How Exercise Affects the Brain

Exercise clears the mind. It gets the blood pumping and more oxygen is delivered to the brain. This is familiar territory, but Dartmouth's David Bucci thinks there is much more going on.

Exercise clears the mind. It gets the blood pumping and more oxygen is delivered to the brain. This is familiar territory, but Dartmouth's David Bucci thinks there is much more going on [Credit: Web]

"In the last several years there have been data suggesting that neurobiological changes are happening -- [there are] very brain-specific mechanisms at work here," says Bucci, an associate professor in the Department of Psychological and Brain Sciences.

From his studies, Bucci and his collaborators have revealed important new findings:

• The effects of exercise are different on memory as well as on the brain, depending on whether the exerciser is an adolescent or an adult.

• A gene has been identified which seems to mediate the degree to which exercise has a beneficial effect. This has implications for the potential use of exercise as an intervention for mental illness.

Bucci began his pursuit of the link between exercise and memory with attention deficit hyperactivity disorder (ADHD), one of the most common childhood psychological disorders. Bucci is concerned that the treatment of choice seems to be medication.

"The notion of pumping children full of psycho-stimulants at an early age is troublesome," Bucci cautions. "We frankly don't know the long-term effects of administering drugs at an early age -- drugs that affect the brain -- so looking for alternative therapies is clearly important."

Anecdotal evidence from colleagues at the University of Vermont started Bucci down the track of ADHD. Based on observations of ADHD children in Vermont summer camps, athletes or team sports players were found to respond better to behavioral interventions than more sedentary children. While systematic empirical data is lacking, this association of exercise with a reduction of characteristic ADHD behaviors was persuasive enough for Bucci.

Coupled with his interest in learning and memory and their underlying brain functions, Bucci and teams of graduate and undergraduate students embarked upon a project of scientific inquiry, investigating the potential connection between exercise and brain function. They published papers documenting their results, with the most recent now available in the online version of the journal Neuroscience.

Bucci is quick to point out that "the teams of both graduate and undergraduates are responsible for all this work, certainly not just me." Michael Hopkins, a graduate student at the time, is first author on the papers.

Early on, laboratory rats that exhibit ADHD-like behavior demonstrated that exercise was able to reduce the extent of these behaviors. The researchers also found that exercise was more beneficial for female rats than males, similar to how it differentially affects male and female children with ADHD.

Moving forward, they investigated a mechanism through which exercise seems to improve learning and memory. This is "brain derived neurotrophic factor" (BDNF) and it is involved in growth of the developing brain. The degree of BDNF expression in exercising rats correlated positively with improved memory, and exercising as an adolescent had longer lasting effects compared to the same duration of exercise, but done as an adult.

"The implication is that exercising during development, as your brain is growing, is changing the brain in concert with normal developmental changes, resulting in your having more permanent wiring of the brain in support of things like learning and memory," says Bucci. "It seems important to [exercise] early in life."

Bucci's latest paper was a move to take the studies of exercise and memory in rats and apply them to humans. The subjects in this new study were Dartmouth undergraduates and individuals recruited from the Hanover community.

Bucci says that, "the really interesting finding was that, depending on the person's genotype for that trophic factor [BDNF], they either did or did not reap the benefits of exercise on learning and memory. This could mean that you may be able to predict which ADHD child, if we genotype them and look at their DNA, would respond to exercise as a treatment and which ones wouldn't."

Bucci concludes that the notion that exercise is good for health including mental health is not a huge surprise. "The interesting question in terms of mental health and cognitive function is how exercise affects mental function and the brain." This is the question Bucci, his colleagues, and students continue to pursue.

Author: Joseph Blumberg | Source: Dartmouth College [May 18, 2013]

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A walk in the park gives mental boost to people with depression

A walk in the park may have psychological benefits for people suffering from depression. In one of the first studies to examine the effect of nature walks on cognition and mood in people with major depression, researchers in Canada and the U.S. have found promising evidence that a walk in the park may provide some cognitive benefits.

The study was led by Marc Berman, a post-doctoral fellow at Baycrest's Rotman Research Institute in Toronto, with partners from the University of Michigan and Stanford University. It is published online this week, ahead of print publication, in the Journal of Affective Disorders.

"Our study showed that participants with clinical depression demonstrated improved memory performance after a walk in nature, compared to a walk in a busy urban environment," said Dr. Berman, who cautioned that such walks are not a replacement for existing and well-validated treatments for clinical depression, such as psychotherapy and drug treatment.

"Walking in nature may act to supplement or enhance existing treatments for clinical depression, but more research is needed to understand just how effective nature walks can be to help improve psychological functioning," he said.

Dr. Berman's research is part of a cognitive science field known as Attention Restoration Theory (ART) which proposes that people concentrate better after spending time in nature or looking at scenes of nature. The reason, according to ART, is that people interacting with peaceful nature settings aren't bombarded with external distractions that relentlessly tax their working memory and attention systems. In nature settings, the brain can relax and enter a state of contemplativeness that helps to restore or refresh those cognitive capacities.

In a research paper he published in 2008 in Psychological Science, Dr. Berman showed that adults who were not diagnosed with any illness received a mental boost after an hour-long walk in a woodland park – improving their performance on memory and attention tests by 20 percent – compared to an hour-long stroll in a noisy urban environment. The findings were reported by The Wall Street Journal, The Boston Globe, The New York Times, and in the Pulitzer Prize finalist book by Nicholas Carr, The Shallows: What the internet is doing to our brains.

In this latest study, Dr. Berman and his research team explored whether a nature walk would provide similar cognitive benefits, and also improve mood for people with clinical depression. Given that individuals with depression are characterized by high levels of rumination and negative thinking, the researchers were skeptical at the outset of the study that a solitary walk in the park would provide any benefit at all and may end up worsening memory and exacerbating depressed mood.

For the study, 20 individuals were recruited from the University of Michigan and surrounding Ann Arbor area; all had a diagnosis of clinical depression. The 12 females and eight males (average age 26) participated in a two-part experiment that involved walking in a quiet nature setting and in a noisy urban setting.

