Exposure therapy is a type of cognitive behavioral therapy commonly used to treat people with posttraumatic stress disorder (PTSD). Some evidence suggests that BDNF mediates the response to exposure therapy, which can vary among people. A 2013 study demonstrated that genetic differences in BDNF expression influences how well a person responds to exposure therapy.
A single-nucleotide polymorphism (SNP) in the region of the DNA that encodes BDNF causes a substitution of the amino acid valine (Val) by methionine (Met) in the BDNF protein. Evidence suggests that carriers of the Met allele (Met/Met or Val/Met genotype) have reduced hippocampal function, poor episodic memory, and decreased exercise-induced secretion of BDNF.
The study involved 55 people between the ages of 18 and 65 years who had previously participated in an eight-week exposure therapy program. The participants provided DNA (via saliva samples) for BDNF genotyping.
The genotyping revealed that 30 participants carried the Val/Val BDNF allele, and 25 participants carried the Met-66 allele. Carriers of the Met-66 allele showed a poorer response to exposure therapy than carriers of the Val/Val allele, suggesting that the SNP influenced BDNF expression and subsequent response to cognitive behavioral therapy.