Does Yo-Yo Dieting Drive Compulsive Eating?

New research on rats seems to find a connection between yo-yo dieting and compulsive eating.

According to researchers at the Boston University School of Medicine (BUSM), a chronic cyclic pattern of overeating followed by undereating reduces the brain’s ability to feel reward and may drive compulsive eating.

The finding suggests that future research into the treatment of compulsive eating behavior should focus on rebalancing the mesolimbic dopamine system, the part of the brain responsible for feeling reward or pleasure, researchers say.

“We are just now beginning to understand the addictive-like properties of food and how repeated overconsumption of high sugar — similar to taking drugs — may affect our brains and cause compulsive behaviors,” said corresponding author Pietro Cottone, Ph.D., an associate professor of pharmacology and experimental therapeutics at BUSM and co-director of the Laboratory of Addictive Disorders.

To better understand compulsive and uncontrollable eating, Cottone and his research team performed a series of experiments on two groups of rats. One, the cycled group, received a high-sugar, chocolate-flavored diet for two days each week and a standard control diet the remaining days of the week, while the control group received the control diet all of the time.

The group that cycled between the palatable food and the less palatable food spontaneously developed compulsive, binge eating on the sweet food and refused to eat regular food, the researchers discovered.

Both groups were then injected with a psychostimulant amphetamine, a drug that releases dopamine and produces reward, and their behavior in a battery of behavioral tests was then observed.

While the control group predictably became very hyperactive after receiving amphetamine, the cycled group did not.

Furthermore, in a test of the conditioning properties of amphetamine, the control group was attracted to environments where they previously received amphetamine, whereas the cycled group were not.

Finally, when measuring the effects of amphetamine while directly stimulating the brain reward circuit, the control group was responsive to amphetamine, while the cycled group was not, according to the findings.

After investigating the biochemical and molecular properties of the mesolimbic dopamine system of both groups, the researchers determined that the cycled group had less dopamine overall, released less dopamine in response to amphetamine, and had dysfunctional dopamine transporters — proteins that carry dopamine back into brain cells — due to deficits in the mesolimbic dopamine system.

“We found that the cycled group display similar behavioral and neurobiological changes observed in drug addiction: specifically, a crash in the brain reward system,” Cottone said. “This study adds to our understanding of the neurobiology of compulsive eating behavior.

“Compulsive eating may derive from the reduced ability to feel reward. These findings also provide support to the theory that compulsive eating has similarities to drug addiction.”

“Our data suggest that a chronic cyclic pattern of overeating will reduce the brain’s ability to feel reward — feeling satiated. This results in a vicious circle, where diminished reward sensitivity may in turn be driving further compulsive eating,” said lead author Catherine (Cassie) Moore, Ph.D., a former graduate student in the Laboratory of Addictive Disorders at BUSM.

The study was published in the journal Neuropsychopharmacology.

Source: Boston University School of Medicine

Excessive Brain Activity Linked to Shorter Life Span

Video: New research links excess neural activity — the flickering light seen in this image — to reduced longevity. Credit: Yankner lab, Harvard Medical School.

The brain’s neural activity — long implicated in disorders ranging from dementia to epilepsy — also plays a role in how long we live.

The study, led by scientists in the Blavatnik Institute at Harvard Medical School and based on findings from human brains, mice, and worms, suggests that excessive activity in the brain is linked to shorter life spans, while suppressing overactivity can extend life.

Neural activity refers to the constant flicker of electrical currents and transmissions in the brain. Excessive activity, or excitation, could manifest in numerous ways, from a muscle twitch to a change in mood or thought, according to the researchers.

“An intriguing aspect of our findings is that something as transient as the activity state of neural circuits could have such far-ranging consequences for physiology and life span,” said study senior author Dr. Bruce Yankner, a professor of genetics and co-director of the Paul F. Glenn Center for the Biology of Aging.

Neural excitation appears to act along a chain of molecular events famously known to influence longevity — the insulin and insulin-like growth factor (IGF) signaling pathway, the researchers explain.

The key in this signaling cascade appears to be a protein called REST, previously shown by researchers in the Yankner Lab to protect aging brains from dementia and other stresses.

Study results could lead to the design of new therapies for conditions that involve neural overactivity, such as Alzheimer’s disease and bipolar disorder, the researchers said.

The findings also raise the possibility that certain medicines, such as drugs that target REST, or certain behaviors, such as meditation, could extend life span by modulating neural activity, they said.

Human variation in neural activity might have both genetic and environmental causes, which would open future avenues for therapeutic intervention, Yankner added.

