Researchers Find Link Between Sugar, Diabetes And Aggression

Main Category: Diabetes
Also Included In: Psychology / Psychiatry
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A spoonful of sugar may be enough to cool a hot temper, at least for a short time, according to new research.

A study 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.

Researchers believe it all has to do with the glucose, a simple sugar found in the bloodstream that provides energy for the brain.

"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 and professor of communication and psychology at Ohio State University.

"Drinking sweetened lemonade helped provide the short-term energy needed to avoid lashing out at others."

The finding is more than just a medical curiosity, Bushman said. In two published papers, he and his colleagues did several studies showing that people who have trouble metabolizing, or using, glucose in their bodies show more evidence of aggression and less willingness to forgive others.

The problem is that the number of people who have trouble metabolizing glucose -- mainly those with diabetes -- is rising rapidly. From 1980 through 2008, the number of Americans with diabetes has more than tripled (from 5.6 million to 18.1 million).

"Diabetes may not only harm yourself -- it is bad for society," Bushman 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."

Bushman conducted the lemonade study with C. Nathan DeWall and Timothy Deckman of the University of Kentucky and Matthew Gailllot of SUNY-Albany. It appears online in the journal Aggressive Behavior and will be published in a future print edition.

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.

The reaction test has been used and verified in other studies as a way to measure aggression. 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 10 -- from 60 decibels to 105 decibels (about the same volume as a smoke alarm).

In actuality, each participant won 12 of the 25 trials (randomly determined).

Aggression was measured by the noise intensity participants chose on the first trial -- before they were provoked by their partner.

Results showed that 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.

"To our knowledge, this is the first study to find that boosting glucose levels can reduce actual aggressive behavior," Bushman said.

"To be sure, consuming sugar should not be considered a panacea for curbing aggression. But the results do suggest that people who reportedly "snap" with aggression may need some way to boost their mental energy, so they can override their aggressive impulses."

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 also tended to have 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 analysis, 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.

"Taken together, these studies offer different types of evidence linking low glucose and other problems metabolizing glucose with aggression and violence," Bushman said.

The findings were further corroborated in another series of studies, published recently in the journal Personality and Individual Differences.

In that paper, Bushman and DeWall, along with University of Kentucky researcher Richard Pond, had participants complete a commonly used and well-accepted checklist that measures the number and severity of Type 2 diabetes symptoms, such as numbness in the feet, shortness of breath at night, and overall sense of fatigue. In three separate studies, the same participants completed different measures of their willingness to forgive others.

On all three measures, people with higher levels of diabetic symptoms were less likely to forgive others for their transgressions.

In a fourth study, participants took part in a prisoner's dilemma game, which is often used to understand how people deal with conflict. In this version, participants had to choose whether to cooperate or compete against an unseen partner in a computer game.

"We were especially interested in how participants responded when their partner behaved in an uncooperative, antagonizing manner when the game began," Bushman said. "Would they forgive their partner or would they refuse to cooperate?"

Results showed that those who scored higher on diabetic symptoms were less likely to forgive an initially uncooperative partner, when compared to those who scored lower on diabetic symptoms.

"These studies are more evidence that diabetic symptoms may cause difficulty in how people relate to each other on a day-to-day basis," Bushman said.

"It's not an excuse diabetes does not mean people have to act aggressively, but it may shed some light on why these behaviors occur."

"With the rate of diabetes increasing worldwide, it is something that should concern all of us."

Source: Ohio State University

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Link Between Childhood Obesity And Increased Risk Of Adult Cardiovascular And Metabolic Disorders

Main Category: Obesity / Weight Loss / Fitness
Also Included In: Pediatrics / Children's Health;??Heart Disease;??Diabetes
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Mounting evidence linking childhood obesity to an increasing risk of obesity, heart disease, type 2 diabetes, and other cardiovascular and metabolic disorders in adulthood is clearly presented in a comprehensive review article in the current issue of Childhood Obesity, published by Mary Ann Liebert, Inc. The article is available free online.

Authors Megan Moriarty-Kelsey, MD and Stephen Daniels, MD, PhD, Department of Pediatrics, University of Colorado School of Medicine, caution that the rising prevalence of obesity in children will lead to higher obesity rates in the adult population, resulting in a greater health burden caused by obesity-related metabolic and cardiovascular complications. In fact, obese children may already exhibit early signs of disorders such as hypertension, elevated cholesterol levels, and insulin resistance.

