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Author: Sima

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Views about exercise and aging have really changed over the last century. Bottom line: walk  - it's good for cognitive health, especially as you age. Try for at least 1 mile per day (1 mile = approx. 20 minutes brisk walk).

From The Atlantic: Walking for a Better Brain

 A “nerve specialist” from New York named J. Leonard Corning said in 1909 that he was opposed to “excessive exercise,” ... He thought that with the “over-cultivation of the physique the mentality suffered.” Corning wrote during a period when experts widely believed that brain cells didn’t regenerate. As a result, graceful aging was in large part a matter of learning to cope with gradually diminishing brain capacity. Modern science has shown that’s not the case; we do generate new brain cells throughout our lives, although the process can become increasingly imperfect and less efficient with age, as it does with much cellular activity.

One of the largest studies ever conducted was on a group of 121,000 nurses, who were surveyed on a wide range of their health and lifestyle habits starting in 1976. The survey was repeated every two years. This established a trove of valuable information, which public-health researchers have been fruitfully mining since. Among them is Rush University assistant professor Jennifer Weuve, who studied the data collected on 18,766 of the nurses, who were then ages 70 to 81, to unearth connections between exercise and cognitive ability. The results, published in The Journal of the American Medical Association, suggested that those who exercised the most—the group that maintained a median level of walking for six hours a week—were 20 percent less likely to show cognitive impairment than those who exercised the least.

Other long-term studies also show that even modest exercise can serve
 as a bulwark against dementia. A study started in 1989 with 299 elderly 
volunteers in the Pittsburgh area tracked mental acuity and exercise habits....The results, published in the journal Neurology, were sweeping and conclusive: Those who walked the most cut in half their risk of developing memory problems. The optimal exercise for cognitive health benefits, the 
researchers concluded, was to walk six to nine miles each week. That’s a mile to a mile and a half a day, without walking on Sundays if you’re inclined to follow Weston’s example of resting on the Sabbath. (This study concluded that walking an additional mile didn’t help all that much.)

A study written up in the Archives of Internal Medicine in 2001 tracked nearly six thousand women ages 65 and older for six to eight years. The women were given a cognitive test at the study’s beginning and end, the results of which were then correlated with how many blocks they walked daily. Those who walked the least had a drop of 24 percent in cognition. Those who walked the most still showed a decline, but of a lesser degree: 17 percent. The results were clear: “Women with higher levels of baseline physical activity were less likely to develop cognitive decline.”

Peter Snyder of Brown University’s Alpert Medical School, who studies the effects of aging on the brain, recently told National Public Radio that “what we’re finding is that of all of these noninvasive ways of intervening, it is exercise that seems to have the most efficacy at this point—more so than nutritional supplements, vitamins and cognitive interventions ... The literature on exercise is just tremendous,” he said.

Indeed, a 20-year-long study in 2010 found that walking just five miles per week “protects the brain structure” over a 10-year period in people with Alzheimer’s disease and in those who exhibit signs of mild cognitive impairment. “The findings showed across the board that greater amounts of physical activity were associated with greater brain volume,” the researchers concluded.

While different studies arrive at moderately different conclusions via various routes, the recent research of dozens of scientists more often than not converges at a single intersection. And that consistently suggests that if you exercise, your brain will be fitter than if you don’t. This applies to the young, those in the prime of their days, and especially to the elderly.

The 20-year 2010 study mentioned above, results from which were released by Cyrus Raji of the University of Pittsburgh, followed 426 older adults, including healthy people along with those showing mild cognitive impairment or the actual onset of Alzheimer’s. Across test subjects, more walking was shown to result in greater brain volume. “Unfortunately, walking is not a cure,” Raji said. “But walking can improve your brain’s resistance to [Alzheimer’s] disease and reduce memory loss over time.”

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The possibilities are exciting. See my earlier posts on psychobiotics for more information. From Medical Xpress:

How gut bacteria ensures a healthy brain – and could play a role in treating depression

But medicine in the 21st century is rethinking its relationship with bacteria and concluding that, far from being uniformly bad for us, many of these organisms are actually essential for our health. Nowhere is this more apparent than in the human gut, where the microbiome  – the collection of bacteria living in the gastrointestinal tract - plays a complex and critical role in the health of its host.

The microbiome interacts with and influences organ systems throughout the body, including, as research is revealing, the brain. This discovery has led to a surge of interest in potential gut-based treatments for neuropsychiatric disorders and a new class of studies investigating how the gut and its microbiome affect both healthy and diseased brains.

