Measuring BDNF in saliva using commercial ELISA: Results from a small pilot study

Effects of Fitlight training on cognitive-motor performance in élite judo athletes

Aims

The aims of this study were to verify if a 5-week cognitive-motor training (CMT) using FitlightsTM induced changes in young adult judo athletes compared to a non-intervention group. Specifically, it was verified if CMT influenced executive functions (EFs), physical fitness and brain-derived neurotrophic factor (BDNF) levels. Additionally, athletes' competitive results were compared between groups.

Method

Twenty-seven athletes (14 males and 13 females; age = 19.5 ± 2.0 years) were assigned to the Fitlight (FG) and control (CG) groups which performed 5 weeks of CMT, respectively, including 25 min per day of Fitlight training or traditional judo practice. All participants performed cognitive (flanker task and forward/backward digit span) and fitness tests (counter movement jump, handgrip test, dynamic and isometric chin up). In addition, BDNF was collected by saliva sampling and competitive results after the intervention period were considered.

Results

RM-ANOVA showed significant differences in FG for the accuracy of flanker (p = 0.028) and backward digit span (p < 0.001). Moreover, significant differences in FG were found for relative dynamic chin up (p = 0.027) and counter movement jump (p = 0.05). In addition, a significant difference in FG was found for competitive results after the intervention period (p < 0.01).No significant differences were found for BDNF and other cognitive and fitness measures (p > 0.05).

Conclusion

A 5-week judo-specific CMT improved EFs and motor performance in élite judo athletes. It seems that CMT with Fitlight™ could be considered an additional support to coaches during the training period.

Finding biomarkers of experience in animals

At a time when there is a growing public interest in animal welfare, it is critical to have objective means to assess the way that an animal experiences a situation. Objectivity is critical to ensure appropriate animal welfare outcomes. Existing behavioural, physiological, and neurobiological indicators that are used to assess animal welfare can verify the absence of extremely negative outcomes. But welfare is more than an absence of negative outcomes and an appropriate indicator should reflect the full spectrum of experience of an animal, from negative to positive. In this review, we draw from the knowledge of human biomedical science to propose a list of candidate biological markers (biomarkers) that should reflect the experiential state of non-human animals. The proposed biomarkers can be classified on their main function as endocrine, oxidative stress, non-coding molecular, and thermobiological markers. We also discuss practical challenges that must be addressed before any of these biomarkers can become useful to assess the experience of an animal in real-life.

Association between salivary mature brain-derived neurotrophic factor and psychological distress in healthcare workers

INTRODUCTION

Previous studies have suggested association between brain-derived neurotrophic factor (BDNF) and the stress level of workers. However, no studies have investigated the potential of salivary mature BDNF (mBDNF) level as a noninvasive biomarker for psychological distress. This study aimed to explore the reliability of salivary mBDNF as a biomarker for psychological distress in healthcare workers. Furthermore, we examined the relationship between salivary and plasma mBDNF levels and their correlation with age, sex, body mass index (BMI), and exercise habits.

METHODS

Fifty-one healthy healthcare workers (26 men) from the University of Occupational and Environmental Health, Japan, participated in this study. In this cross-sectional study, participants provided demographic information. Psychological distress was assessed using the Kessler 6 (K6). Saliva and blood samples were collected, and mBDNF was measured by ELISA. Spearman's rank correlation coefficient was performed to analyze the relationship between mBDNF (saliva and plasma) and K6. Statistical analyses were conducted using Stata 17.0, and a significance level of p < .05 was applied.

RESULTS

The median K6 score was 1 (interquartile range [IQR]: 0-3). The median (IQR) salivary mBDNF was 1.36 (1.12-1.96) pg/mL, whereas the mean (standard deviation) plasma mBDNF was 1261.11 (242.98) pg/mL. No correlation was observed between salivary and plasma mBDNF concentrations or with the K6 score. Additionally, there were no associations between salivary or plasma mBDNF concentrations and age, sex, or exercise habits. Finally, an association between plasma mBDNF concentration and BMI was found only in univariate analysis.

CONCLUSION

Our findings indicate that salivary mBDNF can be accurately measured noninvasively in healthcare workers. Within our study sample, salivary mBDNF did not demonstrate any correlation with K6 and plasma mBDNF. Future studies with a larger study sample and a diverse study population consisting of healthy participants and patients with psychiatric disorders are warranted.

