Western-style diet linked to state-dependent memory inhibition
July 14 2016, Porto, PORTUGAL - Obesity may ultimately be a disease of the brain, involving a progressive deterioration of various cognitive processes that influence eating. Researchers at Macquarie University have now shown that memory inhibition – the useful ability to ‘block out’ memories that are no longer useful, which depends on a brain area called the hippocampus – is linked to dietary excess. Usually, food-related memories should be at the forefront during hunger but then inhibited during fullness, so that thoughts of food are set aside when eating is no longer top priority. Prior animal studies have shown that a Western diet – one high in fats and sugars and low in fruit, vegetable and fiber – impairs the memory inhibition abilities of the hippocampus. Practically, this could mean that a Western-style diet makes it harder to inhibit pleasant memories triggered by seeing or smelling palatable food. This would make it hard to resist delicious treats even if one were full.
The Macquarie researchers have now found evidence for this problem in humans, they reported this week at the annual meeting of the Society for the Study of Ingestive Behavior (SSIB), the foremost society for research into all aspects of eating and drinking behaviour. The study supported by the Australian Research Council and led by PhD student Tuki Attuquayefio looked at healthy young people, some of whom ate a Western-style diet. Participants completed learning and memory tests that depend on the hippocampus and also rated their liking and wanting of palatable snack foods before and after a filling lunch. Participants who habitually ate a Western-style diet were slower at learning and poorer at remembering than those who ate a healthier diet, and more importantly showed much smaller reductions in wanting palatable snacks when tested full compared to hungry. The key finding is that memory performance and snack food ratings were linked. “Even though they were full, they still wanted to eat the sweet and fatty junk food”, explained Tuki Attuquayefio. “What was even more interesting was that this effect was strongly related to their performance on the learning and memory task, suggesting that there is a link between the two via the hippocampus.”
In agreement with the animal research, people with greater intake of a high fat, high sugar diet may do more poorly on the learning and memory tests because of how the diet impacts the hippocampus. The Macquarie University researchers believe inability to inhibit food memories when in a satiated physiological state could then explain the persistent desire for snacks. For otherwise healthy, lean, young people who routinely consume high-fat high-sugar diets, compromised hippocampal function may make it harder to regulate food intake and set them upon the road towards obesity.
Research: Western diet intake predicts hippocampal learning and state-dependent inhibition of wanting for snack foods: Evidence from human subjects..
Lead Author: Tuki Attuquayefio, PhD Candidate, Department of Psychology, Macquarie University
1. R. J. Stevenson, Department of Psychology, Macquarie University
2. R. Boakes, School of Psychology, University of Sydney
3. M. Oaten, School of Applied Psychology, Griffith University
4. M. R. Yeomans, School of Psychology, University of Sussex
5. M. Mahmut, Department of Psychology, Macquarie University
6. H. Francis, Department of Psychology, Macquarie University
A joint study by Canada’s York University and the Centre for Addiction and Mental Health examines oxytocin’s role in binge eating
July 12, 2016, Porto, Portugal - A study by York University researcher Caroline Davis and her colleagues at the Centre for Addiction and Mental Health (CAMH) is the first to demonstrate that variants of the Oxytocin Receptor (OXTR) gene contribute to why some of us overeat or engage in episodes of binge eating. They investigated how the OXTR gene influences appetite, food preferences, food intake and personality risk traits associated with brain-reward mechanisms. These findings will be presented this week at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the society for the research into all aspects of eating and drinking behavior.
Oxytocin is an evolutionarily ancient molecule produced in the brain that acts at sites throughout the body by triggering the OXTR. It influences many survival behaviors including those used to manage stress, according to Dr. Caroline Davis, the lead researcher on the study. “For example, oxytocin enhances prosocial and related behaviors. On the other hand, increases in oxytocin tend to decrease appetite – especially the consumption of sweet carbohydrates.”