In the article entitled "Childhood Obesity is the Fuel That Fires Adult Metabolic Abnormalities and Cardiovascular Disease," the authors emphasize the importance of prevention and early intervention for childhood obesity. This not only minimizes risk of future disease, but also prevents the occurrence of disorders once thought of as conditions of adulthood that have become increasingly common in children, such as type 2 diabetes and fatty liver disease.

Source:
Cathia Falvey
Mary Ann Liebert, Inc./Genetic Engineering News

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New Links Seen Between Depression and Diabetes

Study Shows Depression May Raise Risk of Diabetes and Vice Versa

By Denise Mann
WebMD Health News

Reviewed by Laura J. Martin, MD

Nov. 22, 2010 -- Depression and diabetes may be linked, according to new research in the Archives of Internal Medicine.

"People usually think of these as two isolated conditions, but there is growing evidence that they are linked behaviorally and biologically," says study researcher Frank Hu, MD, PhD, MPH, professor of nutrition and epidemiology at the Harvard School of Public Health in Boston. "This data provide strong evidence that we should not consider these two isolated conditions any longer."

About 23.5 million Americans have diabetes, and about 14.8 million Americans have major depressive disorder in a given year, according to statistics in the new report.

Of the 65,381 women aged 50 to 75 in 1996 who were study participants, 2,844 women were newly diagnosed with type 2 diabetes and 7,415 women developed depression in the ensuing 10 years.

Depression increased the risk for diabetes, and diabetes increased the risk for depression, the study shows. Specifically, women who were depressed were 17% more likely to develop diabetes even after the researchers adjusted for other risk factors such as weight and lack of regular exercise.

Those women who were taking antidepressants were 25% more likely to develop diabetes than their counterparts who were not depressed, the study shows.

Women with diabetes were 29% more likely to develop depression after taking into account other depression risk factors, and those women who took insulin for their diabetes were 53% more likely to develop depression during the 10-year study.

While certain factors such as physical activity and body mass index may partially explain the link between depression and diabetes, they do not completely explain the connection, Hu tells WebMD.

The common denominator may be stress, Hu says.

People who are depressed have elevated levels of stress hormones such as cortisol, which can lead to problems with glucose or blood sugar metabolism, increased insulin resistance, and the accumulation of belly fat -- all diabetes risk factors, he says.

But "there is long-term stress and strain associated with diabetes management such as blood sugar control and treatment for complications, and this can lead to decreased quality of life and increased probability of depression," he says.

"Both are very common diseases," says Leonid Poretsky, MD, director of the Friedman Diabetes Institute at Beth Israel Medical Center in New York City. "Diabetes can make depression worse because diabetes is chronic illness with a lot of worries."

"So much of the treatment for diabetes is self-care, and people who are depressed may not take good care of themselves," he says. "They don't exercise as much and may have other issues in terms of watching their diet, checking their blood sugar, and taking medications."

Certain medications used to treat depression can also increase risk for developing diabetes, he says.

"It can be a vicious cycle. Both diseases have to be addressed at the same time," Poretsky says. "If control of diabetes is deteriorating, look for depression as a possible cause of this deterioration."

"This study is interesting, and one of a number of studies that points to a bi-directional link between diabetes and depression," says Jeffrey Gonzalez, PhD, assistant professor of medicine and epidemiology and population health at Albert Einstein College of Medicine in the Bronx, N.Y. "The emotional side of diabetes is an important one to attend to in the treatments of this illness."

"This speaks to the burden associated with diabetes," Gonzalez says. "Changes in diet and lifestyle, having to take injections can lead to increased levels of distress."

Doctors need to do a better job of addressing the emotional side of diabetes, he says. "We know that if you are distressed once you do have diabetes, you are at increased risk for poor self-management, complications, and death."

SOURCES: Pan, A. Archives of Internal Medicine, 2010; vol 170: pp 1884-1891Leonid Poretsky, MD, director, Friedman Diabetes Institute, Beth Israel Medical Center, New York City.Frank Hu, MD, MPH, PhD, professor, nutrition and epidemiology, Harvard School of Public Health, Boston.Jeffrey Gonzalez, PhD, assistant professor of medicine, epidemiology and population health, Albert Einstein College of Medicine, New York.

ⓒ2010 WebMD, LLC. All Rights Reserved.

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Biologists discover biochemical link between biological clock and diabetes

ScienceDaily (Sep. 20, 2010) ? Biologists have found that a key protein that regulates the biological clocks of mammals also regulates glucose production in the liver and that altering the levels of this protein can improve the health of diabetic mice.

