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Category: brain

Published on Leave a comment on Walking Increases Blood Flow To the Brain

An interesting study looked at what the act of walking does to our brain, and found that it can modify and increase the amount of blood that’s sent to the brain (which is viewed as beneficial for brain function). The study, performed by researchers at New Mexico Highlands University in the United States, found that the foot’s impact on the ground while walking sends pressure waves through the arteries, which can increase the blood supply to the brain. This is referred to as cerebral blood flow or CBF.

These results may help explain other studies that find those that walk frequently (about 6 to 9 miles per week) have "less cognitive impairment" or cognitive decline, fewer memory problems, and greater brain volume with aging.  Another good reason to get out and walk - good for the heart, the body, and the brain. From Science Daily:

How walking benefits the brain

You probably know that walking does your body good, but it's not just your heart and muscles that benefit. Researchers at New Mexico Highlands University (NMHU) found that the foot's impact during walking sends pressure waves through the arteries that significantly modify and can increase the supply of blood to the brain. The research will be presented today at the APS annual meeting at Experimental Biology 2017 in Chicago.

Until recently, the blood supply to the brain (cerebral blood flow or CBF) was thought to be involuntarily regulated by the body and relatively unaffected by changes in the blood pressure caused by exercise or exertion. The NMHU research team and others previously found that the foot's impact during running (4-5 G-forces) caused significant impact-related retrograde (backward-flowing) waves through the arteries that sync with the heart rate and stride rate to dynamically regulate blood circulation to the brain.

In the current study, the research team used non-invasive ultrasound to measure internal carotid artery blood velocity waves and arterial diameters to calculate hemispheric CBF to both sides of the brain of 12 healthy young adults during standing upright rest and steady walking (1 meter/second). The researchers found that though there is lighter foot impact associated with walking compared with running, walking still produces larger pressure waves in the body that significantly increase blood flow to the brain. While the effects of walking on CBF were less dramatic than those caused by running, they were greater than the effects seen during cycling, which involves no foot impact at all.

Published on Leave a comment on Pollution Nanoparticles Found in Human Brains

This post is more on the theme of nanoparticles and human health. My last post was about a study that examined how inhaled nanoparticles  (for example, from air pollution) travel from the lungs to the bloodstream.

Well, today's post is about a pretty shocking 2016 air pollution nanoparticle study which examined the brains (brain tissue) of 45 dead people  (ages 3 to 92) who had lived for a long time in two places with heavy  particulate air pollution - Mexico City and Manchester, England. Some of the British people also had Alzheimer's disease or dementia.

The researchers found evidence that minute nano-sized particles of magnetite from air pollution can find their way into the brain. There are 2 forms of magnetite (which is an iron ore) - one naturally occurring (jagged edges in appearance), and one found commonly in air pollution (smooth and rounded - from being created in the high temperatures of vehicle engines or braking systems). The researchers are concerned that the air pollution nanoparticles may increase the risk for brain diseases such as Alzheimer's.

One of the researchers (Prof Barbara Maher) has previously identified magnetite particles in samples of air gathered beside a busy road in Lancaster, England and outside a power station. She suspected that similar particles may be found in the brain samples, and that is what happened. "It's dreadfully shocking. When you study the tissue you see the particles distributed between the cells and when you do a magnetic extraction there are millions of particles, millions in a single gram of brain tissue - that's a million opportunities to do damage."..."It's a whole new area to investigate to understand if these magnetite particles are causing or accelerating neurodegenerative disease."

However, it must be stressed that at this time there is no proven link between these magnetite particles and any neurodegenerative diseases. They're just wondering.... they call finding these pollution nanoparticles "suggestive observations".

From Medical Xpress: Toxic air pollution nanoparticles discovered in the human brain

Tiny magnetic particles from air pollution have for the first time been discovered to be lodged in human brains – and researchers think they could be a possible cause of Alzheimer's disease. Researchers at Lancaster University found abundant magnetite nanoparticles in the brain tissue from 37 individuals aged three to 92-years-old who lived in Mexico City and Manchester. This strongly magnetic mineral is toxic and has been implicated in the production of reactive oxygen species (free radicals) in the human brain, which are associated with neurodegenerative diseases including Alzheimer's disease.