Over the past decade, Davis and her co-investigator Dr. James Kennedy, Director of the Department of Neurogenetics at CAMH, assessed a large group of participants ranging in age from 27-50 years. The group had a broad range of body weights and included a substantial number with binge-eating habits. Among other measures, a blood sample was collected from each participant in order to analyze their DNA, the molecules that carry each individual’s unique genetic information.
The DNA analysis uncovered a new link between oxytocin and behaviors associated with binge eating. The researchers focused on seven sites in the DNA where chemical instructions for making OXTR could vary between individuals. These “single nucleotide polymorphisms” (SNPs) were already suspected to be associated with psychological traits. The researchers collected questionnaires about their participants’ differences in reward sensitivity, punishment sensitivity, sugar/fat food preferences, and overeating habits, to be correlated with the OXTR genetic information.
The researchers tested the prediction that these SNPs relate to psychological risk factors, which in turn are associated with overeating behaviors. “Three SNPs were significantly related to the psychological traits, which collectively accounted for 37% of the variance in overeating,” says Davis. “Another SNP was directly related to overeating. These results support the role of genes in giving rise to traits that regulate behavior, and highlight the importance of oxytocin in overeating.”
Research: Polymorphisms of the Oxytocin Receptor Gene (OXTR) and Overeating: The Mediating Role of Endophenotypic Risk Factors
Funding: The Canadian Institute of Health Research and Shire Pharmaceuticals
Lead Author: Dr. Caroline Davis, School of Kinesiology and Health Science, Faculty of Heath, York University,Toronto, Canada
- James Kennedy, Director, Department of Neurogenetics, Centre for Addiction and Mental Health, Toronto, Canada
- Elnaz Moghimi, PhD candidate, Faculty of Health, York University
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Research finds social influence can prompt healthier eating choices
Researchers from the University of Birmingham have found that exposure to social-based messages promoting healthy eating can increase consumption of fruit and vegetables and reduce consumption of high-calorie snacks. It has been known for some time that people adapt their behavior to what they think is socially expected for that situation and food choices are no exception. If we are told that other people in our social group eat lots of fruit and vegetables then we may try to do the same. In the new research to be presented this week at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the foremost society for research into all aspects of eating and drinking behavior, the researchers found that a “liking social norm” message – information that other people enjoy eating fruits and vegetables – had a particularly powerful effect on food choices.
Student participants were tested in a laboratory and were first asked to rate some posters. One group saw a poster displaying the results of a survey suggesting that the typical student enjoys eating fruit and vegetables every day (experimental group) whereas others saw unrelated facts about the University of Birmingham (control group). The participants were then asked to take part in another study that involved rating emotions and tasting some healthy snacks (cucumber and grapes) and high calorie snacks (cookies and chips). The participants who discovered that other students like eating fruit and vegetables ate more of the cucumber and grapes during the taste test, but only if they did not report habitually consuming a lot of fruit and vegetables in their daily diet already. Those who already ate fruit and vegetables daily did not consume any more cucumber and grapes, however, they ate less of the cookies and chips. Interestingly, most people were not even aware that the two studies were linked and were not aware that their behavior had been altered by exposure to the message.
According to the authors, these results point towards a new approach to promoting healthier eating. Dr. Jason Thomas said “It might be more effective in terms of health promotion to highlight how much other people enjoy eating fruit and vegetables than to tell people that they should because it is good for them.” The team are now interested in finding out more about why social-based message are effective in altering food choices and whether the strategy can be implemented in realistic settings such as cafeterias and supermarkets.
“The effect of a liking norm message on the consumption of fruit, vegetables and energy dense snack foods.”
Jason Thomas and Suzanne Higgs, University of Birmingham, UK
Jason Thomas, School of Psychology, University of Birmingham
Studies find that manipulating gut microbes may reverse the negative effect of a high fat diet disrupted gut-to-brain signaling.July 12, 2016, Porto, Portugal - Did you know that your gut sends neural messages to the brain to tell it when it is full? Researchers at the University of Georgia, Binghamton University, and Pennsylvania State University have now found that chronic consumption of high fat foods disturbs these neural messages in rats by shifting the populations of bacteria that ordinarily reside inside the gut. Delaying the fullness message can lead to overeating and eventual weight gain. Dr. Claire de La Serre and colleagues found that this negative effect may be reversed by manipulating the gut microbes. This research is to be presented this week at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the foremost society for research into all aspects of eating and drinking behavior.
