Do you often feel the need for a sweet sugar rush or a moment of bacon-induced bliss? A new study offers evidence that that surge of pleasure is similar to a heroin high, and that eating junk food regularly can significantly change the brain’s chemical make-up, creating junk food addicts who are driven to overeat.
Lead researcher Paul Kenny says it had previously been unclear whether extreme overeating was initiated by a chemical irregularity in the brain or if the behavior itself was changing the brain’s biochemical makeup. The new research by Kenny and his colleague Paul Johnson, a graduate student, shows that both conditions are possible [Scientific American].
For the study, published online in Nature Neuroscience, Kenny and colleagues headed to the grocery store. “We basically bought all of the stuff that people really like — Ding-Dongs, cheesecake, bacon, sausage, the stuff that you enjoy, but you really shouldn’t eat too often,” he said [Reuters]. One set of lab rats was allowed unfettered access to these high-calorie foods, while another rat group was allowed just one hour of access to the junk food per day. Both sets of rats also had the option of eating standard healthy lab rat fare. Finally, a control group of rats were kept on a healthy diet.
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The next time a friend says he’s addicted to bacon, you should know he probably isn’t joking. The brains of rats fed only on junk food—like bacon, Ho Hos, cheesecake, and sausage—look similar to the brains of heroin-addicted rats, according to new a study. Pleasure centers in the brains of rats addicted to high-fat, high-calorie diets became less responsive as the binging wore on, making the rats consume more and more food [Science News]. The findings suggest that drug addiction and overeating have similar biological mechanisms, according to the scientists from the Scripps Research Institute. The work is not yet published, but was presented at the Society for Neuroscience’s annual meeting.
The rats fed on junk food displayed a hallmark of addiction. After just five days on the junk food diet, rats showed “profound reductions” in the sensitivity of their brains’ pleasure centers, suggesting that the animals quickly became habituated to the food. As a result, the rats ate more food to get the same amount of pleasure. Just as heroin addicts require more and more of the drug to feel good, rats needed more and more of the junk food [Science News]. To test the depths of the rats addiction, researchers shocked rats every time they ate junk food. Rats that had not previously binged on Ho Hos quickly stopped eating the high-fat foods. However, the fat rats kept eating junk food even though they knew the shock was coming. Now that’s an addiction.
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Image: flickr / asplosh
The movie Fight Club may have been on the right track when it suggested that the fat left over from liposuction procedures was too valuable to throw away–although the idea of making soap from forsaken flab is too gross to catch on. Instead, researchers have found a way to turn fat cells into stem cells, and say the process is much more efficient than the standard technique for stem cell production, which uses human skin cells.
Reprogramming human skin cells remains woefully inefficient; typically, it takes about a month for 1 in 10,000 fibroblast skin cells to give rise to induced pluripotent stem (iPS) cells. Such iPS cells can, like embryonic stem cells, develop into any cell type. So researchers have been on the lookout for tissue types that can more speedily and easily be turned pluripotent [Nature News].
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From the skin cells of humans and mice, scientists have successfully made brown fat, the kind that burns white fat by producing heat and is possessed in the greatest quantities by babies. The study, published in Nature, could potentially lead to a way to help overweight and obese people slim down.
Brown fat was once thought to be found only in children, but earlier this year researchers confirmed that adults also have a small amount of brown adipose tissue. In 2007, researchers discovered that a protein called PRDM16 made immature muscle cells turn into brown fat. In the new Nature study, the same team of scientists found that PRDM16, in combination with a second protein produced in muscle cells, is the master switch for brown fat cells and will also convert skin cells into brown fat, even though this is not the process nature intended. [Scientists] used this master switch to convert mouse skin cells to brown fat cells, which seem to work as expected when transplanted into normal mice [The New York Times]. The next step is to implant brown fat into obese mice to see if they lose weight; that will provide evidence that the discovery might be used outside of the lab.
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Inserting a “pacemaker” into the brain to emit regular pulses of electricity and quell disordered neural activity may sound like a therapy of last resort, but if current experiments show beneficial results the brain surgery may one day be commonplace. But some scientists are cautioning that research on so-called deep brain stimulation may be pressing ahead too quickly, and warn that long-term effects of the surgery are not yet clear.
A growing number of psychiatric researchers are testing the method’s effectiveness on a host of psychiatric disorders. Until recently, deep brain stimulation was approved in the U.S. only to treat certain movement disorders, primarily those of Parkinson’s disease, for which it diminishes tremors and rigidity and improves mobility. To date, more than 60,000 patients worldwide have had the devices implanted [Los Angeles Times]. But now large clinical trials are in the works that will test the use of deep brain stimulation for obsessive compulsive disorder, epilepsy, and depression. Smaller experiments are beginning to assess the therapy’s effectiveness on a wide range of disorders including anorexia, drug addiction, obesity, traumatic brain injury, and Alzheimer’s.
