To assess the relationship between inflammatory burden and Δβ among the study samples, we will repeat association analyses with the inclusion of individual inflammation protein measures. ANCOVA will be used because it is more statistically powerful to detect differences.

Normal-Tension Glaucoma and Potential Clinical Links to Alzheimer's Disease

Glaucoma is a group of optic neuropathies and the world's leading cause of irreversible blindness. Normal-tension glaucoma (NTG) is a subtype of glaucoma that is characterized by a typical pattern of peripheral retinal loss, in which the patient's intraocular pressure (IOP) is considered within the normal range (<21 mmHg). Currently, the only targetable risk factor for glaucoma is lowering IOP, and patients with NTG continue to experience visual field loss after IOP-lowering treatments. This demonstrates the need for a better understanding of the pathogenesis of NTG and underlying mechanisms leading to neurodegeneration. Recent studies have found significant connections between NTG and cerebral manifestations, suggesting NTG as a neurodegenerative disease beyond the eye. Gaining a better understanding of NTG can potentially provide new Alzheimer's Disease diagnostics capabilities. This review identifies the epidemiology, current biomarkers, altered fluid dynamics, and cerebral and ocular manifestations to examine connections and discrepancies between the mechanisms of NTG and Alzheimer's Disease.

Effect of Glycemic Disorders and Habits on the Concentration of Selected Neurotrophic Factors in Patients with Lumbosacral Intervertebral Disc Degeneration

BACKGROUND

Unhealthy habits, such as overeating processed and high-calorie foods, alcohol abuse, and smoking, negatively impact human health. It has been suggested that the inflammatory process and the resulting growth of nerve fibers within the intervertebral disc (IVD) fissures is the main reason for the pain accompanying IVD degeneration (IVDD).

OBJECTIVES

The aim of this study was to determine whether smoking, alcohol consumption, overweight/obesity, or diabetes comorbidity contribute to the development of IVDD and how the aforementioned factors affect the levels of brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), and growth associated protein 43 (GAP-43) in the study and control groups (intervertebral discs, IVDs from cadavers, and serum samples from voluntary blood donors).

METHODS

The study group comprised 113 patients diagnosed with IVDD who qualified for microdiscectomy. Two control groups (I and II) were used in this study. The first included 81 IVDs obtained from Caucasian human cadavers. Control group II, on the other hand, included serum samples obtained from 113 voluntary blood donors. The expression profiles of BDNF, GDNF, and GAP-43 were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Our statistical analysis confirmed that patients who were overweight/obese, smoked tobacco, consumed alcohol, or had diabetes had a higher risk of IVDD (OR > 1). Statistical analysis showed that BDNF, GAP-43, and GDNF concentrations were significantly higher in the IVDs and serum samples obtained from the study group compared to the control group (p < 0.05). In addition, higher levels of BDNF, GDNF, and GAP-43 were noted in IVDD patients who consumed alcohol, smoked tobacco, were overweight/obese, or had comorbid diabetes compared to patients without these risk factors (p < 0.05).

CONCLUSION

We showed that changes in energy metabolism, habits, and lifestyle, as well as the degenerative process of IVD in the lumbosacral spine contribute to changing the concentration profile of the analyzed neurotrophic factors.

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

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

A primary study on rat fetal development and brain-derived neurotrophic factor levels under the control of electromagnetic fields

Background

In previous researches, electromagnetic fields have been shown to adversely affect the behavior and biology of humans and animals; however, body growth and brain-derived neurotrophic factor levels were not evaluated.

Objective

The original investigation aimed to examine whether Electromagnetic Fields (EMF) exposure had adverse effects on spatial learning and motor function in rats and if physical activity could diminish the damaging effects of EMF exposure. In this study, we measured anthropometric measurements and brain-derived neurotrophic factor (BDNF) levels in pregnant rats' offspring to determine if Wi-Fi EMF also affected their growth. These data we report for the first time in this publication.

Methods

Twenty Albino-Wistar pregnant rats were divided randomly into EMF and control (CON) groups, and after delivery, 12 male fetuses were randomly selected. For assessing the body growth change of offspring beginning at delivery, then at 21 postnatal days, and finally at 56 post-natal days, the crown-rump length of the body was assessed using a digital caliper. Examining BDNF factor levels, an Enzyme-linked immunosorbent assay ELISA kit was taken. Bodyweight was recorded by digital scale.

Results

Outcomes of the anthropometric measurements demonstrated that EMF blocked body growth in rats exposed to EMF. The results of the BDNF test illustrated that the BDNF in the EMF liter group was remarkably decreased compared to the CON group. The results indicate that EMF exposure could affect BDNF levels and harm body growth in pregnant rats' offspring.

Conclusions

The results suggest that EMF exposure could affect BDNF levels and impair body growth in pregnant rats' offspring.

Effects of Exogenous Glucocorticoid Infusion on Appetitic Center Development in Postnatal Dairy Bull Calves

The objective of this study was to determine the effects of exogenous glucocorticoid administration on leptin concentrations and brain development markers, such as protein and hypothalamic gene expression, in dairy bull calves. Within 4 h of parturition, Holstein bulls were intravenously infused with either a low cortisol dose (LC; n = 9, 3.5 µg/kg of body weight (BW)), high cortisol dose (HC; n = 9, 7.0 µg/kg BW), or control (CON; n = 9, saline) dose, with a 2nd infusion 24 h postpartum. Jugular blood was collected prior to infusion and daily until the calves were euthanized (day 5). Cerebrospinal fluid (CSF) from the third ventricle and adipose (omental, perirenal, and mesenteric) and hypothalamic tissue were collected. The blood and CSF samples were analyzed for leptin concentrations. The data were analyzed using SAS. Serum (p = 0.013) and CSF (p = 0.005) leptin concentrations in HC- and LC-treated calves were decreased compared with CON-treated calves. Leptin protein expression was decreased (p < 0.044) in perirenal and omental adipose tissue of LC-treated calves compared with CON-treated calves. Gene abundance of brain-derived neurotrophic factor and fibroblast growth factors 1 and 2 were decreased (p < 0.006) in HC- and LC-treated calves compared with CON-treated calves. In summary, cortisol administered to dairy bull calves reduced leptin concentrations, decreased leptin protein expression in perirenal and omental adipose tissue, and altered gene expression in hypothalamic tissue.

