TIME Developmental Disorders

How to Improve a Baby’s Language Skills Before They Start to Talk

Researchers say playing a series of sounds when infants are four months old could speed up the way babies process language and make them linguistic stars when they’re older. How babies respond to the sounds can also predict which infants will have trouble with language as well

The first few months of a baby’s life come with a flurry of challenges on a still-developing brain. Sights, sounds, smells and touches as well as other emotional experiences flood in, waiting to be processed and filed away as the foundation for everything from language to emotions and how to socialize with others. What happens if things are not finding their right place in the brain during these critical months? Some research suggests it results in developmental delays later on—and that’s just what neuroscientist April Benasich and her colleagues from Rutgers University found in a new study, published in the Journal of Neuroscience.

Previous studies done by both Benasich and others show that the brains of children who learn to speak later or who develop reading disorders like dyslexia showed differences in detecting small differences in speech, such as the difference between da and ba, when they were infants. Other research has come to similar conclusions.

Genetic factors certainly play a role, but up to 10% of the babies Benasich has studied had no family history of developmental problems, yet still showed language trouble when they started talking. That’s why she turned to studying the brain maps of healthy babies before they learned to speak. These routes show how infants detect and respond to sounds in their environment—from words spoken to them to the humming of a dishwasher. In these early months, their brains are primed to sort out this cacophony of auditory stimuli and start making more refined distinctions between them. Doing so requires distinguishing between tiny differences, both in the sounds themselves as well as in frequencies. “Babies do this naturally; this is their job, since they want to be able to pick sounds out quickly and figure out whether they need to pay attention to them,” says Benasich.

For the babies in this study, she adorned them with skull caps studded with electronic sensors that would draw a map of their EEGs as they were presented with different, non-linguistic tones. Some of the babies were played sounds that changed ever so slightly, such as in their tone or frequency, and whenever there was a change, a small video in the corner of a screen they were looking at popped up. The babies naturally turned to watch the video, so the scientists used these eye turns as a signal that the babies had heard and recognized the transition in sounds, and were expecting to see the video. Another group of babies were played the same sounds but without the video training, and a control group didn’t hear the sounds at all.

MORE: Want to Learn a Language? Don’t Try So Hard

It wasn’t the sounds themselves that were important, but the changes in them that were key to priming the babies’ brains. Those who were trained to pay attention to the changes in the sounds, for example, showed more robust mapping of language sounds later on when they started to babble; by 18 months, these infants showed brain mapping patterns similar to those in two year olds. They were faster at discriminating different sounds, and quicker to pay attention to even tiny differences in inflection or frequency compared to babies who weren’t given the sounds. The babies who only listened to the sounds without the training fell somewhere between these two groups when it came to their language mapping networks.

Benasich says that the training lays the foundation in babies’ brains to become more efficient in processing language sounds, including very tiny variations among them. Their brains are setting up different neural routes for each sound, like a well-organized airport with separate runways designated for northbound and southbound flights. Other babies were less adept at this, essentially routing every sound through the same neural network, akin to sending every plane off the same runway, leading to delays as some have to bank and redirect in the opposite direction. In similar ways, says Benasich, in language, this cruder processing of sounds could result in delays in reading or speaking or language acquisition, and toddlers end up having to “manually” process the sounds in a more tedious and less automatic process. “Instead of automatically discriminating sounds without pausing, they have to stop and think and what that sound might be, and that leads them to hesitate a little,” she says. “That small hesitation makes a huge difference in how well they learn and process language.”

The training, she says, was minimal – the babies’ parents brought them in for six to eight minute sessions once a week for about six weeks. Yet she was “surprised by how robust the effects are for the babies.”

The study involved healthy babies who did not have risk factors for language disorders, so the training only helped them to enhance their later language learning. But the team is currently studying a group of babies at higher risk of having language deficits, either because of genetic risk factors or by having siblings affected by such disorders. If these babies show different brain patterns compared to those not at risk, then it’s possible that EEG patterns in response to sounds could predict which infants are at risk of developing language problems even before they start to talk.

Benasich is also working on developing her test into a parent-friendly toy that parents can buy and use with their babies; if their babies are developing normally, then the training can only accelerate and enhance their language skills later on, while for those who are struggling, the training could help them to avoid learning disabilities when they start school. It’s not possible to screen every baby, but if parents and doctors are able to take advantage of such a tool, then she hopes that more language-based disorders might be avoided. “Babies naturally do this, but for those who are having trouble, we are guiding them to pay more attention to things that are important in their environment, such as language-based sounds,“ she says. “We think we could make a huge difference in the number of kids who end up with learning problems.”