In one study the researchers found that high fat feeding reorganizes the gut-to-brain neural pathway and triggers inflammation in brain regions responsible for feeding behavior. High fat diets have been found to dramatically affect the gut microbiota composition, so the researchers tested if these resident microbes may be the connection between the diet and neural changes. De La Serre and colleagues developed a protocol to correct the negative shift in gut microbes. By injecting daily a low dose of a large spectrum antibiotic they were able to reverse the effects of high fat diet on the microbiota composition. Interestingly, when the bacteria composition was brought back to normal, the disturbed gut-brain signals and brain inflammation were also corrected. As a result, antibiotic-treated animals ate less and gained less weight. This shows that the gut bacteria which thrive during a high fat diet are playing a role in the damaging effects of the diet on brain signals. Pursuing this research could eventually lead to bacteria-based therapies for treatment of overeating and obesity.
“We then wanted to test if foods known to have anti-bacterial and anti-inflammatory properties could also reverse the negative effect of a high fat diet, similarly to the antibiotic treatment,” explained Claire de La Serre. In a separate study, the researchers fed animals a high fat diet and supplemented some of them with blueberry, a fruit packed with anthocyanins, a natural anti-microbial ingredient. Animals fed blueberries had a completely different microbiota profile, less inflammation, and more stable blood sugar levels. Thus, specific properties of bioactive foods may be used to target and improve the microbiota composition and overall health.
1. Bacteria-driven brain plasticity triggers obesity.
2. Blueberry supplementation impacts gut microbiota and insulin sensitivity in high-fat fed rat.
Lead Author: Claire de La Serre, University of Georgia, Athens GA
Co-Authors: SH. Lee1, PM. DiLorenzo2, A. Hajnal3, T. Sen1, K. Czaja1, University of Georgia, Athens, GA; 2Binghamton University, Binghamton, NY; 3PennState University, Hershey, PA
Claire de La Serre
Study links overeating in obese mice to altered brain responses to food cues
Obese mice are much more likely than lean mice to overeat in the presence of environmental cues, a behavior that could be related to changes in the brain, finds a new study by a Michigan State University neuroscientist. The study is to be presented this week at the Society for the Study of Ingestive Behavior, the foremost society for research into all aspects of eating and drinking behavior.
The findings offer clues in Alexander Johnson’s quest to unpack the interconnected mechanisms of overeating and obesity. Obesity is an epidemic domestically – more than a third of Americans are considered to be obese – and a growing health problem in other parts of the world.
“In today’s society we are bombarded with signals to eat, from fast-food commercials to the smell of barbecue and burgers, and this likely drives overeating behaviors,” said Johnson, Assistant Professor of Psychology at Michigan State University. “Our study suggests both a psychological and neurobiological account for why obese individuals may be particularly vulnerable to these signals.”
The study involved two groups of mice – one group that was fed a high-calorie diet until they became obese and a second group that was fed a regular lab chow diet so they stayed lean. Johnson then trained the mice with different auditory cues. Whenever they heard one cue, such as a tone, the mice received sugar reward; with a second cue, such as a white noise, they received no reward.
The mice were then given access to their assigned maintenance diet for three days so they were satiated (i.e., not hungry) for the final test phase of the study. In that test, the sugar solution was available to the mice at all times, to see what would trigger them to start eating. When no cue was given, and when the white-noise cue was given (which previously offered no reward), the lean mice and obese mice ate roughly the same amount. When the rewarding tone cue was given, however, the obese mice ate significantly more of the sugar solution compared to the lean mice.