Their discovery, detailed in this week's advanced online publication of the journal Nature Medicine, provides an entirely new biochemical approach for scientists to develop treatments for obesity and type 2 diabetes. It also raises the interesting possibility that some of the rise in diabetes in the U.S. and other major industrialized countries could be a consequence of disturbances in sleep-wake cycles from our increasingly around-the-clock lifestyles.

"We know that mice that don't have good biological clocks tend to develop diabetes and obesity," said Steve Kay, Dean of the Division of Biological Sciences at UC San Diego and one of the lead authors of the research study. "And we know that mice that have developed diabetes and obesity tend not to have very good biological clocks. This reciprocal relationship between circadian rhythm and the maintenance of a constant supply of glucose in the body had been known for some time. But what we found that's so significant is that a particular biological clock protein, cryptochrome, is actually regulating how the hormone that regulates glucose production in the liver works in a very specific way."

"We used to think that our metabolism was regulated primarily by hormones that are released from the pancreas during fasting or feeding. This work shows that the biological clock determines how well these hormones work to regulate metabolism," says Marc Montminy, a professor in the Clayton Foundation Laboratories for Peptide Biology at the Salk Institute for Biological Studies. "The study may explain why shift workers, whose biological clocks are often out of kilter, also have a greater risk of developing obesity and insulin resistance."

Cryptochrome was first discovered by scientists as a key protein regulating the biological clocks of plants. It was later found to have the same function in fruit flies and mammals. But its role in regulating glucose production in the liver came as a complete surprise to the UCSD and Salk team, which included scientists from the Genomics Institute of the Novartis Research Foundation in San Diego, the University of Memphis and the Chinese Academy of Sciences in Shanghai.

"What was incredibly surprising is that cryptochrome has a new function that nobody had predicted," said Eric Zhang, the first author of the study and a researcher in Kay's UCSD laboratory. "Until now, cryptochrome had been known as a protein inside the nucleus of mammalian cells that switches genes on and off in a rhythmic way. What we showed was that cryptochrome has a role outside the nucleus as well."

That additional function of cryptochrome in mammalian cells, the scientists discovered, is to regulate a process known as "gluconeogenesis," in which our bodies supply a constant stream of glucose to keep our brain and the rest of our organs and cells functioning. When we're awake and eating, sufficient glucose is supplied to our bloodstream. But when we're asleep or fasting, glucose needs to be synthesized from the glycogen stored in our liver to keep our glucose levels up.

"That is how our energy metabolism evolved to function in concert with our diurnal activity, or in the case of the mice, their nocturnal activity," said Kay. "This molecular mechanism involving cryptochrome presumably evolved to coordinate our energy metabolism with our daily activity and feeding levels. So could some instances of diabetes be the result of a faulty circadian clock? And if that's the case, can we find ways of fixing the clock to treat this disease? Such an approach would be a whole new way of thinking about how to develop new treatments for diabetes."

In their study, the scientists found evidence that such an approach would be feasible. "Our experiments show very nicely that modulating cryptochrome levels in the liver of mice can actually give diabetic animals a benefit," Kay added.

The researchers discovered cryptochrome's role in gluconeogenesis while studying how a signaling molecule known as cyclic AMP interacted with the biological clock.

"It had been known for some time now that there was a connection between cyclic AMP signaling and circadian rhythm regulation and that's where we started," said Kay, "by asking the question: How are those two connected?"

Zhang and his UCSD colleagues conducted a series of experiments that found that the production of the next step after cyclic AMP, a protein called Creb, ebbed and flowed rhythmically in the livers of mice. That led the scientists to their initial discovery that cryptochrome was regulating the production of Creb in the liver.

In their studies with fasting and insulin-resistant mice at the Salk Institute, the scientists found that cryptochrome was regulating how the hormone glucagon, which controls gluconeogenesis, works in a very specific way. By controlling the production of cyclic AMP, crytochrome regulates the activity of Creb in the liver. In this way, the production of glucose in the liver is tied through our daily eating, sleeping and fasting activities through the biological clock.

The scientists say their discovery may open up a whole new area of research into how cryptochrome may be regulating other cell functions outside the nucleus.

"There's a wide role that the biological clock may be playing in influencing other hormones, not just glucagon, that are important for metabolism," said Kay.

In addition, studies on human populations have found links between disturbances in the biological clock, such as shift work and chronic jet lag, and the propensity to develop certain kinds of cancers as well as diabetes. Because of this, the scientists plan to continue their research into cryptochrome, looking for compounds that may enhance or diminish the activity of this critical biological clock protein.

