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Limiting children’s recreational screen time to less than two hours a day linked to better cognition

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Only one in 20 US children in the study met the full recommended guidelines on recreational screen time, physical activity and sleep.

Limiting recreational screen time to less than two hours a day, and having sufficient sleep and physical activity is associated with improved cognition, compared with not meeting any recommendations, according to an observational study of more than 4,500 US children aged 8-11 years old published in The Lancet Child & Adolescent Health journal.

Taken individually, limited screen time and improved sleep were associated with the strongest links to improved cognition, while physical activity may be more important for physical health.

However, only one in 20 US children aged between 8-11 years meet the three recommendations advised by the Canadian 24-hour Movement Guidelines to ensure good cognitive development—9-11 hours of sleep, less than two hours of recreational screen time, and at least an hour of physical activity every day.

The study found that US children spend an average of 3.6 hours a day engaged in recreational screen time.

The authors say that their findings indicate that adhering to the guidelines during childhood and adolescence, particularly for screen time, is important for cognitive development.

“Behaviours and day-to-day activities contribute to brain and cognitive development in children, and physical activity, sedentary behaviour, and sleep might independently and collectively affect cognition,” says Dr. Jeremy Walsh, CHEO Research Institute, Ottawa, Canada. “Evidence suggests that good sleep and physical activity are associated with improved academic performance, while physical activity is also linked to better reaction time, attention, memory, and inhibition. The link between sedentary behaviours, like recreational screen time, is unclear as this research is in the early stages and it appears to vary depending on the types of screen-based activity.”

In the study, data was analysed from 4,520 children from 20 sites across the USA. Children and parents completed questionnaires and measures at the outset of the trial to estimate the child’s physical activity, sleep and screen time. Children also completed a cognition test, which assessed language abilities, episodic memory, executive function, attention, working memory and processing speed. The study controlled for household income, parental and child education, ethnicity, pubertal development, body mass index and whether the child had had a traumatic brain injury.

Almost one in three children (29% – 1,330/4,520) met none of the guidelines, 41% (1,845/4,520) met only one, 25% (1,129/4,520) met two, and 5% (216/4,520) met all three recommendations.

Half of the children met the sleep recommendation (51%, 2,303/4,520), 37% (1,655/4,520 children) met the screen time recommendation, and 18% (793/4,520 children) met the physical activity recommendation.

The more individual recommendations the child met, the better their cognition. In addition, meeting only the screen time recommendation or both the screen time and sleep recommendations had the strongest associations with cognitive development.

Although there is substantial evidence for the association between physical activity and cognitive development, in this study meeting the physical activity recommendation alone showed no association with cognition. The authors note this was a surprising finding and may suggest that the measure used may not have been specific enough. They note that physical activity remains the most important behaviour for physical health outcomes, and there is no indication that it negatively affects cognition.

Dr. Walsh concludes: “We found that more than two hours of recreational screen time in children was associated with poorer cognitive development. More research into the links between screen time and cognition is now needed, including studying the effect of different types of screen time, whether content is educational or entertainment, and whether it requires focus or involves multitasking. Based on our findings, paediatricians, parents, educators, and policymakers should promote limiting recreational screen time and prioritising healthy sleep routines throughout childhood and adolescence.”

The authors note some limitations, including that their study is observational so cannot establish the underlying causes or the direction of the association. The data is also self-reported and could be subject to bias. The questionnaires were only used at the outset of the study, and so do not track how behaviours changed over time so future cycles of the study will need to be analysed to understand trends over time.

Writing in a linked Comment, Dr. Eduardo Esteban Bustamante, University of Illinois, USA, says: “Through a stress-adaptation lens, the strong associations between global cognition and meeting the recreational screen time recommendation found by Walsh and colleagues potentially reflect the interruption of the stress-recovery cycle necessary for growth in children who do not meet the recommendation. Each minute spent on screens necessarily displaces a minute from sleep or cognitively challenging activities. In the case of evening screen use, this displacement may also be compounded by impairment of sleep quality. It is tempting to take solace in findings that cognitively challenging screen activities can benefit cognition, but, if given a choice, most children already consistently and predictably choose more stimulating screen activities over less stimulating ones.”

More information: Associations between 24 hour movement behaviours and global cognition in US children: a cross-sectional observational study, doi.org/10.1016/S2352-4642(18)30278-5 , www.thelancet.com/journals/lan … (18)30278-5/fulltext

Medical Research

Study finds standard treatment for common STD doesn’t eliminate parasite in some women

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A new study led by an infectious disease epidemiologist at Tulane University School of Public Health and Tropical Medicine could change the way doctors treat a common sexually transmitted disease.

Professor Patricia Kissinger and a team of researchers found the recommended single dose of medication isn’t enough to eliminate trichomoniasis, the most common curable STD, which can cause serious birth complications and make people more susceptible to HIV. Results of the research are published in Lancet Infectious Diseases.

Globally, an estimated 143 million new cases of trichomoniasis among women occur each year and most do not have symptoms, yet the infection is causing unseen problems. The recommended treatment for more than three decades has been a single dose of the antibiotics metronidazole or tinidazole.

The researchers recruited more than 600 women for the randomized trial in New Orleans; Jackson, Mississippi; and Birmingham, Alabama. Half the women took a single dose of metronidazole and the other half received treatment over seven days.

Kissinger and her team found the women who received multiple doses of the treatment were half as likely to still have the infection after taking all the medication compared to women who only took a single dose.

