Thursday, August 17, 2017

Children at Higher Risk of Type 2 Diabetes Sleep an Hour Less Each Night


​A study in the September 2017 Pediatrics found that children who slept on average one hour less a night had higher risk factors for Type 2 diabetes, including higher levels of blood glucose and insulin resistance. The study, "Sleep Duration and the Risk of Type 2 Diabetes," (published online Aug. 15), also confirmed prior research that has shown an association between shorter sleep duration and higher levels of body fat. Researchers analyzed the body measurements, blood sample results and questionnaire data from 4,525 children of multi-ethnic descent, aged 9-10 years, in England. Children who slept longer had lower body weight and lower levels of fat mass. Sleep duration was also inversely related to insulin, insulin resistance and blood glucose.

On average, children slept 10.5 hours per night (95% range 8.0–12.0 hours). There were strong inverse graded relationships between sleep duration, adiposity, and diabetes risk markers. In adjusted models, a 1-hour-longer sleep duration was associated with 0.19 lower BMI (95% confidence interval [CI] 0.09 to 0.28), 0.03 kg/m5 lower fat mass index (95% CI 0.00 to 0.05 kg/m5), 2.9% lower homeostasis model assessment insulin resistance (95% CI 1.2% to 4.4%), and 0.24% lower fasting glucose (95% CI 0.03% to 0.44%); there was no association with HbA1c or cardiovascular risk. Associations with insulin and glucose remained after an additional adjustment for adiposity markers.


Wednesday, August 16, 2017

Could olfactory loss point to Alzheimer's disease?


Odor identification tests may help scientists track the evolution of the disease in persons at risk
By the time you start losing your memory, it`s almost too late. That`s because the damage to your brain associated with Alzheimer's disease (AD) may already have been going on for as long as twenty years. Which is why there is so much scientific interest in finding ways to detect the presence of the disease early on. Scientists now believe that simple odor identification tests may help track the progression of the disease before symptoms actually appear, particularly among those at risk.

"Despite all the research in the area, no effective treatment has yet been found for AD," says Dr. John Breitner, the director of the Centre for Studies on Prevention of Alzheimer's Disease at the Douglas Mental Health Research Centre of McGill University. He is one of the authors of the study on the subject that was recently published in the journal Neurology. "But, if we can delay the onset of symptoms by just five years, we should be able to reduce the prevalence and severity of these symptoms by more than 50%."

Bubble gum or gasoline?
Close to 300 people with an average age of 63 who are at risk of developing AD because they had a parent who had suffered from the disease, were asked to take multiple choice scratch-and-sniff tests to identify scents as varied as bubble gum, gasoline or the smell of a lemon. One hundred of them also volunteered to have regular lumbar punctures to measure the quantities of various AD-related proteins whose presence in the cerebrospinal fluid (CSF).

The researchers found that those with the most difficulty in identifying odors were those in whom other, purely biological indicators of AD, were most evident.

"This is the first time that anyone has been able to show clearly that the loss of the ability to identify smells is correlated with biological markers indicating the advance of the disease," says Marie-Elyse Lafaille-Magnan, a doctoral student at McGill and the first author on the study. "For more than 30 years, scientists have been exploring the connection between memory loss and the difficulty that patients may have in identifying different odours. This makes sense because it's known that the olfactory bulb (involved with the sense of smell) and the entorhinal cortex (involved with memory and naming of odours) are among the first brain structures first to be affected by the disease."

A cheaper way to track progression of Alzheimer's disease
"This means that a simple smell test may potentially be able to give us information about the progression of the disease that is similar to the much more invasive and expensive tests of the cerebrospinal fluid that are currently being used," the director of research program on Aging, Cognition and Alzheimer's disease of the Douglas Institute and one of the authors on the study. "However, problems identifying smells may be indicative of other medical conditions apart from AD and so should not be substituted for the current tests."

The researchers caution more that far more work needs to be done to see how changes in a person's ability to identify smells over time relates to the progression of the disease itself. For the time being, smell tests are simply one more avenue to explore as researchers look for ways to identify the disease before the symptoms actually begin to appear.

