Fear is something most people have experienced throughout their lives, and it's evolutionarily essential for survival.
But too much fear can indicate mental health illness: one example is post-traumatic stress disorder (PTSD), which affects up to 10% of the population. One common method for treatment has been exposure therapy, which is when patients are exposed to their trigger in a controlled setting to create memories that compete with the original fearful event. PTSD is very complex in its development and treatment, as not everybody who experiences trauma will have PTSD and exposure therapy is unfortunately not the silver bullet for this condition.
In a study of 91 healthy Han Chinese men, investigators used a fear conditioning test involving visual stimuli (some accompanied by electric shocks) to see how participants with different genes respond. Interestingly, it was found that those who had the GG variant at a locus in the beta-2 adrenergic receptor (ADRB2) gene were more susceptible to becoming fearful, even after undergoing memory extinction (a process by which the visual stimulus is uncoupled from the electric shock). On the other hand, those who had the A allele were less prone to having their fear of the electric shock return after memory extinction. The ADRB2 gene is important because it has previously been linked to PTSD. Specifically, among those who have experienced childhood trauma, whether or not the child had a single mutation of the ADRB2 gene at the same locus in this study was highly predictive of whether the child would experience PTSD or not. To find out more about how this study was conducted, check out the full study here: https://www.ncbi.nlm.nih.gov/pubmed/30423370
Although the sample size of this study is limited for this kind of analysis, the results are very promising in that they can help inform how to identify susceptible populations and, ultimately, develop treatment methods for PTSD and other related psychiatric disorders.
So do your genes make you more susceptible to fear resurgence? Check Genomelink to find out.