A pilot study of the role of the BDNF Val66Met polymorphism in response to exercise-augmented exposure therapy for posttraumatic stress disorder

Abstract

Brain-Derived Neurotrophic Factor (BDNF) is implicated in extinction learning, which is a primary mechanism of exposure therapy for posttraumatic stress disorder (PTSD). Brief aerobic exercise has been shown to promote BDNF release and augment extinction learning. On the premise that the Val allele of the BDNF Val66Met polymorphism facilitates greater release of BDNF, this study examined the extent to which the Val allele of the BDNF polymorphism predicted treatment response in PTSD patients who underwent exposure therapy combined with aerobic exercise or passive stretching. PTSD patients (N = 85) provided saliva samples in order to extract genomic DNA to identify Val/Val and Met carriers of the BDNF Val66Met genotype, and were assessed for PTSD severity prior to and following a 9-week course of exposure therapy combined with aerobic exercise or stretching. The sample comprised 52 Val/Val carriers and 33 Met carriers. Patients with the BDNF high-expression Val allele display greater reduction of PTSD symptoms at posttreatment than Met carriers. Hierarchical regression analysis indicated that greater PTSD reduction was specifically observed in Val/Val carriers who received exposure therapy in combination with the aerobic exercise. This finding accords with animal and human evidence that the BDNF Val allele promotes greater extinction learning, and that these individuals may benefit more from exercise-augmented extinction. Although preliminary, this result represents a possible avenue for augmented exposure therapy in patients with the BDNF Val allele.