Relationship between Brain-Derived Neurotrophic Factor and Cognitive Decline in Patients with Mild Cognitive Impairment and Dementia

In the last decade, increasing evidence has emerged linking alterations in the brain-derived neurotrophic factor (BDNF) expression with the development of Alzheimer's disease (AD). Because of the important role of BDNF in cognition and its association with AD pathogenesis, the aim of this study was to evaluate the potential difference in plasma BDNF concentrations between subjects with mild cognitive impairment (MCI; N = 209) and AD patients (N = 295) and to determine the possible association between BDNF plasma levels and the degree of cognitive decline in these individuals. The results showed a significantly higher (p < 0.001) concentration of plasma BDNF in subjects with AD (1.16; 0.13-21.34) compared with individuals with MCI (0.68; 0.02-19.14). The results of the present study additionally indicated a negative correlation between cognitive functions and BDNF plasma concentrations, suggesting higher BDNF levels in subjects with more pronounced cognitive decline. The correlation analysis revealed a significant negative correlation between BDNF plasma levels and both Mini-Mental State Examination (p < 0.001) and Clock Drawing test (p < 0.001) scores. In conclusion, the results of our study point towards elevated plasma BDNF levels in AD patients compared with MCI subjects, which may be due to the body's attempt to counteract the early and middle stages of neurodegeneration.

A comparative study of Western, high-carbohydrate, and standard lab diet consumption throughout adolescence on metabolic and anxiety-related outcomes in young adult male and female Long-Evans rats

Anxiety and obesity are prevalent health concerns that are affected by diet in rodents and humans. How diet influences the development and maintenance of anxiety and obesity has been challenging to characterize, in part, due to methodological differences in chosen experimental and control diets. Within the same experiment, anxiety- and obesity-related effects were characterized in rats fed a Western diet (WD) relative to two control diets. Sixty Long-Evans rats split equally by sex were given standard diet (SD), control (i.e., high-carbohydrate) diet (HCD), or WD from weaning until sacrifice in early adulthood. Anxiety-related behavior was characterized in a modified open field test (mOFT) that allowed for the measurement of defensive behaviors (e.g., hiding within a refuge area), in addition to traditional OF measures (e.g., time in center). Both anxiety-related behaviors and hippocampal CA3 BDNF revealed specific sex differences. Neither adolescent weight gain of male and female rats, nor total body weight in early adulthood, were dependent on administration of HCD or WD, although the WD group consumed the most calories. In males only, administration of either WD or HCD resulted in elevated leptin levels relative to administration of the SD. Results indicate that SDs and HCDs are two distinct types of control diets that can affect comparability of studies and that using an SD might reveal more subtle metabolic changes. Control diet choice should be strongly considered during study design and interpretation, depending on specific research goals. Such studies should include both males and females as these effects are sex-specific.

Synaptic plasticity and mental health: methods, challenges and opportunities

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

Plasma Amyloid-β dynamics in late-life major depression: a longitudinal study

Depressed individuals are twice as likely to develop Alzheimer's disease (AD) as compared to controls. Brain amyloid-β (Aβ) deposition is believed to have a major role in AD pathogenesis but studies also suggest associations of Aβ dynamics and depression. The aim of this study was to test if plasma Aβ levels are longitudinally associated to late-life depression. We measured plasma levels of amyloid-β_1-40 (Aβ40) and amyloid-β_1-42 (Aβ42) peptides longitudinally for three consecutive years in 48 cognitively intact elderly subjects with late-life major depressive disorder (LLMD) and 45 age-matched cognitively healthy controls. We found that the Aβ42/Aβ40 plasma ratio was significantly and steadily lower in depressed subjects compared to controls (p < 0.001). At screening, Aβ42/Aβ40 plasma did not correlate with depression severity (as measured with Hamilton Depression Scale) or cognitive performance (as measured with Mini-Mental State Examination) but was associated to depression severity at 3 years after adjustment for age, education, cognitive performance, and antidepressants use. This study showed that reduced plasma Aβ42/Aβ40 ratio is consistently associated with LLMD diagnosis and that increased severity of depression at baseline predicted low Aβ42/Aβ40 ratio at 3 years. Future studies are needed to confirm these findings and examine if the consistently lower plasma Aβ42/Aβ40 ratio in LLMD reflects increased brain amyloid deposition, as observed in AD subjects, and an increased risk for progressive cognitive decline and AD.

Dysregulated Methylation Patterns in Exon IV of the Brain-Derived Neurotrophic Factor (BDNF) Gene in Nicotine Dependence and Changes in BDNF Plasma Levels During Smoking Cessation

INTRODUCTION

Several studies reported dysregulated protein levels of brain-derived neurotrophic factor (BDNF) in smokers and during cessation. However, the epigenetic regulation of the BDNF gene has not yet been investigated. We measured the plasma levels of BDNF and the epigenetic regulation of exon IV of the BDNF gene in smokers compared to healthy controls over a cessation period of 14 days.

METHOD

We measured BDNF plasma levels and BDNF promoter methylation in 49 smokers and 51 non-smokers at baseline, day 7, and day 14 of smoking cessation. Mean methylation levels of 11 Cytosine Guanosine dinucleotides of exon IV of the BDNF gene were determined via bisulfite sequencing.

RESULTS

BDNF plasma and methylation levels were significantly lower in healthy controls when compared with smokers across all time points. BDNF levels for smokers decreased significantly during the cessation period. Comparing the sexes, female smokers showed significantly lower plasma BDNF levels than healthy controls at baseline and over 14 days of cessation. Male and female smokers showed significantly higher mean methylation rates than non-smokers at baseline. In male smokers, mean methylation levels decreased significantly during the cessation period.

CONCLUSION

Our findings replicate the findings of previous studies that BDNF plasma levels are altered in smokers. Furthermore, BDNF expression and gene methylation are altered during the first 14 days of cessation. Our novel findings of dysregulated methylation patterns in exon IV of the BDNF gene further support the thesis that BDNF plays a role in nicotine dependence.

Anorexia Nervosa-What Has Changed in the State of Knowledge about Nutritional Rehabilitation for Patients over the Past 10 Years? A Review of Literature

Anorexia nervosa (AN) is a psycho-metabolic disorder with a high risk of somatic complications such as refeeding syndrome (RFS) and carries the highest mortality rate of all psychiatric illnesses. To date, the consensus on the care for patients with AN has been based on recommendations for a combination of alimentation and psychotherapy. It is important to establish an initial caloric intake that will provide weight gain and minimize the risk of complications in the treatment of undernourished patients. Research over the past few years suggests that current treatment recommendations may be too stringent and should be updated. The aim of this paper is to systematize the current reports on nutritional rehabilitation in AN, to present the results of studies on the safe supplementation of patients and its potential impact on improving prognosis and the healing process. This review of literature, from 2011-2021, describes the changing trend in the nutritional protocols used and the research on their efficacy, safety, and long-term effects. In addition, it presents previous reports on the potential benefits of introducing vitamin, pro-and prebiotic and fatty acid supplementation.

The relationship between job stress and job burnout moderated by BDNF rs6265 polymorphism

RATIONALE

Job stress can lead to job burnout, and BDNF polymorphism has been found to be involved in its psychopathological mechanism. Research needs a better understanding of the important role of gene × environment (i.e., BDNF polymorphism × job stress) interaction on job burnout.

OBJECTIVE

This study aimed to explore how BDNF rs6265 polymorphism may moderate the relationship between job stress and job burnout.

