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Category: brain

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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 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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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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Different than my usual post, but oh so interesting. From Science Daily:

Near-death experiences? Results of the world's largest medical study of the human mind and consciousness at time of death

The results of a four-year international study of 2060 cardiac arrest cases across 15 hospitals concludes the following. The themes relating to the experience of death appear far broader than what has been understood so far, or what has been described as so called near-death experiences. In some cases of cardiac arrest, memories of visual awareness compatible with so called out-of-body experiences may correspond with actual events. A higher proportion of people may have vivid death experiences, but do not recall them due to the effects of brain injury or sedative drugs on memory circuits. Widely used yet scientifically imprecise terms such as near-death and out-of-body experiences may not be sufficient to describe the actual experience of death. The recalled experience surrounding death merits a genuine investigation without prejudice.

In 2008, a large-scale study involving 2060 patients from 15 hospitals in the United Kingdom, United States and Austria was launched. The AWARE (AWAreness during REsuscitation) study, sponsored by the University of Southampton in the UK, examined the broad range of mental experiences in relation to death. Researchers also tested the validity of conscious experiences using objective markers for the first time in a large study to determine whether claims of awareness compatible with out-of-body experiences correspond with real or hallucinatory events.

Dr Sam Parnia, Assistant Professor of Critical Care Medicine and Director of Resuscitation Research at The State University of New York at Stony Brook, USA, and the study's lead author, explained: "Contrary to perception, death is not a specific moment but a potentially reversible process that occurs after any severe illness or accident causes the heart, lungs and brain to cease functioning. If attempts are made to reverse this process, it is referred to as 'cardiac arrest'; however, if these attempts do not succeed it is called 'death'. In this study we wanted to go beyond the emotionally charged yet poorly defined term of NDEs to explore objectively what happens when we die."

Thirty-nine per cent of patients who survived cardiac arrest and were able to undergo structured interviews described a perception of awareness, but interestingly did not have any explicit recall of events. "This suggests more people may have mental activity initially but then lose their memories after recovery, either due to the effects of brain injury or sedative drugs on memory recall," explained Dr Parnia, who was an Honorary Research Fellow at the University of Southampton when he started the AWARE study.

Among those who reported a perception of awareness and completed further interviews, 46 per cent experienced a broad range of mental recollections in relation to death that were not compatible with the commonly used term of NDE's. These included fearful and persecutory experiences. Only 9 per cent had experiences compatible with NDEs and 2 per cent exhibited full awareness compatible with OBE's with explicit recall of 'seeing' and 'hearing' events.

One case was validated and timed using auditory stimuli during cardiac arrest. Dr Parnia concluded: "This is significant, since it has often been assumed that experiences in relation to death are likely hallucinations or illusions, occurring either before the heart stops or after the heart has been successfully restarted, but not an experience corresponding with 'real' events when the heart isn't beating. In this case, consciousness and awareness appeared to occur during a three-minute period when there was no heartbeat. This is paradoxical, since the brain typically ceases functioning within 20-30 seconds of the heart stopping and doesn't resume again until the heart has been restarted. Furthermore, the detailed recollections of visual awareness in this case were consistent with verified events.

Thus, while it was not possible to absolutely prove the reality or meaning of patients' experiences and claims of awareness, (due to the very low incidence (2 per cent) of explicit recall of visual awareness or so called OBE's), it was impossible to disclaim them either and more work is needed in this area.

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The link between pesticide exposure (pesticides used in the home or in the garden or lawn) and childhood brain tumors has been known for years. From Science Daily:

Factors associated with childhood brain tumors identified

Older parents, birth defects, maternal nutrition and childhood exposure to CT scans and pesticides are increasingly being associated with brain tumors in children, according to new research. Brain and central nervous system tumors are the second leading cause of cancer death in children.

A team of researchers, led by Kimberly Johnson, PhD, assistant professor of social work at the Brown School, a member of the Institute for Public Health and a research member of Siteman Cancer Center, examined studies published since 2004 that analyzed the incidence of childhood brain tumors and survival in different parts of the world.

In this research, binge drinking was defined as drinking four or more units of alcohol in a day on at least one occasion during the pregnancy.From Science Daily:

Binge drinking in pregnancy can affect child's mental health, school results

Binge drinking during pregnancy can increase the risk of mental health problems (particularly hyperactivity and inattention) in children aged 11 and can have a negative effect on their school examination results, according to new research on more than 4,000 participants.  This builds on earlier research on the same children that found a link between binge drinking in pregnancy and their mental health when aged four and seven, suggesting that problems can persist as a child gets older. Other effects, such as on academic performance, may only become apparent later in a child's life.

Women who are pregnant or who are planning to become pregnant should be aware of the possible risks associated with episodes of heavier drinking during pregnancy, even if this only occurs on an occasional basis.'The consumption of four or more drinks in a day may increase the risk for hyperactivity and inattention problems and lower academic attainment even if daily average levels of alcohol consumption during pregnancy are low.

From Science Daily: Healthy lifestyle could prevent nearly half of all diabetic pregnancies

Nearly half of all cases of diabetes during pregnancy, known as gestational diabetes, could be prevented if young women eat well, exercise regularly and stop smoking before and during pregnancy, finds a study.

