A recent neuroimaging study published in the journal Clinical Psychological Science offers a new look at the connection between the emotion of anger and the functional architecture of your brain’s neural networks. This research has now revealed an array of interconnecting brain regions that are all somehow associated with variations in how we experience and deal with the trait anger.
“Trait anger reflects a person’s dispositional tendency to more easily experience frustration and anger in a wide range of situations. For example, when someone cuts you off in traffic, it’s almost never a pleasant experience — but there is a considerable range of possible responses,” explains study co-author Dr. Justin Minue Kim, an assistant professor at Sungkyunkwan University in Seoul, South Korea, and the director of that university’s Human Affective Neuroscience (HumAN) lab.
Kim has always been intrigued by how we process anger — whether we let it out or try to contain it — and how much of that is due to the individual’s own control. Think of how we deal with something as mundane as a morning commute on a particularly busy day.
“Some people may let it slide and continue driving safely, while others cannot help but retaliate by pulling next to the other driver and yelling at them, tailgating the other drivers, or other reckless acts. Typically, the individuals that react in this aggressive manner possess a greater degree of trait anger than those who do not,” Kim says. “Not surprisingly, higher trait anger is associated with greater aggression and violence.”
Moreover, Kim and his team understood that higher degrees of trait aggression often tend to be associated with poor health outcomes like significantly increased risks of coronary heart disease. What they sought was how individual differences in trait anger revealed themselves in connectivity patterns throughout the entire brain.
Although we often associate parts of the brain with emotions, such as the amygdala and fear, the reality is that often several portions of your brain play a role in processing any given emotion, and the connectivity patterns are often what makes the difference in individual reactions.
In their study, Kim and his fellow researchers hoped they could isolate problematic areas of the brain that produced higher degrees of trait aggression for future study. This was of course, hardly the first time a study looked at the neural correlates responsible for trait anger, but they were typically done on a much smaller scale and the focus of the study targeted specific brain regions rather than looking at the whole picture.
To take a bolder step than their predecessors, the research team pored over data coming from the 1,048 university students who volunteered to participate in the Duke Neurogenetics Study, a comprehensive research effort that makes use of functional magnetic resonance imaging (fMRI) technology to observe the interactions between genes, the brain, and even the external environment and how they all relate to the onset of mental illness among young adults. Important to this experiment was the Duke study’s assessment of trait anger in each of its test subjects.
Using this substantial fMRI data set, Kim and his team embarked upon a connectome-wide study in functional connectivity, allowing them to analyze all the connectivity patterns researchers associated with trait anger, as they occurred throughout the entire human brain. The individuals who reported higher levels of trait anger typically had greater degrees of hyperconnectivity across three different brain regions (that is, the left supplementary motor area, the right supplementary motor area, and the right lateral frontal pole) along with the sensorimotor network.
“Our analyses highlighted a possible role for action-related brain regions in the expression of trait anger, patterns not previously detected in studies with fewer participants,” Kim states. “Our findings suggest a novel interpretation of higher trait anger as possibly reflecting a greater propensity to provoked action. In other words, people who are more likely to experience frustration and anger exhibit altered connectivity patterns in certain action-related brain networks.”
Among the strengths of this study are its large and ethnically-diverse sample of participants. But, as with any study, it also has some limitations.
“As we primarily focused on high-functioning, young university students in the United States, the generalizability of the present findings to the broader population needs confirmation,” Kim explains. “Also, our assessment of trait anger relied on self-report, and as such a more objective measurement of trait anger would be beneficial for future research. Finally, the brain-trait anger associations revealed in our analyses are correlational in nature — the causal relationship between brain connectivity and trait anger is yet to be determined.”
“Our findings suggest that altered brain connectivity in action-related networks may be a useful, novel phenotype in future transdiagnostic studies of aggression and violence,” Kim adds.
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