METHODS

Three hundred forty-one healthy participants (187 males and 154 females) from a Chinese university were included. The present study used a standardized questionnaire including demographic characteristics, job stress assessed by the House and Rizzo's Work Stress Scale, and job burnout assessed by the Maslach Burnout Inventory-General Survey. The BDNF rs6265 polymorphism was genotyped.

RESULTS

Job stress showed a positive correlation with emotional exhaustion (p < 0.001), cynicism (p < 0.001), and reduced personal accomplishment (p < 0.01). The main effects of BDNF rs6265 polymorphism on emotional exhaustion and cynicism were significant [F_(1,333) = 5.136, p = 0.024; F_(1,333) = 4.175, p = 0.042, respectively]. The interaction between job stress and BDNF rs6265 on cynicism was significant (△ R² = 0.013, p = 0.014) after controlling for age, sex, education, and position, indicating that individuals with BDNF rs6265 TT genotype showed higher level of cynicism when in high job stress.

CONCLUSIONS

The results provided evidence for the association of BDNF gene rs6265 polymorphism, job stress, and their interaction with job burnout. Individuals with TT genotype in BDNF rs6265 might be susceptible to stressful situations, which would lead to cynicism.

A randomized controlled trial of exercise on augmenting the effects of cognitive remediation in persons with severe mental illness

BACKGROUND

Preliminary evidence suggests that aerobic exercise may augment the effects of cognitive remediation on improving cognitive functioning in severe mental illness. It has also been hypothesized that increases in cognitive functioning associated with adding exercise are mediated by increases in brain derived neurotrophic factor (BDNF). However, rigorous controlled trials are lacking.

METHODS

A randomized controlled trial was conducted to explore whether adding a 30-h aerobic exercise program over 10 weeks to an equally intensive cognitive remediation program (CR + E) improved cognitive functioning more than cognitive remediation alone (CR-Only). Thirty-four participants with schizophrenia or bipolar disorder were randomly assigned to CR + E or CR-Only, and cognitive functioning was assessed at baseline and post-treatment. Total and mature BDNF were measured in blood serum at baseline, Week-5 pre- and post-exercise, and Week-10 pre- and post-exercise.

RESULTS

Participants in both conditions had high levels of engagement in the interventions and improved significantly in cognitive functioning, but did not differ in amount of cognitive change. The groups also did not differ in changes in BDNF from pre-to post-exercise at Weeks 5 or 10, nor in resting BDNF levels. Exploratory analyses indicated that higher body mass index (BMI) significantly predicted attenuated improvement in cognitive functioning for both groups.

DISCUSSION

Exercise did not augment the effects of cognitive remediation in persons with severe mental illness, possibly because the cognitive remediation program resulted in strong gains in cognitive functioning. Moderate aerobic exercise does not appear to reliably increase BDNF levels in persons with severe mental illness. CLINICALTRIALS.

GOV IDENTIFIER

NCT02326389.

The relationship between brain-derived neurotrophic factor and metabolic syndrome in patients with chronic schizophrenia: A systematic review

BACKGROUND & AIMS

Schizophrenia is a serious long-term disorder in which the metabolic complications and abnormalities of the brain-derived neurotrophic factor (BDNF) can be found. In this study, we conducted a systematic review of the relationship between BDNF, metabolic syndrome (MetS) and its components in schizophrenic patients.

METHODS

Data were collected mainly from PubMed, Google Scholar, Scopus, and ProQuest databases. The keywords related to the BDNF, MetS, schizophrenia were searched. Two reviewers independently screened 1061 abstracts. And eventually, a total of 7 studies (6 observational and 1 interventional) was included in the systematic reviews.

RESULTS

Four of the 7 study ascertained statistically significant inverse relationship between serum BDNF levels and MetS in schizophrenic patients. While in the other two studies, there was no inverse relationship. In the last selected study, the researchers found a weak association between the Val66Met polymorphism in BDNF Gene and clozapine-induced MetS.

CONCLUSION

Although this relationship could not be determined but BDNF levels appear to be reduced in schizophrenic patients with MetS and factors such as sex and antipsychotic class differentiation, sampling and methodology and episodes of illness could play a role in the results and outcomes.

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

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

Brain-derived neurotrophic factor in cerebrospinal fluid and plasma is not a biomarker for Huntington's disease

Brain-derived neurotrophic factor (BDNF) is implicated in the survival of striatal neurons. BDNF function is reduced in Huntington's disease (HD), possibly because mutant huntingtin impairs its cortico-striatal transport, contributing to striatal neurodegeneration. The BDNF trophic pathway is a therapeutic target, and blood BDNF has been suggested as a potential biomarker for HD, but BDNF has not been quantified in cerebrospinal fluid (CSF) in HD. We quantified BDNF in CSF and plasma in the HD-CSF cohort (20 pre-manifest and 40 manifest HD mutation carriers and 20 age and gender-matched controls) using conventional ELISAs and an ultra-sensitive immunoassay. BDNF concentration was below the limit of detection of the conventional ELISAs, raising doubt about previous CSF reports in neurodegeneration. Using the ultra-sensitive method, BDNF concentration was quantifiable in all samples but did not differ between controls and HD mutation carriers in CSF or plasma, was not associated with clinical scores or MRI brain volumetric measures, and had poor ability to discriminate controls from HD mutation carriers, and premanifest from manifest HD. We conclude that BDNF in CSF and plasma is unlikely to be a biomarker of HD progression and urge caution in interpreting studies where conventional ELISA was used to quantify CSF BDNF.

Psychedelics and Neuroplasticity: A Systematic Review Unraveling the Biological Underpinnings of Psychedelics

Clinical studies suggest the therapeutic potential of psychedelics, including ayahuasca, DMT, psilocybin, and LSD, in stress-related disorders. These substances induce cognitive, antidepressant, anxiolytic, and antiaddictive effects suggested to arise from biological changes similar to conventional antidepressants or the rapid-acting substance ketamine. The proposed route is by inducing brain neuroplasticity. This review attempts to summarize the evidence that psychedelics induce neuroplasticity by focusing on psychedelics' cellular and molecular neuroplasticity effects after single and repeated administration. When behavioral parameters are encountered in the selected studies, the biological pathways will be linked to the behavioral effects. Additionally, knowledge gaps in the underlying biology of clinical outcomes of psychedelics are highlighted. The literature searched yielded 344 results. Title and abstract screening reduced the sample to 35; eight were included from other sources, and full-text screening resulted in the final selection of 16 preclinical and four clinical studies. Studies (n = 20) show that a single administration of a psychedelic produces rapid changes in plasticity mechanisms on a molecular, neuronal, synaptic, and dendritic level. The expression of plasticity-related genes and proteins, including Brain-Derived Neurotrophic Factor (BDNF), is changed after a single administration of psychedelics, resulting in changed neuroplasticity. The latter included more dendritic complexity, which outlasted the acute effects of the psychedelic. Repeated administration of a psychedelic directly stimulated neurogenesis and increased BDNF mRNA levels up to a month after treatment. Findings from the current review demonstrate that psychedelics induce molecular and cellular adaptations related to neuroplasticity and suggest those run parallel to the clinical effects of psychedelics, potentially underlying them. Future (pre)clinical research might focus on deciphering the specific cellular mechanism activated by different psychedelics and related to long-term clinical and biological effects to increase our understanding of the therapeutic potential of these compounds.