Prior to the walks, participants completed baseline testing to determine their cognitive and mood status. Before beginning a walk, the participants were asked to think about an unresolved, painful autobiographical experience. They were then randomly assigned to go for an hour-long walk in the Ann Arbor Arboretum (woodland park) or traffic heavy portions of downtown Ann Arbor. They followed a prescribed route and wore a GPS watch to ensure compliance.

After completing their walk, they completed a series of mental tests to measure their attention and short-term/working memory and were re-asssessed for mood. A week later the participants repeated the entire procedure, walking in the location that was not visited in the first session.

Participants exhibited a 16 percent increase in attention and working memory after the nature walk relative to the urban walk. Interestingly, interacting with nature did not alleviate depressive mood to any noticeable degree over urban walks, as negative mood decreased and positive mood increased after both walks to a significant and equal extent. Dr. Berman says this suggests that separate brain mechanisms may underlie the cognitive and mood changes of interacting with nature. 

Source: Baycrest Centre for Geriatric Care [May 14, 2012]

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Regular jogging shows dramatic increase in life expectancy

Undertaking regular jogging increases the life expectancy of men by 6.2 years and women by 5.6 years, reveals the latest data from the Copenhagen City Heart study presented at the EuroPRevent2012 meeting. Reviewing the evidence of whether jogging is healthy or hazardous, Peter Schnohr told delegates that the study's most recent analysis (unpublished) shows that between one and two-and-a-half hours of jogging per week at a "slow or average" pace delivers optimum benefits for longevity. The EuroPRevent2012 meeting, held 3 May to 5 May 2012, in Dublin, Ireland, was organised by the European Association for Cardiovascular Prevention and Rehabilitation (EACPR), a registered branch of the European Society of Cardiology (ESC).

"The results of our research allow us to definitively answer the question of whether jogging is good for your health," said Schnohr, who is chief cardiologist of the Copenhagen City Heart Study, speaking in the "Assessing prognosis: a glimpse of the future" symposium on Saturday. "We can say with certainty that regular jogging increases longevity. The good news is that you don't actually need to do that much to reap the benefits."

The debate over jogging first kicked off in the 1970s when middle aged men took an interest in the past-time. "After a few men died while out on a run, various newspapers suggested that jogging might be too strenuous for ordinary middle aged people," recalled Schnohr.

The Copenhagen City Heart study, which started 1976, is a prospective cardiovascular population study of around 20,000 men and women aged between 20 to 93 years. The study, which made use of the Copenhagen Population Register, set out to increase knowledge about prevention of cardiovascular disease and stroke. Since then the study, which has resulted in publication of over 750 papers, has expanded to include other diseases such as heart failure, pulmonary diseases, allergy, epilepsy, dementia, sleep-apnea and genetics. The investigators have explored the associations for longevity with different forms of exercise and other factors.

For the jogging sub study, the mortality of 1,116 male joggers and 762 female joggers was compared to the non joggers in the main study population. All participants were asked to answer questions about the amount of time they spent jogging each week, and to rate their own perceptions of pace (defined as slow, average, and fast). "With participants having such a wide age span we felt that a subjective scale of intensity was the most appropriate approach," explained Schnohr, who is based at Bispebjerg University Hospital, Copenhagen.

The first data was collected between 1976 to 1978, the second from 1981 to 1983, the third from 1991 to 1994, and the fourth from 2001 to 2003. For the analysis participants from all the different data collections were followed using a unique personal identification number in the Danish Central Person Register. "These numbers have been key to the success of the study since they've allowed us to trace participants wherever they go," said Schnohr.

Results show that in the follow-up period involving a maximum of 35 years, 10,158 deaths were registered among the non-joggers and 122 deaths among the joggers. Analysis showed that risk of death was reduced by 44% for male joggers (age-adjusted hazard ratio 0.56) and 44% for female joggers (age-adjusted hazard ratio 0.56). Furthermore the data showed jogging produced an age adjusted survival benefit of 6.2 years in men and 5.6 years in women.

Further analysis exploring the amounts of exercise undertaken by joggers in the study has revealed a U-shaped curve for the relationship between the time spent exercising and mortality. The investigators found that between one hour and two and a half hours a week, undertaken over two to three sessions, delivered the optimum benefits, especially when performed at a slow or average pace. "The relationship appears much like alcohol intakes. Mortality is lower in people reporting moderate jogging, than in non-joggers or those undertaking extreme levels of exercise," said Schnohr.

The ideal pace can be achieved by striving to feel a little breathless. "You should aim to feel a little breathless, but not very breathless," he advised.

Jogging, said Schnohr, delivers multiple health benefits. It improves oxygen uptake, increases insulin sensitivity, improves lipid profiles (raising HDL and lowering triglycerides), lowers blood pressure, reduces platelet aggregation, increases fibrinolytic activity, improves cardiac function, bone density, immune function, reduces inflammation markers, prevents obesity, and improves psychological function. "The improved psychological wellbeing may be down to fact that people have more social interactions when they're out jogging," said Schnohr.

Source: European Society of Cardiology [May 03, 2012]

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Biophysics: Order in chaos

The process of skeletal muscle contraction is based around protein filaments sliding inside sarcomeres — the structural units of muscle fiber. Inside each sarcomere is a set of filament motors, which appear in different densities in different areas. Scientists previously thought that the motor force would change according to the filament load in the muscle, but recent studies have shown that the motor force actually maintains a constant level during the muscle contraction. Despite such breakthroughs, however, it remains unclear exactly how this constant force is maintained in an otherwise chaotic system.

Bin Chen of the A*STAR Institute of High Performance Computing and Huajian Gao at Brown University, US, have now built a model to illustrate the process of skeletal muscle contraction and show how a constant force can be sustained by the protein motors.

The two key proteins in muscle contraction are actin and myosin. Myosin drives the system, forming a thick filament made up of numerous motors which ‘grab’ onto, bind to and slide past the thinner actin filaments during contraction. This ‘grabbing’ and sliding motion has been shown to be fairly chaotic in nature, with attachment and release happening at random. When the weight of an object exerts a load on the filaments — for example, when you try to lift something up — the muscles must contract, requiring the protein motors to generate a force opposite to the load.

Chen and Gao have created a new skeletal muscle fiber model to demonstrate how contraction forces work. “Our model is designed for the sarcomere,” Chen explains. “We consider the thin filament as an elastic rod under a filament force, which is driven by multiple stochastic myosin motors that convert the chemical energy of adenosine-5'-triphosphate (ATP) hydrolysis into stored elastic energy and then function like swinging arms.”