The research was funded by grants from the National Institutes of Health. Other co-authors of the paper include Tsuyoshi Hirota, Dmitri A Nusinow, Pagkapol Pongsawakul and Andrew Liu of UCSD's Division of Biological Sciences; David Brenner and Yuzo Kodama of the UCSD School of Medicine; Yi Liu, Renaud Dentin and Severine Landais of The Salk Institute; and Xiujie Sun of the Chinese Academy of Sciences.

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of California -- San Diego. The original article was written by Kim McDonald.

Journal Reference:

Eric E Zhang, Yi Liu, Renaud Dentin, Pagkapol Y Pongsawakul, Andrew C Liu, Tsuyoshi Hirota, Dmitri A Nusinow, Xiujie Sun, Severine Landais, Yuzo Kodama, David A Brenner, Marc Montminy, Steve A Kay. Cryptochrome mediates circadian regulation of cAMP signaling and hepatic gluconeogenesis. Nature Medicine, 2010; DOI: 10.1038/nm.2214

Note: If no author is given, the source is cited instead.

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Strong link between diabetes and air pollution found in national U.S. study

ScienceDaily (Sep. 30, 2010) ? A national epidemiologic study finds a strong, consistent correlation between adult diabetes and particulate air pollution that persists after adjustment for other risk factors like obesity and ethnicity, report researchers from Children's Hospital Boston. The relationship was seen even at exposure levels below the current EPA safety limit.

The report, published in the October issue of Diabetes Care, is among the first large-scale population-based studies to link diabetes prevalence with air pollution. It is consistent with prior laboratory studies finding an increase in insulin resistance, a precursor to diabetes, in obese mice exposed to particulates, and an increase in markers of inflammation (which may contribute to insulin resistance) in both the mice and obese diabetic patients after particulate exposure.

Like the laboratory studies, the current study focused on fine particulates of 0.1-2.5 nanometers in size (known as PM2.5), a main component of haze, smoke and motor vehicle exhaust. The investigators, led by John Pearson and John Brownstein, PhD, of the Children's Hospital Informatics Program, obtained county-by-county data on PM2.5 pollution from the Environmental Protection Agency (EPA), covering every county in the contiguous United States for 2004 and 2005.

They then combined the EPA data with data from the Centers for Disease Control (CDC) and the U.S. Census to ascertain the prevalence of adult diabetes and to adjust for known diabetes risk factors, including obesity, exercise, geographic latitude, ethnicity and population density (a measure of urbanization).

"We wanted to do everything possible to reduce confounding and ensure the validity of our findings," says Pearson, the study's first author.

In all analyses, there was a strong and consistent association between diabetes prevalence and PM2.5 concentrations. For every 10 μg/m3 increase in PM2.5 exposure, there was a 1 percent increase in diabetes prevalence. This finding was seen in both 2004 and 2005, and remained consistent and significant when differing estimates of PM2.5 exposure were used.

"We didn't have data on individual exposure, so we can't prove causality, and we can't know exactly the mechanism of these peoples' diabetes," acknowledges Brownstein. "But pollution came across as a significant predictor in all our models."

Even among counties falling within EPA limits for exposure, those with highest versus the lowest levels of PM2.5 pollution had a more than 20 percent increase in diabetes prevalence, which remained after controlling for diabetes risk factors.

"From a policy perspective, the findings suggest that the current EPA limits on exposure may not be adequate to prevent negative public health outcomes from particulate matter exposure," Brownstein says.

"Many environmental factors may contribute to the epidemic of diabetes in the United States and worldwide," notes Allison Goldfine, MD, head of clinical research at the Joslin Diabetes Center and a coauthor on the study. "While a lot of attention has correctly been attributed to caloric excess and sedentary behaviors, additional factors may provide novel approaches to diabetes prevention."

Based on their findings, the researchers call for more study of environmental factors in diabetes, including basic research on the inflammatory mechanisms in diabetes and the role of PM2.5.

"We would like to access better individual-level data on diabetes and exposure," adds Brownstein. "We also have an interest in investigating this finding internationally where standards may be less stringent."

The study was funded by the National Center for Biomedical Computing of the National Institutes of Health.

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Children's Hospital Boston.

Journal Reference:

J. F. Pearson, C. Bachireddy, S. Shyamprasad, A. B. Goldfine, J. S. Brownstein. Association Between Fine Particulate Matter and Diabetes Prevalence in the U.S.. Diabetes Care, 2010; 33 (10): 2196 DOI: 10.2337/dc10-0698

Note: If no author is given, the source is cited instead.

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