Professor Barbara Maher, from Lancaster Environment Centre, and colleagues (from Oxford, Glasgow, Manchester and Mexico City) used spectroscopic analysis to identify the particles as magnetite. Unlike angular magnetite particles that are believed to form naturally within the brain, most of the observed particles were spherical, with diameters up to 150 nm, some with fused surfaces, all characteristic of high-temperature formation – such as from vehicle (particularly diesel) engines or open fires. The spherical particles are often accompanied by nanoparticles containing other metals, such as platinum, nickel, and cobalt.

Professor Maher said: "The particles we found are strikingly similar to the magnetite nanospheres that are abundant in the airborne pollution found in urban settings, especially next to busy roads, and which are formed by combustion or frictional heating from vehicle engines or brakes."

Other sources of magnetite nanoparticles include open fires and poorly sealed stoves within homes. Particles smaller than 200 nm are small enough to enter the brain directly through the olfactory nerve after breathing air pollution through the nose.....The results have been published in the paper 'Magnetite pollution nanoparticles in the human brain' by the Proceedings of the National Academy of Sciences.

A good discussion of the study in The Scientist: Environmental Magnetite in the Human Brain

Image of magnetite nanoparticles from the exhaust plume of a diesel engine. Credit Maher et al study, 2016.

 

 

A microscopic image shows magnetite nanoparticles in the human brain. Barbara Maher et al study, 2016.

 

 

Published on Leave a comment on Common Pesticides and Behavioral Problems in Children

Another study has linked childhood behavioral problems to pesticide exposure, this time to pyrethroid insecticide exposure. Pyrethroids are synthetic pesticides (insecticides) that are increasingly used for personal use (mosquito repellents and treatments for head lice, scabies), on pets (for fleas), home use (e.g., Raid pesticides), and in agriculture.

Until recently, they have been viewed as "safer" and posing fewer risks to human health than older pesticides, but a growing body of research is finding that pyrethroid pesticides share similar neurocognitive health effects as older pesticides. Neurocognitive refers to the neural processes of the brain and central nervous system involved in cognitive functioning. Pyrethroids get into people various ways: through inhalation, absorbed through the skin, and ingested in food. And yes, they cross the placenta (they have been detected in the placental cord immediately after birth).

In this study, researchers looked at levels of pyrethroid metabolites (the breakdown products from pyrethroids) in the mother's urine during early pregnancy and in the child's urine when the child was 6 years of age. They looked at how social a child is (altruism), whether the child is inhibited and has difficulty sharing problems or asking for help (internalizing behaviors), as well as how defiant or disruptive a child is (externalizing behaviors, which can include hyperactivity and oppositionality).

Pyrethroids (the metabolites) were regularly detected in both mothers and children participating in the study. Internalizing disorders were associated with high levels of one pyrethroid metabolite (cis-DCCA, a breakdown product of permethrin, cypermethrin, and clyfluthrin) in pregnant mothers’ urine. Childhood exposure to pyrethroids (as measured in the child's urine) was linked to externalizing disorders. Researchers hypothesized that the behavioral difficulties were due to changes in the child’s brain. The authors stated: “The current study suggests that exposure to certain pyrethroids at the low environmental doses encountered by the general public may be associated with behavioural disorders in children.” "Internalizing behaviors are inhibited and overcontrolled in nature, while children with

Other studies have also found negative health effects on children from pyrethroids -  for example, an association between synthetic pyrethroid exposure and ADHD hyperactivity and impulsivity. Recent research found that living near a farm field where pyrethroids are applied during a mother’s third trimester or just before conception corresponds with a greatly increased risk of having a child with autism spectrum disorder.

What can one do? Main one: try to avoid using and ingesting (in food) synthetic pyrethroids. This means avoid routine "pesticide treatments" of your home and garden, and instead use least-toxic methods to control pests around the home and garden (such as baits for insects, caulk holes, etc.). Try viewing weeds in the lawn as native wildflowers and the flowers as bee habitats (yes, you'll also be saving bees!). Eat as many organic foods (especially fruits and vegetables) as possible - this will lower the amount of pesticides in your body. This is because synthetic pyrethroids are not allowed in organic farming.  The good news is that pyrethroid pesticides leave the body within days, so with some lifestyle changes you can really lower your pesticide levels.