The results show that the unique way in which the myosin motors randomly attach and release from actin, coupled with the elastic properties of the motors, generate a consistent force across the whole sarcomere. When there is a higher filament load, more myosin motors are attached to the actin, but the overall motor force remains constant.

“This regulation mechanism may exist in various biological processes and dramatically induces order within a chaotic system,” explains Chen. “Our modeling framework can also be further adapted to study the behaviors of other actomyosin complex structures, which is part of our plan for future work in this area.”

Author: Lee Swee Heng | Source: ResearchSEA [May 03, 2012]

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Action Videogames Change Brains

A team led by psychology professor Ian Spence at the University of Toronto reveals that playing an action videogame, even for a relatively short time, causes differences in brain activity and improvements in visual attention.

Previous studies have found differences in brain activity between action videogame players and non-players, but these could have been attributed to pre-existing differences in the brains of those predisposed to playing videogames and those who avoid them. This is the first time research has attributed these differences directly to playing video games.

Twenty-five subjects -- who had not previously played videogames -- played a game for a total of 10 hours in one to two hour sessions. Sixteen of the subjects played a first-person shooter game and, as a control, nine subjects played a three-dimensional puzzle game.

Before and after playing the games, the subjects' brain waves were recorded while they tried to detect a target object among other distractions over a wide visual field. Subjects who played the shooter videogame and also showed the greatest improvement on the visual attention task showed significant changes in their brain waves. The remaining subjects -- including those who had played the puzzle game -- did not.

"After playing the shooter game, the changes in electrical activity were consistent with brain processes that enhance visual attention and suppress distracting information," said Sijing Wu, a PhD student in Spence's lab in U of T's Department of Psychology and lead author of the study.

"Studies in different labs, including here at the University of Toronto, have shown that action videogames can improve selective visual attention, such as the ability to quickly detect and identify a target in a cluttered background," said Spence. "But nobody has previously demonstrated that there are differences in brain activity which are a direct result of playing the videogame."

"Superior visual attention is crucial in many important everyday activities," added Spence. "It's necessary for things such as driving a car, monitoring changes on a computer display, or even avoiding tripping while walking through a room with children's toys scattered on the floor."

The research was supported by funding from the Natural Sciences and Engineering Research Council of Canada in the form of Discovery Grants to Spence and co-author Claude Alain of the Rotman Research Institute, Baycrest Centre and U of T's Psychology Department.

The research team also included U of T PhD candidate Cho Kin Cheng, Jing Feng, a postdoc at the Rotman Research Institute, and former undergraduate student Lisa D'Angelo.

Source: University of Toronto [April 26, 2012]

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With you in the room bacteria counts spike by about 37 million bacteria per hour

A person's mere presence in a room can add 37 million bacteria to the air every hour -- material largely left behind by previous occupants and stirred up from the floor -- according to new research by Yale University engineers. 

Rendering of bacteria. A person's mere presence in a room can add 37 million bacteria to the air every hour -- material largely left behind by previous occupants and stirred up from the floor -- according to new research by Yale University engineers [Credit: © Jezper/Fotolia]

"We live in this microbial soup, and a big ingredient is our own microorganisms," said Jordan Peccia, associate professor of environmental engineering at Yale and the principal investigator of a study recently published online in the journal Indoor Air. "Mostly people are re-suspending what's been deposited before. The floor dust turns out to be the major source of the bacteria that we breathe." 

Many previous studies have surveyed the variety of germs present in everyday spaces. But this is the first study that quantifies how much a lone human presence affects the level of indoor biological aerosols. 

Peccia and his research team measured and analyzed biological particles in a single, ground-floor university classroom over a period of eight days -- four days when the room was periodically occupied, and four days when the room was continuously vacant. At all times the windows and doors were kept closed. The HVAC system was operated at normal levels. Researchers sorted the particles by size. 

Overall, they found that "human occupancy was associated with substantially increased airborne concentrations" of bacteria and fungi of various sizes. Occupancy resulted in especially large spikes for larger-sized fungal particles and medium-sized bacterial particles. The size of bacteria- and fungi-bearing particles is important, because size affects the degree to which they are likely to be filtered from the air or linger and recirculate, the researchers note. 

"Size is the master variable," Peccia said. 

Researchers found that about 18 percent of all bacterial emissions in the room -- including both fresh and previously deposited bacteria -- came from humans, as opposed to plants and other sources. Of the 15 most abundant varieties of bacteria identified in the room studied, four are directly associated with humans, including the most abundant, Propionibacterineae, common on human skin. 

Peccia said carpeted rooms appear to retain especially high amounts of microorganisms, but noted that this does not necessarily mean rugs and carpets should be removed. Extremely few of the microorganisms commonly found indoors -- less than 0.1 percent -- are infectious, he said. 

Still, understanding the content and dynamics of indoor biological aerosols is helpful for devising new ways of improving air quality when necessary, he said. 

"All those infectious diseases we get, we get indoors," he said, adding that Americans spend more than 90 percent of their time inside. 

The researchers have begun a series of similar studies outside the United States. 

The paper's lead author is J. Qian of Yale. Other contributors are D. Hospodsky and N. Yamamoto, both of Yale, and W.W. Nazaroff of the University of California-Berkeley. 

The research was supported by the Alfred P. Sloan Foundation. 

Author: Eric Gershon | Source: Yale University [March 28, 2012]

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Testosterone Makes Us Less Cooperative and More Egocentric

Testosterone makes us overvalue our own opinions at the expense of cooperation, research from the Wellcome Trust Centre for Neuroimaging at UCL (University College London) has found. The findings may have implications for how group decisions are affected by dominant individuals. 

Problem solving in groups can provide benefits over individual decisions as we are able to share our information and expertise. However, there is a tension between cooperation and self-orientated behaviour: although groups might benefit from a collective intelligence, collaborating too closely can lead to an uncritical groupthink, ending in decisions that are bad for all. 

Attempts to understand the biological mechanisms behind group decision making have tended to focus on the factors that promote cooperation, and research has shown that people given a boost of the hormone oxytocin tend to be cooperative. Now, in a study recently published in the journal Proceedings of the Royal Society B, researchers have shown that the hormone testosterone has the opposite effect -- it makes people act less cooperatively and more egocentrically. 

