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Category: brain

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New noteworthy research links commonly used household pyrethroid pesticides to attention deficit hyperactive disorder (ADHD) in children and young teens, especially boys. Ome drawback was that the results were based on a single urine sample.Since pyrethroids are non-persistent and rapidly metabolized, then looking at numerous samples over time would have provided a more accurate assessment of typical long-term exposure. Given how many households use pyrethroid pesticides and that there are seasonal variations in pesticide use, then it wouldn't be surprising if there are times when pyrethroid exposure is higher and so the link to ADHD may even be stronger than seen in this original study.From Medical Xpress:

Study links exposure to common pesticide with ADHD in boys

A new study links a commonly used household pesticide with attention deficit hyperactivity disorder (ADHD) in children and young teens.The study found an association between pyrethroid pesticide exposure and ADHD, particularly in terms of hyperactivity and impulsivity, rather than inattentiveness. The association was stronger in boys than in girls.

Due to concerns about adverse health consequences, the United States Environmental Protection Agency banned the two most commonly used organophosphate (organic compounds containing phosphorus) pesticides from residential use in 2000-2001. The ban led to the increased use of pyrethroid pesticides, which are now the most commonly used pesticides for residential pest control and public health purposes. They also are used increasingly in agriculture.

Pyrethroids have often been considered a safer choice because they are not as acutely toxic as the banned organophosphates. Animal studies, on the other hand, suggested a heightened vulnerability to the effects of pyrethroid exposure on hyperactivity, impulsivity and abnormalities in the dopamine system in male mice. Dopamine is a neurochemical in the brain thought to be involved in many activities, including those that govern ADHD.

The researchers studied data on 687 children between the ages of 8 and 15. The data came from the 2000-2001 National Health and Nutrition Examination Survey (NHANES),...included a diagnostic interview of children's ADHD symptoms and pyrethroid pesticide biomarkers. Pesticide exposure measurements were collected in a random sample of the urine of half the 8-11 year olds and a third of the 12-15 year olds. ADHD was determined by meeting criteria on the Diagnosic Interview Schedule for Children,...

Boys with detectable urinary 3-PBA, a biomarker of exposure to pyrethroids, were three times as likely to have ADHD compared with those without detectable 3-PBA. Hyperactivity and impulsivity increased by 50 percent for every 10-fold increase in 3-PBA levels in boys. Biomarkers were not associated with increased odds of ADHD diagnosis or symptoms in girls.

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Much has been written in the past few months on how to keep your brain sharp and avoid cognitive and memory declines due to aging, and especially how to lower the risk of dementia.

Many studies have shown the following to be beneficial to brain health: exercise (any exercise, including walking, is good), having friends and social networks to interact with, eating a lot of healthy foods (fruits, vegetables, whole grains, legumes (beans), seeds, nuts, and fish), having a purpose in life, using the computer, playing video games (action puzzle games such as Portal 2 and NeuroRacer, but according to one study - not Lumosity), participating in arts or crafts, and learning new skills - that is, try out and learn new things (a musical instrument, a new language, take a class, a new craft, etc), or even visit new places.

Many of these can be summarized as: feed your brain and body, and keep your brain and body active. Here is one recent study of aging, from Medical Xpress:

Civic engagement may stave off brain atrophy, improve memory

Instead of shrinking as expected, as part of the normal aging process, the memory center in the brains of seniors maintained their size and, in men, grew modestly after two years in a program that engaged them in meaningful and social activities, new Johns Hopkins Bloomberg School of Public Health-led research suggests. At the same time, those with larger increases in the brain's volume over two years also saw the greatest improvements on memory tests, showing a direct correlation between brain volume and the reversal of a type of cognitive decline linked to increased risk for Alzheimer's disease.

The research, published online in Alzheimer's & Dementia: The Journal of the Alzheimer's Association, studied participants in the Baltimore Experience Corps, a program that brings retired people into public schools to serve as mentors to young children, working with teachers to help them learn to read in understaffed school libraries."By helping others, participants are helping themselves in ways beyond just feeding their souls. They are helping their brains. The brain shrinks as part of aging, but with this program we appear to have stopped that shrinkage and are reversing part of the aging process."