TIME child development

Health of Mom Key Factor in Baby Size, Study Says

hands on pregnant stomach
Alex Mares—Asia Images RM/MantonGetty Images

And not race or ethnicity, researchers find

The size of a baby at birth has a significant impact on its future health, and a far-reaching new study shows that the greatest disparities in infant size worldwide are due to mothers’ health, not their race or ethnicity.

The large study, led by Oxford University researchers, looked at 60,000 pregnancies in urban areas in Brazil, China, India, Italy, Oman, Kenya, the U.K. and the U.S. During women’s pregnancies, the researchers used ultrasounds to measure the babies’ bone growth in the womb. When the babies were born, they measured their length and head circumference. They found that the babies’ growth in the womb and their size at birth were very similar across countries, if their mothers were healthy and well-educated.

The study debunks the belief that race or ethnicity are the primary factors for a baby’s size at birth. The good news is that the findings suggest if a mother is educated, healthy and well-nourished, her child has an equal shot at good health in the womb and beyond. But the bad news is that women in less fortunate circumstances are already at a disadvantage when it comes to raising a healthy child.

“Currently we are not all equal at birth. But we can be,” lead study author Jose Villar, a professor in the Nuffield Department of Obstetrics & Gynaecology at University of Oxford said in a statement. “Don’t tell us nothing can be done. Don’t say that women in some parts of the world have small children because they are predestined to do so. It’s simply not true.”

The researchers argue that all mothers can have a similar start if they can be educated and nourished and have access to infection treatments and adequate antenatal care.

The ultimate goal of the study is to create international standards for babies’ optimal growth.


Preschoolers’ Innate Knowledge Means They Can Probably Do Algebra

Imgorthand—Getty Images/Vetta

Child development specialists are uncovering evidence that toddlers may understand much more than we think

Give a three-year old a smartphone and she’ll likely figure out how to turn it on and operate a few simple functions. But confront her with an algebra problem and ask her to solve for x? Not likely.

For decades, child developmental psychologist Jean Piaget convinced us that young, undeveloped minds couldn’t handle complex concepts because they simply weren’t experienced or mature enough yet. Piaget, in fact, believed that toddlers could not understand cause and effect, that they couldn’t think logically, and that they also couldn’t handle abstract ideas.

That’s because, he argued, children learn to develop these higher skills through trial and error. But child development specialists are finding out that preschoolers without any formal education may have the capacity to understand more complex concepts than we give them credit for, such as complicated rules for operating a toy or even solving for an unknown in algebra. Some of this is due to their ability to be more open and flexible about their world than adults. But beyond that, toddlers may have the innate ability to understand abstract concepts like quantities and causality, and that’s fueling an exciting stream of experiments that reveal just how sophisticated preschoolers’ brains might be.

MORE: The Brain: What Do Babies Know?

Alison Gopnik, professor of psychology at University of California Berkeley and her team devised a way to test how well young kids understand the abstract concept of multiple causality — the idea that there may be more than one cause for a single effect. They pitted 32 preschoolers around 4 years old against 143 undergrads. The study centered around a toy that could be turned on by placing a single blue-colored block on the toy’s tray, but could also be activated if two blocks of different colors – orange and purple – were placed on the tray. Both the kids and the undergraduates were shown how the toy worked and then asked which blocks activated the toy.

The preschoolers were adept at figuring out that the blue blocks turned on the toy, as did the purple and orange ones, but that the purple and orange ones needed to be paired together. The Berkeley undergraduates, however, had a harder time accepting the scenario. Their previous experience in the world, which tends to work in a single-cause-equals-single-effect way, hampered their ability to accept the unusual rules that activated they toy; they wanted to believe that it was activated either by a single color or by a combination of colors, but not both. “The training didn’t seem to give them a hint that the world might work in different ways,” says Gopnik, who published her work in the journal Cognition.

The preschoolers’ lack of bias about causality likely contributed to their ability to learn the multiple ways to activate the toy, but the results also suggest that preschoolers really can think logically and in more complicated ways. Just because they can’t express themselves or aren’t as adept at demonstrating such knowledge, doesn’t mean they don’t have it.