MTORC1 signaling as a biomarker in major depressive disorder and its pharmacological modulation by novel rapid-acting antidepressants

Major depressive disorder (MDD) is a multifactorial psychiatric disorder with obscure pathophysiology. A biomarker-based approach in combination with standardized interview-based instruments is needed to identify MDD subtypes and novel therapeutic targets. Recent findings support the impairment of the mammalian target of rapamycin complex 1 (mTORC1) in MDD. No well-established biomarkers of mTORC1 disease- and treatment-modulated activity are currently available for use in early phase antidepressant drug (AD) development. This review aims to summarize biomarkers of mTORC1 activity in MDD and to suggest how these could be implemented in future early clinical trials on mTORC1 modulating ADs. Therefore, a PubMed-based narrative literature review of the mTORC1 involvement in MDD was performed. We have summarized recent pre-clinical and clinical findings linking the MDD to the impaired activity of several key biomarkers related to mTORC1. Also, cases of restoration of these impairments by classical ADs and novel fast-acting investigational ADs are summarized. The presented biomarkers may be used to monitor pharmacological effects by novel rapid-acting mTORC1-targeting ADs. Based on findings in the peripheral blood mononuclear cells, we argue that those may serve as an ex vivo model for evaluation of mTORC1 activity and propose the use of the summarized biomarkers for this purpose. This could both facilitate the selection of a pharmacodynamically active dose and guide future early clinical efficacy studies in MDD. In conclusion, this review provides a blueprint for the rational development of rapid-acting mTORC1-targeting ADs.

Brain-derived neurotrophic factor (BDNF) levels in first-episode schizophrenia and healthy controls: A comparative study

BACKGROUND

Abnormalities in brain development and plasticity have been associated with the pathophysiology of schizophrenia. The role of brain-derived neurotrophic factor (BDNF) in schizophrenia is the recent area of interest because it regulates neurogenesis. The current study aimed to assess and compare serum BDNF levels between first-episode schizophrenia patients and healthy controls, and evaluate its correlation with the socio-demographic and clinical variables.

METHODOLOGY

It was a cross-sectional comparative study for the assessment of serum BDNF levels between patients with first-episode schizophrenia (N=50) and healthy controls (N-50) conducted in the Department of Psychiatry at a tertiary care public hospital attached to a medical school in North India. Participants were assessed for the socio-demographic parameters, nicotine dependence, and clinical details using structured scales. Serum BDNF level estimated using the sandwich ELISA technique. The comparison between the groups was done by using a Student t-test or chi-square test. Spearman correlation was performed between mean BDNF scores and demographic or illness variables in both first-episode schizophrenia and healthy control groups.

RESULTS

There was a significantly lower mean score of total serum BDNF levels in first-episode schizophrenia patients as compared to controls (8.44 ± 1.54 vs 10.44 ± 2.04; t = 5.52, p < 0.001; 95% CI = 1.28-2.71). The total FTND scores for smokeless tobacco use were negatively correlated to BDNF levels among healthy controls (r=-0.30, p=0.03) as well as in the first-episode schizophrenia group (r=-0.32, p= 0.04). None of the other illness-related variables were correlated to serum BDNF values in the first episode schizophrenia group.

CONCLUSION

Individuals with first-episode schizophrenia have lower serum BDNF levels than healthy controls. The illness-related factors such as duration of untreated psychosis or psychopathology were not correlated with BDNF levels. Thus abnormal signaling of BDNF can lead to abnormal brain functioning which can make an individual more susceptible to schizophrenia.

Plasma Brain-Derived Neurotrophic Factor (BDNF) Concentration and BDNF/TrkB Gene Polymorphisms in Croatian Adults with Asthma

Brain-derived neurotrophic factor (BDNF) and its tropomyosin-related kinase B (TrkB) receptor might contribute to normal lung functioning and immune responses; however, their role in asthma remains unclear. Plasma BDNF concentrations, as well as BDNF and NTRK2 (TrkB gene) polymorphisms, were investigated in 120 asthma patients and 120 healthy individuals using enzyme-linked immunosorbent assay and polymerase chain reaction, respectively. The genotype and allele frequencies of BDNF Val66Met (rs6265) and NTRK2 rs1439050 polymorphisms did not differ between healthy individuals and asthma patients, nor between patients grouped according to severity or different asthma phenotypes. Although plasma BDNF concentrations were higher among healthy subjects carrying the BDNF Val66Met GG genotype compared to the A allele carriers, such differences were not detected in asthma patients, suggesting the influences of other factors. Plasma BDNF concentration was not affected by NTRK2 rs1439050 polymorphism. Asthma patients had higher plasma BDNF concentrations than control subjects; however, no differences were found between patients subdivided according to asthma severity, or Type-2, allergic, and eosinophilic asthma. Higher plasma BDNF levels were observed in asthma patients with aspirin sensitivity and aspirin-exacerbated respiratory disease. These results suggest that plasma BDNF may serve as a potential peripheral biomarker for asthma, particularly asthma with aspirin sensitivity.

α2-Adrenergic Disruption of β Cell BDNF-TrkB Receptor Tyrosine Kinase Signaling

Adrenergic signaling is a well-known input into pancreatic islet function. Specifically, the insulin-secreting islet β cell expresses the Gi/o-linked α2-adrenergic receptor, which upon activation suppresses insulin secretion. The use of the adrenergic agonist epinephrine at micromolar doses may have supraphysiological effects. We found that pretreating β cells with micromolar concentrations of epinephrine differentially inhibited activation of receptor tyrosine kinases. We chose TrkB as an example because of its relative sensitivity to the effects of epinephrine and due to its potential regulatory role in the β cell. Our characterization of brain-derived neurotrophic factor (BDNF)-TrkB signaling in MIN6 β cells showed that TrkB is activated by BDNF as expected, leading to canonical TrkB autophosphorylation and subsequent downstream signaling, as well as chronic effects on β cell growth. Micromolar, but not nanomolar, concentrations of epinephrine blocked BDNF-induced TrkB autophosphorylation and downstream mitogen-activated protein kinase pathway activation, suggesting an inhibitory phenomenon at the receptor level. We determined epinephrine-mediated inhibition of TrkB activation to be Gi/o-dependent using pertussis toxin, arguing against an off-target effect of high-dose epinephrine. Published data suggested that inhibition of potassium channels or phosphoinositide-3-kinase signaling may abrogate the negative effects of epinephrine; however, these did not rescue TrkB signaling in our experiments. Taken together, these results show that (1) TrkB kinase signaling occurs in β cells and (2) use of epinephrine in studies of insulin secretion requires careful consideration of concentration-dependent effects. BDNF-TrkB signaling in β cells may underlie pro-survival or growth signaling and warrants further study.

