Association of BDNF VAL66MET with post-stroke functional recovery

Abstract

The Val66Met single nucleotide polymorphism (SNP rs6265) of the Brain-Derived Neurotrophic Factor ( BDNF ) gene decreases BDNF secretion. Previous studies in patients with stroke have shown that the Val66Met polymorphism is associated with poorer outcome. The aim of this study was to determine whether or not the BDNF Val66Met genotype is associated with functional outcome after stroke in our inpatient rehabilitation sample. One hundred and five individuals admitted for inpatient rehabilitation following a stroke and who were also enrolled in the Partners HealthCare Biobank. The genotypes for BDNF SNP rs6265 for individuals with stroke were obtained from the Partners HealthCare Biobank Portal. Main outcome measures were the Functional Independence Measure (FIM) on admission and discharge. Stroke outcome was defined as the change in FIM scores between discharge and admission. The prediction of motor and cognitive outcome at discharge was modeled using BDNF Val66Met genotype. Regression analyses were performed to identify the significant associations of the genetic factor with functional outcome. Individuals with stroke who were homozygous for the GG genotype had significantly lower FIM cognition subscale ( P = 0.023) and memory subscores ( P = 0.011) as compared to those with either the heterozygous AG or homozygouse AA genotypes. In addition, the GG genotype was a significant predictor for poor memory outcome ( P = 0.021, OR = −0.036 [B = −0.067 to −0.005]) when controlling for age and gender. This association may be due to the association with memory since the memory score is contained within the cognition subscale. The preliminary data suggests that BDNF Val66Met polymorphsim may impede stroke recovery, especially cognitive function. Further studies with larger samples are warranted to elucidate the role and mechanism of BDNF genetic variants in stroke recovery.