People who are prone to outbursts of impulsive aggression that may result in rage attacks have smaller emotional brains, a new study has found.
Neuroimaging studies suggest that frontolimbic regions of the brain, structures that regulate emotions, play an important role in the biology of aggressive behaviour.
Scientists found that individuals with intermittent explosive disorder (IED) have significantly lower grey matter volume in these frontolimbic brain structures. In other words, these people have smaller "emotional brains."
"Intermittent explosive disorder is defined in DSM-5 as recurrent, problematic, impulsive aggression," said lead author Emil Coccaro, from the University of Chicago in US.
"While more common than bipolar disorder and schizophrenia combined, many in the scientific and lay communities believe that impulsive aggression is simply 'bad behaviour' that requires an 'attitude adjustment'," said Coccaro.
"However, our data confirm that IED, as defined by DSM-5, is a brain disorder and not simply a disorder of 'personality,'" said Coccaro.
The researchers also report a significant inverse correlation between measures of aggression and frontolimbic grey matter volume.
They collected high-resolution magnetic resonance imaging (MRI) scans in 168 subjects, including 57 subjects with IED, 53 healthy control subjects, and 58 psychiatric control subjects.
They found a direct correlation between history of actual aggressive behaviour and the magnitude of reduction in grey matter volume, linking both in a dimensional relationship.
"Across all subjects, reduced volume in frontolimbic brain structures was associated with increased aggressiveness," said Cameron Carter, Professor of Psychiatry and Behavioural Sciences at University of California, Davis.
"These important findings suggest that disrupted development of the brain's emotion-regulating circuitry may underlie an individual's propensity for rage and aggression," he said.
The study was published in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.
