FRIDAY, Sept. 16 (HealthDay News) -- When people are hungry,
they are more likely to be angry or aggressive. And now researchers
have found the reason why: serotonin levels -- a hormone that helps
regulate behavior -- fluctuate when people are stressed out or
haven't eaten, according to a new study.
Rising and falling serotonin levels affect parts of the brain
that allow people to control their anger, researchers from the
University of Cambridge explained in the report published in the
Sept. 15 issue of the journal
"We've known for decades that serotonin plays a key role in aggression, but it's only very recently that we've had the technology to look into the brain and examine just how serotonin helps us regulate our emotional impulses. By combining a long tradition in behavioral research with new technology, we were finally able to uncover a mechanism for how serotonin might influence aggression," the study's co-first author, Molly Crockett, who worked on the research as a Ph.D. student at Cambridge's Behavioural and Clinical Neuroscience Institute, said in a university news release.
In conducting the study, the researchers controlled the diet of
healthy volunteers to manipulate their serotonin levels. The
participants' brains were then scanned using functional magnetic
resonance imaging (fMRI) as they viewed faces with different
expressions -- angry, sad and neutral -- to determine how various
parts of their brains reacted and communicated with each other.
The study revealed that low levels of serotonin made
communications between certain parts of the brain weaker than
normal. The researchers concluded that when this happens it may be
harder for the brain to control emotional responses to anger.
The participants also completed a personality questionnaire to
assess whether or not they had a natural tendency towards
aggression. Those that were predisposed to aggression had even
weaker communication between certain regions of their brain when
serotonin levels were low, the investigators found.
The findings could be applied to a range of psychiatric
disorders in which violence is a common problem, such as
intermittent explosive disorder, which is characterized by extreme
and uncontrollable outbursts of violence, the authors
"We are hopeful that our research will lead to improved diagnostics as well as better treatments for this and other conditions," the study's co-first author, Dr. Luca Passamonti, who worked on the research while a visiting scientist at the Cognition and Brain Sciences Unit of the Medical Research Council in Cambridge, England, said in a news release.
The U.S. National Institute of Neurological Disorders and Stroke
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