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While initial public panic about the swine flu outbreak has largely subsided, the virus continues to spread through our species: The World Health Organization has tallied more than 10,000 cases worldwide, with 80 deaths confirmed. As patterns begin to emerge regarding who gets infected with the H1N1 flu virus, health officials are beginning to map out strategies for a potential wide-spread vaccination campaign.
Young people are particularly prone to infection, researchers say. Preliminary studies of family transmission showed that when one member gets infected, the most likely to follow are those under 18, not parents or grandparents [The New York Times]. The virus’s spread through the young has led to the closing of schools in infection hotspots–Japan is the most recent country to shut school doors–but most cases in young people have not been severe. The people who do get more serious cases that lead to hospitalization have tended to have underlying health conditions like heart problems, lung ailments, immune diseases, and diabetes. Surprisingly, obesity has also emerged as a risk factor.
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Brown fat—the “good” kind of fat—is often thought of as baby fat, but new research has found that it exists in adults and may play a role in regulating metabolism and staving off type 2 diabetes. White fat, or “bad fat,” stores energy, but also clogs arteries and accumulates as visible body fat. Brown adipose tissue burns calories for heat, but until now has been thought to exist only in childhood, disappearing as the body became more muscular. Now, three new studies published in The New England Journal of Medicine not only found adults still had brown fat, but that slim adults had more of it than fatter ones [BBC]. The researchers are now seeking a way to activate brown fat to improve both weight control and glucose metabolism, which would help prevent obesity and diabetes.
The studies found that brown fat stores decrease as people age, and that thinner people with normal blood glucose levels have more brown fat. However, it isn’t yet clear whether increased brown fat is a cause or a result of being thin. Brown fat was also more active during colder weather, when it plays a key role in burning energy to produce heat [AFP]. For now the only safe way known to activate brown fat is to stay chilly, right at the verge of shivering, for prolonged periods. That reproduces the conditions that led to the evolution of brown fat—namely, life-threatening cold in babies and small furry animals that can’t put on clothes to keep themselves warm [Los Angeles Times].
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The rate at which infants gain weight in the first six months of their lives is linked to those babies’ risk of becoming obese by age three, a new study has found. Researchers determined that sudden weight gain in early infancy was more important than how much a baby weighed at birth, the weight of the infant’s parents, or the number of pounds put on by the mother during pregnancy. “The perception has been that a chubby baby and a baby that grows fast early in life is healthier and all the baby fat will disappear,” said the paper’s lead author, Dr. Elsie Taveras…. “But [that] is not the case” [Chicago Tribune].
While the researchers note that early childhood obesity does not necessarily lead to obesity later in life, they say it does raise the risks. Obesity rates among U.S. children have doubled in the last 20 years, and almost a third of American children are either overweight or obese. The epidemic of obesity is linked to a host of health problems such as higher risks for heart disease, diabetes and cancer [Reuters].
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The hearts of African-American adults are apparently under extraordinary stress. A broad, long-term study has found that African-Americans are developing heart failure at a rate 20 times higher than whites, and some are dying of the disease decades before the condition typically proves fatal in whites. “Blacks in our study who were in their 30s and 40s had the same rate of heart failure as whites in their 50s and 60s,” said [lead researcher] Kirsten Bibbins-Domingo…. “These are people who are in the prime of their life and should be contributing in all kinds of ways,” Dr. Bibbins-Domingo added, “so this disease has a devastating effect, not just on the individual patient but on the family, the community and society in general” [The New York Times].
Researchers say the findings show that narrowly focused research in the past has left striking gaps in our understanding of heart disease, which is the top cause of death for Americans. Says Bibbins-Domingo: “We usually thought of heart failure as a disease of older people, but that’s based on studies by mostly white participants.” … Researchers and cardiology specialists called the findings alarming and a call to action. The scientific community should step up its research on the risk factors and design clinical trials to study specialized treatment for black patients, they said [Baltimore Sun]. They also urge young African-Americans to take the threat seriously, and hedge against it with a healthy diet and exercise.
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It may be old news that people who work the night shift tend to have higher rates of certain medical conditions. But researchers say they have established a direct link between an abnormal sleep cycle and altered hormone levels, which can disrupt metabolism and increase the risk of heart disease, diabetes, and obesity. As soon as their circadian rhythms became separated from a day-night cycle, test subjects’ levels of key metabolic hormones went haywire—the most compelling evidence yet that shift work isn’t just an inconvenience, but an occupational hazard [Wired News].
The study, published in the Proceedings of the National Academy of Sciences, maps a clear path from work-sleep cycles to metabolic disregulation to disease [Wired News]. Scientists cannot yet explain the exact connection between metabolism and the circadian rhythm, the roughly 24-hour cycle that biological and behavioral processes are based on. But they believe the trigger to be a decrease in the hormone leptin, which the body uses to regulate appetite, that results when the circadian rhythm is disrupted.
