Living Near Major Roads Linked to Increased Risk of Dementia, Parkinson’s, Alzheimer’s and MS

Living near major roads or highways is linked to higher incidence of dementia, Parkinson’s disease, Alzheimer’s disease and multiple sclerosis (MS), suggests new research published this week in the journal Environmental Health.

Researchers from the University of British Columbia analyzed data for 678,000 adults in Metro Vancouver. They found that living less than 50 metres from a major road or less than 150 metres from a highway is associated with a higher risk of developing dementia, Parkinson’s, Alzheimer’s and MS—likely due to increased exposure to air pollution.

The researchers also found that living near green spaces, like parks, has protective effects against developing these neurological disorders.

“For the first time, we have confirmed a link between air pollution and traffic proximity with a higher risk of dementia, Parkinson’s, Alzheimer’s and MS at the population level,” says Weiran Yuchi, the study’s lead author and a PhD candidate in the UBC school of population and public health. “The good news is that green spaces appear to have some protective effects in reducing the risk of developing one or more of these disorders. More research is needed, but our findings do suggest that urban planning efforts to increase accessibility to green spaces and to reduce motor vehicle traffic would be beneficial for neurological health.”

Neurological disorders—a term that describes a range of disorders, including Alzheimer’s disease and other dementias, Parkinson’s disease, multiple sclerosis and motor neuron diseases—are increasingly recognized as one of the leading causes of death and disability worldwide. Little is known about the risk factors associated with neurological disorders, the majority of which are incurable and typically worsen over time.

For the study, researchers analyzed data for 678,000 adults between the ages of 45 and 84 who lived in Metro Vancouver from 1994 to 1998 and during a follow-up period from 1999 to 2003. They estimated individual exposures to road proximity, air pollution, noise and greenness at each person’s residence using postal code data. During the follow-up period, the researchers identified 13,170 cases of non-Alzheimer’s dementia, 4,201 cases of Parkinson’s disease, 1,277 cases of Alzheimer’s disease and 658 cases of MS.

For non-Alzheimer’s dementia and Parkinson’s disease specifically, living near major roads or a highway was associated with 14 per cent and seven per cent increased risk of both conditions, respectively. Due to relatively low numbers of Alzheimer’s and MS cases in Metro Vancouver compared to non-Alzheimer’s dementia and Parkinson’s disease, the researchers did not identify associations between air pollution and increased risk of these two disorders. However, they are now analyzing Canada-wide data and are hopeful the larger dataset will provide more information on the effects of air pollution on Alzheimer’s disease and MS.

When the researchers accounted for green space, they found the effect of air pollution on the neurological disorders was mitigated. The researchers suggest that this protective effect could be due to several factors.

“For people who are exposed to a higher level of green space, they are more likely to be physically active and may also have more social interactions,” said Michael Brauer, the study’s senior author and professor in the UBC school of population and public health. “There may even be benefits from just the visual aspects of vegetation.”

Brauer added that the findings underscore the importance for city planners to ensure they incorporate greenery and parks when planning and developing residential neighbourhoods.

Source: University of British Columbia


Today’s Comic

Study Uses Eye Movement Test to Confirm Brain-ageing Effects

A new study, published in PeerJ, shows how University of Liverpool researchers have used a newly developed eye movement test to improve the understanding of how parts of the brain work.

Healthy, older adults are widely reported to experience cognitive decline, including impairments in inhibitory control (the ability to stop ourselves thinking or doing things). However, because ageing effects on inhibitory control are highly variable between individuals, vary depending on tests used, and are sometimes not distinguished from general age-related slowing, this general view is a matter of debate.

Inhibitory control is also important in conditions like schizophrenia, ADHD and forms of Parkinson’s disease; patients can become jumpy, distractible or have problems with unwanted thoughts. Researchers from the University’s Department of Eye and Vision Science, led by Dr Paul Knox, developed a new test, using measurements of eye movements, to provide an improved method of investigating inhibitory control, and have applied to study the effects of ageing on this ability.