Several modifiable risk factors before pregnancy have been identified over the past decade. These include maintaining a healthy weight, consuming a healthy diet, regular physical activity, and not smoking.So a team of researchers based in the United States set out to examine the effect of these "low risk" lifestyle factors on the risk of gestational diabetes -- and measure the portion of the condition that may be preventable through adhering to them.

The strongest individual risk factor for gestational diabetes was pre-existing overweight or obesity -- having a body mass index (BMI) above 25 before pregnancy. Women with a BMI above 33 were over four times more likely to develop gestational diabetes than women who had a normal BMI before pregnancy. ..Compared with women who did not meet any of the low risk lifestyle factors, those meeting all four criteria had an 83% lower risk of developing gestational diabetes.

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A small, but interesting study of 46 young adults (about 20 to 21 years old).

From Medical Xpress: Lift weights, improve your memory

Here's another reason why it's a good idea to hit the gym: it can improve memory. A new Georgia Institute of Technology study shows that an intense workout of as little as 20 minutes can enhance episodic memory, also known as long-term memory for previous events, by about 10 percent in healthy young adults.

While many existing studies have demonstrated that months of aerobic exercises such as running can improve memory, the current study had participants lift weights just once two days before testing them. The Georgia Tech researchers also had participants study events just before the exercise rather than after workout. They did this because of extensive animal research suggesting that the period after learning (or consolidation) is when the arousal or stress caused by exercise is most likely to benefit memory.

"Our study indicates that people don't have to dedicate large amounts of time to give their brain a boost," said Lisa Weinberg, the Georgia Tech graduate student who led the project.

But why does it work? Existing, non-Georgia Tech human research has linked memory enhancements to acute stress responses, usually from psychological stressors such as public speaking. Other studies have also tied specific hormonal and norepinephrine releases in rodent brains to better memory. Interestingly, the current study found that exercise participants had increased saliva measures of alpha amylase, a marker of central norepinephrine.

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Two related stories that look at children, exercise, and academic performance. Boys, in general, have higher activity levels than girls, and they need exercise and recess to be able to get through the rest of the school day. Sitting quietly in class and doing classwork is hard when one has lots of excess energy. In fact, sitting still for hours on end is NOT healthy in any way for anyone! Fidget, fidget, fidget... From Science Daily:

High levels of physical activity linked to better academic performance in boys

Higher levels of physical activity are related to better academic achievement during the first three school years, particularly in boys, research shows. For instance, boys with higher levels of physical activity, and especially walking and bicycling to and from school, had better reading skills than less active boys....The findings of the present study highlight the potential of physical activity during recess and participation in organized sports in the improvement of academic achievement in children. 

 Instead of medicine, why aren't doctors prescibing exercise? From The Atlantic:

Exercise Is ADHD Medication

Physical movement improves mental focus, memory, and cognitive flexibility; new research shows just how critical it is to academic performance.

...More insipid but also more clearly critical to addressing what's being called the ADHD epidemic is plain old physical activity.

This morning the medical journal Pediatrics published research that found kids who took part in a regular physical activity program showed important enhancement of cognitive performance and brain function. The findings, according to University of Illinois professor Charles Hillman and colleagues, "demonstrate a causal effect of a physical program on executive control, and provide support for physical activity for improving childhood cognition and brain health." If it seems odd that this is something that still needs support, that's because it is odd, yes. Physical activity is clearly a high, high-yield investment for all kids, but especially those attentive or hyperactive. This brand of research is still published and written about as though it were a novel finding, in part because exercise programs for kids remain underfunded and underprioritized in many school curricula, even though exercise is clearly integral to maximizing the utility of time spent in class.

Earlier this month, another study found that a 12-week exercise program improved math and reading test scores in all kids, but especially in those with signs of ADHD.

Last year a very similar study in the Journal of Attention Disorders found that just 26 minutes of daily physical activity for eight weeks significantly allayed ADHD symptoms in grade-school kids. The modest conclusion of the study was that "physical activity shows promise for addressing ADHD symptoms in young children." 

"If physical activity is established as an effective intervention for ADHD," they continued, "it will also be important to address possible complementary effects of physical activity and existing treatment strategies ..." Which is a kind of phenomenal degree of reservation compared to the haste with which millions of kids have been introduced to amphetamines and other stimulants to address said ADHD. The number of prescriptions increased from 34.8 to 48.4 million between 2007 and 2011 alone. The pharmaceutical market around the disorder has grown to several billion dollars in recent years while school exercise initiatives have enjoyed no such spoils of entrepreneurialism. 

Over all, the pandemic of physical inactivity, as Hillman and colleagues put it in their Pediatrics journal article today, is "a serious threat to global health" responsible for around 10 percent of premature deaths from noncommincable diseases. 

John Ratey, an associate professor of psychiatry at Harvard, suggests that people think of exercise as medication for ADHD. Even very light physical activity improves mood and cognitive performance by triggering the brain to release dopamine and serotonin, similar to the way that stimulant medications like Adderall do.