Stress and hunger have a huge influence on anger since the brain’s ability to regulate aggression relies heavily on serotonin levels, according to new research performed by University of Cambridge that was published in the journal of Biological Psychiatry.
Serotonin levels fluctuate when someone hasn’t eaten or is stressed. Decreasing serotonin levels has been linked to increasing aggression levels in the past but this is the first study that explains why some individuals are prone to have higher aggression than others. This is also the first study that shows how chemicals help regulate behavior.
Healthy volunteers participated in the study. Researchers manipulating their diets to alter serotonin levels. On the serotonin depletion day, they were given a mixture of amino acids that lacked tryptophan, the building block for serotonin. On the placebo day, they were given the same mixture but with a normal amount of tryptophan.
Researcher Luca Passamonti said, "Although these results came from healthy volunteers they are also relevant for a broad range of psychiatric disorders.”
The researchers then scanned the volunteers' brains using functional magnetic resonance imaging (fMRI) as they viewed faces with angry, sad, and neutral expressions. They were able to measure how different brain regions reacted and communicated with one another when the volunteers saw angry faces, as opposed to sad or neutral faces.
The results showed that low brain serotonin made communications between specific brain regions of the emotional system of the brain -- a structure called the amygdala -- and the frontal lobes weaker compared to when serotonin levels are normal.
Passamonti, who worked on the research with colleagues at the Cognition and Brain Sciences Unit of the Medical Research Council in Cambridge said, "We are hopeful that our research will lead to improved diagnostics as well as better treatments for this and other conditions."