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Two studies showing detrimental effects on children from pyrethroids in 2 weeks! The June 3 post was about research linking household pyrethroid exposure to ADHD in children and young teens. The second study found that low level childhood exposures to pyrethroid insecticides was linked to lower scores on an IQ test (Wechsler Intelligence Scale for Children - verbal comprehension and working memory) in 6 year old children. The researchers viewed this as evidence that pyrethroid insecticides may "negatively affect neurocognitive development".

Bottom line: even though pyrethroid pesticides are considered safer than many other pesticides, they still can have undesirable effects on humans, especially developing children. To be safe, use least toxic pest control that uses non-toxic, safe "alternative" or "natural" methods rather than just "spraying a chemical". Another possibility is looking for "organic pest control" or"least-toxic Integrated Pest Management" (IPM) that looks to deal with pest problems with non-toxic methods (which may include sealing holes, heat, caulking, trapping, using sticky traps, and even vacuuming up insects). From Science Daily:

Impact of insecticides on the cognitive development of 6-year-old children

Researchers have provided new evidence of neurotoxicity in humans from pyrethroid insecticides, which are found in a wide variety of products and uses. An increase in the urinary levels of two pyrethroid metabolites (3-PBA and cis-DBCA) in children is associated with a significant decrease in their cognitive performances , particularly verbal comprehension and working memory. This study was carried out on nearly 300 mother and child pairs from the PELAGIE cohort (Brittany).

Pyrethroids constitute a family of insecticides widely used in a variety of sectors: agriculture (various crops), veterinary (antiparasitics) and domestic (lice shampoo, mosquito products). Their mode of action involves blocking neurotransmission in insects, leading to paralysis. Because of their efficacy and relative safety for humans and mammals, they have replaced older compounds (organochlorides, organophosphates, carbamate) considered more toxic.

Exposure of children to pyrethroids is common. It is different to adult exposure, due to the closer proximity of children to ground-level dust (which stores pollutants), more frequent hand-to-mouth contact, lice shampoos, etc. In children, pyrethroids are mainly absorbed via the digestive system, but are also absorbed through the skin. They are rapidly metabolised in the liver, and mainly eliminated in the urine as metabolites within 48 hours.

Pregnancy is also an important period of life for the future health of the child. For this reason, the researchers studied the PELAGIE mother-child cohort established between 2002 and 2006, which monitors 3,500 mother-child pairs. This cohort simultaneously considers exposure to pyrethroid insecticides during fetal life and childhood. A total of 287 women, randomly selected from the PELAGIE cohort and contacted successfully on their child's sixth birthday, agreed to participate in this study.

Two psychologists visited them at home. One assessed the child's neurocognitive performances using the WISC scale (verbal comprehension index, VCI, and working memory index, WMI). The other psychologist characterised the family environment and stimuli that might have had a role on the child's intellectual development, collected a urine sample from the child, and collected dust samplesExposure to pyrethroid insecticides was estimated by measuring levels of five metabolites (3-PBA, 4-F-3-PBA, cis-DCCA, trans-DCCA and cis-DBCA) in urine from the mother (collected between the 6th and 19th weeks of pregnancy) and from the child (collected on his/her 6th birthday).

Results show that an increase in children's urinary levels of two metabolites (3 PBA and cis-DBCA) was associated with a significant decrease in cognitive performances, whereas no association was observed for the other three metabolites (4-F-3-PBA, cis-DCCA and trans-DCCA). With respect to metabolite concentrations during pregnancy, there was no demonstrable association with neurocognitive scores.

Yes! An approach to ADHD that makes sense. Nice piece from Richard A. Friedman, professor of clinical psychiatry and director of the psychopharmacology clinic at the Weill Cornell Medical College. From NY Times:

A Natural Fix for A.D.H.D.

Attention deficit hyperactivity disorder is now the most prevalent psychiatric illness of young people in America, affecting 11 percent of them at some point between the ages of 4 and 17. The rates of both diagnosis and treatment have increased so much in the past decade that you may wonder whether something that affects so many people can really be a disease.

And for a good reason. Recent neuroscience research shows that people with A.D.H.D. are actually hard-wired for novelty-seeking — a trait that had, until relatively recently, a distinct evolutionary advantage. Compared with the rest of us, they have sluggish and underfed brain reward circuits, so much of everyday life feels routine and understimulating.