The lives of the bacteria in our gut are intimately entwined with our immune, endocrine and nervous systems. The relationship goes both ways: the microbiome influences the function of these systems, which in turn alter the activity and composition of the bacterial community. We are starting to unravel this complexity and gain insight into how gut bacteria interface with the rest of the body and, in particular, how they affect the brain.

The microbiome-immune system link is established early on. Over the first year of life, bacteria populate the gut, which is largely sterile at birth, and the developing immune system learns which bacteria to consider normal residents of the body and which to attack as invaders. This early learning sets the stage for later immune responses to fluctuations in the microbiome's composition.

When a normally scarce strain becomes too abundant or a pathogenic species joins the community of gut bacteria, the resulting response by the immune system can have wide-reaching effects. Depression has been linked with elevated levels of such molecules in some individuals, suggesting that treatments that alter the composition of the microbiome could alleviate symptoms of this disorder.

Such an intervention could potentially be achieved using either prebiotics – substances that promote the growth of beneficial bacteria – or probiotics – live cultures of these bacteria. It is even possible that the microbiome could be manipulated by dietary changes.

In one experiment, researchers transplanted the human microbiome into germ-free mice (animals that have no gut bacteria) in order to study it in a controlled setting. They found that, simply by changing the carbohydrate and fat content of the mice's food, they could alter basic cellular functions and gene expression in the microbiome.

Depression is not the only psychiatric disorder in which the microbiome may play a role.Research in rodents, as well as a few preliminary studies in humans, indicate that the state of our resident microbes is tied to our anxiety levels.

This research also reveals the complexity of the relationship between the microbiome and psychological state. ...Researchers have shown that the presence or absence of microbes in young mice affects the sensitivity of the hypothalamic-pituitary-adrenal (HPA) axis – a key pathway in the body's stress response system. The activity of the microbiome during development thus sways how we respond to future stressors and how much anxiety they cause us.

How do the bacteria in our gut wield such influence over our brains and bodies? The mechanisms of microbiome-host interactions appear to be as numerous and varied as the interactions themselves.

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Another interesting factoid about the human gut microbiome - it has circadian rhythms. This also has implications for timing of medical treatments and medicines. From Science Daily:

Jet lag can cause obesity by disrupting the daily rhythms of gut microbes

Organisms ranging from bacteria to humans have circadian clocks to help them synchronize their biological activities to the time of day. A study now reveals that gut microbes in mice and humans have circadian rhythms that are controlled by the biological clock of the host in which they reside. Disruption of the circadian clock in the host alters the rhythms and composition of the microbial community, leading to obesity and metabolic problems.

Disruption of the circadian clock in humans is a hallmark of relatively recent lifestyle changes involving chronic shift work or frequent flights across time zones. These widespread behavioral patterns have been linked to a wide range of diseases, including obesity, diabetes, cancer, and cardiovascular disease. But, until now, it has not been clear how changes in circadian rhythms increase the risk for these diseases.

In the new study, Elinav and his team set out to determine whether gut microbes could be the missing link. When they analyzed microbes found in fecal samples collected from mice and humans at different times of day, they discovered rhythmic fluctuations in the abundance of microbes and their biological activities. The host's circadian clock and normal feeding habits were required for the generation of these rhythmic fluctuations in the gut microbes.

When mice were exposed to changing light-dark schedules and abnormal 24 hr feeding habits, the microbial community lost its rhythmic fluctuations and changed in composition. Moreover, a high-fat diet caused these jet-lagged mice to gain weight and develop metabolic problems associated with diabetes. Similarly, jet lag in two humans who had traveled from the United States to Israel changed the composition of gut microbes, favoring the growth of bacteria that have been linked to obesity and metabolic disease.

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Another reason to be concerned about air pollution. And another study showing a link with environmental chemicals (this time coarse and fine particulate matter, known as PM10, which arises in part from traffic-related air pollution) and autism. From Science Daily:

Researcher adds to evidence linking autism to air pollutants

A researcher at the University of Wisconsin-Milwaukee (UWM) has added to a growing body of evidence that links autism to air pollutants such as those generated by cars and trucks.

Amy Kalkbrenner's study, published this week online at the journal Epidemiology, showed that pollution's impact on autism rates in North Carolina is similar to results of pollution-autism studies in California -- despite weather and climate differences between the two states. In addition, the work of Kalkbrenner and her colleagues, building on previous studies, showed that women in the third trimester of pregnancy were more susceptible to the damaging effects of air pollution on their unborn child.

"It adds another piece supporting the hypothesis that environmental chemicals are part of the autism puzzle," says Kalkbrenner, an assistant professor in UWM's Joseph J. Zilber School of Public Health. Autism, a spectrum of disorders affecting interpersonal relations and work achievement, now affects some 1 in 68 children in the U.S.