From Medscape:  'Safe' Insecticides Tied to Neurobehavioral Problems in Kids

Prenatal and childhood exposure to pyrethroid insecticides may adversely affect neurobehavioral development in children up to age 6 years, new research shows. A group of French researchers led by Jean-François Viel, MD, PhD, and Prof Andreas G. Franke, MD, both of the University of Mainz, Germany, investigated the associations between exposure to pyrethroid insecticides and behavioral skills in 6-year-olds.

Using a longitudinal design, the researchers assessed pyrethroid exposure in children prenatally and at age 6 years. They found that in 6-year-old children, increased prenatal concentrations of the cis-dimethylcyclopropane carbolic acid metabolite were associated with internalizing difficulties. A positive association was also found between the presence of childhood 3-phenoxybenzoic acid (3-PBA) and externalizing difficulties.

The researchers used a longitudinal design to assess the relationship between prenatal and childhood pyrethroid concentrations, using data from the French PELAGIE mother-child study. That study enrolled 3421 pregnant women from Brittany, France, between 2002 and 2006. Of this cohort, 287 randomly selected mothers agreed to participate in neuropsychological follow-up. Psychologists who were blinded to pyrethroid exposure levels in the study participants conducted neurodevelopmental assessments and maternal interviews to assess the home environment. They also collected children's urine samples as well as dust samples.

Published on Leave a comment on Benefit of Tea Drinking?

A study found that daily drinking of  tea (either black tea/oolong or green tea) is associated with a lower risk of "neurocognitive disorders" - in cognitive impairment in women, and in a lower risk of Alzheimer's disease in both men and women who are genetically predisposed to the disease (apolipoprotein E (APOE) genotype) - when compared to those who never or rarely drank tea. The researchers called long-term daily tea drinking as "neuroprotective".

The study followed 957 residents of Singapore for several years. All were "cognitively normal" when the study started (average age 64 1/2 years), but 72 people or 7.5% had developed neurocognitive disorders by the second follow-up (after 4 years). The study found that there was a dose-dependent relationship - the more tea that was drunk daily, the more protective it appeared to be. And it was most protective in those who consistently drank tea at both time points - when the study started and till the end. However, there was a gender difference - it seemed to protect women from neurocognitive disorders, but not men. But in those who were genetically predisposed to Alzheimer's - tea drinking was protective for both males and females. Further studies will follow up to see if the gender difference holds - they couldn't explain it.

The researchers also point out that tea drinking has a long history in Chinese culture as an natural "attention enhancer" and strong tea is drunk as to maintain alertness and concentration. Sounds a lot like why people drink coffee. From Medical Xpress:

Daily consumption of tea protects the elderly from cognitive decline

Tea drinking reduces the risk of cognitive impairment in older persons by 50 per cent and as much as 86 per cent for those who are genetically at risk of Alzheimer's. A cup of tea a day can keep dementia away, and this is especially so for those who are genetically predisposed to the debilitating disease, according to a recent study led by Assistant Professor Feng Lei from the Department of Psychological Medicine at National University of Singapore's (NUS) Yong Loo Lin School of Medicine. The longitudinal study involving 957 Chinese seniors aged 55 years or older has found that regular consumption of tea lowers the risk of cognitive decline in the elderly by 50 per cent, while APOE e4 gene carriers who are genetically at risk of developing Alzheimer's disease may experience a reduction in cognitive impairment risk by as much as 86 per cent.

He added, "Based on current knowledge, this long term benefit of tea consumption is due to the bioactive compounds in tea leaves, such as catechins, theaflavins, thearubigins and L-theanine. These compounds exhibit anti-inflammatory and antioxidant potential and other bioactive properties that may protect the brain from vascular damage and neurodegeneration. Our understanding of the detailed biological mechanisms is still very limited so we do need more research to find out definitive answers.

Published on Leave a comment on Blueberries and the Aging Brain

A new study was published that supports eating lots of blueberries (or drinking blueberry juice) for health - this time better brain functioning in people aged 65 to 77 who drank concentrated blueberry juice daily for 12 weeks. The people randomly assigned to the group drinking blueberry juice daily showed improvements in cognitive function, blood flow to the brain, and activation of the brain while carrying out cognitive tests. The people received MRIs (magnetic resonance imaging), as well as various blood tests and cognitive tests.

And how much did they drink of the juice daily? Thirty ml or 1 ounce of blueberry concentrate (which provided 387 mg anthocyanins) which was diluted with tap water. Anthocyanins are anti-oxidants that belong to a class of compounds called flavonoids, and are found in high concentrations in blueberries, cherries, and plums. The blueberry concentrate amount was equivalent to about 230 grams of blueberries - about 1 1/3 cups blueberries.