Walnuts activate brain region involved in appetite control


Packed with nutrients linked to better health, walnuts are also thought to discourage overeating by promoting feelings of fullness. Now, in a new brain imaging study, researchers at Beth Israel Deaconess Medical Center (BIDMC) have demonstrated that consuming walnuts activates an area in the brain associated with regulating hunger and cravings. The findings, published online in the journal Diabetes, Obesity and Metabolism, reveal for the first time the neurocognitive impact these nuts have on the brain.

"We don't often think about how what we eat impacts the activity in our brain," said the study's first author Olivia M Farr, PhD, an instructor in medicine in the Division of Endocrinology, Diabetes and Metabolism at BIDMC. "We know people report feeling fuller after eating walnuts, but it was pretty surprising to see evidence of activity changing in the brain related to food cues, and by extension what people were eating and how hungry they feel."

To determine exactly how walnuts quell cravings, Farr and colleagues, in a study led by Christos Mantzoros, MD, DSc, PhD hc mult, director of the Human Nutrition Unit at Beth Israel Deaconess Medical Center and professor of medicine at Harvard Medical School, used functional magnetic resonance imaging (fMRI) to observe how consuming walnuts changes activity in the brain.
The scientists recruited 10 volunteers with obesity to live in BIDMC's Clinical Research Center (CRC) for two five-day sessions. The controlled environment of the CRC allowed the researchers to keep tabs on the volunteers' exact nutritional intake, rather than depend on volunteers' often unreliable food records - a drawback to many observational nutrition studies.

During one five-day session, volunteers consumed daily smoothies containing 48 grams of walnuts - the serving recommended by the American Diabetes Association (ADA) dietary guidelines. During their other stay in the CRC, they received a walnut-free but nutritionally comparable placebo smoothie, flavored to taste exactly the same as the walnut-containing smoothie. The order of the two sessions was random, meaning some participants would consume the walnuts first and others would consume the placebo first. Neither the volunteers nor the researchers knew during which session they consumed the nutty smoothie.

As in previous observational studies, participants reported feeling less hungry during the week they consumed walnut-containing smoothies than during the week they were given the placebo smoothies. fMRI tests administered on the fifth day of the experiment gave Farr, Mantzoros and the team a clear picture as to why.

While in the machine, study participants were shown images of desirable foods like hamburgers and desserts, neutral objects like flowers and rocks, and less desirable foods like vegetables.

When participants were shown pictures of highly desirable foods, fMRI imaging revealed increased activity in a part of the brain called the right insula after participants had consumed the five-day walnut-rich diet compared to when they had not.

"This is a powerful measure," said Mantzoros. "We know there's no ambiguity in terms of study results. When participants eat walnuts, this part of their brain lights up, and we know that's connected with what they are telling us about feeling less hungry or more full."

This area of the insula is likely involved in cognitive control and salience, meaning that participants were paying more attention to food choices and selecting the less desirable or healthier options over the highly desirable or less healthy options. Farr and Mantzoros next plan to test different amounts, or dosages, of walnuts to see whether more nuts will lead to more brain activation or if the effect plateaus after a certain amount. This experiment will also allow researchers to test other compounds for their effect on this system.

Similar studies could reveal how other foods and compounds, such as naturally-occurring hormones, impact the appetite-control centers in the brain. Future research could eventually lead to new treatments for obesity.

"From a strategic point of view, we now have a good tool to look into people's brains - and we have a biological read out." said Mantzoros. "We plan to use it to understand why people respond differently to food in the environment and, ultimately, to develop new medications to make it easier for people to keep their weight down."

Tuesday, August 15, 2017

Why expensive wine appears to taste better: It's the price tag



Previous research has shown that a higher price, for instance for chocolate or wine, increased the expectation that the product will also taste better and in turn affects taste processing regions in the brain. 

"However, it has so far been unclear how the price information ultimately causes more expensive wine to also be perceived as having a better taste in the brain," says Prof. Bernd Weber, Acting Director of the Center for Economics and Neuroscience (CENs) at the University of Bonn. The phenomenon that identical products are perceived differently due to differences in price is called the "marketing placebo effect." As with placebo medications, it has an effect solely due to ascribed properties: "Quality has its price!"

The researchers assessed how different prices are translated into corresponding taste experiences in the brain, even if the wine tasted does not differ. 30 participants took part in the study, of which 15 were women and 15 were men, with an average age of around 30 years.