Dr Nick Wright and colleagues at the Wellcome Trust Centre for Neuroimaging at UCL carried out a series of tests using 17 pairs of female volunteers* who had previously never met. The test took place over two days, spaced a week apart. On one of the days, both volunteers in each pair were given a testosterone supplement; on the other day, they were given a placebo. 

During the experiment, both women sat in the same room and viewed their own screen. Both individuals saw exactly the same thing. First, in each trial they were shown two images, one of which contained a high-contrast target -- and their job was to decide individually which image contained the target. 

If their individual choices agreed, they received feedback and moved on to the next trial. However, if they disagreed, they were asked to collaborate and discuss with their partner to reach a joint decision. One of the pair then input this joint decision. 

The researchers found that, as expected, cooperation enabled the group to perform much better than the individuals alone when individuals had received only the placebo. But, when given a testosterone supplement, the benefit of cooperation was markedly reduced. In fact, higher levels of testosterone were associated with individuals behaving egocentrically and deciding in favour of their own selection over their partner's. 

"When we are making decisions in groups, we tread a fine line between cooperation and self-interest: too much cooperation and we may never get our way, but if we are too self-orientated, we are likely to ignore people who have real insight," explains Dr Wright. 

"Our behaviour seems to be moderated by our hormones -- we already know that oxytocin can make us more cooperative, but if this were the only hormone acting on our decision-making in groups, this would make our decisions very skewed. We have shown that, in fact, testosterone also affects our decisions, by making us more egotistical. 

"Most of the time, this allows us to seek the best solution to a problem, but sometimes, too much testosterone can help blind us to other people's views. This can be very significant when we are talking about a dominant individual trying to assert his or her opinion in, say, a jury." 

Testosterone is implicated in a variety of social behaviours. For example, in chimpanzees, levels of testosterone rise ahead of a confrontation or a fight. In female prisoners, studies have found that higher levels of testosterone correlate with increased antisocial behaviour and higher aggression. Researchers believe that such findings reflect a more general role for testosterone in increasing the motivation to dominate others and increase egocentricity. 

Commenting on the findings, Dr John Williams, Head of Neuroscience and Mental Health at the Trust, said: "Cooperating with others has obvious advantages for sharing skills and experience, but we know it doesn't always work, particularly if one alpha male or alpha female dominates the decision making. This result helps us understand at a hormonal level the factors that can disrupt our attempts to work together." 

The Wellcome Trust funded this study. 

*Testosterone is naturally secreted in men and women, and testosterone levels are correlated with important behaviours (e.g. antisocial behaviour) in both men and women. For the size of dose given experimentally, in women this markedly increases their testosterone from its low baseline level. In men, however, the situation is more complicated: men already have high baseline levels of testosterone, so giving such doses will decrease their own production of testosterone, a feedback effect that will act to offset the increase caused by the treatment itself. The researchers therefore used female subjects because giving standard experimental doses causes a straightforward and well-characterised increase in their testosterone levels. 

Source: Wellcome Trust [January 31, 2012]

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How work tells muscles to grow

We take it for granted, but the fact that our muscles grow when we work them makes them rather unique. Now, researchers have identified a key ingredient needed for that bulking up to take place. A factor produced in working muscle fibers apparently tells surrounding muscle stem cell "higher ups" that it's time to multiply and join in, according to a study in the January Cell Metabolism, a Cell Press journal. 

In other words, that so-called serum response factor (Srf) translates the mechanical signal of work into a chemical one. 

"This signal from the muscle fiber controls stem cell behavior and participation in muscle growth," says Athanassia Sotiropoulos of Inserm in France. "It is unexpected and quite interesting." It might also lead to new ways to combat muscle atrophy. 

Sotiropoulos' team became interested in Srf's role in muscle in part because their earlier studies in mice and humans showed that Srf concentrations decline with age. That led them to think Srf might be a culprit in the muscle atrophy so common in aging. 

The new findings support that view, but Srf doesn't work in the way the researchers had anticipated. Srf was known to control many other genes within muscle fibers. That Srf also influences the activities of the satellite stem cells came as a surprise. 

Mice with muscle fibers lacking Srf are no longer able to grow when they are experimentally overloaded, the new research shows. That's because satellite cells don't get the message to proliferate and fuse with those pre-existing myofibers. 

Srf works through a network of genes, including one known as Cox2. That raises the intriguing possibility that commonly used Cox2 inhibitors—think ibuprofen—might work against muscle growth or recovery, Sotiropoulos notes. 

Treatments designed to tweak this network of factors might be used to wake muscle stem cells up and enhance muscle growth in circumstances such as aging or following long periods of bed rest, she says. Most likely, such therapies would be more successfully directed not at Srf itself, which has varied roles, but at its targets. 

"It may be difficult to find a beneficial amount of Srf," she says. "Its targets, interleukins and prostaglandins, may be easier to manipulate." 

Source: Cell Press [January 03, 2012]

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New study puts eco-labels to the test

A new report released today by the University of Victoria ranks eco-labels intended to distinguish seafood produced with less damage to the environment. It is the first study to evaluate how eco-labels for farmed marine fish compare to unlabeled options in the marketplace.

"How Green is Your Eco-label?" is designed to help seafood buyers sort through competing sustainability claims and better identify those labels that result in farming methods with less damage to the ocean. Key findings include:

• "Organic" labels lead the pack, although a few fall noticeably short;

• Many eco-labels are not much better than conventional farmed seafood options when it comes to protecting the ocean environment;

• Scale is a big challenge for eco-labels: For the most part, eco-labels are awarded based on an individual farm's environmental footprint. However, the cumulative environmental effects of many farms can quickly overwhelm the benefits of reductions in impacts by a single farm or small group of certified farms. 

"Our research shows that most eco-labels for farmed marine fish offer no more than a 10 percent improvement over the status quo," said John Volpe, Ph.D., a marine ecologist at the University of Victoria and lead author of the report. "With the exception of a few outstanding examples, one-third of the eco-labels evaluated for these fish utilize standards at the same level or below what we consider to be conventional or average practice in the industry."