What was good about the study was that to eliminate bias people were both randomly assigned to the blueberry juice group or a placebo group (they drank a synthetic fruit cordial) - and it was "double-blind" so that no one knew who was in which group. Interestingly, people who were already eating more than 5 portions of fruits daily were excluded from the study - because so many other studies have already found all sorts of brain benefits from a diet with lots of fruits and berries. But the main conclusion from this and other related research is: eating lots of berries is good for you and has health benefits. From Medical Xpress:

Blueberry concentrate improves brain function in older people

Drinking concentrated blueberry juice improves brain function in older people, according to research by the University of Exeter. In the study, healthy people aged 65-77 who drank concentrated blueberry juice every day showed improvements in cognitive function, blood flow to the brain and activation of the brain while carrying out cognitive tests. There was also evidence suggesting improvement in working memory. Blueberries are rich in flavonoids, which possess antioxidant and anti-inflammatory properties.

Of the 26 healthy adults in the study, 12 were given concentrated blueberry juice - providing the equivalent of 230 g of blueberries - once a day, while 14 received a placebo. Before and after the 12-week period, participants took a range of cognitive tests while an MRI scanner monitored their brain function and resting brain blood flow was measured. Compared to the placebo group, those who took the blueberry supplement showed significant increases in brain activity in brain areas related to the tests. The study excluded anyone who said they consumed more than five portions of fruit and vegetables per day, and all participants were told to stick to their normal diet throughout. [Original study.]

Published on Leave a comment on Gut Bacteria Associated With Strokes

After writing about Lactobacillus sakei in the sinuses for several years (present in healthy sinuses, absent or less in those with chronic sinusitis, and also a treatment for chronic sinusitis), I wondered whether L. sakei is found anywhere else in the body. Today I read a study (conducted in Japan) about gut microbes and strokes and there it was - the presence of L. sakei in the gut.

Specifically, a study found that people who have ischemic strokes tend to have lower amounts ("depletion") of L. sakei in the gut than healthy people, even though it was detected in 80% of both groups.

The study found that in people with ischemic strokes there was evidence for the gut microbes being out of whack (dysbiosis), as well as more inflammation, and more of certain bacteria species (Atopobium cluster and Lactobacillus ruminis), and depletion of L. sakei bacteria.

The researchers took samples of stool (fecal samples) from each person of both groups (ischemic stroke group and healthy group) and analyzed the stool with modern tests (genetic sequencing) to see whether 22 groups of bacteria were in it. (Note that there are normally hundreds of species of bacteria living in a healthy person's gut, as well as viruses, fungi, etc.).

So once again it looks like L. sakei may be beneficial bacteria, even in the gut. The researchers were careful to point out that they couldn't say that certain bacteria caused the strokes - just that there was an association.

And what diet is associated with lower levels of inflammation in the body? Once again - a diet with lots of fruits, vegetables, whole grains, nuts, seeds, and legumes (think Mediterranean style diet). You want to feed the beneficial bacteria in the gut.

Excerpts from a research article by Yamashiro et al in PLoS One: Gut dysbiosis is associated with metabolism and systemic inflammation in patients with ischemic stroke

The role of metabolic diseases in ischemic stroke has become a primary concern in both research and clinical practice. Increasing evidence suggests that dysbiosis is associated with metabolic diseases. The aim of this study was to investigate whether the gut microbiota, as well as concentrations of organic acids, the major products of dietary fiber fermentation by the gut microbiota, are altered in patients with ischemic stroke, and to examine the association between these changes and host metabolism and inflammation.

We analyzed the composition of the fecal gut microbiota and the concentrations of fecal organic acids in 41 ischemic stroke patients and 40 control subjects via 16S and 23S rRNA-targeted quantitative reverse transcription (qRT)-PCR and high-performance liquid chromatography analyses..... Although only the bacterial counts of Lactobacillus ruminis were significantly higher in stroke patients compared to controls, multivariable analysis showed that ischemic stroke was independently associated with increased bacterial counts of Atopobium cluster and Lactobacillus ruminis, and decreased numbers of Lactobacillus sakei subgroup, independent of age, hypertension, and type 2 diabetes....Together, our findings suggest that gut dysbiosis in patients with ischemic stroke is associated with host metabolism and inflammation.   ...continue reading "Gut Bacteria Associated With Strokes"

Published on Leave a comment on Should Pregnant Women Be Warned To Avoid Licorice?