For the study, Carlson and her colleagues randomized 111 men and women to either participate in the Experience Corps (58) or not (53).... The control arm of the study, those not involved in Experience Corps, exhibited age-related shrinkage in brain volumes. Typically, annual rates of atrophy in adults over age 65 range from .8 percent to two percent. The men who were enrolled in Experience Corps, however, showed a .7 percent to 1.6 percent increase in brain volumes over the course of two years. 

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Image result for Mediterranean dietMore support for health benefits of a Mediterranean diet. Results of a  study comparing brain health in groups of older people (in their 60s and 70s) suggest that a Mediterranean diet supplemented with olive oil or nuts may counter-act age-related cognitive decline (overall their cognitive test scores held steady). But the group assigned to the low-fat diet (the control group) worsened on cognitive tests. The Mediterranean diet emphasizes eating vegetables, fruits, legumes (beans), nuts, whole grains, seeds, olive oil, fish, moderate consumption of dairy products (mostly as cheese and yogurt), moderate wine consumption (optional), and low consumption of meat and meat products.From the Wall Street Journal:

Mediterranean Diet Boosts Brain Power, Clinical Study Finds

The Mediterranean diet, supplemented with a handful of nuts or a few tablespoons of olive oil a day, can counteract the effects of aging on the brain’s ability to function, a new clinical study suggests.

The study, published online Monday in JAMA Internal Medicine, was unusual in that it employed rigorous scientific practices to test the effect of the diet on health....Data gathered from previous observational studies suggested that adhering to a Mediterranean-type diet related to better cognitive function and a reduced risk of dementia, but observational studies have limitations, he said.

The Mediterranean diet, which has also shown benefits in cardiovascular health, emphasizes vegetables and fruits, unrefined grains and beans. It also includes fish and wine and minimal consumption of meat and full-fat dairy products.

The study involved 447 cognitively healthy participants, 55 to 80 years of age, who were divided into three groups. Two groups followed the Mediterranean diet and added either 30 grams of mixed nuts (walnuts, hazelnuts and almonds) a day, or five tablespoons of extra virgin olive oil a day. The third group, acting as a control, was advised to follow a low-fat diet. The subjects were followed for a median of just over four years.

The results showed that, compared with the control group, memory function remained stronger in the Mediterranean diet plus nuts group, while frontal (attention and executive function) and global cognition benefited in the Mediterranean diet plus olive oil group.

The diminished decline in cognitive function likely stems from the abundance of antioxidants and anti-inflammatory agents found in the supplemental foods, Dr. Ros said. Olive oil and nuts are rich in phenolic compounds that might counteract oxidative processes in the brain, leading to neurodegeneration, the study said. “If you can delay your age-related cognitive decline, you can process tasks with higher speed,” said Dr. Ros.

The research was a substudy of a larger investigation, designed by Dr. Ros, that found the Mediterranean diet, supplemented with additional olive oil or nuts, reduced the incidence of major cardiovascular events among people at high cardiovascular risk. That study, which involved nearly 7,500 participants and known by the acronym Predimed, was published in 2013.

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Image result for dark chocolateGreat results (dark chocolate improves attention and lowers blood pressure), but keep in mind that the research was sponsored by the Hershey company. But not to worry, it basically found what other studies have found - that chocolate is a stimulant that activates the brain. From Science Daily:

Eat dark chocolate to beat the midday slump?

Larry Stevens eats a piece of high-cacao content chocolate every afternoon, which is in part because he has developed a taste for the unsweetened dark chocolate. It's also because research shows that it lowers blood pressure and his new study reveals that it improves attention, which is especially important when hitting that midday slump.

"Chocolate is indeed a stimulant and it activates the brain in a really special way," said Stevens, a professor of psychological sciences at NAU. "It can increase brain characteristics of attention, and it also significantly affects blood pressure levels."

Historically, chocolate has been recognized as a vasodilator, meaning that it widens blood vessels and lowers blood pressure in the long run, but chocolate also contains some powerful stimulants. Stevens said his team wanted to investigate if people who consume chocolate would see an immediate stimulant effect.

Stevens and his colleagues in the Department of Psychological Sciences performed the EEG study with 122 participants between the ages of 18 and 25 years old. The researchers examined the EEG levels and blood pressure effects of consuming a 60 percent cacao confection compared with five control conditions...The results for the participants who consumed the 60 percent cacao chocolate showed that the brain was more alert and attentive after consumption. Their blood pressure also increased for a short time.