Wine tasting while lying down

The wine tasting took place lying down in an MRI scanner, allowing brain activity to be recorded "online" while participants were tasting the wines. Each time, the price of the wine was shown first. Only then around a milliliter of the respective wine was administrated to the test person via a tube in their mouths. The participants were then asked to rate via a button on a nine-point scale how good the wine tasted to them. Their mouths were then rinsed with a neutral liquid and the next identical wine sample was given for tasting. All of the experiments were performed in the brain scanner at the Life & Brain Center at the University of Bonn.

"The marketing placebo effect has its limits: If, for example, a very low-quality wine is offered for 100 euros, the effect would predictably be absent," says Prof. Weber. This is why the researchers conducted the tests using an average to good quality red wine with a retail bottle prize of 12 €. In the MRI scanner, the price of this wine was shown randomly as 3, 6 and 18 €. In order to make the study as realistic as possible, the participants were given 45 euros of initial credit. For some of the tastings, the displayed sum was deducted from this account in some of the trials.

"As expected, the subjects stated that the wine with the higher price tasted better than an apparently cheaper one," reports Professor Hilke Plassmann from the INSEAD Business School, with campuses in Fontainebleau (France), Singapore and Abu Dhabi. "However, it was not important whether the participants also had to pay for the wine or whether they were given it for free." Identical wine leads to a better taste experience when a greater quality expectation is associated with the wine due to its price.

The measurements of brain activity in the MRI scanner confirmed this. The research team discovered that above all parts of the medial pre-frontal cortex and also the ventral striatum were activated more when prices were higher. While the medial pre-frontal cortex particularly appears to be involved in integrating the price comparison and thus the expectation into the evaluation of the wine, the ventral striatum forms part of the brain's reward and motivation system. "The reward and motivation system is activated more significantly with higher prices and apparently increases the taste experience in this way," says Prof. Weber.

How can placebo effects be inhibited?

"Ultimately, the reward and motivation system plays a trick on us," explains INSEAD post-doctoral fellow Liane Schmidt. When prices are higher, it leads us to believe that a taste is present that is not only driven by the wine itself, because the products were objectively identical in all of the tastings. "The exciting question is now whether it is possible to train the reward system to make it less receptive to such placebo marketing effects," says Prof. Weber. This may be possible by training one's own physical perception -- such as taste -- to a greater extent.

Monday, August 14, 2017

Automatic blood pressure devices are prone to significant errors



An estimated 1 in 3 U.S. adults have high blood pressure. Blood pressure levels are often assessed by using automatic blood pressure devices. But these automatic devices are prone to significant errors, sometimes leading to the prescription of blood pressure-lowering medications to patients who don't actually need them. Now researchers at the Jerusalem College of Technology and the Shaare Zedek Medical Center in Israel have developed a method to more accurately measure systolic blood pressure. They present their research findings today at the Cardiovascular Aging: New Frontiers and Old Friends conference in Westminster, Colo.

A systolic blood pressure measurement of 140 mmHg or higher and a diastolic measurement of 90 mmHG or higher (140/90 mmHg) is considered high. Blood pressure is usually assessed using either a manual (auscultatory) or automatic (oscillometry) meter in a doctor's office or hospital. However, these measurements can be affected by "white coat syndrome" -- a patient's fear or anxiety in a doctor's office causes their blood pressure to measure above normal levels. To avoid the white coat effect, at-home automatic measurements taken by the patient may be required, but available oscillometry-based automatic meters offer a low level of accuracy.

"The automatic oscillometric technique is less accurate than the manual auscultatory technique, when both are used in the clinician's office," Meir Nitzan, PhD, the new study's first author, said. Currently available automatic blood pressure measurement devices are commonly off by 10 to 15 mmHg. This is mainly due to indirect determination of the blood pressure from the oscillometric air-pressure wave measurements taken by automatic devices.

A patient with an incorrect high blood pressure diagnosis may be prescribed blood pressure-lowering medication unnecessarily. These medications can cause patients' blood pressure to dip too low (hypotension); elderly patients are especially at risk. Side effects of hypotension can include short-term symptoms such as dizziness and fainting and long-term problems such as insufficient blood supply to vital organs, which can lead to acute kidney injury and cognitive impairment.

