Medical Research: What is the background for this study? What are the main findings?
Dr. Todd: This study brings together two lines of research. First, a couple of years ago my colleagues and I reported that in general people literally see emotional aspects of the world as more vivid – as if they burn more brightly on the eye – than mundane things. We call this effect emotionally enhanced vividness, or EEV. Here we wanted to look at how this phenomenon of emotionally enhanced vividness might differ between individuals.
Second, in another previous study we found that people who carry a very common variation in the ADRA2b gene, which influences levels of norepinephrine (a neuromodulator in the brain that is important to the stress response and for emotional influences on memory) were more likely to have their attention captured by emotionally relevant aspects of the world. We also found that how arousing they perceived an event to be at the time it happened predicted how well they remembered it better than for people who did not carry this variation. Here we continued to examine what is unique to this group of people by testing to see if they showed higher levels of the other phenomenon we had found, emotionally enhanced vividness, and what patterns of brain activation would play a role.
Here we found that ADRA2b deletion carriers show greater emotionally enhanced vividness than people who do not carry the deletion variant. We also used functional magnetic resonance imaging (fMRI) to look at brain function and found that deletion carriers showed different patterns of brain activation that were associated with EEV. In particular, they showed greater activity in the ventromedial prefrontal cortex, a region that plays a key role when we evaluate the value or emotional importance of things in the world. So for some people, emotional aspects of the world burn brighter than for others, and they recruit additional brain activity in brain regions that care about emotional relevance.
An example of emotionally enhanced vividness would be if you were walking down the street on a foggy evening, the emotionally relevant objects would stand out more clearly in the mist. So for example, the face of a crying child would stand out more than the neutral face of a casual pedestrian. And our findings show that this is more true for some people than others. For people who have a gene that influences the availability of a neurochemical that is important for the stress response, the crying child’s face would stand out more brightly and sharply than for people who do not, and this is related to greater brain activity that tracks what we care about or what is relevant to us because it is either good or bad.
Medical Research: What should clinicians and patients take away from your report?
Dr. Todd: Well to me the biggest message is that different individuals literally perceive the world very differently, and one thing that contributes is genetic variations that influence brain activity related to differences in perception. These differences can also contribute to how different individuals respond to traumatic events and also how they respond to treatment. So, for example, clinicians can be aware that treatments that target the noradrenergic system, or exposure therapy, may work very differently in different individuals depending on which variant of the ADRA2b gene they carry. In general I think it adds evidence to support clinician approaches working towards more customized treatments for PTSD and mood disorders than a one-sized fits all prescription. And of course, the genetics is only one piece of the puzzle, as other genes and life experience also play a huge role.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Todd: I’m very interested in whether deletion carriers show this enhanced sensitivity to emotionally relevant aspects of the world because they have a greater capacity for emotional learning – that they learn associations between objects and environments and good or bad consequences faster or harder. And whether this applies to positive or appetitive learning that may be linked to addictive behavior as well as to learning associations with negative or fearful events.
MedicalResearch.com Interview with: Rebecca Todd Ph.D. (2015). Emotional Reactivity May Be Genetically Predisposed