To compensate, they are drawn to new and exciting experiences and get famously impatient and restless with the regimented structure that characterizes our modern world. In short, people with A.D.H.D. may not have a disease, so much as a set of behavioral traits that don’t match the expectations of our contemporary culture.

From the standpoint of teachers, parents and the world at large, the problem with people with A.D.H.D. looks like a lack of focus and attention and impulsive behavior. But if you have the “illness,” the real problem is that, to your brain, the world that you live in essentially feels not very interesting.The more novel and unpredictable the experience, the greater the activity in your reward center. But what is stimulating to one person may be dull — or even unbearably exciting — to another. There is great variability in the sensitivity of this reward circuit.

These findings suggest that people with A.D.H.D are walking around with reward circuits that are less sensitive at baseline than those of the rest of us. Having a sluggish reward circuit makes normally interesting activities seem dull and would explain, in part, why people with A.D.H.D. find repetitive and routine tasks unrewarding and even painfully boring.

Another patient of mine, a 28-year-old man, was having a lot of trouble at his desk job in an advertising firm. Having to sit at a desk for long hours and focus his attention on one task was nearly impossible. He would multitask, listening to music and texting, while “working” to prevent activities from becoming routine. Eventually he quit his job and threw himself into a start-up company, which has him on the road in constantly changing environments. He is much happier and — little surprise — has lost his symptoms of A.D.H.D.

My patient “treated” his A.D.H.D simply by changing the conditions of his work environment from one that was highly routine to one that was varied and unpredictable. All of a sudden, his greatest liabilities — his impatience, short attention span and restlessness — became assets. And this, I think, gets to the heart of what is happening in A.D.H.D.

Consider that humans evolved over millions of years as nomadic hunter-gatherers. It was not until we invented agriculture, about 10,000 years ago, that we settled down and started living more sedentary — and boring — lives. As hunters, we had to adapt to an ever-changing environment where the dangers were as unpredictable as our next meal. In such a context, having a rapidly shifting but intense attention span and a taste for novelty would have proved highly advantageous in locating and securing rewards — like a mate and a nice chunk of mastodon. In short, having the profile of what we now call A.D.H.D. would have made you a Paleolithic success story.

So if you are nomadic, having a gene that promotes A.D.H.D.-like behavior is clearly advantageous (you are better nourished), but the same trait is a disadvantage if you live in a settled context.

You may wonder what accounts for the recent explosive increase in the rates of A.D.H.D. diagnosis and its treatment through medication. The lifetime prevalence in children has increased to 11 percent in 2011 from 7.8 percent in 2003 — a whopping 41 percent increase — according to the Centers for Disease Control and Prevention. And 6.1 percent of young people were taking some A.D.H.D. medication in 2011, a 28 percent increase since 2007. Most alarmingly, more than 10,000 toddlers at ages 2 and 3 were found to be taking these drugs, far outside any established pediatric guidelines.

Some of the rising prevalence of A.D.H.D. is doubtless driven by the pharmaceutical industry, whose profitable drugs are the mainstay of treatment. Others blame burdensome levels of homework, but the data show otherwise. Studies consistently show that the number of hours of homework for high school students has remained steady for the past 30 years.

I think another social factor that, in part, may be driving the “epidemic” of A.D.H.D. has gone unnoticed: the increasingly stark contrast between the regimented and demanding school environment and the highly stimulating digital world, where young people spend their time outside school. Digital life, with its vivid gaming and exciting social media, is a world of immediate gratification where practically any desire or fantasy can be realized in the blink of an eye. By comparison, school would seem even duller to a novelty-seeking kid living in the early 21st century than in previous decades, and the comparatively boring school environment might accentuate students’ inattentive behavior, making their teachers more likely to see it and driving up the number of diagnoses.

Perhaps one explanation is that adults have far more freedom to choose the environment in which they live and the kind of work they do so that it better matches their cognitive style and reward preferences. If you were a restless kid who couldn’t sit still in school, you might choose to be an entrepreneur or carpenter, but you would be unlikely to become an accountant. 

From NPR:

More Hints That Dad's Age At Conception Helps Shape A Child's Brain

Traditionally, research has focused on women's "biological clock." But in recent years, scientists have been looking more and more at how the father's age at conception might affect the baby, too. A study published Wednesday hints that age really might matter — in terms of the child's mental health.