The research team has developed a device -- using a technique called photoplethysmography -- to more accurately measure systolic blood pressure. The device uses a pressure cuff wrapped around the arm and an electro-optic probe on the finger. "The finger probe is similar to that of pulse oximeter: It includes a light-source emitting light into the finger and a detector, which measures the light transmitted through the finger," Nitzan explained. "The transmitted light exhibits pulses at the heart rate, due to cardiac-induced blood volume changes in the finger tissue. When the cuff pressure increases to above systolic blood pressure these pulses disappear, and when the cuff pressure decreases to below systolic blood pressure they reappear. This effect enables the determination of systolic blood pressure."

Knee arthritis on the rise


The average American today is twice as likely to be diagnosed with knee osteoarthritis than in the years before World War II, Harvard scientists say, but that increase can't be blamed on the reasons most might think.

Based on the examination of more than 2,000 skeletons from cadaveric and archaeological collections across the U.S., the Harvard study is the first to definitively show that knee osteoarthritis prevalence has dramatically increased in recent decades. The research also upends the popular belief that knee osteoarthritis is a wear-and-tear disease that is widespread today simply because more people are living longer and are more commonly obese. The study is described in a paper published this week in the Proceedings of the National Academy of Sciences.

"Before this study, it was assumed without having been tested that the prevalence of knee osteoarthritis has changed over time," said Ian Wallace, the study's first author and a post-doctoral fellow in the lab of Daniel Lieberman, the Edwin M. Lerner II Professor of Biological Sciences and senior author of the study. "We were able to show, for the first time, that this pervasive cause of pain is actually twice as common today than even in the recent past. But the even bigger surprise is that it's not just because people are living longer or getting fatter, but for other reasons likely related to our modern environments."

Understanding the disease, Wallace and Lieberman said, is important not only because it is extremely prevalent today, affecting an estimated one-third of Americans over age 60, but also because it is responsible for more disability than almost any other musculoskeletal disorder.

"Understanding the origins of knee osteoarthritis is an urgent challenge because the disease is almost entirely untreatable apart from joint replacement, and once someone has knee osteoarthritis, it creates a vicious circle," Lieberman said. "People become less active, which can lead to a host of other problems, and their health ends up declining at a more rapid rate."

Wallace and Lieberman think that this study has the potential to shift the popular perception of knee osteoarthritis as an inevitable consequence of aging, and instead focus on efforts to prevent the disease - much like we now do with heart disease.

"There are a lot of well-understood risk factors for heart disease, so doctors can advise their patients to do certain things to decrease their chances of getting it," Lieberman said. "We think knee osteoarthritis belongs in the same category because it's evidently more preventable than commonly assumed. But to prevent the disease more work needs to be done to figure out its causes."

To do that, Wallace and Lieberman are currently addressing the question of the etiology of knee osteoarthritis from a variety of methodological approaches including studies of living human populations and animal models, but their first goal was to figure out how ancient the disease actually is, and whether it really is on the rise.

"There are famous examples in the fossil record of individuals, even Neanderthals, with osteoarthritis," Lieberman said. "But we thought, let's look at the data, because nobody had really done that in a comprehensive way before."

To find those data, Wallace undertook the daunting task of crisscrossing the country to examine thousands of skeletons spanning more than 6,000 years of human history to search for evidence of eburnation - a tell-tale sign of osteoarthritis.

"When your cartilage erodes away, and two bones that comprise a joint come into direct contact, they rub against each other causing a glass-like polish to develop," Wallace said. "That polish, called eburnation, is so clear and obvious that we can use it to very accurately diagnose osteoarthritis in skeletal remains."

The data Wallace collected was combined with analyses from other contributors to the study, making this the largest sample ever studied of older-aged individuals from three broad time periods - prehistoric times, early industrial times (mainly the 1800s), and the modern post-industrial era.

"The most important comparison is between the early industrial and modern samples," Lieberman said. "Because we had data on each individual's age, sex, body weight, ethnicity, and in many cases, their occupation and cause of death, we were able to correct for a number of factors that we considered important covariates. So using careful statistical methods, we are able to say that if you were born after World War II you have approximately twice the likelihood of getting knee osteoarthritis at a given age or BMI than if you were born earlier."

Wallace and Lieberman are now working to identify what factors may be behind the increase, and said the evolutionary approach to the study is a critical part of that ongoing work.

