Peripheral brain-derived neurotrophic factor (BDNF) and salivary cortisol levels in college students with different levels of academic stress. Study protocol

Abstract

Introduction Brain-derived neurotrophic factor (BDNF) is essential for brain physiological processes influencing memory and learning. BDNF levels can be affected by many factors, including stress. Stress increase serum and salivary cortisol levels. Academic stress is of the chronic type. BDNF levels can be measure from serum, plasma or platelets, and there is still no standard methodology, which is relevant to ensure reproducibility and comparability between studies. Hypothesis (i) BDNF concentrations in serum show greater variability than in plasma. (ii) In college students with academic stress, peripheral BDNF decreases and salivary cortisol increases. General objective To standardize plasma and serum collection for BDNF levels and to determine whether academic stress affects peripheral BDNF and salivary cortisol levels. Design Quantitative research, with a non-experimental cross-sectional descriptive design. Participants Student volunteers. Under convenience sampling, 20 individuals will be included for standardization of plasma and serum collection and between 70 and 80 individuals to determine the effect of academic stress on BDNF and salivary cortisol. Peripheral blood and salivary cortisol sampling, measurements 12 mL of peripheral blood (with and without anticoagulant) will be drawn per participant, separated from plasma or serum and cryopreserved at -80°C. Additionally, they will be instructed in the collection of 1 mL of saliva samples, which will be centrifuged. Val66Met polymorphism will be performed by allele-specific PCR, while BDNF and salivary cortisol levels will be determined by ELISA. Statistical analysis (i) descriptive analysis of the variables, through measures of central tendency and dispersion, and the categorical variables through their frequency and percentage. (ii) Then a bivariate analysis will be performed comparing groups using each variable separately. Expected results We expect to (i) determine the analytical factors that allow a better reproducibility in the measurement of peripheral BDNF, and (ii) the effect of academic stress on BDNF and salivary cortisol levels.

Plasma and Platelet Brain-Derived Neurotrophic Factor (BDNF) Levels in Bipolar Disorder Patients with Post-Traumatic Stress Disorder (PTSD) or in a Major Depressive Episode Compared to Healthy Controls

“…To our knowledge, the present study is the first that evaluated and compared the amount of two circulating components of the neurotrophin BDNF, the platelet-poor plasmatic (PPP-BDNF) and the intraplatelet (PLT-BDNF) pools, in a group of patients with a lifetime diagnosis of bipolar disorder, distinguished with respect to the presence of current post-traumatic symptoms or depressive episodes, and a group of healthy controls without somatic or mental diseases. Essentially, these two BDNF circulating parameters were evaluated as presumed biomarkers of the activity of the CNS periphery communication networks involving the neurotrophin system in these groups of enrolled subjects [ 35 , 36 , 41 , 42 , 65 , 66 ]. First, results showed that the two BDNF parameters were not significantly correlated to each other, in support of their distinct origin [ 29 , 43 , 67 ].…”

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

“…Previous studies have observed a decrease in plasma and serum BDNF levels in patients with depression (Polyakova et al., 2015 ; Yoshimura et al., 2007 ), bipolar disorder (Cunha et al., 2006 ; Polyakova et al., 2015 ), and eating disorders (Nakazato et al., 2009 ; Yamada et al., 2012 ) and increases after treatment for these disorders (Nakazato et al., 2009 ; Yamada et al., 2012 ; Yoshimura et al., 2007 ). Plasma and serum BDNF have been identified as indicators of stress in both the general population and healthcare workers (Castillo‐Navarrete et al., 2023 ; Håkansson et al., 2017 ; He et al., 2018 ; Okuno et al., 2011 ). A recent study found that higher academic stress is associated with lower peripheral BDNF, with sensitivity to the duration of stress (Castillo‐Navarrete et al., 2023 ).…”

“…Plasma and serum BDNF have been identified as indicators of stress in both the general population and healthcare workers (Castillo‐Navarrete et al., 2023 ; Håkansson et al., 2017 ; He et al., 2018 ; Okuno et al., 2011 ). A recent study found that higher academic stress is associated with lower peripheral BDNF, with sensitivity to the duration of stress (Castillo‐Navarrete et al., 2023 ). Reduced serum BDNF levels have been observed in nurses experiencing insomnia (Furihata et al., 2020 ), and BDNF gene polymorphisms, such as Val66Met and rs6265, have been implicated in moderating occupational distress among Chinese healthcare workers (He et al., 2018 ; Jia et al., 2021 ).…”

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

“…Higher education epitomizes this stress due to hefty workloads. Concurrently, students often face family separation, job entry, and new environments ( Barraza-Macías, 2007 ; Castillo-Navarrete et al, 2023a ). University students encounter notably stressful periods, requiring significant adaptation.…”

“…BDNF is vital for functions like dendritic branching, spine morphology, synaptic plasticity, and long-term potentiation (LTP). Consequently, it affects memory, learning, appetite, and sleep ( Castillo-Navarrete et al, 2023a ; Karege et al, 2002 ; Lommatzsch et al, 2005 ; Nagahara & Tuszynski, 2011 ).…”