Supported by the Pew Environment Group, the study, which was reviewed by several independent experts, uses a well-established quantitative methodology derived from the 2010 Global Aquaculture Performance Index  to determine numerical scores of environmental performance for 20 different eco-labels for farmed marine finfish, such as salmon, cod, turbot, and grouper. These scores were used to rank performance among the various eco-labels. The assessment did not look at eco-labels for freshwater farmed fish, such as tilapia or catfish.

The authors used 10 environmental factors to assess the eco-labels, including antibiotic use, the ecological effect of farmed fish that escape from pens, sustainability of the fish that serve as feed, parasiticide use, and industrial energy needed in aquaculture production.

"Eco-labels can help fish farmers produce and consumers select environmentally preferable seafood, but only if the labels are based on meaningful standards that are enforced," said Chris Mann, director of Pew's Aquaculture Standards Project. "Seafood buyers at the retail or wholesale level should demand that evidence of sustainability be demonstrated, not merely asserted."

The report concludes that government policies and regulations, as well as effective eco-labels, are necessary to limit the environmental impacts of production.

Source: Pew Environment Group [December 07, 2011]

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Vegetables, fruits, grains reduce stroke risk in women

Swedish women who ate an antioxidant-rich diet had fewer strokes regardless of whether they had a previous history of cardiovascular disease, in a study reported in Stroke: Journal of the American Heart Association. 

"Eating antioxidant-rich foods may reduce your risk of stroke by inhibiting oxidative stress and inflammation," said Susanne Rautiainen, M.Sc., the study's first author and Ph.D. student at the Karolinska Institutet in Sweden. "This means people should eat more foods such as fruits and vegetables that contribute to total antioxidant capacity." 

Oxidative stress is an imbalance between the production of cell-damaging free radicals and the body's ability to neutralize them. It leads to inflammation, blood vessel damage and stiffening. 

Antioxidants such as vitamins C and E, carotenoids and flavonoids can inhibit oxidative stress and inflammation by scavenging the free radicals. Antioxidants, especially flavonoids, may also help improve endothelial function and reduce blood clotting, blood pressure and inflammation. 

"In this study, we took into account all the antioxidants present in the diet, including thousands of compounds, in doses obtained from a usual diet," Rautiainen said. Researchers collected dietary data through a food-frequency questionnaire. They used a standard database to determine participants' total antioxidant capacity (TAC), which measures the free radical reducing capacity of all antioxidants in the diet and considers synergistic effects between substances. 

Researchers categorized the women according to their TAC levels — five groups without a history of cardiovascular disease and four with previous cardiovascular disease. 

For women with no history of cardiovascular disease who had the highest TAC, fruits and vegetables contributed about 50 percent of TAC. Other contributors were whole grains (18 percent), tea (16 percent) and chocolate (5 percent). 

The study found: 

• Higher TAC was related to lower stroke rates in women without cardiovascular disease. 

• Women without cardiovascular disease with the highest levels of dietary TAC had a statistically significant 17 percent lower risk of total stroke compared to those in the lowest quintile. 

• Women with history of cardiovascular disease in the highest three quartiles of dietary TAC had a statistically significant 46 percent to 57 percent lower risk of hemorrhagic stroke compared with those in the lowest quartile. 

"Women with a high antioxidant intake may be more health conscious and have the sort of healthy behaviors that may have influenced our results," Rautiainen said. "However, the observed inverse association between dietary TAC and stroke persisted after adjustments for potential confounders related to healthy behavior such as smoking, physical activity and education." 

For the study, researchers used the Swedish Mammography Cohort to identify 31,035 heart disease-free women and 5,680 women with a history of heart disease in two counties. The women were 49-83 years old. 

Researchers tracked the cardiovascular disease-free women an average 11.5 years and the women with cardiovascular disease 9.6 years, from September 1997 through the date of first stroke, death or Dec. 31, 2009, whichever came first. 

Researchers identified 1,322 strokes among cardiovascular disease-free women and 1,007 strokes among women with a history of cardiovascular disease from the Swedish Hospital Discharge Registry. 

"To the best of our knowledge, no study has assessed the relation between dietary TAC and stroke risk in participants with a previous history of cardiovascular disease," Rautiainen said. "Further studies are needed to assess the link between dietary TAC and stroke risk in men and in people in other countries, but we think our results are applicable." 

Source: American Heart Association [December 01, 2011]

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"Just Chill?" Relaxing Can Make You Fatter

Conventional wisdom says that exercise is a key to weight loss — a no-brainer. But now, Tel Aviv University researchers are revealing that life as a couch potato, stretched out in front of the TV, can actually be "active inactivity" — and cause you to pack on the pounds. 

Such inactivity actually encourages the body to create new fat in fat cells, says Prof. Amit Gefen of TAU's Department of Biomedical Engineering. Along with his Ph.D. student Naama Shoham, Prof. Gefen has shown that preadipocyte cells — the precursors to fat cells — turn into fat cells faster and produce even more fat when subject to prolonged periods of "mechanical stretching loads" — the kind of weight we put on our body tissues when we sit or lie down. 

The research, which has been published in the American Journal of Physiology — Cell Physiology, demonstrates another damaging effect of a modern, sedentary lifestyle, Prof. Gefen notes. "Obesity is more than just an imbalance of calories. Cells themselves are also responsive to their mechanical environment. Fat cells produce more triglycerides, and at a faster rate, when exposed to static stretching." 

Stretching the fat 

Prof. Gefen, who investigates chronic wounds that plague bed-ridden or wheelchair-bound patients, notes that muscle atrophy is a common side effect of prolonged inactivity. Studying MRI images of the muscle tissue of patients paralyzed by spinal cord injuries, he noticed that, over time, lines of fat cells were invading major muscles in the body. This spurred an investigation into how mechanical load — the amount of force placed on a particular area occupied by cells — could be encouraging fat tissue to expand. 

In the lab, Prof. Gefen and his fellow researchers stimulated preadipocytes with glucose or insulin to differentiate them into fat cells. Then they placed individual cells in a cell-stretching device, attaching them to a flexible, elastic substrate. The test group of cells were stretched consistently for long periods of time, representing extended periods of sitting or lying down, while a control group of cells was not. 

