Fluctuations of serotonin levels in the brain, which often occur when someone hasn’t eaten or is stressed, affects brain regions that enable people to regulate anger, new research from the University of Cambridge has shown. Although reduced serotonin levels have previously been implicated in aggression, this is the first study which has shown how this chemical helps regulate behaviour in the brain as well as why some individuals may be more prone to aggression. The research findings were published today, 15 September, in the journal Biological Psychiatry.