MORE: Developmental Psychology: Baby Monitor

Researchers from Johns Hopkins University, for example, found a similar effect among preschoolers when it came to math. Previous studies showed that if you present infants with eight objects over and over until they got bored, and then showed them 16, they suddenly regained interest and sensed that things changed. Even before they are taught about numbers or amounts, then, infants seem to have a grasp on quantity. “All the evidence so far leads us to believe that this is something that babies come into the world with,” says Melissa Kibbe, co-author of that study.

MORE: High Anxiety: How Worrying About Math Hurts Your Brain

She and her colleague Lisa Feigenson wondered if that innate sense of quantity might translate into an understanding of numbers and higher math functions, including solving for unknowns — one of the foundations of algebra — which often isn’t taught until seventh or eighth grades. So they conducted a series of experiments using a cup with a fixed amount of objects that substituted for x in the equation 5 + x = 17.

To divert the four- and six-year olds’ attention away from Arabic numerals to quantities instead, the researchers used a puppet and a “magic” cup that contained 12 buttons. In one of the experiments, the children saw five buttons on the table. After watching the researchers add the 12 buttons from the cup, they were told there were 17 buttons on the table. In another test, the youngsters saw three piles of objects — buttons, coins or small toys — in varying amounts, and observed the researchers adding the fixed number of contents of the puppet’s cup to each.

After training the kids on how the cup worked, the researchers tried to confuse them with another cup containing fewer (such as four) or more (such as 24) objects. However, the kids understood intuitively that the decoy cup contained the wrong amount of items and that a specific amount — x, the “magic” cup amount — had to be added to reach the sum.

When the children were presented with the straight algebraic equation on a card, 5 + _ = 17, and asked to fill in the blank, their answers were no better than chance; that’s because they were simply guessing. In the puppet and cup scenarios, however, which did not involve numerals, they were able to accurately identify the correct amount, increasing their accuracy dramatically, to between 59% to 79%.

MORE: Study: Employers Assume Women Are Worse At Math

That suggested that the preschoolers had some concept of quantity, and the appropriate amount that they needed to get from a small quantity (five) to a larger one (17). What surprised Kibbe was not just that preschoolers understood the concept of adding “more,” but that they could also calibrate how much more was needed to fill in the unknown quantity.

“These kids had very little formal schooling so far, but what we are finding is that when we tap into their gut sense, something we call the Approximate Number Sense (ANS), kids are able to do much more complex calculations than if we gave them numbers and letters,” says Kibbe of her results, which were reported in the journal Developmental Science. And there doesn’t seem to be any gender differences in this innate ability, at least not among the girls and boys Kibbe studied.

MORE: Your Brain On Sesame Street: Big Bird Helps Researchers See How the Brain Learns

There’s also precedent for such innate pre-learning in reading, says Jon Star, at the Harvard University Graduate School of Education. To improve reading skills, some teachers have tapped into children’s memorization skills to make the connection between words and meaning more efficient.

Kibbe’s and Gopnik’s recent work may have broader implications for education, since current math curricula in schools, which focuses on teaching Arabic numerals and on solving equations, may not be ideal for nurturing the number sense that kids are born with. “There’s an exciting movement in psychology over the past decade, as we learn that students bring certain capabilities, or innate knowledge that we hadn’t thought they had before,” says Star.

Though it may be too early to translate such findings to the classroom, the results lay the groundwork for studying similar innate skills and how they might be better understood. ANS, for example, is one of many so-called cognitive primitives, or constructs that young children may have that could enhance their learning but that current curricula aren’t exploiting. Developmental experts are still trying to figure out how malleable these constructs are, and how much of an impact they can have on future learning. For instance, do kids who hone their ANS skills become better at algebra and calculus in high school? “We still need to figure out which constructs matter most, and which are most amenable to interventions to help children improve their learning,” says Star.

MORE: How To Make Your Kids Smarter: 10 Steps Backed By Science

“The hard part is, educationally, how do you build up and upon this intuitive knowledge in a way that allows a child to capture the complexity but not hold them back,” says Tina Grotzer, associate professor of education at Harvard. Tapping into a child’s still developing sense of numbers and quantities is one thing, but overloading it with too many new constructs about algebra, unknowns, and problem solving may just gum up the working memory and end up adversely affecting his learning and academic performance. “As soon as concepts get big and complex, there are all sorts of perceptual, attentional, and cognitive costs and challenges involved,” she says.