Tracking the cultures over time, the researchers noted the development of lipid droplets in both the test and control groups of cells. However, after just two weeks of consistent stretching, the test group developed significantly more — and larger — lipid droplets. By the time the cells reached maturity, the cultures that received mechanical stretching had developed fifty percent more fat than the control culture. 

They were, in effect, half-again fatter. 

According to Prof. Gefen, this is the first study that looks at fat cells as they develop, taking into account the impact of sustained mechanical loading on cell differentiation. "There are various ways that cells can sense mechanical loading," he explains, which helps them to measure their environment and triggers various chemical processes. "It appears that long periods of static mechanical loading and stretching, due to the weight of the body when sitting or lying, has an impact on increasing lipid production." 

Counting more than calories 

These findings indicate that we need to take our cells' mechanical environment into account as well as pay attention to calories consumed and burned, believes Prof. Gefen. Although there are extreme cases, such as people confined to wheelchairs or beds due to medical conditions, many of us live a too sedentary lifestyle, spending most of the day behind a desk. Even somebody with healthy diet and exercise habits will be negatively impacted by long periods of inactivity. 

Next, Prof. Gefen and his fellow researchers will be investigating how long a period of time a person can sit or lie down without the mechanical load becoming a factor in fat production. But in the meantime, it certainly can't hurt to get up and take an occasional stroll, he suggests. 

Source: American Friends of Tel Aviv University [December 01, 2011]

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Dieters should eat foods rich in protein, mostly from dairy, to protect bones during weight loss

New research suggests that a calorie-restricted diet higher in protein—mostly from dairy foods—and lower in carbohydrates coupled with daily exercise has a major positive impact on bone health in overweight and obese young women. 

The study, published online in the Journal of Clinical Endocrinology and Metabolism, found bone health improvements were particularly evident due to the high density of bone-supporting nutrients such as calcium, vitamin D and dairy-based protein. 

For 16 weeks, three groups of overweight and obese, but otherwise healthy, premenopausal women each consumed either low, medium or high amounts of dairy foods coupled with higher or lower amounts of protein and carbohydrates. Calcium and vitamin D levels were also graded from low to high across the groups in conjunction with the dairy foods they consumed. 

The women exercised seven days per week, a routine that included aerobic exercise every day and two additional workouts of circuit weightlifting per week. 

"Our findings demonstrate the importance of diet composition to the maintenance of bone health status during weight loss," said Andrea Josse, of the Department of Kinesiology at McMaster and lead author of the study. "Our data clearly show dairy-source protein is important when aiming to avoid harmful consequences such as accelerated bone loss during weight loss. In our view, young women attempting to lose weight should consume a diet higher in dairy-source protein." 

A previous study from the same team in the same subjects showed that there were identical total weight losses across the groups, but very different results for body composition change with the higher-protein, high-dairy group experiencing greater whole-body fat and abdomen fat losses and greater lean mass gains. 

The same subjects consuming higher-protein and high-dairy diets for this study also showed the greatest improvements in markers of bone formation, no change in bone loss, an increase in circulating vitamin D levels, and a decrease in levels of parathyroid hormone, which when elevated is typically associated with bone loss. 

Maintaining or even improving bone health in young women, particularly in those trying to lose weight, is important for overall health, and may have great implications for decreasing the risk of diseases like osteoporosis later in life, say the researchers. 

"Our data provide further rationale to recommend consumption of dairy foods to aid in 'high quality' weight loss, which we defined as loss of fat and sparing of muscle, and the promotion of bone health in young women," says Stuart Phillips, senior author and a professor in the Department of Kinesiology. "These women are not only at the age when achieving and maintaining peak bone mass is of great importance, but in whom adequate dairy consumption would offset sub-optimal intakes of calcium and vitamin D." 

Subjects undergoing weight loss while consuming marginally adequate protein without dairy foods showed markedly elevated levels of markers of bone loss indicating that following such a diet in the long-run would weaken bones.  

Source: McMaster University [November 30, 2011]

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The ethics of smart drugs

Professor Barbara Sahakian, Professor of Clinical Neuropsychology at the University of Cambridge, has been researching cognitive enhancers for over a decade.  Here she discusses the emergence of ‘smart drugs’ and the ethical and practical issues they raise.  

There is an increasing lifestyle use of cognitive enhancing drugs, or smart drugs by healthy people. Why might this be? And how will it change our society? Are people using these drugs just realize their potential, or is it that pressures to perform in a globally competitive environment means that individuals’ feel that they cannot afford an ‘off day’ due to lack of sleep or stress?  This is perhaps particularly true of certain professions, where there are issues of safety to oneself or others, such as the military, doctors, etc. 

Caffeine is the current stimulant of use for many people, as it is widely available, and effective: however, its wakefulness-promoting effects are transient. For doctors there is the undesirable side-effect of tremors at the dose required for maximum effects (600mg), which is common. Therefore, it is useful to examine whether there are more effective cognitive enhancers, with fewer detrimental side effects, for those whose failures in attention, concentration and problem solving may lead to deleterious effects, including jeopardy of safety in the military arena, or serious adverse events during operations. 

Although measures to reduce doctors’ working hours have been implemented in both the United Sates and Europe, surgeons performing long, arduous operations remain susceptible to the effects of fatigue, and frequent transitions from day to night work expose junior doctors to the risk of impaired psychomotor performance. Indeed, fatigued doctors risk making poor judgements and committing serious medical errors. Given the continued need for innovation in this area, pharmacological methods could conceivably be used to combat fatigue at some time in the future. 

In an exciting collaboration between the University of Cambridge, Department of Psychiatry and the Imperial College London, Division of Surgery, it has recently been discovered that the ‘smart drug’ Modafinil improves cognitive flexibility and reduces impulsivity in sleep deprived doctors. These results have just been published in the journal Annals of Surgery. 

In a proof of concept randomized placebo controlled study, run by Charlotte Housden (Cambridge) and Dr Colin Sugden (Imperial), 39 doctors were deprived of sleep overnight and given a dose of 200mg of Modafinil or placebo. The doctors taking Modafinil had cognitive improvements, including flexibility of thinking, and reduced impulsivity. These executive functions are clearly important for conducting surgical operations under stress and time pressure. However, there was no change on their clinical psychomotor performance on a laparoscopic task, which mimics and measures the dexterity necessary to perform surgery. 