The most interesting results came from one of the control conditions, a 60 percent cacao chocolate which included L-theanine, an amino acid found in green tea that acts as a relaxant. This combination hasn't been introduced to the market yet, so you won't find it on the candy aisle...."L-theanine is a really fascinating product that lowers blood pressure and produces what we call alpha waves in the brain that are very calm and peaceful," Stevens said. For participants who consumed the high-cacao content chocolate with L-theanine, researchers recorded an immediate drop in blood pressure. 

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Another study finding negative effects of air pollution - this time high levels of traffic-related air pollution is linked to slower cognitive development among 7 to 10 year old children in Barcelona, Spain. From Science Daily:

Air pollution linked to slower cognitive development in children

Attendance at schools exposed to high levels of traffic-related air pollution is linked to slower cognitive development among 7- to 10-year-old children in Barcelona, according to a new study.

The researchers measured three cognitive outcomes (working memory, superior working memory, and attentiveness) every 3 months over a 12-month period in 2715 primary school children attending 39 schools. By comparing the development of these cognitive outcomes in the children attending schools where exposure to air pollution was high to those children attending a school with a similar socio-economic index where exposure to pollution was low, they found that the increase in cognitive development over time among children attending highly polluted schools was less than among children attending paired lowly polluted schools, even after adjusting for additional factors that affect cognitive development.

Thus, for example, there was an 11.5% 12-month increase in working memory at the lowly polluted schools but only a 7.4% 12-month increase in working memory at the highly polluted schools. These results were confirmed using direct measurements of traffic related pollutants at schools.

The findings suggest that the developing brain may be vulnerable to traffic-related air pollution well into middle childhood, a conclusion that has implications for the design of air pollution regulations and for the location of new schools. While the authors controlled for socioeconomic factors, the accuracy of these findings may be limited by residual confounding, that is, the children attending schools where traffic-related pollution is high might have shared other unknown characteristics that affected their cognitive development.

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Long-term air pollution can cause damage to the brain: covert brain infarcts ("silent strokes") and smaller brain volume (equal to one year of brain aging).

The authors of a study looking at 900 men in the Boston area concluded that, on average, participants who lived in more polluted areas had the brain volume of someone 1 year older vs participants who lived in less polluted areas, and they also had a 46% higher risk for silent strokes. While the mechanisms of how air pollution may affect brain aging is unclear, the researchers think that inflammation resulting from the deposit of fine particles in the lungs is important. From Science Daily:

Long-term exposure to air pollution may pose risk to brain structure, cognitive functions

Air pollution, even at moderate levels, has long been recognized as a factor in raising the risk of stroke. A new study led by scientists from Beth Israel Deaconess Medical Center and Boston University School of Medicine suggests that long-term exposure can cause damage to brain structures and impair cognitive function in middle-aged and older adults. 

Writing in the May 2015 issue of Stroke, researchers who studied more than 900 participants of the Framingham Heart Study found evidence of smaller brain structure and of covert brain infarcts, a type of "silent" ischemic stroke resulting from a blockage in the blood vessels supplying the brain.

The study evaluated how far participants lived from major roadways and used satellite imagery to assess prolonged exposure to ambient fine particulate matter, particles with a diameter of 2.5 millionth of a meter, referred to as PM2.5. These particles come from a variety of sources, including power plants, factories, trucks and automobiles and the burning of wood. They can travel deeply into the lungs and have been associated in other studies with increased numbers of hospital admissions for cardiovascular events such as heart attacks and strokes.

Study participants were at least 60 years old and were free of dementia and stroke. The evaluation included total cerebral brain volume, a marker of age-associated brain atrophy; hippocampal volume, which reflect changes in the area of the brain that controls memory; white matter hyperintensity volume, which can be used as a measure of pathology and aging; and covert brain infarcts.

The study found that an increase of only 2µg per cubic meter in PM2.5, a range commonly observed across metropolitan regions in New England and New York, was associated with being more likely to have covert brain infarcts and smaller cerebral brain volume, equivalent to approximately one year of brain aging...."This is concerning since we know that silent strokes increase the risk of overt strokes and of developing dementia, walking problems and depression."

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The following is a list of nutrients that some researchers (from the Institute of Food Technology) think of as especially beneficial to the brain. Other researchers may (or probably will) focus on other nutrients. I am posting it even though I generally dislike articles that talk about "superfoods" or an itemized list of foods that one should eat to the exclusion of others. Because, of course, focusing on some nutrients may leave out many just as important nutrients.

