In humans, the short allele of a common polymorphism in the serotonin transporter 5-HTT gene is associated with a higher risk to develop depression and anxiety disorders.
Furthermore, individuals carrying this allele are characterized by negative judgment biases, as they tend to interpret ambiguous information in a more pessimistic way. In the present study, we aimed to prove the anxiety-like phenotype of the 5-HTT mouse model, and to investigate whether 5-HTT genotype also causes differences in judgment bias. While our results confirm that homozygous 5-HTT knockout mice display highest levels of anxiety-like behavior, it was decreased in heterozygous mice.
These results indicate that at least in mice the association between 5-HTT genotype and judgment bias is not straightforward and that other factors, including multiple genes as well as environmental influences, are implicated in the modulation of judgment biases.
More research is needed to gain further insights into their function as potential endophenotypes for psychopathology. Environmental and genetic factors as well as their interaction are regarded as contributing causes Caspi and Moffitt, ; Caspi et al. Among the genetic risk factors, the serotonin transporter 5-HTT gene constitutes an important candidate, with a common polymorphism in the 5-HTT-linked polymorphic region, appearing in form of either a short s or a long l allele Lesch et al.
Carrying the s-allele has been linked to anxiety-related personality traits and is associated with an increased risk to develop anxiety disorders and depression, especially following adverse life events Lesch et al. A shared characteristic of individuals with anxiety disorders is that they selectively process information in a way favoring negative emotional valence, a phenomenon also referred to as cognitive bias Mathews and MacLeod, , Such negative cognitive biases comprise attention e.