Anorexia nervosa, zinc deficiency and the glutamate system: The ketamine option

Anorexia nervosa (AN) is a severe, biological brain disorder with significant medical risks and a tenacious development over time. Unfortunately, few treatments show efficacy in people with AN although numerous therapies including pharmacological have been explored. Zinc deficiency has been implicated in AN and zinc is important in a large range of processes in the brain. In particular, it is an allosteric modulator of NMDA receptors - the maintenance of zinc levels within a normal, narrow range is essential for glutamatergic functioning. Chronic zinc deficiency increases neuronal stores of calcium and reduces direct modulation of NMDA receptors which collectively lead to overactivation and upregulation of NMDA receptors. This may facilitate pathologically high levels of glutamate, calcium influx and subsequent excitotoxicity, which can disrupt synaptogenesis and synaptic plasticity. While studies of zinc supplementation in AN have shown some promise, the efficacy of this treatment is limited. This may be due to AN illness chronicity and the significant changes already made, as well as a reduced potency of zinc to inhibit NMDA receptors in a pathological state. Thus, we propose that the safe (at low doses) yet more potent NMDA receptor antagonist, ketamine, may act to normalise a perturbed glutamatergic system and increase synaptogenesis in the short term. This 'kickstart' via ketamine could then allow zinc supplementation and other forms of treatment to enhance recovery in AN.

BDNF Val66Met polymorphism alters food intake and hypothalamic BDNF expression in mice

Obesity, a rising public health burden, is a multifactorial disease with an increased risk for patients to develop several pathological conditions including type 2 diabetes mellitus, hypertension, and cardiovascular disease. Increasing evidence suggests a relationship between the human brain-derived neurotrophic factor (BDNF) Val66Met single-nucleotide polymorphism (SNP) and obesity, although the underlying mechanisms of this connection are still not completely understood. In the present study, we found that homozygous knock-in BDNF^Met/Met mice were overweight and hyperphagic compared to wildtype BDNF^Val/Val mice. Increased food intake was associated with reduction of total BDNF and BDNF1, BDNF4 and BDNF6 transcripts in the hypothalamus of BDNF^Met/Met mice. In contrast, in the white adipose tissue total BDNF and Glut4 expression levels were augmented, while sirtuin 1 and leptin receptor (Ob-R) expression levels were reduced in BDNF^Met/Met mice. Moreover, plasmatic leptin levels were decreased in BDNF^Met/Met mice. However, BDNF^Val/Val and BDNF^Met/Met mice showed a similar response to the insulin tolerance test and glucose tolerance test. Altogether, these results suggest that BDNF Val66Met SNP strongly contributes to adipose tissue pathophysiology, resulting in reduced circulating leptin levels and hypothalamic expression of BDNF, which, in turn, promote increased food intake and overweight in BDNF^Met/Met mice.

BDNF Serum Levels are Associated With White Matter Microstructure in Schizophrenia - A Pilot Study

Brain derived neurotrophic factor (BDNF) has been implicated in the pathophysiology of schizophrenia. As BDNF regulates axonal and dendritic growth, altered BDNF levels in schizophrenia patients might underlie changes in structural connectivity that have been identified by magnetic resonance imaging (MRI). We investigated a possible correlation between BDNF serum levels, fiber tract architecture, and regional grey matter volumes in 19 schizophrenia patients and a gender- and age-matched control group. Two patients had to be excluded due to abnormalities in their MRI scans. Serum samples were obtained to determine BDNF levels, and T1- as well as diffusion-weighted sequences were acquired. We, then, investigated correlations between BDNF serum levels with neuroimaging parameters, using Voxel-based Morphometry (VBM) and Tract-based Spatial Statistics (TBSS). We found a significant negative correlation between BDNF serum levels and FA values in the right inferior fronto-occipital fasciculus and the right superior longitudinal fasciculus. These regions also showed a decrease in AD values in schizophrenia patients. Grey matter volumes were reduced in patients but there was no correlation between regional grey matter volumes and BDNF. The right superior longitudinal fasciculus has been repeatedly identified to exhibit microstructural changes in schizophrenia patients. Our findings of a negative correlation between BDNF and FA values in patients might indicate that BDNF is upregulated to compensate decreased structural connectivity as it induces neural plasticity and shows increased levels in damaged tissue. These findings of our pilot study are encouraging leads for future research in larger samples.

The Brain-Derived Neurotrophic Factor (BDNF) gene Val66Met (rs6265) polymorphism and stress among preclinical medical students in Malaysia

OBJECTIVE

This study aimed to determine the allelic and genotypic association of the Val66Met (rs6265) polymorphism in the BDNF gene with stress levels in preclinical medical students of Universiti Sultan Zainal Abidin (UniSZA), Terengganu, Malaysia.

METHODS

In this cross-sectional study, we recruited all 122 preclinical medical students. The validated depression anxiety stress scales-21 (DASS-21) questionnaire was distributed and blood samples were collected from each subject for DNA extraction. Genotyping analysis of the BDNF gene (Val66Met) polymorphism was performed via an optimised polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

A total of 105 subjects agreed to participate in this study. Indian students were found to more likely have the Val/Val genotype, whereas Malay students were more likely to have the Met/Met genotype (p = 0.027). Individuals carrying any one of the three BDNF genotypes (Val/Val, Val/Met and Met/Met) differed significantly from each other in terms of their perception of stress (p = 0.010); students carrying the Val/Val genotype (M = 10.6) perceived significantly lower stress than students carrying the Val/Met (M = 14) and Met/Met (M = 15.1) genotypes.

CONCLUSION

In our study, the Met-allele was associated with higher stress levels. To the best of our knowledge, this is the first study investigating this stress-related gene in medical students. The findings from this study should trigger more investigators to focus on the impact of stress on genetically predisposed medical students.

Plasma and serum brain-derived neurotrophic factor (BDNF) levels and their association with neurocognition in at-risk mental state, first episode psychosis and chronic schizophrenia patients

Objectives: Brain-derived neurotrophic factor (BDNF) is involved in numerous cognitive processes. Since cognitive deficits are a core feature of psychotic disorders, the investigation of BDNF levels in psychosis and their correlation with cognition has received increased attention. However, there are no studies investigating BDNF levels in individuals with an at-risk mental state (ARMS) for psychosis. Hence, the aims of the present study were: (1) assessing peripheral BDNF levels across different (potential) stages of psychosis; (2) investigating their association with cognition.Methods: Plasma and serum BDNF levels and neuropsychological performance were assessed in 16 ARMS, six first-episode psychosis (FEP), and 11 chronic schizophrenia (CS) patients. Neuropsychological assessment covered intelligence, verbal memory, working memory, attention and executive functioning.Results: Both plasma and serum BDNF levels were highest in CS, intermediate in FEP and lowest in ARMS. Multiple regression analysis revealed a significant positive association of plasma BDNF levels with planning ability across all groups.Conclusions: The lower peripheral BDNF levels in ARMS compared to FEP and CS might point towards an important drop of this neurotrophin prior to the onset of frank psychosis. The associations of peripheral BDNF with planning-abilities match previous findings.

