BDNF Val66Met genetic variation and its plasma level in patients with morbid obesity: A case-control study

Increased academic stress is associated with decreased plasma BDNF in Chilean college students

Introduction

Academic stress (AS) is a prevalent challenge faced by university students, potentially affecting molecular indicators such as brain-derived neurotrophic factor (BDNF) and global DNA methylation (G-DNA-M). These indicators could illuminate the physiological ramifications of academic stress.

Study Design and Methods

This research followed a quantitative, non-experimental, longitudinal panel design spanning two academic semesters, observing phenomena in their natural context. Students from the Medical Technology program at Universidad de Concepción, Chile were involved, with assessments at the beginning and during heightened academic stress periods.

Sample

Of the total participants, 63.0% were females, with an average age of 21.14 years at baseline, and 36.92% were males, averaging 21.36 years. By the study's conclusion, female participants averaged 21.95 years, and males 22.13 years.

Results

Significant differences were observed between initial and final assessments for the SISCO-II Inventory of Academic Stress and Beck Depression Inventory-II, notably in stressor scores, and physical, and psychological reactions. Gender differences emerged in the final physical and psychological reactions. No significant changes were detected between the two assessments in plasma BDNF or G-DNA-M values. A refined predictive model showcased that, on average, there was a 3.56% decrease in females' plasma BDNF at the final assessment and a 17.14% decrease in males. In the sample, the G-DNA-M percentage at the final assessment increased by 15.06% from the baseline for females and 18.96% for males.

Conclusions

The study underscores the physiological impact of academic stress on university students, evidenced by changes in markers like BDNF and G-DNA-M. These findings offer an in-depth understanding of the intricate mechanisms regulating academic stress responses and highlight the need for interventions tailored to mitigate its physiological and psychological effects.

Microelectrode-Based Electrochemical Impedance Determination of Brain-Derived Neurotrophic Factor in Aqueous Humor for Diagnosis of Glaucoma

The abundance of brain-derived neurotrophic factor (BDNF) in aqueous humor (AH) is an ideal biomarker for the diagnosis of glaucoma, a chronic progressive optic neuropathy and the most frequent cause of irreversible blindness. The difficulty of AH-based BDNF detection is from the small amount of extracted AH in a paracentesis (<100 μL) and the ultra-low abundance of BDNF. In this work, we systematically studied the non-specific adsorption of biofluids on the bare gold electrode by electrochemistry and Raman spectroscopy techniques, revealing the unexpected negative correlation of the extent of non-specific adsorption with the size of the electrode. Based on it, a simple microelectrode-based sensor without the introduction of the blocking layer was developed for the detection of BDNF in the AH sample. Using electrochemical impedance spectroscopy (EIS) and extracting the changes of electron-transfer resistance of the electrochemical probe [Fe(CN)6]3-/4- on the sensor surface, the BDNF was quantified. The dynamic range was from 0.5 to 50 pg·mL-1, with a detection limit of 0.3 pg·mL-1 and a sample consumption of 5 μL. The real AH sample analysis confirmed the significant decrease of BDNF abundance in the AH of glaucoma patients. Our microelectrode-based EIS sensor displayed prominent advantages on simplified preparation, sensitive response, and low sample consumption. This AH-based BDNF analysis is expected to be used for the screening and diagnosis of glaucoma, especially for the high-risk population who have ocular diseases and have to undergo surgeries.

Dyslexia with and without Irlen syndrome: A study of influence on abilities and brain-derived neurotrophic factor level

The presence of comorbid Irlen syndrome (IS) in children with developmental dyslexia (DD) may have an impact on their reading and cognitive abilities. Furthermore, the brain-derived neurotrophic factor (BDNF) was reported to be expressed in brain areas involved in cognitive and visual processing. The aim of this study was to evaluate some cognitive abilities of a group of dyslexic children with IS and to measure and compare the plasma BDNF level to dyslexic children without IS and neurotypical (NT) children. The participants were 60 children with DD (30 in the DD + IS group; 30 in the DD group) and 30 NT children. The Irlen reading perceptual scale, the Stanford Binet intelligence scale, 4th ed, the dyslexia assessment test, and the Illinois test of psycholinguistic abilities were used. The BDNF level was measured using the enzyme-linked immunosorbent assay. One-minute writing and visual closure deficits were more prevalent, while phonemic segmentation deficits were less prevalent in the DD + IS group compared to the DD group. The BDNF level in the DD groups was lower than that in NT children (p < 0.001). Some reading and non-reading tasks were influenced by the presence of a coexisting IS. The reduced BDNF level could play a role in the deficits noticed in the abilities of children with DD.

Pattern of serum brain-derived neurotrophic factor levels after acute interval exercise versus acute continuous exercise in obese adolescent females

