Association of a functional BDNF polymorphism and anxiety-related personality traits.

Background: Converging lines of evidence point to brain-derived neurotrophic factor (BDNF) as a factor in the pathophysiology of depression. Recently, it was shown that the Val allele of the BDNF Val66Met substitution polymorphism showed a significant association with higher mean neuroticism scores of the NEO-Five Factor Inventory (NEO-FFI) in healthy subjects, and previous studies suggested the Val allele to be increased in bipolar disorder families. The association to anxiety-related traits has not been investigated so far.

Methods: We tested a total of 343 unrelated subjects of German descent (171 male, 172 female, age: 39.0+/-14.6 years) who were carefully screened for psychiatric health. The self-ratable State-Trait Anxiety Inventory (STAI), which allows anxiety to be quantified as a comparatively stable personality trait, and the NEO-Five Factor Inventory (NEO-FFI) was applied.

Results: In the trait-related anxiety score, a significant (F=3.2, df=2, p<0.042) effect of the genotype was observed with higher levels of trait anxiety in Val/Val (35.0+/-7.4) compared to Val/Met (33.4+/-6.5) and Met/Met (32.0+/-4.6) genotypes. The NEO neuroticism scores were also higher in Val/Val (29.5+/-7.0) than in Val/Met (28.4+/-6.5) or Met/Met (26.8+/-5.8) genotype, but not at a significant rate.

Conclusions: Our findings support the hypothesis that anxiety- and depression-related personality traits are associated with the BDNF polymorphism although the explained variance is low.