Plasma brain-derived neurotrophic factor (BDNF) concentration and the BDNF Val66Met polymorphism in suicide: a prospective study in patients with depressive disorder

Purpose

The relationship was investigated between brain-derived neurotrophic factor (BDNF) concentrations, a BDNF polymorphism (196G>A), and the response to selective serotonin reuptake inhibitors (SSRIs) among Chinese patients with major depressive disorder (MDD).

Patients and methods

A total of 125 patients and 91 healthy controls were enrolled. The disease progression and treatment responses were evaluated using the Hamilton depression rating scale (HAMD24), the Hamilton anxiety scale, the Beck depression index, and BDNF concentrations at the baseline, 4, 8, and 12 weeks after treatment. Responders were defined as patients with at least a 50% decrease in the HAMD24.

Results

The BDNF concentrations were significantly lower in MDD (947±297 vs 1187±236 pg/mL, p=0.019), in MDD with attempted suicide than those without (779±231 vs 993±298, p=0.024) at the baseline. The BDNF concentrations remarkably increased in response to SSRI treatment. Significant correlations were noted between the BDNF concentrations and suicide ideation or attempted suicide (p<0.01), but not with HAMD24 or depression. BDNF 196G>A correlated with neither suicide ideation nor treatment responses.

Conclusion

BDNF concentrations were significantly lower in patients with attempted suicide/ideation. BDNF concentrations could serve as a response marker for antidepressant treatment in MDD.

Increased plasma Brain-Derived Neurotrophic Factor (BDNF) levels in females with schizophrenia

Brain-Derived Neurotrophic Factor (BDNF) acts as a critical regulator of synaptogenesis and synaptic plasticity. Sex differences have been demonstrated in many aspects of schizophrenia. This study tested for sex-specific differences in peripheral BDNF levels in people with schizophrenia and healthy controls. We measured circulating plasma BDNF levels in 95 people with schizophrenia and 80 healthy controls. Plasma BDNF levels were significantly elevated in females with schizophrenia compared to males with schizophrenia and to female healthy controls. These results suggest that sex differences in peripheral BDNF levels may contribute to other sex related differences in schizophrenia.

Demographic and lifestyle correlates of brain-derived neurotrophic factor in a working population: The Furukawa Nutrition and Health Study

This study aimed to examine the cross-sectional association of demographic and lifestyle factors with serum brain-derived neurotrophic factor (BDNF) concentrations in a Japanese working population. Participants were 1678 men and 172 women aged 19-69 years who received health check-ups and participated in a nutrition and health survey. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) scale. Dietary intake was assessed using a validated self-administered diet history questionnaire. Serum BDNF concentrations were measured using a solid phase sandwich enzyme-linked immunosorbent assay. Multiple linear regression analysis was used to estimate the mean and 95% confidence interval of serum BDNF concentrations according to demographic and lifestyle factors. Higher body mass index (BMI) was significantly associated with higher circulating BDNF concentrations. Current smokers had significantly higher mean BDNF concentrations than never-smokers. BDNF concentrations were not associated with folate and 25-hydroxyvitamin D concentrations in serum, or dietary eicosapentaenoic acid and docosahexaenoic acid intake. Serum BDNF concentrations were not associated with depressive symptoms or CES-D score per se. In this study, higher BMI and smoking were associated with higher concentrations of serum BDNF, while nutrients that have been linked to depression were not associated with BDNF concentrations among Japanese workers.

Dental pulp stem cells: Novel cell-based and cell-free therapy for peripheral nerve repair

The regeneration of peripheral nerves comprises complicated steps involving a set of cellular and molecular events in distal nerve stumps with axonal sprouting and remyelination. Stem cell isolation and expansion for peripheral nerve repair (PNR) can be achieved using a wide diversity of prenatal and adult tissues, such as bone marrow or brain tissues. The ability to obtain stem cells for cell-based therapy (CBT) is limited due to donor site morbidity and the invasive nature of the harvesting process. Dental pulp stem cells (DPSCs) can be relatively and simply isolated from the dental pulps of permanent teeth, extracted for surgical or orthodontic reasons. DPSCs are of neural crest origin with an outstanding ability to differentiate into multiple cell lineages. They have better potential to differentiate into neural and glial cells than other stem cell sources through the expression and secretion of certain markers and a range of neurotropic factors; thus, they should be considered a good choice for PNR using CBT. In addition, these cells have paracrine effects through the secretion of neurotrophic growth factors and extracellular vesicles, which can enhance axonal growth and remyelination by decreasing the number of dying cells and activating local inhabitant stem cell populations, thereby revitalizing dormant or blocked cells, modulating the immune system and regulating inflammatory responses. The use of DPSC-derived secretomes holds great promise for controllable and manageable therapy for peripheral nerve injury. In this review, up-to-date information about the neurotrophic and neurogenic properties of DPSCs and their secretomes is provided.

Decreased Serum Brain-Derived Neurotrophic Factor (BDNF) Levels in Patients with Alzheimer's Disease (AD): A Systematic Review and Meta-Analysis

Findings from previous studies reporting the levels of serum brain-derived neurotrophic factor (BDNF) in patients with Alzheimer's disease (AD) and individuals with mild cognitive impairment (MCI) have been conflicting. Hence, we performed a meta-analysis to examine the aggregate levels of serum BDNF in patients with AD and individuals with MCI, in comparison with healthy controls. Fifteen studies were included for the comparison between AD and healthy control (HC) (n = 2067). Serum BDNF levels were significantly lower in patients with AD (SMD: -0.282; 95% confidence interval [CI]: -0.535 to -0.028; significant heterogeneity: I² = 83.962). Meta-regression identified age (p < 0.001) and MMSE scores (p < 0.001) to be the significant moderators that could explain the heterogeneity in findings in these studies. Additionally, there were no significant differences in serum BDNF levels between patients with AD and MCI (eight studies, n = 906) and between MCI and HC (nine studies, n = 5090). In all, patients with AD, but not MCI, have significantly lower serum BDNF levels compared to healthy controls. This meta-analysis confirmed the direction of change in serum BDNF levels in dementia. This finding suggests that a significant change in peripheral BDNF levels can only be detected at the late stage of the dementia spectrum. Molecular mechanisms, implications on interventional trials, and future directions for studies examining BDNF in dementia were discussed.

