Low Glucose Levels Linked to Aggression

COLUMBUS, OhioResearchers at Ohio State University say they have discovered a connection between glucose, diabetes and aggression. Their findings suggest a boost in glucose levels may help dampen a hot temper, especially in individuals who have difficulty metabolizing glucose.

The researchers conducted several studies showing that people who have trouble metabolizing glucose in their bodies show more evidence of aggression and less willingness to forgive others.

One study, published in the journal Aggressive Behavior, found that people who drank a glass of lemonade sweetened with sugar acted less aggressively toward a stranger a few minutes later than did people who consumed lemonade with a sugar substitute.

In the study, 62 college students fasted for three hours to reduce glucose instability. They were told they were going to participate in a taste-test study, and then have their reaction times evaluated in a computerized test against an opponent. Half of the participants were given lemonade sweetened with sugar, while the others were given lemonade with a sugar substitute. After waiting eight minutes to allow the glucose to be absorbed in their bloodstream, the participants took part in the reaction test.

Participants were told they and an unseen partner would press a button as fast as possible in 25 trials, and whoever was slower would receive a blast of white noise through their headphones. At the beginning of each trial, participants set the level of noise their partner would receive if they were slower.  The noise was rated on a scale of 1 to 10from 60 decibels to 105 decibels. In actuality, each participant won 12 of the 25 trials. Aggression was measured by the noise intensity participants chose on the first trialbefore they were provoked by their partner.

Participants who drank the lemonade sweetened with sugar behaved less aggressively than those who drank lemonade with a sugar substitute. Those who drank the sugar-sweetened beverage chose a noise level averaging 4.8 out of 10, while those with the sugar substitute averaged 6.06.

Avoiding aggressive impulses takes self control, and self control takes a lot of energy. Glucose provides that energy in the brain," said Brad Bushman, co-author of the study. Drinking sweetened lemonade helped provide the short-term energy needed to avoid lashing out at others."

The findings are especially interesting for diabetics who have trouble metabolizing glucose. Diabetes may not only harm yourselfit is bad for society," he said. The healthy metabolism of glucose may contribute to a more peaceful society by providing people with a higher level of energy for self-control."

In two other studies in the same paper, the researchers showed how problems metabolizing glucose may translate to problems on a societal level. Using 2001 data, the researchers found that the diabetes rates for each of the 50 states were linked to violent crime rates. Those states with higher diabetes rates had higher rates of murder, assault, rape and robbery, even after controlling for poverty rates in each state.

This suggests that diabetes did not predict violent crime simply because poverty contributes to both diabetes and violent crime," he said.  There is a real correlation between diabetes and violence."

In a separate paper, the researchers tested whether another medical problem related to glucose metabolism was linked to violence worldwide.

They examined the prevalence, in the populations of 122 countries around the world, of a deficiency in an enzyme called glucose-6-phosphate dehydrogenase.  This enzyme is related to glucose metabolism.  It is the most common enzyme deficiency in the world, afflicting more than 400 million people. Countries with higher levels of the disorder also had more violent killings, even outside of war.