Aggression Decreased by Increased Glucose Levels

Summary
Studies have shown that control of aggressive and violent behaviors require self-control. This self-control exhausts blood sugar, which is taken up by the brain and experts suggest that low amount of glucose in the brain could lead to more aggressive behaviors. This was examined further using four studies. Results from the four studies showed that high blood sugar due to consumption could reduce aggressive behavior. On the other hand, high blood sugar that is not accessible to the brain in conditions like diabetes is linked to higher aggression and violence.  Per the authors, “All four studies suggest that a spoonful of sugar helps aggressive and violent behaviors go down.”

Introduction
There are many causes of aggression and violence, including provocation, frustration, alcohol intoxication, violence in the media, weapons, hot temperatures, loud noises, pollution, crowding, and many other unpleasant events. Self-control to stop or reduce aggression needs a good amount of energy. This comes from glucose in the blood, which is also used by the brain. Low glucose is linked to poor performance on numerous self-control tasks. Also conditions that hamper utilization of blood glucose like diabetes or excessive drop of blood sugar may also lead to poor self control. There are no studies that establish this link directly. Hence, this study was conducted to understand the link between blood sugar and violent behavior.

Methodology

  • Study 1 included 62 undergraduate students. Some of them were given a sweetened drink to consume and thereafter set tasks to test their measure of aggression. A control group was given a drink with a sugar substitute.
  • Study 2 included 112 adults. They were tested for diabetes. Thereafter, the measures for aggression were tested using questionnaires.
  • Study 3 looked into the rates of diabetes and rates of violent crimes from all 50 states in the US, for the year 2001.
  • Study 4 checked for rates of Glucose 6 phosphate dehydrogenase enzyme deficiency and “violence, in the form of violent (nonaccidental) killings not related and related to war.” This enzyme helps in utilization of blood glucose in normal individuals.

Results

  • Study 1 showed “participants who drank the lemonade sweetened with sugar behaved less aggressively than did participants who drank the lemonade sweetened with a sugar substitute.”
  • Study 2 showed that the diabetic individuals have poorer self-control and higher levels of aggressiveness.
  • Study 3 showed that higher prevalence of diabetes was associated with higher rates of violent crimes.
  • Study 4 showed “prevalence of glucose-6-phosphate dehydrogenase deficiency in countries throughout the world predicted non-war violent killings and war killings.”

Next steps
The authors admit that self-control could predict only a very small part of the association between diabetes and aggression in study 2. Also, further studies to explore the association between the enzyme deficiency and aggression and killings are warranted, since the association in study 4 is poorly explained. At the same time, it is also suggested that for war killings, the killing is carried out by one set of people with another set being killed. Therefore, higher levels of this enzyme deficiency in one country may relate to more war killings in other countries instead of more killings in the same country.

Conclusion
This study showed that, “Increasing glucose levels to adequate levels among aggressive-prone individuals could greatly reduce aggression in society…Indeed, one report showed that the ‘‘sweet lollipop intervention’’ decreased the annual rate of physical assaults by 10 percent over a one year period.” This study also brings to notice the fact that those with disorders like diabetes are not only at various health risks due to poorly utilized high blood sugars but are also at risk of being more aggressive and violent. Thus authors conclude, “The healthy metabolism of glucose may contribute to a more peaceful society by providing individuals with a higher level of self-control energy.”

For More Information:
Sweetened Blood Cools Hot Tempers
Aggressive Behavior, November 2010
By C. Nathan DeWall and Timothy Deckman
From the Department of Psychology, University of Kentucky, Kastle Hall, Lexington, Kentucky

*FYI Living Lab Reports Are Summaries of the Original Research.
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