The relationship between BDNF Val66Met polymorphism and functional mobility in chronic stroke survivors.

Background A single nucleotide polymorphism, Val66Met, in the Brain Derived Neurotrophic Factor (BDNF) gene has been studied for its role in recovery following stroke. Despite this work, the role of BDNF genotype on long-term recovery is unclear. Additionally, no study has examined its impact on functional mobility. As a result, the purpose of this study was to examine the relationship between BDNF genotype and functional mobility in chronic stroke survivors by first accounting for factors related to the Val66Met polymorphism and post-stroke recovery. Methods Participants 6 months post-stroke completed the Fugl-Meyer Lower Extremity Assessment (FMLE), Yesavage Geriatric Depression Scale (YGDS), 10 meter walk test (SSWS), and BDNF genotype testing. A regression model was used to determine if including genotype (Val or Met) and the genotype's interactions with age, gender, and depression increased the model's fit in predicting functional mobility, as measured by SSWS, after accounting for physical impairment (FMLE) and personal information (age, gender, and YGDS). Results Sixty-three subjects, twenty-two percent of whom had at least one Met allele, were included. Impairment and personal information significantly predicted SSWS (R2  = 0.268, p < 0.001 and ΔR2  = 0.158, p = 0.002, respectively). The addition of genotype and genotype's interactions did not significantly increase the variance accounted for in SSWS (ΔR2  = 0.012, p = 0.27, and ΔR2  = 0.006, p = 0.723, respectively). Conclusions Our results suggest that the Val66Met polymorphism does not predict long-term, functional mobility following stroke. This difference may be due to differences in model variables or a reduced impact of the polymorphism as recovery progresses.