Study

In the study two cohorts of healthy people were recruited from two different age groups, 19 to 27 years old and 50 to 72 years old. Participants viewed a dot in the centre of a computer a screen and then had to to look at a second dot that appeared to the left or right not when it appeared, but when it disappeared. As people instinctively look at things when they appear, this requires the inhibition of a normal automatic eye movement. Eye movements were measured precisely using an infrared eye tracker, revealing how often they looked too early.

Results

The results showed that older participants were much more likely to look at the dot when it appeared (not when it disappeared) and were slower compared to younger participants.

Dr Paul Knox, said: “We are designed to react to things appearing in our visual world. It is something we do automatically. However, we also have the ability to stop ourselves responding and this prevents us becoming slaves to our sensory environment.

“This new test allows us to measure inhibitory behaviour precisely. It is clear that older participants found it more difficult to inhibit their actions, even once we had accounted for the general slowing that occurs with ageing.

“This confirms that a decline in inhibitory control is a part of normal ageing. We are doing experiments to refine the test, and then we hope to use it to study inhibitory control in a range of important diseases.”

Source: University of Liverpool


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Yoga May Bring a Brain Boost

Alan Mozes wrote . . . . . . . . .

Looking for a way to improve your memory, gain control over your emotions, and boost your ability to multitask?

A new brain scan study may be just the incentive you need to put yoga at the top of your New Years’ to-do list.

The review of 11 published studies found a link between yoga’s movements, meditation and breathing practices and an increase in the size of key brain areas. Those areas are involved in thinking clearly, decision-making, memory and regulating emotions.

“The science is pointing to yoga being beneficial for healthy brain function, but we need more rigorous and well-controlled intervention studies to confirm these initial findings,” study co-author Jessica Damoiseaux said in a news release. She’s an assistant professor of gerontology and psychology at Wayne State University in Detroit.

The review, published in the journal Brain Plasticity, found the brain benefits of yoga are similar to those from aerobic exercise.

Why isn’t yet clear. More study is needed, the authors said.

“Yoga is not aerobic in nature, so there must be other mechanisms leading to these brain changes,” lead author Dr. Neha Gothe said in the news release. “So far, we don’t have the evidence to identify what those mechanisms are.”

Gothe is director of the Exercise Psychology Lab at the University of Illinois at Urbana-Champaign.

Five of the 11 studies used brain imaging before and after newbies followed a regimen of at least one yoga session per week for 10 to 24 weeks. All used a regimen called hatha yoga.

Other studies compared brain scans of yoga practitioners and people who had never tried yoga.

Collectively, the studies pointed to a link between yoga and increased size in the brain’s hippocampus. Involved in memory and learning, the hippocampus shrinks with age and is the first part of the brain affected by Alzheimer’s and dementia.

Yoga also appeared to expand the amygdala, a brain area involved in emotions; the prefrontal cortex, which is involved in planning and making choices; and the cingulate cortex, which plays an important part in regulating emotions, learning and memory.

Yoga practitioners were also found to fare better on mental performance tests, the study team observed.

Dr. Thomas Vidic, a neurologist at Elkhart General Hospital in Elkhart, Ind., who was not involved in the study, said he was not surprised by the findings.

“There have been numerous studies that show that mental and physical activity is useful [and] probably necessary — to maintaining brain function,” said Vidic, who is also a member of the American Academy of Neurology.

For now, however, “we cannot separate out what it is about yoga that is causing these effects, [but] it would be an easy guess that yoga combines both mind and body, and is thus able to activate numerous pathways,” Vidic added.

So should those who’ve never been drawn to yoga before but might like the potential brain benefits give it a go?

Definitely, Vidic said. But, he added, if you haven’t been active, start slow and join an appropriate group.

“Yoga is not for sissies,” he said. “It is a serious discipline and within this concept is the significant physical and cognitive stimulation.”

And, remember, you won’t become competent overnight. But, Vidic said, you can become an enthusiast on day one.

