A neuroimaging study published in Clinical Psychological Science provides new insights into the link between anger and the functional architecture of brain networks. The new research has uncovered a collection of brain regions that are associated with variations in 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,” explained study author Justin Minue Kim, an assistant professor at Sungkyunkwan University and director of the Human Affective Neuroscience (HumAN) lab.
“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 drive, 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. Not surprisingly, higher trait anger is associated with greater aggression and violence.”
“Moreover, higher trait aggression is associated with negative health outcomes such as increased risk for coronary heart disease,” Kim said. “We were interested in how such individual differences in trait anger are reflected in patterns of functional connectivity across the whole brain. In doing so, we hoped to deepen our understanding of possible brain mechanisms giving rise to trait anger and, subsequently, representing possible targets for modification or intervention.”
Several studies have examined the neural correlates of trait anger. But the research was limited by small sample sizes and a narrow focus on particular brain regions.
To overcome those limitations, the researchers analyzed data from 1,048 university students who participated in the Duke Neurogenetics Study, a comprehensive research project that uses functional magnetic resonance imaging (fMRI) to examine how interactions between genes, the brain, and the environment are related to mental illness in young adults. Importantly, the study included an assessment of trait anger.
Kim and his colleagues used the large fMRI dataset to conduct a connectome-wide functional connectivity study, which allowed the researchers to uncover connectivity patterns associated with trait anger across the entire brain. They found that higher levels of trait anger were associated with hyperconnectivity between three brain regions (the left supplementary motor area, right supplementary motor area, and right lateral frontal pole) and 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 told PsyPost. “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.”
The study has several strengths, including 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 explained. “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,” he added.
The study, “A Connectome-Wide Functional Signature of Trait Anger“, was authored by M. Justin Kim, Maxwell L. Elliott, Annchen R. Knodt, and Ahmad R. Hariri.