Also, medical thinking changes over time and what was once considered "unhealthy" may later be considered a wonderful food (remember when eggs, nuts, and coconuts were almost considered evil?). And vice versa (remember when margarine with partially hydrogeneated oils and trans-fats was considered healthier than butter?) And study after study says it is better to eat the foods, rather than take supplements. So keep in mind that the following nutrients are found in whole foods and in a varied diet. And when they mention a specific food such as blueberries, remember that ALL berries have benefits (though they vary), so eat a variety of berries. Same with nuts - eat a variety and not just walnuts. From Science Daily:

Eight nutrients to protect the aging brain

Brain health is the second most important component in maintaining a healthy lifestyle according to a 2014 AARP study. As people age they can experience a range of cognitive issues from decreased critical thinking to dementia and Alzheimer's disease. In the March issue of Food Technology published by the Institute of Food Technologists (IFT), contributing editor Linda Milo Ohr writes about eight nutrients that may help keep your brain in good shape.

1. Cocoa Flavanols: Cocoa flavanols have been linked to improved circulation and heart health, and preliminary research shows a possible connection to memory improvement as well. A study showed cocoa flavanols may improve the function of a specific part of the brain called the dentate gyrus, which is associated with age-related memory (Brickman, 2014). {NOTE: good sources are cocoa and dark chocolate}

2. Omega-3 Fatty Acids: Omega-3 fatty acids have long been shown to contribute to good heart health are now playing a role in cognitive health as well....Foods rich in omega-3s include salmon, flaxseed oil, and chia seeds.

3. Phosphatidylserine and Phosphatidic Acid: Two pilot studies showed that a combination of phosphatidylserine and phosphatidic acid can help benefit memory, mood, and cognitive function in the elderly (Lonza, 2014). {NOTE: good sources are fish and meat}

4. Walnuts: A diet supplemented with walnuts may have a beneficial effect in reducing the risk, delaying the onset, or slowing the progression of Alzheimer's disease in mice (Muthaiyah, 2014).

5. Citicoline: Citicoline is a natural substance found in the body's cells and helps in the development of brain tissue, which helps regulate memory and cognitive function, enhances communication between neurons, and protects neural structures from free radical damage.... {NOTE: Citocoline is synthesized in the body from choline, so see foods high in choline}

6. Choline: Choline, which is associated with liver health and women's health, also helps with the communication systems for cells within the brain and the rest of the body. Choline may also support the brain during aging and help prevent changes in brain chemistry that result in cognitive decline and failure. A major source of choline in the diet are eggs. { NOTE: Good sources of choline are eggs, meat, fish, beans, and cruciferous vegetables.}

7. Magnesium: Magnesium supplements are often recommended for those who experienced serious concussions. Magnesium-rich foods include avocado, soy beans, bananas and dark chocolate.

8. Blueberries: Blueberries are known to have antioxidant and anti-inflammatory activity because they boast a high concentration of anthocyanins, a flavonoid that enhances the health-promoting quality of foods. Moderate blueberry consumption could offer neurocognitive benefits such as increased neural signaling in the brain centers.

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People are living longer these days, but the desire is to age with mental faculties intact. Thus it is great to find research that looks at how one can increase the odds of not having cognitive problems or dementia in old age.

The research here suggests several things one can do, starting in middle-age, that may help in delaying thinking and memory problems: participating in arts, crafts, socializing, and computer activities. The lead researcher Dr. Roberts said: "The key point we want to get across is that you need to start these activities early"....if you start these activities earlier, perhaps in your 20s, "keep doing them throughout your life; don't stop as you get older."

Note that: Mild cognitive impairment (MCI) is an intermediate stage between the expected cognitive decline of normal aging and the more serious decline of dementia. It can involve problems with memory, language, thinking and judgment that are greater than normal age-related changes. From Medical Xpress:

Can arts, crafts and computer use preserve your memory?

People who participate in arts and craft activities and who socialize in middle and old age may delay the development in very old age of the thinking and memory problems that often lead to dementia, according to a new study published in the April 8, 2015, online issue of Neurology.