“I believe that everyone needs to find an activity that is physically and mentally stimulating,” he said. “And for many people yoga is a great activity.”

Source: HealthDay

Study: Exercise Good for Your Brain’s Gray Matter

Jay Furst wrote . . . . . . . . .

Cardiorespiratory exercise — walking briskly, running, biking and just about any other exercise that gets your heart pumping — is good for your body, but can it also slow cognitive changes in your brain?

A study in Mayo Clinic Proceedings from the German Center for Neurodegenerative Diseases provides new evidence of an association between cardiorespiratory fitness and brain health, particularly in gray matter and total brain volume — regions of the brain involved with cognitive decline and aging.

Brain tissue is made up of gray matter, or cell bodies, and filaments, called white matter, that extend from the cells. The volume of gray matter appears to correlate with various skills and cognitive abilities. The researchers found that increases in peak oxygen uptake were strongly associated with increased gray matter volume.

The study involved 2,013 adults from two independent cohorts in northeastern Germany. Participants were examined in phases from 1997 through 2012. Cardiorespiratory fitness was measured using peak oxygen uptake and other standards while participants used an exercise bike. MRI brain data also were analyzed.

The results suggest cardiorespiratory exercise may contribute to improved brain health and decelerate a decline in gray matter. An editorial by three Mayo Clinic experts that accompanies the Mayo Clinic Proceedings study says the results are “encouraging, intriguing and contribute to the growing literature relating to exercise and brain health.”

Ronald Petersen, M.D., Ph.D., a Mayo Clinic neurologist and first author of the editorial, says the most striking feature of the study is the measured effect of exercise on brain structures involved in cognition, rather than motor function. “This provides indirect evidence that aerobic exercise can have a positive impact on cognitive function in addition to physical conditioning,” he says. “Another important feature of the study is that these results may apply to older adults, as well. There is good evidence for the value of exercise in midlife, but it is encouraging that there can be positive effects on the brain in later life as well.”

Dr. Petersen is the Cora Kanow Professor of Alzheimer’s Disease Research and the Chester and Debbie Cadieux Director of the Mayo Clinic Alzheimer’s Disease Research Center.

The study’s finding of higher gray matter volume associated with cardiorespiratory exercise are in brain regions clinically relevant for cognitive changes in aging, including some involved in Alzheimer’s disease. The editorial calls those associations interesting but cautions against concluding that cardiorespiratory fitness correlations would affect Alzheimer’s disease.

“This is another piece of the puzzle showing physical activity and physical fitness is protective against aging-related cognitive decline,” says Michael Joyner, M.D., a Mayo Clinic anesthesiologist and physiologist, and editorial co-author. “There’s already good epidemiological evidence for this, as well as emerging data showing that physical activity and fitness are associated with improved brain blood vessel function. This paper is important because of the volumetric data showing an effect on brain structure.”

Dr. Joyner is the Frank R. and Shari Caywood Professor at Mayo Clinic.

Long-term studies on the relationship between exercise and brain health are needed, which will be costly and logistically challenging to produce. “Nevertheless, these data are encouraging,” says Clifford Jack Jr., M.D., a Mayo Clinic neuroradiologist and co-author of the editorial. “The findings regarding cardiorespiratory fitness and certain brain structures are unique.”

Dr. Jack is the Alexander Family Professor of Alzheimer’s Disease Research.

According to Mayo Clinic experts, moderate and regular exercise — about 150 minutes per week — is recommended. Good cardiorespiratory fitness also involves:

  • Not smoking
  • Following healthy eating habits
  • Losing weight or maintaining a healthy weight level
  • Managing blood pressure and avoiding hypertension
  • Controlling cholesterol levels
  • Reducing blood sugar, which over time can damage your heart and other organs

Source: Mayo Clinic

Why Your Brain Needs Exercise

See large image . . . . .

David Raichlen and Gene Alexander wrote . . . . . . . . .