While a chronic Modafinil study is required to determine the long term effects of the drug as a safe and effective means of improving cognitive impairment due to sleep deprivation, this acute study has demonstrated that benefits are obvious on at least the first occasion. 

Given these important findings, it is possible to speculate that doctors who take these drugs may be able to plan an intervention more effectively or show greater cognitive flexibility when approaching a challenging clinical problem.  However, it is critical that the long-term safety of the use of these drugs in healthy people remains to be determined. 

The many ethical discussions that I and Charlotte Housden have had with the public on the use of cognitive enhancing drugs by healthy people have been revealing.  A variety of views have emerged, ranging from ‘These drugs should only be used by people with neuropsychiatric disorders such as Attention Deficit Hyperactivity disorder, or Alzheimer’s Disease’, to ‘If they are safe, why not use them, to make up for fatigue, to improve memory or other forms of cognition?’, and ‘Why not use them to get in an especially productive working day?’. 

This increasing lifestyle use has to be balanced against other important facets of life, such as a good work/life balance. The possibility to accelerate into a 24/7 society for many people is a serious concern, as are issues of cheating and coercion. As a society, we certainly need to be concerned about the use of these drugs by healthy children and adolescents where their brains are still in development. Furthermore, the purchasing of prescription medication over the internet is dangerous. However, if long-term safety and efficacy are proven in healthy people, it may well be, at least for certain segments of the population, these drugs will prove life-savers. 

Source: University of Camridge [October 31, 2011]

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Exercise helps us to eat a healthy diet

A healthy diet and the right amount of exercise are key players in treating and preventing obesity but we still know little about the relationship both factors have with each other. A new study now reveals that an increase in physical activity is linked to an improvement in diet quality. 

A healthy diet and the right amount of exercise are key players in treating and preventing obesity but we still know little about the relationship both factors have with each other. A new study now reveals that an increase in physical activity is linked to an improvement in diet quality [Credit: SINC]

Many questions arise when trying to lose weight. Would it be better to start on a diet and then do exercise, or the other way around? And how much does one compensate the other? 

"Understanding the interaction between exercise and a healthy diet could improve preventative and therapeutic measures against obesity by strengthening current approaches and treatments," explains Miguel Alonso Alonso, researcher at Harvard University (USA) who has published a bibliographical compilation on the subject, to SINC. 

The data from epidemiological studies suggest that tendencies towards a healthy diet and the right amount of physical exercise often come hand in hand. Furthermore, an increase in physical activity is usually linked to a parallel improvement in diet quality. 

Exercise also brings benefits such as an increase in sensitivity to physiological signs of fullness. This not only means that appetite can be controlled better but it also modifies hedonic responses to food stimuli. Therefore, benefits can be classified as those that occur in the short term (of metabolic predominance) and those that are seen in the long term (of behavioural predominance). 

According to Alonso Alonso, "physical exercise seems to encourage a healthy diet. In fact, when exercise is added to a weight-loss diet, treatment of obesity is more successful and the diet is adhered to in the long run." 

The authors of the study state how important it is for social policy to encourage and facilitate sport and physical exercise amongst the population. This should be present in both schools and our urban environment or daily lives through the use of public transport or availability of pedestrianised areas and sports facilities. 

Exercise modifies the brain 

Eating and physical activity are behaviours and are therefore influenced by cognitive processes that are a result of activity in different areas of the brain. Previous studies have already assessed changes in the brain and cognitive functions in relation to exercise: regular physical exercise causes changes in the working and structure of the brain. 

The experts point out that these changes seem to have a certain specificity. The Harvard researcher supports the notion that "regular exercise improves output in tests that measure the state of the brain's executive functions and increases the amount of grey matter and prefrontal connections." 

Inhibitory control is one of the executive functions of the brain and is basically the ability to suppress inadequate and non-conforming answers to an aim (the opposite of this would be impulsiveness), which makes modification or self-regulations of a behaviour possible. 

With regards to losing weight and sustaining weight loss in the long run, various recent studies suggest that executive functions such as inhibitory control and optimal functioning of the brain's prefrontal areas could be the key to success. This success is mainly the fruit of a behavioural change. Inhibitory control could also help to prevent weight gain in healthy people. 

The researcher outlines that "in time, exercise produces a potentiating effect of executive functions including the ability for inhibitory control, which can help us to resist the many temptations that we are faced with everyday in a society where food, especially hypercaloric food, is more and more omnipresent." 

Spain – leader in obesity 

There has been an alarming rise in cases of obesity in Spain in recent years, so much so that prevalence in various areas of the country is higher than in many parts of the USA, which is traditionally thought of as the paradigm of obesity in the western world. 

Furthermore, along with other Mediterranean countries, Spain has one of the highest rates of childhood obesity in Europe. The experts are urging society to become aware of the problem and join forces to prevent and treat all types of obesity. 

Source: FECYT - Spanish Foundation for Science and Technology via EurekAlert! [November 23, 2011]

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Physical activity impacts overall quality of sleep

People sleep significantly better and feel more alert during the day if they get at least 150 minutes of exercise a week, a new study concludes. 

A nationally representative sample of more than 2,600 men and women, ages 18-85, found that 150 minutes of moderate to vigorous activity a week, which is the national guideline, provided a 65 percent improvement in sleep quality. People also said they felt less sleepy during the day, compared to those with less physical activity. 

The study, out in the December issue of the journal Mental Health and Physical Activity, lends more evidence to mounting research showing the importance of exercise to a number of health factors. Among adults in the United States, about 35 to 40 percent of the population has problems with falling asleep or with daytime sleepiness. 

“We were using the physical activity guidelines set forth for cardiovascular health, but it appears that those guidelines might have a spillover effect to other areas of health,” said Brad Cardinal, a professor of exercise science at Oregon State University and one of the study’s authors. 

“Increasingly, the scientific evidence is encouraging as regular physical activity may serve as a non-pharmaceutical alternative to improve sleep.” 

After controlling for age, BMI (Body Mass Index), health status, smoking status, and depression, the relative risk of often feeling overly sleepy during the day compared to never feeling overly sleepy during the day decreased by 65 percent for participants meeting physical activity guidelines. 

Similar results were also found for having leg cramps while sleeping (68 percent less likely) and having difficulty concentrating when tired (45 percent decrease). 

