BDNF and concussion: 52 Other report showed that the val/val genotype was associated with experience dependent plasticity in the motor cortex.32 Finally, recently, the met genotype was associated with better olfactory functions following concussion.63 This study broadens the contribution of genetic variability within the BDNF gene locus to pain and post-concussion symptoms by finding that val/met polymorphism is not the only important variant in outcome following mTBI but that there are other functional polymorphisms in the same haploblock.