BDNF gene Val66met polymorphism associated grey matter changes in human brain

Objective: A frequent single nucleotide polymorphism (SNP) in the targeting region of the human brain-derived neurotrophic factor (BDNF) gene (val66met) has been associated with abnormal intracellular trafficking and regulated secretion of BDNF in cultured neurons transfected with met allele. Moreover, normal individuals with met alleles have poor episodic memory performance, reduced hippocampal volume and reduced physiological engagement during memory encoding and retrieval. However, the effects of this SNP on other brain areas and functions have not been studied well. In this study, we aimed to explore the effects of BDNF val66met polymorphism on human brain without defining a region of interest a priori. Methods: Twenty-eight healthy volunteers were studied by voxel-based morphometry according to their genotype. The imaging tool was 1.5T MRI scanner and images were analyzed by Statistical Parametric Mapping 2 software. Results: The met carriers had decreased grey matter in left uncus, Brodmann Area (BA) 36, right inferior parietal lobule, BA 40 and left occipital lobe, BA 18 compared to those of val homozygote volunteers. On the other hand, they had more grey matter in right inferior frontal gyrus, BA10 and left inferior temporal gyrus, BA 20. Conclusion: BDNF val66met polymorphism has a significant effect on brain structures which are involved in the working memory network of healthy people. However, further structural and functional imaging studies are needed to understand the effects of this SNP better in the physiology of working memory of healthy people and pathophysiology of psychiatric disorders