Her research team focused on exposure to coarse and fine particulate matter, known as PM10, which arises in part from traffic-related air pollution...Researchers used a new, more exact tool to measure the levels of particulate matter in smaller slices of time, based on pollution at the family's address during pregnancy. With this method, they were able to compare exposures during specific weeks of pregnancy. The approximately one thousand children who later developed some form of autism spectrum disorders were then compared to all other children.

Reasons for increased susceptibility in the third trimester of pregnancy are not known at this time. However, Kalkbrenner says this finding is consistent with theories that show links between autism and altered brain network development, specifically synaptic connections that are developing during the final months of pregnancy.

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There have been a number of recent studies finding various harms from air pollution - both for children and adults.The following are all from Science Daily:

Living near major roads may increase risk of sudden cardiac death in women

Living near a major road was associated with an increased risk of sudden cardiac death in women. Environmental exposure may increase heart disease risk as much as smoking, poor diet or obesity.

In 523 cases of sudden cardiac death, living within 50 meters (164 feet) of a major road increased the risk of sudden cardiac death by 38 percent, compared to living at least 500 meters (.3 miles) away. Each 100 meters (328 feet) closer to roadways was associated with a 6 percent increased risk for sudden cardiac death.

Air pollution harmful to young brains, study finds

Pollution in many cities threatens the brain development in children. Findings from a recent study reveal that children living in megacities are at increased risk for brain inflammation and neurodegenerative changes, including Alzheimer's or Parkinson's disease.

The study found when air particulate matter and their components such as metals are inhaled or swallowed, they pass through damaged barriers, including respiratory, gastrointestinal and the blood-brain barriers and can result in long-lasting harmful effects..."We asked why a clinically healthy kid is making autoantibodies against their own brain components," Calderón-Garcidueñas said. "That is indicative of damage to barriers that keep antigens and neurotoxins away from the brain. Brain autoantibodies are one of the features in the brains of people who have neuroinflammatory diseases like multiple sclerosis."

High-pollution days linked to increased risk of cardiac arrest

Rates of out-of-hospital cardiac arrest are elevated after days with high levels of air pollutants, reports a Japanese study. For example, 48 to 72 hours after days with high levels of particulate air pollution, the risk of out-of-hospital cardiac arrest increased by 17 percent, the researchers report.

Strong link between higher levels of pollution, lung health of European citizens

New data has identified a clear link between higher levels of exposure to air pollution and deteriorating lung health in adult European citizens. This study confirms previous findings that children growing up in areas with higher levels of pollution will have lower levels of lung function and a higher risk of developing symptoms such as cough and bronchitis symptoms. The new study also identified that people suffering from obesity are particularly vulnerable to the negative effects of air pollution, possibly due to an increased risk of lung inflammation.

Air pollution linked to irregular heartbeat, lung blood clots

Air pollution is linked to an increased risk of developing an irregular heartbeat -- a risk factor for stroke -- and blood clots in the lung, finds a large study. The evidence suggests that high levels of certain air pollutants are associated with a higher risk of cardiovascular problems, but exactly how this association works has not been clarified.

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Two articles which together point out that there are alternative approaches to the treatment of depression.

From Medscape: Patient Expectations Largely Dictate Antidepressant Response

People's expectations about how effective their antidepressant medication is going to be almost entirely predicts their response to it, such that giving patients a placebo pill as active therapy during an 8-week period results in very similar reductions in symptoms, new research shows.

Investigators at the David Geffen School of Medicine at the University of California, Los Angeles, found that patients assigned to either active antidepressant therapy or placebo pills had better clinical outcomes than supportive care alone and that there was little difference between outcomes for the medication and placebo groups.

"Supportive interaction with the subject helped them get better, and antidepressant therapy helped them get better, but I think our key finding was that patients' belief in the effectiveness of medication was a unique factor that contributed to them getting well. So belief in the power or effectiveness of the medication may be a contributor to placebo responses in the treatment of depression."

From Science Daily:

Sport, physical activity help against depression

Depression is the most frequently diagnosed mental illness. In the western industrial nations, at least every tenth person suffers from depression once in the course of their life. Depression influences physical health more than diabetes or arthritis, clinicians say. Treatment of depression traditionally occurs with antidepressants and psychotherapy. But as research has shown, sport and physical activity partially encounters the same neurophysiological changes as antidepressants. That is why a large number of meta-analyses showed a positive effect of sport and physical activity on depression.