“From a psychological perspective, this tells us that the obese mice are more vulnerable to the effects of environmental triggers on evoking overeating behavior,” Johnson said. “Looking at it through a human lens, this suggests that obese individuals may be more sensitive to overeating food in the presence of say, the McDonald’s Golden Arches.”
But why? The final part of the study may offer an explanation.Johnson also examined the mice’s lateral hypothalamus, which is known as a key brain area in appetite and feeding behavior. Using a procedure called immunofluorescence to label neurons in this area of the brain, he found that neurons releasing a certain hormone– Melanin-Concentrating Hormone, or MCH – were more abundant in obese mice. But importantly, these MCH-releasing neurons were more active when the obese mice encountered the environmental reminders of sugar.
“In other words, if you become obese this leads to increases in MCH expression, which may make you more sensitive to this form of overeating,” Johnson said.
The novel findings, he added, start to paint a picture of the relationship between brain-behavior mechanisms that may underlie learned overeating in obese individuals.
“This could be one of perhaps many reasons why obese people may have the urge to eat more when presented with food cues.”
The study was funded by the Michigan Diabetes Research Center and the National Institutes of Health.
Research: Dietary obesity leads to upregulation of feeding signals in lateral hypothalamus and an enhanced vulnerability to overeating in the presence of food cues
Lead Author: Alexander W. Johnson, Department of Psychology, Michigan State University, East Lansing, MI, USA.
Co-Author: Lauren Raycraft and Ryan Gifford
Stress relief by ‘comfort foods’ may vary between sexes and across the estrous cycle.
Researchers at the University of Cincinnati have found that the brain networks that mediate stress relief after eating highly palatable foods may vary between males and females, and may also depend on the stage of the estrous cycle. The study performed by Ann Egan, a doctoral candidate in the University of Cincinnati Neuroscience Graduate Program in the laboratory of Dr. Yvonne Ulrich-Lai, PhD, used a rodent model of ‘comfort food’ to investigate the neurocircuitry behind this phenomenon. The research is to be presented this week at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the foremost society for all aspects of eating and drinking behavior.
“We know that both men and women eat tasty foods as a strategy to reduce stress, and in fact there is some evidence that suggests that women may be more prone to this ‘comfort food’ style of eating,” explained Egan. “This study is important because it suggests that males and females may be using slightly different brain regions, and the stress relief in females may also be affected by the stage of the estrous cycle. This can help us understand how eating behaviors can affect men and women differently, and how eating behaviors are affected by fluctuating hormone levels.”
The researchers used a rodent model that is based on human snacking patterns. Female rats were given twice-daily access to a small amount of a sweet sugar drink for 14 days, while other female rats were only given water as a control. Then rats were subjected to a stress test, and their stress hormone response was measured. Similar to previous studies done in male rats, female rats that had been given the sugar solution had a lower stress hormone response to the stress challenge. However, in the female rats the reduced stress response only occurred if the rats were in the proestrus/estrus stage of their estrous cycle, when levels of estrogen are high.
Previous studies in male rats have identified particular brain regions that are important for the stress relief, including the basolateral amygdala and prefrontal cortex. The researchers looked at protein markers of activity (FosB/deltaFosB and pCREB) in these brain regions to see if the sugar drink altered these protein levels similarly in male and female rats. FosB/deltaFosB was increased in the amygdala of males who were given the sugar drink compared to those drinking only water. Female rats also showed this increase in amygdala FosB/deltaFosB after the sugar drink, but only when they were in the proestrus/estrus stage of their cycle. In contrast, amygdala pCREB was increased by the sugar drink in males but not females. Instead amygdala pCREB varied across the estrous cycle in female rats and was unaffected by sugar drink. These different patterns show that comfort eating has some similar effects in male and female brains, but also has unique effects in the female brain that vary across the hormonal cycle. Pursuing these findings could lead to different strategies that could be useful for women and men who habitually eat to manage stress.
