Objective:Numerous studies have shown that neuroplasticity plays an important role in the pathogenesis of depression. This study aimed to investigate the relationship between the brain derived neurotrophic factor (BDNF) (Val66Met, rs6265) genotype and gray matter volume (GMV) in the first episode and treatment-naive patients with major depressive disorder (MDD) and healthy subjects.Methods:This study included 41 first episode and treatment-naive MDD patients (MDD group) and 44 sex and age matched healthy controls (HC group). All participants were arranged to take magnetic resonance imaging (MRI) scan. Meanwhile, BDNF rs6265 polymorphism was detected. Voxel-based morphometry (VBM) method was then performed to test the impact of the diagnosis (MDD vs. HC) and BDNF genotype (Met allele vs. Val/Val homozygous) on GMV. Results:There was no statistically significant difference on BDNF rs 6265 sites alleles frequency and genotype between MDD and HC groups (MDD χ 2=0.004, P>0.05; HC χ2=0.048, P>0.05). Gray matter volume in the left precuneus ( F=3.702, P<0.001), right middle temporal gyrus ( F=4.020, P<0.001) and cerebellum vermis_4_5 ( F=3.836, P<0.001) was larger in MDD patients than in the control group. BDNF genotype had effects on left fusiform gyrus ( F=-4.152, P<0.001). BDNF genotype-diagnosis interaction was found to be associated with left anterior cingulate cortex ( F=-4.775, P<0.001) and right anterior cingulate ( F=-3.795, P<0.001). For participants with Val/Val homozygous, compared to HC group, the volume of left anterior cingulate was reduced in MDD patients ( F=-3.729, P<0.001). For participants with the Met allele, compared to healthy controls, MDD patients showed significantly increased GMV in the left middle frontal gyrus ( F=4.317, P<0.001), right inferior occipital gyrus ( F=4.744, P<0.001), right supramarginal gyrus ( F=3.838, P<0.001), and left median cingulate gyrus( F=4.041, P<0.001). Separately in MDD patients and the control group, the GMV did not differ between the Val/Val homozygous group and the Met allele group. Conclusion:BDNF rs6265 alleles could be related to brain structural abnormalities in MDD patients, and could further explain the pathological mechanism of MDD.

Objective:Numerous studies have shown that neuroplasticity plays an important role in the pathogenesis of depression. This study aimed to investigate the relationship between the brain derived neurotrophic factor (BDNF) (Val66Met, rs6265) genotype and gray matter volume (GMV) in the first episode and treatment-naive patients with major depressive disorder (MDD) and healthy subjects.Methods:This study included 41 first episode and treatment-naive MDD patients (MDD group) and 44 sex and age matched healthy controls (HC group). All participants were arranged to take magnetic resonance imaging (MRI) scan. Meanwhile, BDNF rs6265 polymorphism was detected. Voxel-based morphometry (VBM) method was then performed to test the impact of the diagnosis (MDD vs. HC) and BDNF genotype (Met allele vs. Val/Val homozygous) on GMV. Results:There was no statistically significant difference on BDNF rs 6265 sites alleles frequency and genotype between MDD and HC groups (MDD χ 2=0.004, P>0.05; HC χ2=0.048, P>0.05). Gray matter volume in the left precuneus ( F=3.702, P<0.001), right middle temporal gyrus ( F=4.020, P<0.001) and cerebellum vermis_4_5 ( F=3.836, P<0.001) was larger in MDD patients than in the control group. BDNF genotype had effects on left fusiform gyrus ( F=-4.152, P<0.001). BDNF genotype-diagnosis interaction was found to be associated with left anterior cingulate cortex ( F=-4.775, P<0.001) and right anterior cingulate ( F=-3.795, P<0.001). For participants with Val/Val homozygous, compared to HC group, the volume of left anterior cingulate was reduced in MDD patients ( F=-3.729, P<0.001). For participants with the Met allele, compared to healthy controls, MDD patients showed significantly increased GMV in the left middle frontal gyrus ( F=4.317, P<0.001), right inferior occipital gyrus ( F=4.744, P<0.001), right supramarginal gyrus ( F=3.838, P<0.001), and left median cingulate gyrus( F=4.041, P<0.001). Separately in MDD patients and the control group, the GMV did not differ between the Val/Val homozygous group and the Met allele group. Conclusion:BDNF rs6265 alleles could be related to brain structural abnormalities in MDD patients, and could further explain the pathological mechanism of MDD.