Although aggressive and impulsive behavior may result from a combination of factors, new research suggests low levels of a brain neurotransmitter may be at least partly to blame.
Impulsive individuals often display aggressive behavior and have challenges ranging from drug and alcohol abuse, to problem gambling and difficult relationships. They often have trouble adapting to different social situations.
A new study published in the journal Biological Psychiatry shows that people may react this way, in part, because they have lower levels of the neurotransmitter GABA (gamma-aminobutyric acid).
GABA is the most important inhibitory neurotransmitter and is expressed in a specific part of the brain involved in regulating self-control.
“Advances in brain imaging techniques mean we are able to investigate different and specific areas of the human brain and see how they regulate people’s behavior,” said Frederic Boy, Ph.D., who led the research.
“What is clear is that the way people behave results from a complex interaction between a number of genetic, social and environmental factors.”
Researchers had men with no history of psychiatric disorders or substance dependence complete a questionnaire designed to assess different aspects of impulsivity. Then they underwent a kind of brain imaging technique (magnetic resonance spectroscopy) to measurement the amount of GABA in small regions of the brain.
Investigators found that men with more GABA in their prefrontal area of the brain had lower scores in one aspect of impulsivity called the “feeling of urgency” — the tendency to act rashly in response to distress or other strong emotions and urges.
Conversely, men with lower GABA tended to have higher urgency ratings. These findings add to evidence that “low GABA may be a risk factor for cortical dysfunction across a number of disorders, as depression and panic disorder are associated with low cortical GABA,” commented Dr. John Krystal, Editor of Biological Psychiatry, which published the research.
Researchers say the findings may also hold true in women, but women were not included in this study due to the possible effect of natural hormonal fluctuations.
The authors say the next component of the research will focus on understanding the relationship between GABA and the prefrontal cortex.
“After that we can start evaluating whether there’s any way in which we could treat a GABA deficit in this area. I suspect this could be difficult, as GABA is present throughout the brain, and raising the level indiscriminately may have all sorts of unforeseen consequences,” said Boy.
“The other area which needs further research is whether GABA levels in the prefrontal cortex fluctuate over time, as this study is simply a snapshot of levels on one given day.”