In the 1990s researchers announced a series of discoveries that would upend a bedrock tenet of neuroscience. For decades the mature brain was understood to be incapable of growing new neurons. Once an individual reached adulthood, the thinking went, the brain began losing neurons rather than gaining them. But evidence was building that the adult brain could, in fact, generate new neurons. In one particularly striking experiment with mice, scientists found that simply running on a wheel led to the birth of new neurons in the hippocampus, a brain structure that is associated with memory. Since then, other studies have established that exercise also has positive effects on the brains of humans, especially as we age, and that it may even help reduce the risk of Alzheimer’s disease and other neurodegenerative conditions. But the research raised a key question: Why does exercise affect the brain at all?

Physical activity improves the function of many organ systems in the body, but the effects are usually linked to better athletic performance. For example, when you walk or run, your muscles demand more oxygen, and over time your cardiovascular system responds by increasing the size of the heart and building new blood vessels. The cardiovascular changes are primarily a response to the physical challenges of exercise, which can enhance endurance. But what challenge elicits a response from the brain?

Answering this question requires that we rethink our views of exercise. People often consider walking and running to be activities that the body is able to perform on autopilot. But research carried out over the past decade by us and others would indicate that this folk wisdom is wrong. Instead exercise seems to be as much a cognitive activity as a physical one. In fact, this link between physical activity and brain health may trace back millions of years to the origin of hallmark traits of humankind. If we can better understand why and how exercise engages the brain, perhaps we can leverage the relevant physiological pathways to design novel exercise routines that will boost people’s cognition as they age—work that we have begun to undertake.

Flexing the Brain

To explore why exercise benefits the brain, we need to first consider which aspects of brain structure and cognition seem most responsive to it. When researchers at the Salk Institute for Biological Studies in La Jolla, Calif., led by Fred Gage and Henriette Van Praag, showed in the 1990s that running increased the birth of new hippocampal neurons in mice, they noted that this process appeared to be tied to the production of a protein called brain-derived neurotrophic factor (BDNF). BDNF is produced throughout the body and in the brain, and it promotes both the growth and the survival of nascent neurons. The Salk group and others went on to demonstrate that exercise-induced neurogenesis is associated with improved performance on memory-related tasks in rodents. The results of these studies were striking because atrophy of the hippocampus is widely linked to memory difficulties during healthy human aging and occurs to a greater extent in individuals with neurodegenerative diseases such as Alzheimer’s. The findings in rodents provided an initial glimpse of how exercise could counter this decline.

Following up on this work in animals, researchers carried out a series of investigations that determined that in humans, just like in rodents, aerobic exercise leads to the production of BDNF and augments the structure—that is, the size and connectivity—of key areas of the brain, including the hippocampus. In a randomized trial conducted at the University of Illinois at Urbana-Champaign by Kirk Erickson and Arthur Kramer, 12 months of aerobic exercise led to an increase in BDNF levels, an increase in the size of the hippocampus and improvements in memory in older adults.

Other investigators have found associations between exercise and the hippocampus in a variety of observational studies. In our own study of more than 7,000 middle-aged to older adults in the U.K., published in 2019 in Brain Imaging and Behavior, we demonstrated that people who spent more time engaged in moderate to vigorous physical activity had larger hippocampal volumes. Although it is not yet possible to say whether these effects in humans are related to neurogenesis or other forms of brain plasticity, such as increasing connections among existing neurons, together the results clearly indicate that exercise can benefit the brain’s hippocampus and its cognitive functions.

Researchers have also documented clear links between aerobic exercise and benefits to other parts of the brain, including expansion of the prefrontal cortex, which sits just behind the forehead. Such augmentation of this region has been tied to sharper executive cognitive functions, which involve aspects of planning, decision-making and multitasking—abilities that, like memory, tend to decline with healthy aging and are further degraded in the presence of Alzheimer’s. Scientists suspect that increased connections between existing neurons, rather than the birth of new neurons, are responsible for the beneficial effects of exercise on the prefrontal cortex and other brain regions outside the hippocampus.