People age 85 and older make up the fastest growing age group in the United States and worldwide."As millions of older US adults are reaching the age where they may experience these memory and thinking problem called Mild Cognitive Impairment (MCI), it is important we look to find lifestyle changes that may stave off the condition," said study author Rosebud Roberts, MB, ChB, MS, of Mayo Clinic in Rochester, Minn. and a member of the American Academy of Neurology. "Our study supports the idea that engaging the mind may protect neurons, or the building blocks of the brain, from dying, stimulate growth of new neurons, or may help recruit new neurons to maintain cognitive activities in old age."

The study involved 256 people with an average age of 87 who were free of memory and thinking problems at the start of the study. The participants reported their participation in arts, such as painting, drawing and sculpting; crafts, like woodworking, pottery, ceramics, quilting, quilting and sewing; social activities, such as going to the theater, movies, concerts, socializing with friends, book clubs, Bible study and travel; and computer activities such as using the Internet, computer games, conducting web searches and online purchases.

After an average of four years, 121 people developed mild cognitive impairment. Participants who engaged in arts in both middle and old age were 73 percent less likely to develop MCI than those who did not report engaging in artistic activities. Those who crafted in middle and old age were 45 percent less likely to develop MCI and people who socialized in middle and old age were 55 percent less likely to develop MCI compared to those who did not engage in like activities. Computer use in later life was associated with a 53 percent reduced risk of MCI.

On the other hand, risk factors such as having the APOE gene, having high blood pressure in middle age, depression and risk factors related to blood vessels increased the risk of developing MCI.

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The following study raises the question  of how to lower BPA levels in all people, not just children with autism spectrum disorder.

The absolute quickest and easiest is to buy (whenever possible) loose foods (fresh fruits, vegetables, breads, etc) or foods in glass containers (and not plastic bottles, jars, or containers), store food in glass, porcelain, or stainless steel containers, and microwave in glass dishes (and not plastic containers).

In other words, think glass and not plastic. This is because BPA is in polycarbonate containers or packaging.

Lower your use of canned foods and avoid soda in cans. This is because cans have a lining that contains BPA or a BPA substitute (and research suggests it has the same effects as BPA). By the way, clear cling wrap made from polyethylene is considered safe to wrap and store food in.

From Medical Express: New study links BPA exposure to autism spectrum disorder

A newly published study is the first to report an association between bisphenol-A (BPA), a common plasticizer used in a variety of consumer food and beverage containers, with autism spectrum disorder (ASD) in children. The study, by researchers at Rowan University School of Osteopathic Medicine (RowanSOM) and Rutgers New Jersey Medical School (NJMS), shows that BPA is not metabolized well in children with ASD. The research appears online in Autism Research.

"It has been suspected for a lot of years that BPA is involved in autism, but there was no direct evidence," said T. Peter Stein, of RowanSOM and the study's lead author. "We've shown there is a link. The metabolism of BPA is different in some children with autism than it is in otherwise healthy children."

The research team – which included Margaret Schluter and Robert Steer, of RowanSOM who were responsible for laboratory analysis, and child neurologist Xue Ming, of NJMS who recruited and ascertained the study populations – examined urine specimens from 46 children with ASD and 52 healthy control children for both free BPA and total BPA concentrations.

Like many chemicals, BPA becomes water soluble when it is bound to glucose in the liver – a process called glucuronidation. Conversion to a glucuronide and then excretion of the glucuronide in the urine is a major pathway for removing toxins from the body.

The researchers also conducted a metabolomic analysis to screen for all the chemicals found in the children's urine. The metabolomics analyses showed the mean number of statistically significant correlations between metabolites detected and total BPA excreted to be approximately three times greater with the ASD group than the controls, and the number of statistical significant correlations with fraction of BPA bound was approximately 15 times higher in the children with ASD (p<0.001).

"Other studies involving rodent data have shown that BPA functions as an endocrine disruptor, but ours is the first to show this in humans and the first to associate it to autism," Stein said. "The observations show that for some children there was a relationship between intermediary metabolism, the ability to conjugate BPA and symptoms of autism."

Although the study involves a relatively small number of subjects, Stein said, "The key point is that the study seems to link BPA to autism and creates an open area for further research. One implication of our study is that there might be a benefit to reducing BPA exposure for pregnant women and for children with autism."