“There about 3.7 million new cases of trichomoniasis each year in the United States,” Kissinger said. “That means a lot of women have not been getting inadequate treatment for many decades.”

Trichomoniasis can cause preterm delivery in pregnant women and babies born to infected mothers are more likely to have low birth weight. The parasite can also increase the risk of getting or spreading HIV.

Kissinger believes the CDC will change its treatment recommendations because of the results of this study.

“We need evidence-based interventions to improve health,” Kissinger says. “We can no longer do something because it’s what we’ve always done. I hope that this study will help to change the recommendations so that women can get the proper treatment for this common curable STD.”

More information: Lancet Infectious Diseases (2018). DOI: 10.1016/S1473-3099(18)30423-7

Provided by: Tulane University

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Medical Research

Researchers find how natural killer cells regulate protective HIV antibodies

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In the quest to develop a vaccine that triggers the immune system to prevent HIV infection, researchers have focused on identifying and eliciting a particular type of antibody that is capable of neutralizing the virus.

These broadly neutralizing antibodies, or bnAbs, eventually arise naturally in about half of HIV-infected people, but they develop too late to be effective, long after the virus has repeatedly mutated and inserted itself into the genome of host cells.

Searching for a way to elicit bnAbs before HIV infection so they can block the virus if they encounter it, a research team led by the Duke Human Vaccine Institute identified an important protein that is highly active in people who develop bnAbs compared to those who don’t.

The protein, called RAB11FIP5, appears to be involved in changing the distribution and function of natural-killer cells, which are among the immune system’s early responders during a viral infection. Natural killer cells also play a role in autoimmune diseases, when the body’s immune system turns on itself.

“This type of immune cell wasn’t previously known to regulate bnAbs,” said Barton Haynes, M.D., director of the Duke Human Vaccine Institute and senior author of a study published online Sept. 27 in the journal Cell. “We found a new natural killer cell cargo-carrying pathway that appears to be important in regulating the bnAb production.”

Haynes and colleagues, including lead author Todd Bradley, Ph.D., designed the study to analyze the molecular differences between HIV-infected people who make bnAbs, and those who don’t. They identified 239 infected people, and screened them to find approximately 50 on each extreme—those with the highest numbers of bnAbs, and those with the lowest.

The researchers used RNA sequencing analyses to determine the molecular differences that distinguished between those who produce bnAbs and those who do not, finding a marked discrepancy in the RAB11FIP5 gene expression.

“These data suggest that natural killer cell dysfunction permits bnAb development, implicating Rab11 as a modulator of the HIV antibody response,” Bradley said. “This is a new pathway that we hope to modulate during vaccination to generate a better HIV antibody response.”

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Diabetes

Beer’s bitter delight is tasted in the gut

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Hoppy beers are famous as a driver of craft brewing. But the challenging taste of hops goes far beyond the palate. According to a new study from Scripps Research scientists, the bitter flavor literally reaches into your gut.

Moreover, chemicals in hops called isohumulones may help control obesity, type 2 diabetes and other diseases.

Intestinal taste receptors detect isohumulones, according to the study. While the work was performed in mice and needs to be confirmed in humans, it’s already known that people also have taste receptors in their gut.

Previous research indicates that intestinal taste receptors influence the production of hormones as well as appetite, said Enrique Saez, a Scripps Research associate professor. And hops extracts have been shown to reduce weight gain and decrease insulin resistance.

So the study fills a gap in research between the observed effects of hops extracts and the chemicals and molecular mechanism causing the effects, Saez said.

The study was recently published in the journal Molecular Metabolism.

Isohumulones are being studied by Seattle’s KinDex Pharmaceuticals as therapy for metabolic diseases such as Type 2 diabetes and polycystic ovary syndrome. The company is studying the compounds in people under the name KDT501.

KinDex asked Saez and associates to study isohumulones to better characterize what they do. With that knowledge, KinDex could optimize the drugs, said Saez. He is on the KinDex advisory board with colleagues Paul Schimmel and Ben Cravatt.

“We were quite surprised when reviewing the literature,” Saez said. “It turned out that these taste receptors are expressed not only in the mouth, but also in the gut, the airway epithelia, the liver, and some other organs.”

These receptors appeared to have evolved as protection against eating bitter substances, which are often poisonous, Saez said.

Isohumulones work indirectly. They stimulate release of a hormone called glucagon-like peptide-1, or GLP-1, that works with insulin to decrease blood sugar levels, he said. The chemicals also promotes satiety.

“It makes you feel fuller, and other hormones that this bitter taste receptor also regulates limit the absorption of nutrients in the gut,” he said. “So in effect it probably limits absorbing these potentially poisonous compounds.”

A mimic of GLP-1 was developed by San Diego’s Amylin Pharmaceuticals as a diabetes medication, exenatide. It was discovered in an unlikely place, the saliva of the Gila monster.

The drug is sold as Byetta and in extended release form as Bydureon. It was attractive enough that Amylin was purchased for $7 billion by Bristol-Myers Squibb in 2012.

However, exenatide must be injected, limiting its usefulness, Saez said.

“Isohumulones are small molecules that you can eat,” he said.

More information: Bernard P. Kok et al. Intestinal bitter taste receptor activation alters hormone secretion and imparts metabolic benefits, Molecular Metabolism (2018). DOI: 10.1016/j.molmet.2018.07.013

©2018 The San Diego Union-Tribune
Distributed by Tribune Content Agency, LLC.

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