Upright and Active

With mounting evidence that aerobic exercise can boost brain health, especially in older adults, the next step was to figure out exactly what cognitive challenges physical activity poses that trigger this adaptive response. We began to think that examining the evolutionary relation between the brain and the body might be a good place to start. Hominins (the group that includes modern humans and our close extinct relatives) split from the lineage leading to our closest living relatives, chimpanzees and bonobos, between six million and seven million years ago. In that time, hominins evolved a number of anatomical and behavioral adaptations that distinguish us from other primates. We think two of these evolutionary changes in particular bound exercise to brain function in ways that people can make use of today.

First, our ancestors shifted from walking on all fours to walking upright on just their hind legs. This bipedal posture means that there are times when our bodies are precariously balanced over one foot rather than two or more limbs like in other apes. To accomplish this task, our brains must coordinate a great deal of information and, in the process, make adjustments to muscle activity throughout the body to maintain our balance. While coordinating these actions, we must also watch out for any environmental obstacles. In other words, simply because we are bipedal, our brains may be more cognitively challenged than those of our quadrupedal ancestors.

Second, the hominin way of life changed to incorporate higher levels of aerobic activity. Fossil evidence indicates that in the early stages of human evolution, our ancestors were probably relatively sedentary bipedal apes who ate mainly plants. By some two million years ago, however, as habitats dried out under a cooling climate, at least one group of ancestral humans began to forage in a new way, hunting animals and gathering plant foods. Hunting and gathering dominated human subsistence strategies for nearly two million years until the advent of farming and herding around 10,000 years ago. With Herman Pontzer of Duke University and Brian Wood of the University of California, Los Angeles, we have shown that because of the long distances traversed in search of food, hunting and gathering involves much more aerobic activity than seen in other apes.

Increased demands on the brain accompanied this shift toward a more physically active routine. When out foraging afar, hunter-gatherers must survey their surroundings to make sure they know where they are. This kind of spatial navigation relies on the hippocampus, the same brain region that benefits from exercise and that tends to atrophy as we get older. In addition, they have to scan the landscape for signs of food, using sensory information from their visual and auditory systems. They must remember where they have been before and when certain kinds of food were available. The brain uses this information from both short- and long-term memory, allowing people to make decisions and plan their routes—cognitive tasks that are supported by the hippocampus and the prefrontal cortex, among other regions. Hunter-gatherers also often forage in groups, in which case they may have conversations while their brains are maintaining their balance and keeping them spatially located in their environment. All of this multitasking is controlled, in part, by the prefrontal cortex, which also tends to diminish with age.

Although any foraging animal must navigate and figure out where to find food, hunter-gatherers have to perform these functions during fast-paced treks that can extend over more than 20 kilometers. At high speeds, multitasking becomes even more difficult and requires faster information processing. From an evolutionary perspective, it would make sense to have a brain ready to respond to an array of challenges during and after foraging to maximize the chances of success in finding food. But the physiological resources required to build and maintain such a brain—including those that support the birth and survival of new neurons—cost the body energy, meaning that if we do not regularly make use of this system, we are likely to lose these benefits.

This evolutionary neuroscience perspective on exercise and the brain, which we detailed in an article published in 2017 in Trends in Neurosciences, has profound implications for humans today. In our modern society, we do not need to engage in aerobic physical activity to find food for survival. The brain atrophy and attendant cognitive declines that commonly occur during aging may be partly related to our sedentary habits.

But simply exercising more may not realize the full potential of physical activity for keeping brain decline at bay. Indeed, our model suggests that even people who already get a lot of aerobic activity may want to rethink their routines. It is possible that we might not always exercise in ways that take full advantage of our evolved mechanisms for sustaining brain performance.

Think about the ways in which many of us get our aerobic exercise. Often we go to gyms and use a stationary exercise machine; the most cognitively demanding task in such a workout might be deciding what channel to watch on the built-in television. What is more, these machines remove some of the demands of maintaining balance and adjusting speed, among many other intrinsic cognitive challenges of movement through a changing environment.