Research: “Sex-dependent brain activation by palatable food intake and the implications for stress relief by ‘comfort’ foods”
Authors: AE EGAN, AMK THOMPSON, D BUESING, S FOURMAN, AEB PACKARD, T TEREFE, MB SOLOMON, YM ULRICH-LAI, Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati
Alison Sampson, Public Information Officer
Brain pathway contributes to restraining from food temptation triggered by environmental cues
It is often difficult to resist the presentation of a dessert tray or a display of candy bars near a cashier. Eating those excess calories can contribute to overweight and obesity and is often driven by environmental cues – the sight of beautiful dessert or the colorful wrapper of a candy bar – rather than metabolic need. Researchers at the University of Illinois at Chicago have identified a pathway in the brain responsible for the ability to control this impulsive behavior. The findings will be presented this week at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the society for research into all aspects of eating and drinking behavior.
“We have found that stopping a behavior that typically leads to reward is an active process,” says Jamie Roitman, PhD, the principal investigator of the study. “While it is intuitive to think that we have to actively initiate an action, putting on the brake is also an active process to stop these kinds of behaviors”.
To test how the brain exercises this inhibitory control over behavior, the authors trained rats to press a lever to obtain sugar pellets. Then the rats had to learn to hold the press in check when presented with a “stop” signal. The researchers discovered that the ability to stop depended on the activity of the medial prefrontal cortex (mPFC), a region of the brain implicated in executive control over behavior. They found that individual neurons in mPFC became activated in response to both ‘go’ and ‘stop’ environmental cues, suggesting that it may play a role in both types of control. When mPFC activity was temporarily suppressed with a drug infusion, rats’ ability to stop their behavior was strongly diminished. In addition, the researchers found they could improve rats’ stopping ability by applying a chemogenetic treatment that enhanced neural activity in that region. These results suggest that mPFC activity plays a critical role in exercising control over behavior when a stop signal is presented.
To examine how mPFC may exert this control, the researchers turned their attention to another brain area which receives commands from the mPFC, the nucleus accumbens (NAc). The NAc plays an important role in processing rewards and has been implicated in a wide range of motivated behaviors, such as feeding, sex, and drug abuse. When the communication between the mPFC and NAc was blocked, rats were again unable to hold their behavior in check when encountering a stop cue.
“Taken together, the results suggest that medial prefrontal cortex actively puts a hold on behavior in the moment that an environmental cue may trigger it. If we can boost this hold signal – perhaps with another cue to remind us at the right time why we should forego the tasty treat – we could gain better control over this kind of impulsive eating. We need an app for that,” suggests Roitman.
Research: Response of medial prefrontal neurons to cues for behavioral restraint. KF MANSON, SR EBNER, LR AMODEO, B JAMAL, JD ROITMAN
Lead Author: Kirk F Manson, Doctoral Student, Department of Psychology, University of Illinois at Chicago, Chicago, IL, USA.
Jamie D Roitman, Assistant Professor
STUDY FINDS INCREASE IN SNACKING RELATED TO PARENTAL OVERSIGHT - Children turning more to sugary and salt-laden snacks
In a new study examining how parenting contributes to snacking, researchers found that parents who have a hands-off approach to feeding children may unknowingly contribute to an increase in children’s snacking.
In the 18-month study researchers from Baylor College of Medicine, the University of Michigan and Temple University’s College of Public Health determined that more than 40 percent of children’s daily intake of added sugars came from snacks. Researchers focused on Hispanic children, as they are disproportionately affected by obesity.
Parents with uninvolved child feeding styles, according to Sheryl Hughes of Baylor College of Medicine, “may be engaged in lots of other aspects of parenting, but make few demands and have a relatively uninvolved approach when it comes to feeding children.” The longitudinal study viewed the snacking habits of children from their preschool years into their early school years.
“We know that U.S. kids are consuming a significant proportion of daily calories from snacks,” said lead author Kate Bauer of the University of Michigan. “Snacks are not a trivial part of kids’ diet—rather, they’re pretty central at this stage. The findings suggest that children of uninvolved feeders could potentially be at risk for greater dietary excess from snacks.”