Effects of Exercise Training on Neurotrophic Factors and Subsequent Neuroprotection in Persons with Multiple Sclerosis-A Systematic Review and Meta-Analysis

Background: Evidence indicates that exercise holds the potential to counteract neurodegeneration experienced by persons with multiple sclerosis (pwMS), which is in part believed to be mediated through increases in neurotrophic factors. There is a need to summarize the existing evidence on exercise-induced effects on neurotrophic factors alongside neuroprotection in pwMS. Aim: To (1) systematically review the evidence on acute (one session) and/or chronic (several sessions) exercise-induced changes in neurotrophic factors in pwMS and (2) investigate the potential translational link between exercise-induced changes in neurotrophic factors and neuroprotection. Methods: Five databases (Medline, Scopus, Web of Science, Embase, Sport Discus) were searched for randomized controlled trials (RCT) examining the effects of exercise (all modalities included) on neurotrophic factors as well as measures of neuroprotection if reported. The quality of the study designs and the exercise interventions were assessed by use of the validated tool TESTEX. Results: From N = 337 identified studies, N = 14 RCTs were included. While only N = 2 of the identified studies reported on the acute changes in neurotrophic factors, all N = 14 RCTs reported on the chronic effects, with N = 9 studies revealing between-group differences in favor of exercise. This was most prominent for brain-derived neurotrophic factor (BDNF), with between-group differences in favor of exercise being observed in N = 6 out of N = 12 studies. Meta-analyses were applicable for three out of 10 different identified neurotrophic factors and revealed that exercise can improve the chronic levels of BDNF (delta changes; N = 9, ES = 0.78 (0.27; 1.28), p = 0.003, heterogeneity between studies) and potentially also ciliary neurotrophic factor (CNTF) (N = 3, ES = 0.24 (−0.07; 0.54), p = 0.13, no heterogeneity between studies) but not nerve growth factor (NGF) (N = 4, ES = 0.28 (−0.55; 1.11), p = 0.51, heterogeneity between studies). Indicators of neuroprotection (e.g., with direct measures of brain structure assessed by MRI) were assessed in N = 3 of the identified studies only, with N = 2 partly supporting and thus indicating a potential translational link between increases in neurotrophic factors and neuroprotection. Conclusion: The present study reveals that exercise can elicit improvements in chronic levels of BDNF in pwMS, whereas the effects of exercise on chronic levels of other neurotrophic factors and on acute levels of neurotrophic factors in general, along with a potential translational link (i.e., with exercise-induced improvements in neurotropic factors being associated with or even mediating neuroprotection), are sparse and inconclusive. There is a need for more high-quality studies that assess neurotrophic factors (applying comparable methods of blood handling and analysis) concomitantly with neuroprotective outcome measures. Review Registration: PROSPERO (ID: CRD42020177353).

Effects of Playing Angklung and Practicing Silence on Emotion, Cognition and Oxytocin Levels in Children: A Preliminary Study

Background

Playing angklung, an Indonesian traditional musical instrument and practicing silence have been shown to exert beneficial effects on emotion and cognition; the mechanism of such an effect possibly involve oxytocin. To date, only a few clinical and biomolecular studies have investigated the effects of playing angklung and practicing silence. This study aimed to examine the effects of playing angklung and practicing silence on human emotion and cognition and on oxytocin levels.

Methods

This experimental study involved 61 Fourth Grade students from Surabaya, East Java, Indonesia. The participants were divided into two groups: the angklung intervention group and silence intervention group. The two interventions were performed for 15 min before the morning classes for 2 months. The control group attended their classes as usual. Clinical parameters, namely, emotion and cognition, as well as the saliva oxytocin levels were measured.

Results

No significant differences were observed among the three groups in terms of concentration and cognitive flexibility. However, changes in oxytocin levels significantly differed among the three groups (P < 0.001) and the oxytocin levels were highest in the silence intervention group.

Conclusion

Practicing silence significantly increased the oxytocin levels, but it did not elicit changes in cognitive function and emotion of the students.

Minimally-invasive methods for examining biological changes in response to chronic stress: A scoping review

BACKGROUND

Nurse researchers are increasingly interested in incorporating biological indicators related to chronic stress, or repeated or constant exposure to psychological stressors. Minimally invasive collection methods may improve access to vulnerable populations.

OBJECTIVE

To map biological indicators measured through minimally invasive methods investigating biological changes in response to chronic stress.

DESIGN, DATA SOURCES, AND METHODS

The paper seeks to answer two questions: What are the characteristics of the minimally-invasive methods used to measure the biological correlates of chronic stress? What are the limitations regarding the use of the minimally-invasive methods and/or biological indicators identified above? Authors completed a scoping review following guidelines from the Joanna Briggs Institute Manual and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for Scoping Reviews. A literature search was completed in PubMed, PsycINFO, and Scopus. 2518 articles were screened and 145 studies were included. Data were extracted using a standardized extraction tool, compiled, and coded.

RESULTS

Studies included minimally-invasive methods to measure the hypothalamic-adrenal-pituitary axis (N = 173), immune and inflammatory markers (N = 118), and adult neurogenesis (N = 6). Cortisol was most frequently measured (N = 136), usually in saliva (N = 86). Studies included a variety of limitations for the methods and indicators, including concerns about timing and accuracy of collection, frequency of sampling, and controlling for acute stressors.