The researchers began their investigation by analyzing gene expression patterns — the extent to which various genes are turned on and off — in donated brain tissue from hundreds of people who died at ages ranging from 60 to over 100.

The information was collected through three separate research studies of older adults. Those analyzed in the current study were cognitively intact, meaning they had no dementia, the researchers noted.

The researchers immediately noticed a striking difference between the older and younger study participants, Yankner said. The longest-lived people — those over 85 — had lower expression of genes related to neural excitation than those who died between the ages of 60 and 80.

Next came the question that all scientists confront: Correlation or causation? Was this disparity in neural excitation merely occurring alongside more important factors determining life span or were excitation levels directly affecting longevity? If so, how?

To answer these questions, the researchers conducted a barrage of experiments, including genetic, cell, and molecular biology tests in the model organism Caenorhabditis elegans, analyses of genetically altered mice, and additional brain tissue analyses of people who lived for more than a century.

These experiments revealed that altering neural excitation does indeed affect life span and illuminated what might be happening on a molecular level, the researchers said, noting all signs pointed to the protein REST.

REST, which is known to regulate genes, also suppresses neural excitation, the researchers found.

Blocking REST or its equivalent in the animals led to higher neural activity and earlier deaths, while boosting REST did the opposite.

The researchers also discovered that people who lived to 100 and beyond had significantly more REST in the nuclei of their brain cells than people who died in their 70s or 80s.

“It was extremely exciting to see how all these different lines of evidence converged,” said study co-author Dr. Monica Colaiácovo, a professor of genetics at Harvard Medical School, whose lab collaborated on the C. elegans work.

The researchers found that from worms to mammals, REST suppresses the expression of genes that are centrally involved in neural excitation, such as ion channels, neurotransmitter receptors, and structural components of synapses.

Lower excitation activates a family of proteins known as forkhead transcription factors. These proteins have been shown to mediate a “longevity pathway” via insulin/IGF signaling in many animals. It’s the same pathway that scientists believe can be activated by caloric restriction, according to the researchers.

In addition to its emerging role in staving off neurodegeneration, discovery of REST’s role in longevity provides additional motivation to develop drugs that target the protein, the researchers said.

Although it will take time and many tests to determine whether such treatments reduce neural excitation, promote healthy aging, or extend life span, the concept has captivated some researchers.

“The possibility that being able to activate REST would reduce excitatory neural activity and slow aging in humans is extremely exciting,” said Colaiácovo.

The study was published in Nature.

Source: Harvard Medical School

 

Physical Activity During Lessons Can Boost Learning

Students who take part in physical exercises like running in place during school lessons do better in tests than students who stick to sedentary learning.

A meta-analysis of 42 studies around the world conducted by researchers at the University College London, Leiden University, the National University of Singapore, and the University of Sydney, aimed to assess the benefits of incorporating physical activity in academic lessons. This approach has been adopted by schools that want to increase activity levels among students without reducing academic teaching time.

Typical activities include using movement to signify whether a fact is true or false, or jumping on the spot a certain number of times to answer a math question, the researchers explained.

The study concluded that incorporating physical activity had a large, significant effect on educational outcomes during the lesson, assessed through tests or by observing pupils’ attention to a given task. It also had a smaller effect on overall educational outcomes, as well as increasing the students’ overall levels of physical activity.

“Physical activity is good for children’s health, and the biggest contributor of sedentary time in children’s lives is the seven or eight hours a day they spend in classrooms,” said lead author Dr. Emma Norris of University College London. “Our study shows that physically active lessons are a useful addition to the curriculum. They can create a memorable learning experience, helping children to learn more effectively.”

“These improvements in physical activity levels and educational outcomes are the result of quite basic physical exercises,” added co-author Dr. Tommy van Steen of Leiden University in The Netherlands. “Teachers can easily incorporate these physical active lessons in the existing curriculum to improve the learning experience of students.”

For the study, researchers looked at data from 12,663 students between the ages of three and 14. Nearly half of the studies took place in the United States, with seven conducted in Australia, five in the UK, four in the Netherlands, and one in China, Croatia, Ireland, Israel, Portugal, and Sweden.

In one of the 42 studies analyzed, eight- and nine-year-olds simulated traveling the world by running in place in between answering questions relating to different countries.

The research team, also led by Norris at UCL, concluded that the children were more active and more focused on the task than peers in a control group, following teachers’ instructions more closely.

In another study in the Netherlands, primary school children who took part in physically active lessons three times a week over two years made significantly better progress in spelling and mathematics than their peers, equating to four months of extra learning gains, according to researchers.

The  study published in the British Journal of Sports Medicine.

