PET Scans Link Low Dopamine Levels and Aggression

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By Marijke Vroomen Durning, RN |June 12, 2012

PET imaging has demonstrated a link between low dopamine levels and aggression in young healthy adults — surprisingly opposite results from what was previously hypothesized, said researchers in a presentation at the Society of Nuclear Medicine’s Annual Meeting, in Miami Beach, Fla., this week.

The neurobiology of aggression is not well understood, but researchers have been aware that there is a relationship between serotonin, a neurotransmitter, and certain aggressive behaviors. To investigate this further, researchers from RWTH Aachen University in Aachen, Germany, assessed 18 hea lthy adults in their 20s for aggression using the psychological behavioral task known as point subtraction aggression paradigm (PSAP). They wanted to determine if higher levels of dopamine, involved in pleasure and reward, increased aggressiveness, but the results weren’t as theorized.

(MORE: PET Tracer Shows Active Brains Have Less Beta-Amyloid)

By playing a computer game, in which the participants were told that an opponent in another room would be able to cheat and steal some of the participants’ winnings, the subjects could punish the cheater (who did not exist in reality), shield against the adversary by repeatedly pressing a defense button, or continue to play the game in order to maximize their ability to win cash. This indicated resilience.

The subjects underwent PET scanning with F-18 FDOPA, a biomarker that lights up enzymes’ ability to synthesize serotonin. The uptake was analyzed to gauge the correlation between the subjects’ dopamine synthesis capacity and aggressive behavior.

The researchers found that there was a significant impact on aggressive response in areas in the brain where dopamine synthesis was present, especially in the basal ganglia, which among other functions, include the motivation center. Minimized aggression was associated with higher dopamine levels in both the midbrain and the striatum, which plays a role in planning and investigative functioning.

Focus on the monetary reward aspect of the PSAP was seen among subjects with a greater capacity for dopamine synthesis, while those with lower capacities had higher vulnerability to act either aggressively, defensively, or both, researchers said.

“We think that a well-functioning reward system causes more resilience against provocation,” said lead author Ingo Vernaleken, MD. “However, we cannot exclude that in a situation where the subject would directly profit from aggressive behavior, in absence of alternatives, the correlation may be the other way around.”





This reminds

me of a statement from the first Daoist book I read about how the ancient Chinese had noticed that a disproportionate number of violent crimes were committed shortly after ejaculation "because some men scare more easily and therefore react more violently" (or something to that effect).

Human sexuality is a far more fascinating subject than we imagine today.


You know I thought that violent men were just victims of anxiety and fear, but I thought that said fear/anxiety came from very high dopamine. Maybe the variable is the dopamine receptors? Less receptors means that there appears to be less dopamine but in reality there is more? I'm a little confused.

Maybe militaries discourage

Maybe militaries discourage sex because they can't predict how soldiers will react. It's better to have less aggressive, predicable behavior than madmen/women on the loose. The military might want to get in on the orgasm research. At least it would be willing to steamroll the current paradigm if it's not in the military's interest. 

Some years back

there was a rumor floating around that the British military had shown soldiers violent porn on the way to the Falklands for the brief war there. I could never run it to ground, but I wonder.


Makes sense, perhaps, for a blitz. Though one then needs a plan for if the blitz fails. I wonder if the aggression can be trained so that the units stay cohesive while the enemy gets their wrath.

Could drone pilots be experiencing some of these aspects? There could be a lot of stimulation there without the same releases as a traditional pilot.

Has anyone tried analyzing cases of police aggression?

Still waiting for the orgasm defense.

This applies to me

As I reboot more and more I find myself less defesive and irratable. It is much easier for me to shrug things of and be "the bigger man". When I PMOed and had low dopamine levels, id always snap at people who may have said negative things to me or always had to have the last word or best comeback, but i realize that its a little immature. I definitely feel a lot less aggressive in a good way.