Association of Val66Met polymorphism at brain derived neurotrophic factor gene with depression among Chinese adolescents after Wenchuan earthquake: An 18Â months longitudinal study

To longitudinally investigate the association of Val66Met polymorphism at brain derived neurotrophic factor (BDNF) gene (BDNF) with depression in Chinese Han adolescents after the 2008 Wenchuan earthquake, BDNF Val66Met was identified by polymerase chain reaction-restriction fragment length polymorphism analyses and verified by DNA sequencing. Depression was assessed by Beck Depression Inventory (BDI) among high school students at 6, 12 and 18 months after the earthquake. The results showed that the females constantly had higher depression prevalence than the males during the follow-up in the Met allele carriers, but not in the Val/Val homozygotes. When compared to that at 6 months, the prevalence was lowered at 12 months in the male Met allele carriers, and at 18 months in all the females and the male Met allele carriers. Moreover, the Met allele carriers had higher BDI scores than the Val/Val homozygotes only in the females at 18 months. The females had higher BDI scores than the males constantly during the follow-up in the Met allele carriers and at 12 months only in the Val/Val homozygotes. When compared to those at 12 months, the scores decreased at 18 months in all the females and the male Met allele carriers. In addition, the potential factors of prevalence or predictors of severity of depression were different between the Val/Val homozygotes and the Met allele carriers at different times after the earthquake. The results suggest that interactions may occur after stresses among BDNF Val66Met, gender and time course to influence depression. This may be one of the explanations for the inconsistent relationships reported before between depression and BDNF Val66Met and need to take into account for precision medical and more effective interference of depression in adolescents after disasters.