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Since people have abandoned using iodized salt and started using kosher salt or sea  salts, iodine deficiency has increased (especially during pregnancy when iodine needs are greater). The medical journal The Lancet noted in 2008: "According to World Health Organization, in 2007, nearly 2 billion individuals had insufficient iodine intake, a third being of school age. ... Thus iodine deficiency, as the single greatest preventable cause of mental retardation, is an important public-health problem." From Wikipedia : Iodine deficiency is the leading cause of preventable mental retardation, a result which occurs primarily when babies or small children are rendered hypothyroidic by a lack of the element. The addition of iodine to table salt has largely eliminated this problem in the wealthier nations. The article states that iodine deficiency typically lowers IQ by 10 to 15 points. So it's a big deal, a really big deal.  But don't overdo the iodine! Excess iodine also has serious problems.From Medscape:

New Recommendations Call for Iodine in All Prenatal Vitamins

Endocrinology groups are applauding a new recommendation from a dietary-supplement trade association that calls for iodine supplementation in all prenatal vitamins prescribed for pregnant and breastfeeding women.

In addition, the public health committee of the American Thyroid Association (ATA) recently published a statement reiterating the ATA recommendation that women take a daily multivitamin containing 150 μg of iodine during prepregnancy, pregnancy, and lactation. The statement also warns of the potential risks of excess iodine consumption and exposure, particularly through the use of unregulated kelp supplements.

The US Council for Responsible Medicine's new guidelines call for all dietary-supplement manufacturers and marketers to begin including at least 150 μg of iodine in all daily multivitamin/mineral supplements intended for pregnant and lactating women in the United States within the next 12 months.

In the past several years, removal of iodized salt from commercial products such as bread and milk, along with increased use of kosher salt and sea salt, which don't contain iodine, and the adoption of vegetarian and vegan diets have led to a reduction in dietary iodine consumption. "There never was a coherent US policy about iodization," Dr Stagnaro-Green noted.

Worldwide, about two billion people are iodine-deficient. While most of the US population has adequate iodine levels, data from the National Health and Nutrition Examination Survey suggest that more than half of pregnant women have urinary iodine concentrations below 150 mg/dL (Thyroid. 2011;21:419-427). 

Pregnant women actually need more iodine than other people because of increased thyroid-hormone production, renal losses, and fetal iodine requirements. Iodine deficiency during pregnancy can result in maternal and fetal goiter, cretinism, intellectual impairment, neonatal hypothyroidism, and increased pregnancy loss and mortality, Dr Stagnaro-Green and colleagues explained in a 2012 editorial (JAMA2012;308:2463-2464).

"So, women of childbearing age are the subpopulation of Americans with the lowest iodine levels yet have the greatest need during pregnancy and breastfeeding, for the neurodevelopment of the fetal and neonatal brain," he told Medscape Medical News. 

In 2009, a study found that only 51% of US prenatal multivitamin brands contained any iodine and, in a number of randomly selected brands, the actual dose of iodine contained in the supplements did not match values on the labeling.

However, the American College of Obstetricians and Gynecologists (ACOG) has not joined in these efforts. While the group does recommend the 150-μg dose for pregnant and lactating women, it does not currently endorse the prenatal-supplement recommendation, advising instead that women get their iodine through dietary sources.

In the ATA's public health committee statement, Angela M Leung, MD, from the University of California Los Angeles David Geffen School of Medicine, and colleagues, including Dr Stagnaro-Green, note that iodine is a micronutrient required for normal thyroid function. The US recommended daily allowances (RDA) for iodine intake are 150 μg in adults, 220 to 250 μg in pregnant women, and 250 to 290 μg in breastfeeding women. Dietary sources such as iodized salt, dairy products, some breads, and seafood usually contain enough to meet the RDA for most people who aren't pregnant or lactating.

However, there is an upper safety limit, with ingestion of more than 1100 μg/day not recommended due to the risk for thyroid dysfunction. In particular, infants, the elderly, pregnant and lactating women, and people with preexisting thyroid disease are at risk for adverse effects of excess iodine on the thyroid.

Many iodine, potassium iodide, and kelp supplements contain hundredfold greater amounts of iodine than the recommended upper limit, Leung and colleagues caution."Given the increasing popularity of iodine and kelp supplements, recommendations cautioning against excess iodine were indicated. The potential result of iodine-induced thyroid dysfunction, which may be particularly harmful during pregnancy and breastfeeding and in the elderly, may not be well-known," she told Medscape Medical News.