Researchers from the University of Indiana and the Karolinska Institute found that compared with children fathered by men who were 20-24 years old, kids born to dads who were 45 or older were three times as likely to have autism and 13 times as likely to have ADHD. Kids born to older dads were also more likely to go on to develop substance abuse problems and get lower grades in school. The findings appear in JAMA Psychiatry.

To figure out how paternal age was related to children's psychiatric health, the researchers looked at millions of parents in Sweden who had children between 1973 and 2001. The researchers took into account the mother's age, as well as other demographic factors that might play a role in the child's cognitive development and mental health.

"There's a growing body of literature that suggests that advancing paternal age is associated with a host of problems," D'Onofrio tells Shots. Another study, published in JAMA Psychiatrylast month, found that the children of older fathers seemed to be at greater risk for developing schizophrenia and autism.

D'Onofrio and his colleagues paid special attention to siblings and cousins, and found that even among kids in the same extended family, a dad's age when his child was born made a difference.

The results are in line with a growing body of research linking older fatherhood with various developmental problems in children.

However, the study looks only at how paternal age and children's mental health are associated — it's a correlation, Reichenberg cautions, not a proven causal link. Scientists haven't yet determined the mechanisms of the effect. But it doesn't seem to be simply a matter of overdiagnosis among the children of older parents, the scientists say. Other research has found that as men get older, their sperm cells are more likely to contain random mutations that might, theoretically, contribute to disorders like autism in their kids.

Ultimately, men and women of all ages, he says, should remember that age is only one of many factors influencing the developing baby's health.

"The most important thing is [that] future mothers and fathers should still go ahead and have children, even if the father is older than 45 or 50," Reichenberg says. "Most of these children will be absolutely fine."

Acetaminophen was the one nonprescription medication that for decades pregnant women thought was safe to take. Looks like not any more - a study found that taking acetaminophen during pregnancy was associated with hyperkinetic disorder and ADHD at age 7. And the longer it was taken during pregnancy, the stronger the association. From Science Daily:

Use of acetaminophen during pregnancy linked to ADHD in children, researchers say

Acetaminophen, found in over-the-counter products such as Excedrin and Tylenol, provides many people with relief from headaches and sore muscles. When used appropriately, it is considered mostly harmless. Over recent decades, the drug, which has been marketed since the 1950s, has become the medication most commonly used by pregnant women for fevers and pain.

In a report in the current online edition of JAMA Pediatrics,researchers from the UCLA Fielding School of Public Health show that taking acetaminophen during pregnancy is associated with a higher risk in children of attention-deficity/hyperactivity disorder and hyperkinetic disorder. The data raises the question of whether the drug should be considered safe for use by pregnant women.

ADHD, one of the most common neurobehavioral disorders worldwide, is characterized by inattention, hyperactivity, increased impulsivity, and motivational and emotional dysregulation. Hyperkinetic disorder is a particularly severe form of ADHD.

The UCLA researchers used the Danish National Birth Cohort, a nationwide study of pregnancies and children, to examine pregnancy complications and diseases in offspring as a function of factors operating in early life. The cohort focuses especially on the side effects of medications and infections. The researchers studied 64,322 children and mothers who were enrolled in the Danish cohort from 1996 to 2002. 

More than half of all the mothers reported using acetaminophen while pregnant. The researchers found that children whose mothers used acetaminophen during pregnancy were at a 13 percent to 37 percent higher risk of later receiving a hospital diagnosis of hyperkinetic disorder, being treated with ADHD medications or having ADHD-like behaviors at age 7. The longer acetaminophen was taken -- that is, into the second and third trimesters -- the stronger the associations. The risks for hyperkinetic disorder/ADHD in children were elevated 50 percent or more when the mothers had used the common painkiller for more than 20 weeks in pregnancy.

"It's known from animal data that acetaminophen is a hormone disruptor, and abnormal hormonal exposures in pregnancy may influence fetal brain development," Ritz said. Acetaminophen can cross the placental barrier, Ritz noted, and it is plausible that acetaminophen may interrupt fetal brain development by interfering with maternal hormones or through neurotoxicity, such as the induction of oxidative stress, which can cause the death of neurons.