Paul Loprinzi, an assistant professor at Bellarmine University is lead author of the study, which was conducted while he was a doctoral student in Cardinal’s lab at OSU. He said it is the first study to examine the relationship between accelerometer-measured physical activity and sleep while utilizing a nationally representative sample of adults of all ages. 

‘Our findings demonstrate a link between regular physical activity and perceptions of sleepiness during the day, which suggests that participation in physical activity on a regular basis may positively influence an individual's productivity at work, or in the case of a student, influence their ability to pay attention in class,” he said. 

Cardinal said past studies linking physical activity and sleep used only self-reports of exercise. The danger with this is that many people tend to overestimate the amount of activity they do, he said. 

He added that the take-away for consumers is to remember that exercise has a number of health benefits, and that can include helping feel alert and awake. 

“Physical activity may not just be good for the waistline and heart, but it also can help you sleep,” Cardinal said. “There are trade-offs. It may be easier when you are tired to skip the workout and go to sleep, but it may be beneficial for your long-term health to make the hard decision and get your exercise.” 

Source: Oregon State University [November 22, 2011]

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Hefty impact of poor eating habits

Too much fast food, poor meal choices and bad eating habits are causing more Canadians to be overweight or obese. Despite this trend, individuals who eat well are 20 per cent less likely to be obese, according to a study by Concordia University economists published in the Journal of Primary Care & Community Health. 

"The risk of being obese or overweight is directly related to bad eating habits such as skipping meals, eating away from home, high consumption of fast and processed foods, as well as low consumption of fruit and vegetables," says first author Sunday Azagba, a PhD candidate in the Concordia Department of Economics. "In Canada, food purchased from restaurants accounts for more than 30 per cent of the average weekly food expenditure per household." 

As part of their study, the researchers examined data from the Canadian National Population Health Survey to evaluate how eating habits could impact obesity trends among adults aged 18 to 65. The World Health Organization, which uses the body mass index (BMI) to measure weight-for-height, estimates that a BMI greater than or equal to 25 makes for an overweight person and a BMI greater than or equal to 30 equals obesity. 

"More than 25 per cent of Canadians aged 31 to 50 exceed the safe limit of total calories derived from fats," adds co-author Mesbah Sharaf, a PhD candidate in the Concordia Department of Economics, noting advances in food engineering by producers may have contributed to the difficulty of resisting food craving and increase obesity rates. 

Measures to encourage healthier eating 

Higher taxes on fatty foods might encourage healthier eating, the economists suggest, yet higher prices won't sway everyone to choose a better diet. "Some people are unresponsive to taxes and such added costs to fast food would reduce their spending power without altering their eating behavior," says Azagba, noting an alternative would be for governments to subsidize less calorie-dense foods such as fruit and vegetables. "This might induce more people to substitute healthy foods for unhealthy ones." 

Other measures to encourage healthier eating could entail subsidizing healthy meal plans at schools and universities, restricting junk food in educational institutions and improving physical education programs in schools. "Education programs that raise awareness of the benefits of physical activity and the health implications of food choices, as well as compulsory warning labels about the health risks on food packaging, similar to those on cigarette packages, may also help to mitigate obesity rates," says Sharaf. 

It's imperative that obesity rates across Canada decline, says Azagba: "Health-care costs for caring for obese individuals are estimated to be 42 per cent greater than for people with normal weight. Research has found excessive body weight to be a risk factor for many chronic disease, such as cardiovascular diseases, type 2 diabetes, hypertension, liver diseases, as well as prostate, breast and colon cancer." 

Excessive body weight is an epidemic with repercussions beyond Canada. The World Health Organization estimates that 1 billion adults are overweight and that obesity accounts for more than 2.6 million deaths each year. The European Union estimates the combined direct and indirect costs of obesity to be €33 billion a year, whereas in the United States the total cost of obesity is estimated to be $139 billion annually. 

Source: Concordia University [November 22, 2011]

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Tuning out: How brains benefit from meditation

Experienced meditators seem to be able switch off areas of the brain associated with daydreaming as well as psychiatric disorders such as autism and schizophrenia, according to a new brain imaging study by Yale researchers. 

Experienced meditators seem to switch off areas of the brain associated with wandering thoughts, anxiety and some psychiatric disorders such as schizophrenia. Researchers used fMRI scans to determine how the brains of meditators differed from subjects who were not meditating. The areas shaded in blue highlight areas of decreased activity in the brains of meditators [Credit: Yale University]

Meditation's ability to help people stay focused on the moment has been associated with increased happiness levels, said Judson A. Brewer, assistant professor of psychiatry and lead author of the study published the week of Nov. 21 in the Proceedings of the National Academy of Sciences. Understanding how meditation works will aid investigation into a host of diseases, he said. 

"Meditation has been shown to help in variety of health problems, such as helping people quit smoking, cope with cancer, and even prevent psoriasis," Brewer said. 

The Yale team conducted functional magnetic resonance imaging scans on both experienced and novice meditators as they practiced three different meditation techniques. 

They found that experienced meditators had decreased activity in areas of the brain called the default mode network, which has been implicated in lapses of attention and disorders such as anxiety, attention deficit and hyperactivity disorder, and even the buildup of beta amyloid plaques in Alzheimer's disease. The decrease in activity in this network, consisting of the medial prefrontal and posterior cingulate cortex, was seen in experienced meditators regardless of the type of meditation they were doing. 

The scans also showed that when the default mode network was active, brain regions associated with self-monitoring and cognitive control were co-activated in experienced meditators but not novices. This may indicate that meditators are constantly monitoring and suppressing the emergence of "me" thoughts, or mind-wandering. In pathological forms, these states are associated with diseases such as autism and schizophrenia. 

The meditators did this both during meditation, and also when just resting — not being told to do anything in particular. This may indicate that meditators have developed a "new" default mode in which there is more present-centered awareness, and less "self"-centered, say the researchers. 

"Meditation's ability to help people stay in the moment has been part of philosophical and contemplative practices for thousands of years," Brewer said. "Conversely, the hallmarks of many forms of mental illness is a preoccupation with one's own thoughts, a condition meditation seems to affect. This gives us some nice cues as to the neural mechanisms of how it might be working clinically."  

Source: Yale University [November 21, 2011]

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