The relationship between BDNF rs6265 (Val66Met) polymorphism and serum BDNF levels in anxiety disorders

Introduction and Aim: Our study aims to investigate serum BDNF levels and BDNF rs6265 (Val66Met) polymorphism in individuals with anxiety disorders and healthy volunteers and uncover the role of serum BDNF levels and Val66Met polymorphism in the etiology of anxiety disorders, evaluate their relationship with symptom severity, and determine the effects of Val66Met polymorphism on serum BDNF levels. Methods and Tools: The study included 64 patients diagnosed with at least one of the disorders under the umbrella of anxiety disorders, according to DSM V-TR criteria, and 64 healthy volunteers. Participants were recruited from the Psychiatry Policlinic of Balıkesir University Health Application and Research Hospital. Blood samples collected from participants were analyzed in biochemistry and genetics laboratories using ELISA and RT-PCR methods. Prior to participation, informed consent was obtained from all participants. They were then asked to fill out a Sociodemographic and Clinical Information Form, and all participants underwent SCID-5-CV, HAM-A, HADS, and Level 2 Somatic Symptom Scales. Results: The median (min-max) serum BDNF levels in the patient and control groups were found to be 1.50 (0.19-3.28) ng/mL and 1.62 (1.05-9.50) ng/mL, respectively, with a statistically significant difference between the two groups (p=0.007). A negative correlation was identified between serum BDNF levels and HAM-A, HADS, and Level 2 Somatic Symptom Scale scores (rs= -0.386, rs= -0.317, rs= -0.224, respectively). When the diagnostic performance of serum BDNF levels was evaluated using the ROC curve, a cutoff value of 1.54 ng/mL was found to have a sensitivity of 59.4% and a specificity of 57.8%, indicating significant discriminative power for disease detection. No significant difference was observed between the patient and control groups regarding the presence of Val66Met polymorphism (p=0.843). Additionally, no statistically significant relationship was found between serum BDNF levels and Val66Met polymorphism (p=0.215). Conclusion: The significantly lower serum BDNF levels in individuals with anxiety disorders support the role of BDNF, proposed as a biomarker in many psychiatric disorders, in the pathophysiology of anxiety. However, the inability to confirm the significant effect of Val66Met polymorphism on BDNF levels suggests that genetic variations should be examined in larger sample groups and different populations.