Changes in Circulating BDNF in relation to Sex, Diet, and Exercise: A 12-Week Randomized Controlled Study in Overweight and Obese Participants

Circulating BDNF is higher in women than in men and suggested to be affected by changes in food intake, body weight, and exercise. The purpose of this study was to compare BDNF concentrations in women and men during a 12-week weight loss intervention. Using a previously published 12-week randomized study, serum BDNF was assessed at baseline and after 12 weeks using an enzyme-linked immunosorbent assay method. Fifty overweight or obese but healthy individuals (26 women, mean age of 36.4 ± 7.9 years; 24 men, mean age of 38.0 ± 5.9 years) were included and allocated into three groups: exercise-only (EXO; 12 weeks of aerobic exercise and isocaloric diet), diet-only (DIO; 8 weeks of very low energy diet (VLED 600 kcal/day) followed by a 4-week weight maintenance diet), or diet and exercise (DEX; 12 weeks of aerobic exercise in parallel with 8 weeks of VLED (800 kcal/day) followed by a 4-week weight maintenance diet). At baseline, BDNF levels were 25% higher in women compared to men (p=0.006). Body weight was reduced in all intervention groups (p < 0.006). Exercise (EXO group) induced a 22% reduction in circulating BDNF in men (p=0.037) and women (p=0.080). In the DIO and DEX groups, a significant reduction in BDNF levels (29.9%; p=0.035 and 32.5%; p=0.003, respectively) was observed in women but not in men. In conclusion, circulating BDNF was significantly changed by diet alone or combined with exercise in women and only by exercise alone in men. This suggests that changes in circulating BDNF depend on weight loss methods (diet/exercise) as well as sex.

BDNF, endurance activity, and mechanisms underlying the evolution of hominin brains

OBJECTIVES

As a complex, polygenic trait, brain size has likely been influenced by a range of direct and indirect selection pressures for both cognitive and non-cognitive functions and capabilities. It has been hypothesized that hominin brain expansion was, in part, a correlated response to selection acting on aerobic capacity (Raichlen & Polk, 2013). According to this hypothesis, selection for aerobic capacity increased the activity of various signaling molecules, including those involved in brain growth. One key molecule is brain-derived neurotrophic factor (BDNF), a protein that regulates neuronal development, survival, and plasticity in mammals. This review updates, partially tests, and expands Raichlen and Polk's (2013) hypothesis by evaluating evidence for BDNF as a mediator of brain size.

DISCUSSION

We contend that selection for endurance capabilities in a hot climate favored changes to muscle composition, mitochondrial dynamics and increased energy budget through pathways involving regulation of PGC-1α and MEF2 genes, both of which promote BDNF activity. In addition, the evolution of hairlessness and the skin's thermoregulatory response provide other molecular pathways that promote both BDNF activity and neurotransmitter synthesis. We discuss how these pathways contributed to the evolution of brain size and function in human evolution and propose avenues for future research. Our results support Raichlen and Polk's contention that selection for non-cognitive functions has direct mechanistic linkages to the evolution of brain size in hominins.

Predicting relapse in schizophrenia: Is BDNF a plausible biological marker?

Understanding the biological processes that underlie why patients relapse is an issue of fundamental importance to the detection and prevention of relapse in schizophrenia. Brain Derived Neurotrophic Factor (BDNF), a facilitator of brain plasticity, is reduced in patients with schizophrenia. In the present study, we examined whether decreases in plasma BDNF levels could be used as a biological predictor of relapse in schizophrenia. A total of 221 patients were prospectively evaluated for relapse over 30months in the Preventing Relapse in Schizophrenia: Oral Antipsychotics Compared to Injectables: eValuating Efficacy (PROACTIVE) study. Serial blood samples were collected at a maximum of 23 time points during the 30-month trial and BDNF levels were measured in plasma samples by ELISA. Receiver Operating Characteristic (ROC) curve analysis indicated that BDNF was not a significant predictor of relapse, hospitalization or exacerbation. Regardless of treatment group (oral second generation antipsychotic vs. long-acting injectable risperidone microspheres), baseline BDNF value did not differ significantly between those who experienced any of the adverse outcomes and those who did not. While contrary to the study hypothesis, these robust results offer little support for the use of plasma BDNF alone as a biomarker to predict relapse in schizophrenia.

Sex Differences in the Impact of BDNF Genotype on the Longitudinal Relationship between Physical Activity and Cognitive Performance

BACKGROUND

Physical activity may preserve cognitive function in older adults, but benefits vary by sex and genetic factors.

OBJECTIVE

We tested the longitudinal association between physical activity and cognitive performance to de termine whether a common genetic polymorphism for brain-derived neurotrophic factor (BDNF Val66Met) moderated this effect.

METHODS

In a 12-year longitudinal population-based sample of older adults (n = 2,218), we used growth curve modeling to investigate whether the benefits of physical activity on cognitive preservation differed by BDNF genotype and sex across multiple cognitive domains including processing speed, attention, working memory, and episodic verbal memory.

RESULTS

The relationship between physical activity and cognitive performance was dependent on BDNF carrier status in males (Δχ2 [Δdf] = 12.94 [4], p = 0.01), but not in females (Δχ2 [Δdf] = 4.38 [4], p = 0.36). Cognition benefited from physical activity in male BDNF met noncarriers, but not met carriers, whereas cognition was not statistically significantly related to physical activity in females regardless of genotype.

CONCLUSION

We observed longitudinal, but not cross-sectional, effects of physical activity on cognitive performance. Our study highlights the importance of longitudinal follow-up and consideration of sex differences in the relationships between physical activity, BDNF genotype, and cognitive decline. The findings contribute to understanding gene-lifestyle interactions in promoting cognitive health.

Serum Brain-Derived Neurotrophic Factor, and Plasma Catecholamine Metabolites in People with Major Depression: Preliminary Cross-Sectional Study

BACKGROUND

There are complicated interactions between catecholaminergic neurons and brain-derived neurotrophic factor (BDNF) in the brain. However, no reports have addressed the relationship among 3-methoxy-4-hydroxyphenylglycol (MHPG), homovanillic acid (HVA), and BDNF in the blood.

OBJECTIVE

This paper sought to investigate correlations between serum BDNF and plasma levels of MHPG and HVA in people with major depression (MD).

MATERIALS AND METHODS

A total of 148 patients (male/female 65/83, age 49.5 ± 12.1 years old) who satisfied criteria for MD based on the Diagnostic and Statistical Manual of Mental Disorders IV were enrolled in the present study. Plasma levels of MHPG and HVA were analyzed using high-performance liquid chromatography, and serum BDNF was measured using ELISA.