Avoid eating licorice during pregnancy? That licorice is a food to avoid during pregnancy (or only eat in tiny amounts) will be news to many. Most people think of licorice (or liquorice) as a candy, but it can also be used as a herbal medicine that can have negative health effects, especially in large doses (e.g, high blood pressure, loss of potassium). The licorice flavor comes from the root of the plant (licorice root). Licorice contains glycyrrhizin, which is in black licorice candy, and in some chewing gums, ice creams, syrups, soft drinks, supplements, herbal teas, and other products.

In 2016, the government of Finland warned against consuming licorice (including black licorice and salty licorice) during pregnancy. In the United States, the FDA does not warn pregnant women about eating licorice or licorice root. The National Institutes of Health (NIH) recommends that pregnant women avoid consuming large amounts of licorice root in food or taking it as a supplement. But how about small amounts of licorice? And what are possible effects during pregnancy?

A recent study in Finland compared children (average age of 12 1/2 years) whose mothers had either consumed little to no licorice during pregnancy or had consumed large amounts of licorice (high glycyrrhizin levels were calculated as more than 500 milligrams per week). Note that 500 mg glycyrrhizin is equal to 250 grams or 8.8 oz licorice. The researchers found that children whose mothers ate large amounts of licorice during pregnancy  were about 7 points lower on IQ tests, had poorer memory, and had higher rates of attention deficit/hyperactivity disorder problems than those whose mothers had eaten little or no licorice during pregnancy. High-consumption group girls had earlier and more advanced puberty, and were taller and heavier than those in the low-licorice group.

The researchers wrote that glycyrrhizin results in "glucocorticoid overexposure", which may affect the developing fetus, and the effects persist into early adolescence. The study researchers concluded that pregnant women should be informed that consumption of licorice and other food products containing glycyrrhizin may be associated with harm to their developing baby. A little licorice candy here and there during pregnancy seems to be OK (so don't panic!), but licorice or licorice root is not something that should be eaten or drunk (e.g.,in a tea) regularly. From Science Daily:

Pregnant women should avoid liquorice

A new Finnish study supports food recommendations for families with children in that women should avoid consuming large amounts of liquorice during pregnancy. The limit for safe consumption is not known. In the study, youths that were exposed to large amounts of liquorice in the womb performed less well than others in cognitive reasoning tests carried out by a psychologist. The difference was equivalent to approximately seven IQ points. Those exposed to liquorice also performed less well in tasks measuring memory capacity, and according to parental estimates, they had more ADHD-type problems than others. With girls, puberty had started earlier and advanced further.

The Glaku study carried out by the University of Helsinki, the National Institute for Health and Welfare and the Helsinki and Uusimaa hospital districts compared 378 youths of about 13 years whose mothers had consumed "large amounts" or "little/no" liquorice during pregnancy. In this study a large amount was defined as over 500 mg and little/no as less than 249 mg glycyrrhizin per week. These cutoffs are not based on health effects. 500 mg glycyrrhizin corresponds on average to 250 g liquorice.

Researchers suggest that pregnant women and women planning pregnancy should be informed of the harmful effects that products containing glycyrrhizin -- such as liquorice and salty liquorice -- may have on the fetus. In Finland, this is already reality. In January 2016, the National Institute for Health and Welfare published food recommendations for families with children, in which liquorice was placed in the 'not recommended' category for pregnant women. According to the recommendations, occasional consumption of small amounts such as a portion of liquorice ice cream or a few liquorice sweets is not dangerous.

As a result of animal experiments, the biological mechanism of the effects of liquorice is well known. Glycyrrhizin intensifies the effects of stress hormone cortisol by inhibiting the enzyme that inactivates cortisol. While cortisol is essential to the development of a fetus, it is detrimental in large amounts. It has long been known that glycyrrhizin causes higher blood pressure and shorter pregnancies in humans, but such long-lasting effects on the fetus have not been proven before. [Original study.]

Published on Leave a comment on Eating An Egg A Day May Be Beneficial?

Remember all the dietary advice that for years told us to avoid or limit consumption of eggs - that since they were high in cholesterol, they were bad for us and would increase our risk for heart disease? And the nonsense that we should only eat the egg whites while throwing out the yolks? Hah...That advice was wrong, which another recent study confirms.