Sport and physical activity bring about various changes in the brain which are otherwise achieved only through drugs. Similar to sport and physical activity, drugs for treatment of depressions act on the brain's capacity to absorb serotonin. They strengthen the epinephrine activity and ensure the release of various factors for nerve growth. These factors promote cell growth in the brain and prevent the death of cells in the hippocampus which is otherwise caused by depression. Together with these changes, sport and physical activity also lead to a reduced activity of the stress hormone cortisol and therefore have an effect similar to psychotropic drugs.

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Interesting term "actively sedentary", which may describe many of us. From Medscape:

Walking Is the Superfood of Fitness, Experts Say

NEW YORK (Reuters) - Walking may never become as trendy as CrossFit, as sexy as mud runs or as ego-boosting as Ironman races but for fitness experts who stress daily movement over workouts and an active lifestyle over weekends of warrior games, walking is a super star.

For author and scientist Katy Bowman, walking is a biological imperative like eating. In her book, "Move Your DNA: Restore Your Health Through Natural Movement," she suggests there are movement nutrients, just like dietary nutrients, that the body needs. "Walking is a superfood. It's the defining movement of a human," said Bowman, a biomechanist based in Ventura, California. 

Researchers say emerging evidence suggests that combined physical activity and inactivity may be more important for chronic disease risk than physical activity alone. "Actively sedentary is a new category of people who are fit for one hour but sitting around the rest of the day," Bowman said. "You can't offset 10 hours of stillness with one hour of exercise."

She added that a small study of non-obese men published in the journal Medicine & Science in Sports and Exercise by scientists at Indiana University suggests that three five-minute walks done throughout three hours of prolonged sitting reverses the harmful effects of prolonged sitting on arteries in the legs.

Three miles (5 kilometers) per hour is a good beginning, gradually working to 4 miles per hour, she said about walking.

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According to a recent large Swedish study, a healthy lifestyle lowers the risk of ischemic stroke (caused by a blood clot) - up to 54% lower risk. But unfortunately it does not lower the risk for a hemorrhagic stroke.

A healthy lifestyle was considered to be: healthy diet, moderate alcohol consumption, not smoking, being physically active, and being a normal weight (not overweight or obese). The more healthy life-style factors, the lower the risk for an ischemic stroke. In this study, healthy foods were considered to be: fruits, vegetables, legumes (beans), nuts, low-fat dairy foods, whole grain foods, and fish. 

From Science Daily: Healthy lifestyle may cut stroke risk in half for women

Women with a healthy diet and lifestyle may be less likely to have a stroke by more than half, according to a study. The study looked at five factors that make up a healthy lifestyle: healthy diet; moderate alcohol consumption; never smoking; physically active; and healthy body mass index (BMI). Compared with women with none of the five healthy factors, women with all five factors had a 54-percent lower risk of stroke.

For the study, 31,696 Swedish women with an average age of about 60 completed a 350-item questionnaire about their diet and lifestyle. They were then followed for an average of 10 years. A healthy diet was defined as within the top 50 percent of a recommended food score measuring how often the participants ate healthy foods such as fruits, vegetables and low-fat dairy products. Moderate alcohol consumption was defined as three to nine drinks per week. Physically active was defined as walking or biking at least 40 minutes a day along with more vigorous exercise at least one hour per week. Healthy BMI was considered below 25.

Most of the women had two or three of the healthy factors. Only 589 women had all five healthy factors, and 1,535 had none. There were 1,554 strokes among study participants. The risk of stroke steadily decreased with each additional healthy lifestyle factor.

Women who had a healthier diet were 13 percent less likely to have a type of stroke called a cerebral infarction than those whose diet was not as healthy. Women with healthier diets had a rate of 28 strokes per 10,000 women per year compared to 43 strokes per 10,000 women per year among those with a less healthy diet.

Cerebral infarction is the most common cause of stroke, accounting for up to 80 to 85 percent of all strokes. Cerebral infarction is caused by a blockage in a blood vessel preventing blood and oxygen from getting to an area of the brain.

There was no relationship between the healthy factors and the risk of hemorrhagic stroke. Hemorrhagic stroke, which is caused by bleeding in and around the brain, accounts for about 15 to 20 percent of all strokes.

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Research finding benefits from various foods. From Science Daily:

Drinking decaf or regular coffee maybe good for the liver

Researchers report that decaffeinated coffee drinking may benefit liver health. Results show that higher coffee consumption, regardless of caffeine content, was linked to lower levels of abnormal liver enzymes. This suggests that chemical compounds in coffee other than caffeine may help protect the liver. Previous studies found that coffee consumption may help lower the risk of developing diabetes, cardiovascular disease, non-alcoholic fatty liver disease, cirrhosis, and liver cancer.