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A small study suggests that men are better able to resist food cravings than women, which researchers say could partially explain why more women than men are obese, and why women are more prone to overeating when they’re under emotional stress. In a new brain-scan study, researchers flashed tasty food in front of men and women who hadn’t eaten anything in at least 17 hours. Both were told to fight their hunger, but only men showed a drop in activity in brain regions involved in emotion and motivation [CNN]. However, some researchers say that it’s risky to generalize based on a study with just 23 test subjects.
In the study, which will be published in Proceedings of the National Academy of Sciences, researchers engaged their volunteers in a somewhat torturous experiment. They first surveyed the volunteers about their favorite foods: Did they favor pizza, chocolate cake, burgers, or fried chicken? Then they were asked to fast overnight. When they returned to the lab the next day, the subjects got PET brain scans while being subjected to a barrage of craving-inducing stimuli. They looked at pictures of their favorite food, smelled its aroma wafting in from the next room, and even tasted it with cotton swabs placed on their tongues.
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Researchers recently went to an Amish community in Pennsylvania with an odd request: Will you drink milkshakes for the sake of science? In a study about cardiovascular health and genetics that had more than 800 Amish people slurping high-fat shakes, researchers discovered that about five percent of their subjects had a genetic mutation that defends the heart against the effects of a high-fat diet—specifically, breaking down triglycerides, those fats that clog arteries like hair in your bathroom drain [Newsweek].
In the study, published in Science [subscription required], Amish men and women agreed to drink a rich milkshake that was made mostly of heavy cream. Over the next six hours, a group of investigators took samples of their blood, determining how much fat was churning through their bloodstreams. Most of the study participants responded as expected — their levels of triglycerides, a common form of fat in the blood, rose steadily for three to four hours and then declined. But about 5 percent had an extraordinary reaction: their triglyceride levels started out low and hardly budged [The New York Times].
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Happiness is catching and spreads like the flu, according to a study that followed a whole community of people for 20 years. The effect of one happy person could ripple through three degrees of separation, researchers report. “It is sometimes said that you can’t be happier than your least happy child. It is truly amazing to discover that when you replace the word ‘child’ with ‘best friend’s neighbor’s uncle,’ the sentence is still true,” [Boston Globe] said psychologist Daniel Gilbert, who was not involved in the study. The researchers liken the pattern of happiness transmission to the spread of a virus: those with the most number of happy contacts are the mostly likely to catch the happy bug.
The study, published in the British Medical Journal, followed more than 4,700 people living in Framingham, Massachusetts from 1983 to 2003. The participants answered periodic questionnaires about their emotional well-being and listed the names of relatives, friends, and co-workers, many of whom were also participating in the study. Researchers found that happiness wasn’t scattered evenly throughout the population but instead seemed to spread through social networks. “Happiness is like a stampede,” said [co-author] Nicholas Christakis… “Whether you’re happy depends not just on your own actions and behaviors and thoughts, but on those of people you don’t even know” [AP].
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In yet another warning signal of the toll that childhood obesity will take on health and health care budgets, a small study has shown that overweight kids as young as 10 years old have the thickened arteries of 45-year-olds. Researchers say the findings raise the possibility that these kids could develop serious heart disease in their 20s or 30s. “There’s a saying that ‘you’re as old as your arteries,’ meaning that the state of your arteries is more important than your actual age in the evolution of heart disease and stroke,” said [lead researcher] Dr Geetha Raghuveer [Telegraph].
The findings, while preliminary, should serve as a serious alarm bell in the United States, where about one-third of children are overweight and almost one-fifth are obese. Many parents think that “baby fat” will melt away as kids get older. But research increasingly shows that fat kids become fat adults, with higher risks for many health problems. “Obesity is not benign in children and adolescents,” said Dr. Robert Eckel, a former heart association president [AP].
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A drug that mimics the effects of a compound found in red wine has been shown to prevent obesity and diabetes in mice that were fed a high-calorie diet and prevented from exercising, taking another step towards the target of a anti-obesity pill. The natural compound found in grapes and red wine, called resveratrol, is believed to have numerous health benefits related to longevity, heart health, and metabolism. But tests in mice suggested gallons of wine would be necessary for humans to stand a chance of getting the same benefits. The scientists turned their attention to creating a more potent drug [BBC News].
The new experimental drug, called SRT1720, was developed by the pharmaceutical company GlaxoSmithKline. Researchers explain that mice fed a high-fat diet were tricked into switching their metabolisms to a fat-burning mode that normally takes over when energy levels are low…. “We are activating the same enzymes that are activated when people go to the gym,” said Peter Elliott, a vice president at Sirtris Pharmaceuticals, the Glaxo unit that developed the drug. “That is why we believe the profile for this drug is very safe” [Reuters].
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