Eggs are an amazingly nutritious food. They’re loaded with high quality protein, healthy fats, vitamins, minerals, high in choline (a brain nutrient), biotin, antioxidants, lutein, and zeaxanthin. One review of studies (involving millions of people) looked at whole egg consumption  and found that high egg consumption (up to one egg per day) is not associated with increased risk of coronary heart disease or stroke, and in fact there was a reduced risk of hemorrhagic stroke. Only among diabetics was there an elevated risk of coronary heart disease with high egg consumption (up to 1 egg per day). Another study found a lower risk of type 2 diabetes in middle-aged men (see post).

A recent study from Finland found that neither cholesterol nor egg intake (eating one egg per day) was associated with an increased risk of dementia or Alzheimer's disease in Finnish men who were followed for 22 years. Instead, eating eggs was associated with better cognitive performance in certain areas such as executive function, which includes memory, problem solving, and planning (they were given neuropsychological tests). From Science Daily:

High cholesterol intake and eggs do not increase risk of memory disorders

A new study from the University of Eastern Finland shows that a relatively high intake of dietary cholesterol, or eating one egg every day, are not associated with an elevated risk of dementia or Alzheimer's disease. Furthermore, no association was found in persons carrying the APOE4 gene variant that affects cholesterol metabolism and increases the risk of memory disorders. APOE4 is common in Finland.

The dietary habits of 2,497 men aged between 42 and 60 years and with no baseline diagnosis of a memory disorder were assessed at the onset the Kuopio Ischaemic Heart Disease Risk Factor Study, KIHD, in 1984-1989 at the University of Eastern Finland. During a follow-up of 22 years, 337 men were diagnosed with a memory disorder, 266 of them with Alzheimer's disease. 32.5 per cent of the study participants were carriers of APOE4.

The study found that a high intake of dietary cholesterol was not associated with the risk of dementia or Alzheimer's disease -- not in the entire study population nor in the carriers of APOE4. Moreover, the consumption of eggs, which are a significant source of dietary cholesterol, was not associated with the risk of dementia or Alzheimer's disease. On the contrary, the consumption of eggs was associated with better results in certain tests measuring cognitive performance. 

Published on Leave a comment on Older Adults, Exercise, and the Brain

 Once again, research supports that you should get off your butt and exercise! Or do a moderate to vigorous physical activity at least several times a week, which can include housework, gardening, dancing, swimming, or walking briskly. Most important is to MOVE. And why is this so important? Not just for physical health and prevention of certain diseases, but also for the health of your brain, especially as it ages.

The research looked at both 31 young healthy adults (18 to 31 years old) and 26 older healthy adults (55 to 74 years old), assessed their cardiorespiratory (heart/lung) fitness on the treadmill, gave them a number of neurological tests, and also a memory task while their brain activity was observed during functional Magnetic Resonance Imaging (fMRI). They found that the older adults with higher heart/lung fitness had better performance on the memory task and greater brain activity in multiple regions than the older adults with low heart/lung fitness. The increased brain activity in those with higher levels of heart/lung fitness occurred in brain regions typically affected by age-related decline - in other words, higher fitness in older adults reduced some age-related differences.

The researchers thought these and other study results indicate that heart/lung fitness (cardiorespiratory fitness) may keep the brain younger (that is, it preserves neurological function and "neuroplasticity") as people age. They pointed out that some recent studies have revealed that lower cardiorespiratory (heart/lung) fitness was associated with accelerated cognitive decline and that older adults with lower heart/lung fitness had an increased risk for dementia.

From Health Day: Fitter Seniors May Have Healthier Brains

Good heart and lung fitness can benefit older adults' brains, researchers report.They assessed the heart/lung fitness of healthy young adults (aged 18 to 31) and older adults (aged 55 to 74), and compared their ability to learn and remember the names of strangers in photos. MRI scans recorded images of their brain activity as they learned the names.

The older adults had more difficulty with the memory test than the young adults. But older adults with high levels of heart/lung fitness did better on the test and showed more brain activity when learning new names than those of their peers with lower levels of heart/lung fitness. The increased brain activity in those with higher levels of heart/lung fitness occurred in regions typically affected by age-related decline. The findings suggest that heart/lung fitness may also help keep the brain healthy as people get older, according to the researchers. But the study did not prove a cause-and-effect link.