CONCLUSIONS

Nurse researchers have access to many minimally-invasive methods to measure altered biological processes related to chronic stress. A gap identified by this review is the paucity of minimally-invasive methods for investigating neurogenesis; the measurement of brain derived neurotrophic factor in plasma is a distal proxy and further research is needed to test the response of peripheral levels to psychosocial stress interventions. Additionally, while this scoping review allows nurse researchers to consider possible biological indicators to include in their research, future research is still needed on some of the basic premises of stress research, including agreement on the conceptualization of chronic stress.

Elevated levels of serum, but not salivary, brain-derived neurotrophic factor following mild traumatic brain injury in collegiate athletes post return-to-play

Brain-derived neurotrophic factor (BDNF) helps restore neuronal function following mild traumatic brain injury. BDNF levels can be obtained in blood serum and more recently in saliva. However, the relationship between serum and salivary BDNF is poorly understood—especially in relation to alterations in BDNF levels following mild traumatic brain injury. In this study, serum and salivary BDNF were collected from a sample of 42 collegiate student athletes. Half of the participants were recently cleared by a physician and/or an athletic trainer to return-to-play after experiencing a sports-related concussion. The other half had not experienced a concussion within the past year and were matched by age, sex, sport, and time of sample. Results suggest that incidences of depression, anxiety, and stress were all elevated in the concussion group, relative to the control participants. When controlling for stress-related negative affect, serum BDNF was elevated in the concussion group. However, there was no difference in salivary BDNF. Serum and salivary BDNF were uncorrelated across the entire sample. Yet, these measures of BDNF were correlated in the concussion group, but not the control group. In sum, serum BDNF is elevated in concussion post return-to-play; however, further research is needed to explore the utility of salivary BDNF following concussion.

Salivary BDNF and Cortisol Responses During High-Intensity Exercise and Official Basketball Matches in Sedentary Individuals and Elite Players

Salivary cortisol increases in response to stressors, including physical exertion and psychological stress associated with sports competition. In addition, stress may induce change in brain-derived neurotrophic factor (BDNF). However, there are still no data available to compare the salivary BDNF level in sedentary male individuals and elite team-sport male athletes, regularly involved in activities that require elevated attention and concentration. This information could contribute to the advance of understanding of the effect of regular exercise on the salivary level of BDNF, the pre-to-post change in salivary BDNF during exercise, and the association between salivary cortisol and salivary BDNF responses to physical exercise. Therefore, this study aimed to compare the concentration of salivary cortisol and BDNF, before and after exercise, in sedentary individuals and elite male basketball players. The sedentary group (23.0 ± 4.2 yrs) performed a high-intensity exercise protocol and the basketball players (18.6 ± 0.5 yrs) participated in three official basketball matches. Saliva samples were tested for cortisol and BDNF using ELISA. A significant increase in salivary cortisol from pre- to post-match was observed only for the basketball players (p < 0.05). Basketball players also presented a higher salivary BDNF concentration for both resting (pre) and post-physical exercise (p < 0.05); however, no change in pre- to post-exercise salivary BDNF was observed for either group (p > 0.05). Elevated BDNF in athletes may be associated to their repeated exposure to stressful competition situations. The current findings also suggest that different mechanisms might be involved in salivary cortisol and BDNF responses during physical exercise.

Increased BDNF methylation in saliva, but not blood, of patients with borderline personality disorder

Background

The importance of epigenetic alterations in psychiatric disorders is increasingly acknowledged and the use of DNA methylation patterns as markers of disease is a topic of ongoing investigation. Recent studies suggest that patients suffering from Borderline Personality Disorder (BPD) display differential DNA methylation of various genes relevant for neuropsychiatric conditions. For example, several studies report differential methylation in the promoter region of the brain-derived neurotrophic factor gene (BDNF) in blood. However, little is known about BDNF methylation in other tissues.

Results

In the present study, we analyzed DNA methylation of the BDNF IV promoter in saliva and blood of 41 BPD patients and 41 matched healthy controls and found significant hypermethylation in the BPD patient’s saliva, but not blood. Further, we report that BDNF methylation in saliva of BPD patients significantly decreased after a 12-week psychotherapeutic intervention.

Conclusions

Providing a direct comparison of BDNF methylation in blood and saliva of the same individuals, our results demonstrate the importance of choice of tissue for the study of DNA methylation. In addition, they indicate a better suitability of saliva for the study of differential BDNF methylation in BPD patients. Further, our data appear to indicate a reversal of disease-specific alterations in BDNF methylation in response to psychotherapy, though further experiments are necessary to validate these results and determine the specificity of the effect.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0544-6) contains supplementary material, which is available to authorized users.