RESULTS

No interactions were observed between plasma HVA levels (mean ± SD = 4.5 ± 1.5 ng/mL) and age, sex, HAMD scores, or serum BDNF levels (mean ± SD = 9.8 ± 2.9 ng/mL). No correlations were not also observed between plasma MHPG levels (mean ± SD = 5.9 ± 2.1 ng/mL) and age, sex, the HAMD17 scores (mean ± SD = 22.2 ± 2.9 ng/mL), or serum BDNF levels. Serum BDNF levels were negatively associated with HAMD17 scores.

CONCLUSION

The results suggest that there are no significant correlations between catecholamine metabolites and BDNF in the blood for MDD patients.

The role of DNA methylation in the association between childhood adversity and cardiometabolic disease

Growing evidence suggests that adverse environmental stimuli, especially during sensitive periods in early life, may lead to cardiometabolic disease in later life. However, the underlying biological mechanisms remain a mystery. Recent studies inferred that epigenetic modifications are likely involved. We review recent studies, primarily focused on the findings from human studies, to indicate the role of DNA methylation in the associations between childhood adversity and cardiometabolic disease in adulthood. In particular, we focused on DNA methylation modifications in genes regulating the hypothalamus-pituitary-adrenal axis as well as the immune system.

Meta-Analysis of BDNF Levels in Autism

Brain-derived neurotrophic factor (BDNF) centrally mediates growth, differentiation and survival of neurons, and the synaptic plasticity that underlies learning and memory. Recent meta-analyses have reported significantly lower peripheral BDNF among individuals with schizophrenia, bipolar disorder, and depression, compared with controls. To evaluate the role of BDNF in autism, and to compare autism to psychotic-affective disorders with regard to BDNF, we conducted a meta-analysis of BDNF levels in autism. Inclusion criteria were met by 15 studies, which included 1242 participants. The meta-analysis estimated a significant summary effect size of 0.33 (95 % CI 0.21-0.45, P < 0.001), suggesting higher BDNF in autism than in controls. The studies showed notable heterogeneity, but no evidence of publication biases. Higher peripheral BDNF in autism is concordant with several neurological and psychological theories on the causes and symptoms of this condition, and it contrasts notably with the lower levels of BDNF found in schizophrenia, bipolar disorder, and depression.

Association of Val66Met polymorphism at brain derived neurotrophic factor gene with depression among Chinese adolescents after Wenchuan earthquake: An 18months longitudinal study

To longitudinally investigate the association of Val66Met polymorphism at brain derived neurotrophic factor (BDNF) gene (BDNF) with depression in Chinese Han adolescents after the 2008 Wenchuan earthquake, BDNF Val66Met was identified by polymerase chain reaction-restriction fragment length polymorphism analyses and verified by DNA sequencing. Depression was assessed by Beck Depression Inventory (BDI) among high school students at 6, 12 and 18months after the earthquake. The results showed that the females constantly had higher depression prevalence than the males during the follow-up in the Met allele carriers, but not in the Val/Val homozygotes. When compared to that at 6months, the prevalence was lowered at 12months in the male Met allele carriers, and at 18months in all the females and the male Met allele carriers. Moreover, the Met allele carriers had higher BDI scores than the Val/Val homozygotes only in the females at 18months. The females had higher BDI scores than the males constantly during the follow-up in the Met allele carriers and at 12months only in the Val/Val homozygotes. When compared to those at 12months, the scores decreased at 18months in all the females and the male Met allele carriers. In addition, the potential factors of prevalence or predictors of severity of depression were different between the Val/Val homozygotes and the Met allele carriers at different times after the earthquake. The results suggest that interactions may occur after stresses among BDNF Val66Met, gender and time course to influence depression. This may be one of the explanations for the inconsistent relationships reported before between depression and BDNF Val66Met and need to take into account for precision medical and more effective interference of depression in adolescents after disasters.

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.

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.

Reduced serum levels of oestradiol and brain derived neurotrophic factor in both diabetic women and HFD-feeding female mice

The estrogen levels in the pre and post menstrual phases interact with brain-derived neurotrophic factor in a complex manner, which influences the overall state of the body. To study the role of oestradiol and brain-derived neurotrophic factor in modulating obesity related type 2 diabetes and the interactions between two factors, we enrolled 15 diabetic premenopausal women and 15 diabetic postmenopausal women respectively, the same number of healthy pre and postmenopausal women were recruited as two control groups. The fasting blood glucose, insulin, lipids, estrogen, and brain-derived neurotrophic factor levels were measured through clinical tests. Additionally, we set up obese female mouse model to mimic human trial stated above, to verify the relationship between estrogen and brain-derived neurotrophic factor. Our findings revealed that there is a moderately positive correlation between brain-derived neurotrophic factor and oestradiol in females, and decreased brain-derived neurotrophic factor may worsen impaired insulin function. The results further confirmed that high fat diet-fed mice which exhibited impaired glucose tolerance, showed lower levels of oestradiol and decreased expression of brain-derived neurotrophic factor mRNA in the ventromedial hypothalamus. The level of brain-derived neurotrophic factor reduced on condition that the level of oestradiol is sufficiently low, such as women in postmenopausal period, which aggravates diabetes through feeding-related pathways. Increasing the level of brain-derived neurotrophic factor may help to alleviate the progression of the disease in postmenopausal women with diabetes.

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

OBJECTIVE

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

SUBJECTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Preclinical amyloid pathology biomarker positivity: effects on tau pathology and neurodegeneration

Brain autopsy and biomarker studies indicate that the pathology of Alzheimer's disease (AD) is initiated at least 10-20 years before clinical symptoms. This provides a window of opportunity to initiate preventive treatment. However, this emphasizes the necessity for biomarkers that identify individuals at risk for developing AD later in life. In this cross-sectional study, originating from three epidemiologic studies in Sweden (n=1428), the objective was to examine whether amyloid pathology, as determined by low cerebrospinal fluid (CSF) concentration of the 42 amino acid form of β-amyloid (Aβ42), is associated with biomarker evidence of other pathological changes in cognitively healthy elderly. A total of 129 patients were included and CSF levels of Aβ42, total tau, tau phosphorylated at threonine 181 (p-tau), neurogranin, VILIP-1, VEGF, FABP3, Aβ40, neurofilament light, MBP, orexin A, BDNF and YKL-40 were measured. Among these healthy elderly, 35.6% (N=46) had CSF Aβ42 levels below 530 pg ml^-1. These individuals displayed significantly higher CSF concentrations of t-tau (P<0.001), p-tau (181) (P<0.001), neurogranin (P=0.009) and FABP3 (P=0.044) compared with amyloid-negative individuals. Our study indicates that there is a subpopulation among healthy older individuals who have amyloid pathology along with signs of ongoing neuronal and synaptic degeneration, as well as tangle pathology. Previous studies have demonstrated that increase in CSF tau and p-tau is a specific sign of AD progression that occurs downstream of the deposition of Aβ. On the basis of this, our data suggest that these subjects are at risk for developing AD. We also confirm the association between APOE ɛ4 and amyloid pathology in healthy older individuals.

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

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