The American Academy of Pediatrics and the U.S. Department of Agriculture recommend two snacks per day for preschool-aged children. However, since 1977 preschoolers in the U.S. – regardless of socioeconomic status or ethnicity – have consumed an additional 182 calories per day from snacks. Desserts, sugar-sweetened beverages, and salty foods are among the most frequently consumed snacks by U.S. children 2 to 18 years old.
Other findings from the same study suggest that snacking may not pose an appreciable risk of dietary excess for normal-weight preschoolers, but may be problematic for overweight and obese children with greater appetitive drives.
“While children consume a significant amount of energy from snacks and the snacks eaten tend to be of poor nutritional quality, the extent to which snacking contributes to excessive dietary intakes was unclear until now,” said Jennifer Fisher of Temple University.
Funding for the study was provided by the National Institute of Child Health and Development.
Research: Uninvolved feeding styles are associated with increased snacking during preschool among Hispanic children” presented at the annual meeting of the Society for the Study of Ingestive Behavior, Porto, Portugal, July 12-16, 2016
KW BAUER, University of Michigan Ann Arbor, MI, USA
SO HUGHES, Baylor College of Medicine Houston, TX, USA
TG POWER, Washington State University Pullman, WA, USA
TM O'CONNOR, Baylor College of Medicine Houston, TX, USA
K VOLLRATH, Baylor College of Medicine Houston, TX, USA
NEM CORREA, Baylor College of Medicine Houston, TX, USA
TA CHEN, Baylor College of Medicine Houston, TX, USA
JO FISHER, Temple University Philadelphia, PA, USA
Jennifer Fisher, Center for Obesity Research and Education, Temple University
Just add water? New MRI technique shows what drinking water does to your appetite, stomach and brain
Stomach MRI images combined with functional fMRI of the brain activity have provided scientists new insight into how the brain listens to the stomach during eating. Research from Wageningen University in the Netherlands shows - for the first time - real time data of the brain, the stomach, and people’s feelings of satiety measured simultaneously during a meal, in a study to be reported this week at the annual meeting of the Society for the Study of Ingestive Behavior, held in Porto, Portugal. The researchers collected data from 19 participants during two separate sessions with different consumption procedures and found that a simple change like drinking more water can alter messages from the stomach interpreted as fullness by the brain. This new research approach can be used to investigate the interplay between satiety feelings, volume of the stomach and activity in the brain.
In the experiment, participants drank a milk-shake on an empty stomach, which was followed by a small (50 mL) or large glass of water (350 mL). MRI images were used to see how the different amounts of water affected stretching of the stomach: the large glass of water doubled the stomach content compared to the small glass. Together with this larger volume subjects reported to have less hunger and felt fuller.
This novel approach - combining information obtained simultaneously from MRI images of the stomach, feelings reported by the subjects, and brain scans – can offer new insights which would otherwise have been unknown, for example that activation in a brain area called the mid-temporal gyrus seems is in some way influenced by the increased water load in this experiment. The Wageningen University scientists developed the combined MRI method as part of the European Nudge-it research project, which seeks to discover simple changes that promote healthier eating. They will use it to search for a brain signature that leads people to decide to stop eating, to determine how strategies like water with a meal can be effective at feeling fuller sooner.
“Combining these types of measurements is difficult, because MRI scanners are usually set-up to perform only one type of scan. We’ve been able to very quickly switch the scanner from one functionality to another to do this type of research” says Guido Camps, lead author of the study. “In conclusion, we’ve found that simply adding water increases stomach distension, curbs appetite in the short term and increases regional brain activity.”
Research: “Just add water: how water affects gastric distension, appetite and brain activity”
Authors: G CAMPS, R VEIT, M MARS, C DE GRAAF, P SMEETS
Guido Camps, Division of Human Nutrition, Wageningen Universiy, Netherlands
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