What if this form of exercise is shortchanging us? Our ancestors evolved in an unpredictable world. What if we could modify our exercise routines to include cognitive challenges like those faced by our hunter-gatherer forebears? If we can augment the effects of exercise by including a cognitively demanding activity, then perhaps we can increase the efficacy of exercise regimens aimed at boosting cognition during aging and potentially even alter the course of neurodegenerative diseases such as Alzheimer’s.

Move and Think

In fact, a growing body of research suggests that exercise that is cognitively stimulating may indeed benefit the brain more than exercise that does not make such cognitive demands. For example, Gerd Kempermann and his colleagues at the Center for Regenerative Therapies Dresden in Germany explored this possibility by comparing the growth and survival of new neurons in the mouse hippocampus after exercise alone or after exercise combined with access to a cognitively enriched environment. They found an additive effect: exercise alone was good for the hippocampus, but combining physical activity with cognitive demands in a stimulating environment was even better, leading to even more new neurons. Using the brain during and after exercise seemed to trigger enhanced neuron survival.

We and others have recently begun to extend these studies from animals to humans—with encouraging results. For example, researchers have been exploring combining exercise and cognitive challenges in individuals experiencing notable cognitive decline. Cay Anderson-Hanley of Union College in Schenectady, N.Y., has tested simultaneous exercise and cognitive interventions in people with mild cognitive impairment, a condition associated with increased risk for Alzheimer’s. More work certainly needs to be done in populations such as this one before we can draw any firm conclusions, but the results so far suggest that people who are already experiencing some cognitive decline may benefit from exercising while playing a mentally demanding video game. In studies of healthy adults, Anderson-Hanley and her colleagues have also shown that simultaneously exercising and playing a cognitive challenging video game may elicit a greater increase in circulating BDNF than exercise alone. These findings further bolster the idea that BDNF is instrumental in bringing about exercise-induced brain benefits.

In our own work, we have developed a game designed to specifically challenge aspects of cognition that tend to decline with age and that are probably needed during foraging. In the game, players spatially navigate and complete attention and memory tasks while cycling at a moderate aerobic intensity level. To evaluate the potential of this approach to boost cognitive performance in healthy older adults, we are comparing a group exercising while playing the game with a group exercising without the game, a group playing the game without exercising, and a control group that only watches nature videos. The results to date are promising.

Many other research groups are testing combinations of exercise and cognitive tasks. In the near future, we will probably have a better idea of how best to deploy them to support and enhance cognition in both healthy individuals and those experiencing disease-related cognitive decline.

In addition to specially designed interventions similar to the ones described here, it is possible that participation in sports that require combinations of cognitive and aerobic tasks may be a way to activate these brain benefits. For example, we recently showed that collegiate cross-country runners who train extensively on outdoor trails have increased connectivity among brain regions associated with executive cognitive functions compared with healthy but more sedentary young adults. Future work will help us understand whether these benefits are also greater than those seen in runners who train in less complex settings—on a treadmill, for instance.

Much remains to be discovered. Although it is still too early to make specific prescriptions for combining exercise and cognitive tasks, we can say with certainty that exercise is a key player in preserving brain function as we age. The U.S. Department of Health and Human Services guidelines suggest that people should engage in aerobic exercise for at least 150 minutes a week at a moderate intensity or at least 75 minutes a week at a vigorous intensity (or an equivalent combination of the two). Meeting or exceeding these exercise recommendations is good for the body and may improve brain health.

Clinical trials will tell us much more about the efficacy of cognitively engaged exercise—what kinds of mental and physical activities are most impactful, for example, and the optimal intensity and duration of exercise for augmenting cognition. But in light of the evidence we have so far, we believe that with continued careful research we can target physiological pathways linking the brain and the body and exploit our brain’s evolved adaptive capacity for exercise-induced plasticity during aging. In the end, working out both the body and the brain during exercise may help keep the mind sharp for life.

Source: Scientific American