Obesity has been linked to lower cognitive function, while exercise is known to be beneficial in enhancing the cognitive function. Exercise is also known to increase brain-derived neurotrophic factor (BDNF), as the biological marker of cognitive function. This study aimed to analyse the pattern of serum BDNF levels after acute interval exercise (MIE) versus acute continuous exercise (MCE) in obese adolescent females. A total of 24 obese females were enrolled in this study and given acute interval exercise and acute continuous exercise with moderate intensity. The serum level of BDNF in all samples was quantified using ELISA. Statistical analysis was performed using two-way repeated measures ANOVA, and LSD post-hoc test with a 5% significance level. The results revealed pre-exercise mean serum BDNF levels of 254.17±86.90 pg/ml (Control), 263.21±79.82 pg/ml (MIE) and 266.01±33.29 pg/ml (MCE) (P=0.948). The mean serum BDNF levels at 10 min post-exercise were 248.84±44.42 pg/ml (Control), 397.00±31.36 pg/ml (MIE), and 582.82±79.24 pg/ml (MCE) (P=0.000). The mean serum BDNF levels at 6 h post-exercise were 250.05±70.44 pg/ml (Control), 344.50±68.84 pg/ml (MIE), and 364.42±100.87 pg/ml (MCE) (P=0.029). The mean serum BDNF levels at 24 h post-exercise were 244.20±48.55 pg/ml (Control), 252.49±89.11 pg/ml (MIE), and 250.99±65.86 pg/ml (MCE) (P=0.986). It was concluded that serum BDNF in obese adolescent females increased but transiently. Serum BDNF levels increased by acute exercise in both MIE and MCE at 10 min and 6 h post-exercise. However, serum BDNF level at 24 h post-exercise decreased close to the pre-exercise serum BDNF level in all groups. Further research is needed studying the effect of chronic exercise on the kinetics of serum BDNF levels in obese adolescent females.

Increased serum brain-derived neurotrophic factor and adrenocorticotropic hormone levels are associated with obsessive compulsive disorder in medication‑free children

This study aimed to investigate serum levels of neurotrophins, including brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF), nerve growth factor (NGF) and neurotrophin-3 (NTF3), and hypothalamic-pituitary-adrenal axis (HPA) members including adrenocorticotropic hormone (ACTH) and cortisol in children with obsessive-compulsive disorder (OCD). The possible relationships between serum neurotrophins and HPA axis members were also addressed. A total of 60 medication-free children with OCD and 57 controls aged 8-18 years were enrolled in this study. The severity of OCD symptoms was determined by the Children's Yale-Brown Obsessive Compulsive Scale. The severity of anxiety and depression symptoms were assessed by self-report inventories. The serum levels of neurotrophins, ACTH, and cortisol were measured using enzyme-linked immunosorbent assay kits. Serum BDNF levels were significantly higher in the OCD group than in the control group for either sex and for the whole sample. Compared to controls, serum ACTH levels were significantly higher in the OCD group for the whole sample. An analysis of covariance was also conducted for the whole sample and indicated that, while controlling the potential confounders, including body-mass index percentile, age, sex, and the severity of depression and anxiety, the results did not change. Strong negative correlations between BDNF, NGF and NTF3, and HPA axis members were determined in the patient group for either sex and for the whole sample. These findings suggest that dysregulations of BDNF and ACTH may be associated with childhood OCD. Furthermore, there may be inverse relationships between certain neurotrophins and HPA axis members in these patients.

The association between BDNF levels and risperidone-induced weight gain is dependent on the BDNF Val66Met polymorphism in antipsychotic-naive first episode schizophrenia patients: a 12-week prospective study

A growing number of studies have shown that brain-derived neurotrophic factor (BDNF) is associated with weight gain during antipsychotic treatment in schizophrenia patients. However, there is still a lack of research results in the initial stage of antipsychotic treatment. This study aimed to evaluate the relationship between weight gain caused by risperidone monotherapy for 12 weeks and BDNF level in antipsychotic-naive and first-episode (ANFE) patients with schizophrenia, and we hypothesize that this may depend on BDNF Val66Met gene polymorphism. In a 12-week longitudinal trial, 225 ANFE patients were enrolled and treated with risperidone. Body weight was measured at baseline and during the 12-week follow-up. After treatment, the average weight of ANFE patients increased by 2.6 kg. Furthermore, we found that in patients with Val/Val genotype, the increase in serum BDNF levels was negatively correlated with risperidone-induced weight gain (r = -0.44, p = 0.008). Regression analysis showed that the baseline BDNF level was a predictor of weight gain after treatment (β = -0.45, t = -3.0, p = 0.005). Our results suggest that the BDNF signaling may be involved in weight gain caused by risperidone treatment. Furthermore, the negative association between weight gain and increased BDNF levels during risperidone treatment in ANFE schizophrenia depends on the BDNF Val66Met polymorphism.

Levels of brain-derived neurotrophic factor in patients with multiple sclerosis

Objective

To determine the levels of brain‐derived neurotrophic factor (BDNF) in the serum of patients suffering from multiple sclerosis (MS) to evaluate the potential of serum BDNF as a biomarker for MS.

Methods

Using a recently validated enzyme‐linked immunoassay (ELISA) we measured BDNF in patients with MS (pwMS), diagnosed according to the 2001 McDonald criteria and aged between 18 and 70 years, participating in a long‐term cohort study with annual clinical visits, including blood sampling, neuropsychological testing, and brain magnetic resonance imaging (MRI). The results were compared with an age‐ and sex‐matched cohort of healthy controls (HC). Correlations between BDNF levels and a range of clinical and magnetic resonance imaging variables were assessed using an adjusted linear model.

Results

In total, 259 pwMS and 259 HC were included, with a mean age of 44.42 ± 11.06 and 44.31 ± 11.26 years respectively. Eleven had a clinically isolated syndrome (CIS), 178 relapsing remitting MS (RRMS), 56 secondary progressive MS (SPMS), and 14 primary progressive MS (PPMS). Compared with controls, mean BDNF levels were lower by 8 % (p˂0.001) in pwMS. The level of BDNF in patients with SPMS was lower than in RRMS (p = 0.004).

Interpretation

We conclude that while the use of comparatively large cohorts enables the detection of a significant difference in BDNF levels between pwMS and HC, the difference is small and unlikely to usefully inform decision‐making processes at an individual patient level.