Source: University College London

Slower Walkers Have Older Brains and Bodies at 45

A new study shows that people with a lower walking speed at the age of 45 have accelerated aging of both their bodies and their brains.

Using a 19-measure scale, researchers at Duke University found that in slower walkers, their lungs, teeth and immune systems tended to be in worse shape than the people who walked faster. MRI exams showed several indications that their brains were also older.

“The thing that’s really striking is that this is in 45-year-old people, not the geriatric patients who are usually assessed with such measures,” said lead researcher Line J.H. Rasmussen, a post-doctoral researcher in the Duke University Department of Psychology and Neuroscience.

“Doctors know that slow walkers in their seventies and eighties tend to die sooner than fast walkers their same age,” said senior author Terrie E. Moffitt, the Nannerl O. Keohane University Professor of Psychology at Duke University, and Professor of Social Development at King’s College London. “But this study covered the period from the preschool years to midlife and found that a slow walk is a problem sign decades before old age.”

The data come from a long-term study of nearly 1,000 people who were born during a single year in Dunedin, New Zealand. The 904 research participants in the current study have been tested, quizzed, and measured their entire lives, mostly recently from April 2017 to April 2019 at age 45.

Researchers note that neurocognitive testing that these individuals took as children predicted who would become slower walkers. At age 3, their scores on IQ, understanding language, frustration tolerance, motor skills, and emotional control predicted their walking speed at age 45, according to the researchers.

MRI exams during their last assessment showed the slower walkers tended to have lower total brain volume, lower mean cortical thickness, less brain surface area and higher incidence of white matter “hyperintensities,” small lesions associated with small vessel disease of the brain. In short, their brains appeared somewhat older, they said.

Adding insult to injury, the slower walkers also looked older to a panel of eight screeners who assessed each participant’s “facial age” from a photograph, the researchers reported.

Walking speed has long been used as a measure of health and aging in geriatric patients, but what’s new in this study is the relative youth of these study subjects and the ability to see how walking speed matches up with health measures the study has collected during their lives, the researchers explained.

“It’s a shame we don’t have gait speed and brain imaging for them as children,” Rasmussen said. (The MRI was invented when they were five, but was not given to children for many years after.)

Some of the differences in health and cognition may be tied to lifestyle choices these individuals have made, the researchers noted.

But the study also suggests that there are already signs in early life of who would become the slowest walkers, Rasmussen said.

“We may have a chance here to see who’s going to do better health-wise in later life.”

The study was published in JAMA Network Open.

Source: Duke University

Photo: A long-term study has found that signs of aging may be detected by a simple walking test at age 45, and that the brains of slower walkers were different at age 3. Credit: Duke University Communications.

Eczema in Children Linked to Anxiety, Depression in Parents

A new study has found that a majority of family members and caregivers of children with atopic dermatitis, the most common form of eczema, suffer from anxiety and depression.

For the study, researchers from the PHI University Clinic of Dermatology assessed the impact of an atopic dermatitis diagnosis on the families of 35 children between the ages of 1 and 6. The researchers, who evaluated 83 family members and caregivers,  found that all of them reported at least mild severity anxiety, with some showing moderate severity anxiety. Almost three in four — 74 percent — were also found to have depression.

According to the study’s findings, depression and anxiety scores were associated with the persistence and longevity of atopic dermatitis.

The researchers noted they did not find an association between scores and the severity of the disease, meaning that depression or anxiety was not observed to increase where atopic dermatitis was more severe.

Atopic dermatitis, the most common form of eczema, affects between 10 and 20 percent of the pediatric population of Europe. It causes the skin to become itchy, red, dry, and cracked. It is a chronic condition that most often occurs in people who have allergies and can develop alongside asthma and hay fever.

Patients with the condition are also known to suffer insomnia, anxiety, and psychosocial stress, linked to the physical manifestation of their eczema, according to the researchers.

For the study, researchers used the Hamilton Depression Rating Scale (HDRS) and Hamilton Anxiety Rating scale (HAM-A).

The researchers also asked participants what their greatest concerns were. The most frequent worry was the information families and caregivers receive about the nature of the disease, since atopic dermatitis is a long-term condition that requires complex and costly medical treatments.

“The chronicity and complexity of chronic dermatitis often leads to overlooked anxiety and depression in family members and caregivers, but our results show the extent of this cannot be overstated,” said lead researcher Dr. Vesna Grivcheva-Panovska.

“In the future, we must take a widened approach to the management of atopic dermatitis, not only of the patients but of their families as well.”

The research was presented at the 2019 European Academy of Dermatology and Venereology (EADV) Congress.

Source: Spink Health