BDNF and panic disorder: The aims of our study are to: (1) discuss the correlation between serum BDNF, STAI, Panic Disorder Severity Scale–Chinese Version (PDSS-CV), and Patient Health Questionnaire 15-item scale (PHQ-15) at baseline and; (2) explore the predictive value of serum BDNF, state/trait anxiety, and panic-related symptom per se on the changes in somatic symptoms post-escitalopram treatment in PD patients.