Aggression in the Brain

Anger and aggressive behavior may come from a lack of dopamine synthesis in the brain

(RxWiki News) Aggressive responses to provocation may be more physiological than previously thought. New brain scans of provoked individuals show how neurotransmitters react in different people.

New research into the brain’s reaction to environmental stimuli could change the way psychologists think about aggression.

Dopamine synthesizes better in individuals who don’t give in to aggressive reactions.

"Talk to a therapist if you have aggression issues."

Ingo Vernaleken, MD, researcher at the department of psychiatry at Rheinisch-Westfaelische Technische Hochschule Aachen University in Germany, was the lead author in a study to uncover the relationship between low dopamine and aggression.

To understand how aggression works in the brain, scientists designed a computer game that played a part in the larger psychological game to trigger frustration and possible aggression.

Eighteen healthy people in their twenties participated in the test. Researchers administered the point subtraction aggression paradigm (PSAP) test, which was the psychological behavioral task designed to measure each subject’s response.

Each participant played a computer game. In order to win money, the participants had to repeatedly press the space bar with the knowledge that an adversary would be trying to steal money from them by cheating.

There was no actual adversary; the computer program was designed to randomly reduce winnings from the players to agitate them.

The participants each had three ways to choose in response: punish the adversary who was cheating them, defend their money by constantly tapping the space bar on the keyboard to defend the money or power through the game and continue to win money in the hopes of coming out on top with enough winnings to sustain the thievery.

Players’ brains were scanned using positron emission tomography (PET). Before the scan, the players were injected with a biomarker that attached to the neurotransmitter, dopamine, so the scan could see what the dopamine did.

Results clearly showed that dopamine behavior was affected by an aggressive response to the game.

People who fell into the category of those who acted to punish their adversary showed their dopamine to go to the basal ganglia, which is the part of the brain that controls motivation. In the defender group, the dopamine collected in areas of the midbrain and striatum, which do planning and executive function. 

The group that focused on generating more winnings to cover the loss, rather than address the adversary, had an overall greater capacity for synthesizing dopamine. Meaning that dopamine didn’t so much collect in areas of the brain, but rather functioned normally allowing the player to focus on winning the game.

Dr. Vernaleken says, “The results of this study were astonishingly opposite of what was previously hypothesized. Subjects with more functional dopaminergic reward-systems were not more aggressive in competitive situations and could concentrate even more on the game. Subjects with lower dopaminergic capacity were more likely to be distracted by the cheating behavior.”

“Thus, we think that a well-functioning reward system causes more resilience against provocation.

However, we cannot exclude that in a situation where the subject would directly profit from aggressive behavior, in absence of alternatives, the correlation might be the other way around.”

This research only scratches the surface of understanding the role of dopamine in aggression. More research will be necessary and could possibly change the way aggression is treated both behaviorally and pharmacologically.

This study was presented at the Society of Nuclear Medicine’s 59th Annual Meeting, June 9, 2012, Miami Beach, Florida. Funding for the research was provided by the IMP Project House in Aachen, Germany. No conflicts of interest were found.

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Review Date: 
June 19, 2012