"Importantly, [heart/lung fitness] is a modifiable health factor that can be improved through regular engagement in moderate to vigorous sustained physical activity such as walking, jogging, swimming or dancing," said study corresponding author Scott Hayes....The researchers said high levels of fitness will not prevent brain decline, but may slow it.

An excerpt from the original study, from Cortex: FMRI activity during associative encoding is correlated with cardiorespiratory fitness and source memory performance in older adults

For brain regions in which older adults showed reduced activation relative to young adults, including left inferior frontal gyrus, medial frontal gyrus, bilateral thalamus, and fusiform gyrus, we observed a step-wise pattern, with the greatest activation in young adults, followed by high CRF [cardiorespiratory fitness] older adults and then low CRF older adults, indicating that higher fitness in older adults reduced age-related differences. These findings suggest that CRF supports successful brain maintenance in aging, in that it promotes the preservation of neural function seen in young adults (Nyberg, Lovden et al., 2012). 

Published on Leave a comment on Air Pollution, the Aging Brain, and Dementia

Another study finding a link between air pollution and negative health effects - this time a higher incidence of decline in cognitive functioning  and dementia in older women (65 and older) exposed to fine particles (PM2.5 ). These extremely small particles from vehicle emissions are a major source of urban air pollution throughout the world. These results match other studies finding a link with urban air pollution, especially vehicle traffic, to negative effects on the brain (dementia, cognitive decline, shrinking of the brain, etc.). The researchers also exposed mice to this air pollution for 15 weeks and then studied their brains for evidence of degenerative effects in their brains - and yes, they did find them.

The researchers found that the adverse effects of fine particulate air pollution was stronger in both women and mice who had the APOE4 gene, a genetic variation that increases the risk for Alzheimer's disease. They said that while the air pollution has negative effects in general, that having the APOE4 gene interacted with the air pollution. The researchers also wrote that the mice studies they did showed that "...exposure to urban airborne particulates can intensify amyloid accumulation and neurodegeneration". Medical Xpress:

Air pollution may lead to dementia in older women

Tiny air pollution particles—the type that mainly comes from power plants and automobiles—may greatly increase the chance of dementia, including Alzheimer's disease, according to USC-led research. Scientists and engineers found that older women who live in places with fine particulate matter exceeding the U.S. Environmental Protection Agency's standard are 81 percent more at risk for global cognitive decline and 92 percent more likely to develop dementia, including Alzheimer's.

If their findings hold up in the general population, air pollution could be responsible for about 21 percent of dementia cases, according to the study. "Microscopic particles generated by fossil fuels get into our body directly through the nose into the brain," said University Professor Caleb Finch at the USC Leonard Davis School of Gerontology and co-senior author of the study. "Cells in the brain treat these particles as invaders and react with inflammatory responses, which over the course of time, appear to exacerbate and promote Alzheimer's disease.

The adverse effects were stronger in women who had the APOE4 gene, a genetic variation that increases the risk for Alzheimer's. "Our study .....provides the inaugural scientific evidence of a critical Alzheimer's risk gene possibly interacting with air particles to accelerate brain aging," said Jiu-Chiuan Chen, co-senior author of the study....[Their study] adds to an emerging body of research from around the world that links air pollution to dementia. The offending pollutants—known as PM2.5—are fine, inhalable particles with diameters 2.5 micrometers or smaller. A human hair is about 70 micrometers in diameter, making it 30 times larger than the largest PM2.5. The researchers analyzed data of 3,647 65- to 79-year-old women from the Women's Health Initiative Memory Study (WHIMS). These women lived across 48 states and did not have dementia when they enrolled.

USC scientists chronically exposed female mice carrying the APOE4 gene to nano-sized air pollution for 15 weeks. Compared to the control group, mice predisposed to Alzheimer's disease accumulated as much as 60 percent more amyloid plaque, the toxic clusters of protein fragments that further the progression of Alzheimer's.

In other studies, Chen and his colleagues linked long-term exposure to high PM2.5 levels to smaller gray and white matter volumes in important areas such as the frontal lobe, which carries out thinking, decision-making and planning. For every 3.5 micrograms of PM2.5 per cubic meter of air, white matter (insulated nerve fibers that connect different brain regions) decreased by 6 cubic centimeters, according to one earlier study. [see post]