Relationship Between BDNF Gene Polymorphism And Brain Structure In First Episode And Treatment-naive Patients With Major Depressive Disorder

Objective:We investigated the relationship between the Val66Met BDNF genotype of first episode and treatment-naive patients with major depressive disorder(MDD) and healthy subjects and the volume of gray matter.Methods:This study included 41 episode and treatment-naive depression patients diagnosed with DSM-IV standara and 44 cases of sex and age matched in normal control group,all participants were arranged to undergo magnetic resonance imaging(MRI) scan session.Based on the results of the genotyping of BDNF,patients and controls were subdivided into groups of MDD Met allele group,MDD Val/Val homozygous group, healthy Met allele control group ,healthy Val/Val homozygous control group.MRI 3D data wre processed automatically by using the software VBM 8 running on MATLAB 2012.Grey matter images of the patient group and the control group were extracted respectively after the normalization,segmentation,and smoothing steps.Within the scope of whole brain,2x2 all full factor model analyze(ANOVA) was then performed to test for the main effects and interaction between the genotyping of BDNF(Met allele vs. Val/Val homozygous)and diagnosis (MDD vs. control) on gray matter volume(GMV).Results:1. rs6265 sites alleles frequency,genotype in patients with depression and there is no difference between groups statistical significance.2. Depressive patients compared with healthy control group ,left precuneus increases.3.Using 2x2 ANOVA all model factor analysis results showed that :(a)BDNF genotype effects:left cerebelum,left fusiform,right Superior parietal;(a) Diagnosis effects :left precuneus increases;(c) BDNF genotype-diagnosis interaction: left anterior cingulate cortex;in the Val/Val homozygous group,contrast with normal comparison,MDD left parahippocampal,right anterior cingulate cortexsignificantly reduce the volume;in the Met allele group,compare with healthy controls,MDD show significantly increased GMV in portions of the bilateral middle frontal gyrus.Conclusion:1.In comparison with healthy controls, MDD show significantly increased GMV in portions of the left precuneus increases.2.The genetic variation of rs6265 locus was associated with the changes in the volume of gray matter in the left cerebelum,left fusiform,right Superior parietal.3.The interaction of BDNF and depression results is the left anterior cingulate cortex gray matter volume change , it shows that the BDNF Val66Met polymorphism may play an important role in the early stage in the pathogenesis of depression, which highlights the importance of the structure of the brain related gene into consideration.