"Epidemiology typically looks at large cohorts of individuals living today to search for associations between a disease and risk factors," Lieberman said. "That's a powerful and valuable method, but it has one critical imitation, which is that the world today is different in many ways from the world in the past, hiding important risk factors that are either no longer prevalent or have become ubiquitous. An evolutionary perspective opens new opportunities to test for associations we might not be able to study in populations like modern day America."

That perspective, Wallace and Lieberman said, allows researchers to zero in on specific things that changed pre- to post-World War II, and understand how they might contribute to the rise in knee osteoarthritis prevalence.

"This is an example of how evolutionary thinking can contribute to our understanding of what causes certain diseases," Wallace said. "We identified the post-war period as a critical time...and it's only with an evolutionary perspective that we gain that insight."

Ultimately, Wallace and Lieberman hope their study inspires new research to prevent knee osteoarthritis.

"Knee osteoarthritis is not a necessary consequence of old age. We should think of this as a partly preventable disease," Lieberman said. "Wouldn't it be great if people could live to be 60, 70 or 80 and never get knee osteoarthritis in the first place? Right now, our society is barely focusing on prevention in any way, shape or form, so we need to redirect more interest toward preventing this and other so-called diseases of aging."

Light-to-moderate alcohol consumption may have protective health effects


Light-to-moderate drinking can lower risk of mortality from all-causes and cardiovascular disease, while heavy drinking can significantly increase risk of mortality from all-causes and cancer, according to a new study published today in the Journal of the American College of Cardiology.

High alcohol consumption has been liked to a host of health issues, including cardiovascular disease, but alcohol in moderation is widely recommended. However, despite these recommendations, studies on the risk of mortality among light-to-moderate drinkers are inconsistent. Researchers in this study examined the association between alcohol consumption and risk of mortality from all causes, cancer and cardiovascular disease in the U.S.

The researchers looked at data from 333,247 participants obtained through the National Health Interview Surveys from 1997 to 2009. Study participants were surveyed regarding their alcohol consumption status and patterns of use. Alcohol consumption patterns were divided into six categories: lifetime abstainers, lifetime infrequent drinkers, former drinkers and current light (less than three drinks per week), moderate (more than three drinks per week to less than 14 drinks per week for men or less than seven drinks per week for women) or heavy drinkers (more than 14 drinks per week for men or seven drinks per week for women).

"Our research shows that light-to-moderate drinking might have some protective effects against cardiovascular disease, while heavy drinking can lead to death. A delicate balance exists between the beneficial and detrimental effects of alcohol consumption, which should be stressed to consumers and patients," said Bo Xi, MD, associate professor at the Shandong University School of Public Health in China and the study's lead author.

Throughout the length of the study, 34,754 participants died from all-causes. Of these, 8,947 mortalities were cardiovascular disease-specific (6,944 heart disease-related and 2,003 cerebrovascular-related deaths) and 8,427 mortalities were cancer-specific.

Researchers found that male heavy drinkers had a 25 percent increased risk of mortality due to all-causes and a 67 percent increase in mortality from cancer. These increases were not significantly noticed in women. There was no association found between heavy drinking and cardiovascular disease mortality. Moderate drinking was associated with a 13 percent and 25 percent decreased risk of all-cause mortality, and 21 percent and 34 percent decreased risk of cardiovascular disease mortality, respectively, in both men and women. Similar findings were observed for light drinking in both genders.

"We have taken rigorous statistical approaches to address issues reported in earlier studies such as abstainer bias, sick quitter phenomenon and limited confounding adjustment in our study. A J-shaped relationship exists between alcohol consumption and mortality, and drinkers should drink with consciousness," said one of the study's authors, Sreenivas Veeranki, MD, DrPH, assistant professor in preventive medicine and community health at University of Texas Medical Branch.

Limitations to the study include obtaining alcohol consumption status through survey responses that may be subject to recall bias, as well as using self-reported responses at baseline.

In an accompanying editorial, Giovanni de Gaetano, MD, PhD, director of the Department of Epidemiology and Prevention at IRCCS Istituto Neurologico Mediterraneo Neuromed said that while younger adults should not expect considerable benefit from moderate drinking, "for most older persons, the overall benefits of light drinking, especially the reduced cardiovascular disease risk, clearly outweigh possible cancer risk."