From Science Daily:

Did fruit contribute to Apple's success?

Steve Jobs swore by a fruit diet, as he believed it improved his ideas. And he wasn't wrong: food with high levels of tyrosine, like bananas, peaches and almonds, allow us to think harder and more creatively.

The researchers found that the test subjects who drank orange juice with added tyrosine were better at solving puzzles than those who were administered a placebo. Tyrosine is an amino acid that increases the production of dopamine in the brain, which positively influences our ability to think creatively. It can be found in various kinds of fruit, but also in soybeans, spinach, eggs and cottage cheese.

Done in mice, but interesting. And think of all the people who have promoted grapefruit diets over the years. From Science Daily:

Grapefruit juice stems weight gain in mice fed a high-fat diet, study finds

Mice fed a high-fat diet gained 18 percent less weight when they drank clarified, no-pulp grapefruit juice compared with a control group of mice that drank water, a new study demonstrated. Juice-drinking mice also showed improved levels of glucose, insulin and a type of fat called triacylglycerol compared with their water-drinking counterparts.

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Maybe bacteria are involved in Multiple sclerosis (MS). From Scientific American:

Could Multiple Sclerosis Begin in the Gut?

MS researchers are focusing on the content of the gut’s microbiome as a possible contributor to the body’s autoimmune attack on its nervous system.

Multiple sclerosis (MS) is an electrical disorder, or rather one of impaired myelin, a fatty, insulating substance that better allows electric current to bolt down our neurons and release the neurotransmitters that help run our bodies and brains. Researchers have speculated for some time that the myelin degradation seen in MS is due, at least in part, to autoimmune activity against the nervous system. Recent work presented at the MS Boston 2014 Meeting suggests that this aberrant immune response begins in the gut.

Eighty percent of the human immune system resides in the gastrointestinal tract. Alongside it are the trillions of symbiotic bacteria, fungi and other single-celled organisms that make up our guts’ microbiomes. Normally everyone wins: The microorganisms benefit from a home and a steady food supply; we enjoy the essential assistance they provide in various metabolic and digestive functions. Our microbiomes also help calibrate our immune systems, so our bodies recognize which co-inhabitants should be there and which should not. Yet mounting evidence suggests that when our resident biota are out of balance, they contribute to numerous diseases, including diabetes, rheumatoid arthritis, autism and, it appears, MS by inciting rogue immune activity that can spread throughout the body and brain.

One study presented at the conference, out of Brigham and Women’s Hospital (BWH), reported a single-celled organism called methanobrevibacteriaceae that activates the immune system is enriched in the gastrointestinal tracts of MS patients whereas bacteria that suppress immune activity are depleted. Other work, which resulted from a collaboration among 10 academic researcher centers across the U.S. and Canada, reported significantly altered gut flora in pediatric MS patients while a group of Japanese researchers found that yeast consumption reduced the chances of mice developing an MS-like disease by altering gut flora.

Sushrut Jangi, a staff physician at Beth Israel Deaconess Medical Center in Boston who co-authored the BWH study, thinks that regional dietary influences might even be at play. “The biomes of people living in different areas and who consume Western versus non-Western diets are demonstratively different,” he says. “People who emigrate from non-Western countries, including India, where MS rates are low, consequently develop a high risk of disease in the U.S. One idea to explain this is that the biome may shift from an Indian biome to an American biome,” although there is not yet data to support this theory.

The microbiome theory is gaining so much steam in academia that a coalition of four U.S. research centers called the MS Microbiome Consortium recently formed to investigate the role of gut microorganisms in the disease. The group presented data in Boston showing significantly different gastrointestinal bacterial populations in patients treated with the MS drug glatiramer acetate compared with untreated subjects. How exactly the drug suppresses MS activity is unknown but the findings suggest that perhaps it works in part by altering gut flora and, as a result, suppressing abnormal immune activity. “But important questions remain, such as how MS medications affect the microbiome, how an individual’s microbiome may affect treatment responses, whether particular bacterial species are associated with more severe disease and ultimately whether we can manipulate the microbiome to benefit our patients.”

Katz Sand says that dietary and probiotic approaches to treating MS are worth pursuing, as is a less palatable approach: fecal transplantation.Yet answers in science and medicine are rarely simple, she added, pointing out that in all likelihood MS arises from a complicated confluence of genetic and environmental influences that might ultimately trigger autoimmune activity. Beyond just our gut flora well over 100 genetic variants —many related to immune function—are now known to contribute to the disease as are external factors including vitamin D deficiency  (MS is more common at higher latitudes), smoking and increased salt intake.