To test if this learned fear could be overcome (also known as fear extinction) the volunteers came back into the lab the following day. There they were shown the same pictures, but without any shocks. If their physiological fear responses disappeared, that meant that they had overcome their fear. In addition, blood samples were drawn from the volunteers and tested for the variants of the two genetic variations the researchers were studying.
The results showed that while the participants with the shorter version of the serotonin transporter gene developed a very strong physiological fear response to picture A, participants with a longer version of the gene did not. In addition, a variation in the gene coding for the COMT enzyme was associated with fear extinction - volunteers with this particular variant were able to very quickly overcome their fear while volunteers with the other variant failed to do so.
The researchers note that these findings have very interesting implications for understanding gene-environment interactions and that "genes may act through the environment by making carriers of particular gene combinations more likely than other individuals to easily pick up and retain fear of stimuli associated with threat and trauma." The authors go on to suggest that these findings may indicate that individuals with specific polymorphisms may be more susceptible to anxiety disorders by being more prone to developing fear and being less likely to overcome that fear by common cognitive behavioral treatments which are based on the extinction principle.
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| Contact: Barbara Isanski bisanski@psychologicalscience.org Association for Psychological Science Source:Eurekalert |