Still, that doesn’t mean that these innate skills shouldn’t be explored and possibly exploited in the classroom. Preschoolers may be smarter than we think, but we still have to figure out how to give them the right opportunities in the classroom so they know what to do with that knowledge.

TIME Family & Parenting

Don’t Text While Parenting — It Will Make You Cranky

Getty Images

A new study from Boston Medical Center reveals that parents who get absorbed by email, games or other apps have more negative interactions with their children, making them feel like they're competing for attention with their parents' gadgets

It’s hard to avoid the lure of the smartphone — so many apps! — and if you’re a parent with rambunctious kids, you may not want to. But a fascinating study of the dynamic between parents, kids and smartphones paints a sobering picture of what the devices are doing to the parent-child relationship.

Dr. Jenny Radesky, a fellow in developmental-and-behavioral pediatrics at Boston Medical Center, specializes in counseling parents about developmental and behavioral issues with their children. So she was naturally curious about how the ubiquity of smartphones, and their distracting allure, might affect the quality of time that parents and their children spent together. Previous studies showed that TVs, even if they are only on in the background, can inhibit children’s creativity and siphon their concentrating and focusing powers.

(MORE: We’re All Doomed: Using Your Smartphone Before Bed Can Cause Cell-Phone ‘Hangover’)

To study the effect of smartphones, Radesky and her colleagues sent in undercover investigators to surreptitiously observe any adult-child grouping with more than one youngster as they ate at a fast-food restaurant. The observers recorded the behavior of both the adults and the children in 55 such groupings, as well as how frequently the adults used their smartphones.

The data provided an unvarnished look at how absorbed many parents were by their devices. One child reached over in an attempt to lift his mother’s face while she looked down at a tablet, but to no avail. Another mother kicked her child under the table in response to the child’s various attempts to get her attention while she looked at her phone. A father responded in curt and irritated tones to his children’s escalating efforts to tear him away from his device.

“What stood out was that in a subset of caregivers using the device almost through the entire meal, how negative their interactions could become with the kids,” she says. While the study did not code or quantify the reactions, Radesky says that there were “a lot of instances where there was very little interaction, harsh interaction or negative interaction” between the adults and the children. “That’s simply unfair to the children,” says Dr. Wendy Sue Swanson of Seattle Children’s Hospital and author of the Seattle Mama Doc blog.

(MORE: The Smartphone App Wars Are Over, and Apple Won)

In light of the data, Radesky is working with the American Academy of Pediatrics to develop some guidelines for the smart smartphone use in front of the kids — just as the academy has advice for parents on TV viewing (none for toddlers younger than 2). She and her group also plan to expand the studies with videotapes of the interactions, to better understand how parents absorbed by their phones engage with and respond to their kids, as well as the kids’ reactions to having their parents or caregivers having their attention diverted by the devices. Part of the broader work will also include a more detailed analysis of what parents are doing on their phones, to determine if there are better and worse things to do while in the company of youngsters.

In the meantime, setting aside devices during specific times, such as meal, story and bed times, can help to minimize any potentially distracting effects that smartphones have on parent-child interactions. Using the phone, says Swanson, “is not recommended at the dinner table — a time that we think is valuable to fostering cohesion.”

Also, recognizing that responding to email or scanning Facebook while your kids are waiting or attempting to get your attention isn’t fair to them and could change the nature of your relationship with your kids if they don’t feel they are as important as the device. “These data are a wake-up call for we parents in that we really need to think about how these enticing devices not only distract us but potentially change who we are as parents,” says Swanson.

Establishing no-device rules at certain times of day or places in the home can also help. That not only can improve relations between young children and their parents, but also teach the children about how to properly engage with people during conversations or interactions as they grow older. “My concern is that if the device use becomes really excessive, and it replaces our day-to-day interactions, then kids won’t get much practice with having conversations, reading social cues and responding sensitively to something that the other person expresses,” she says. Kids learn by watching and participating, and if parents aren’t engaging with their children, then the young ones could start to lose their social role models. And who wants a generation of people who text each other while sitting at the same table?

TIME mental health

More Bad News for Older Dads: Higher Risk of Kids With Mental Illness

Getty Images

The effect of paternal age on autism, schizophrenia, and ADHD may be greater than previously thought

For so long, mothers – particularly older moms — bore the brunt of responsibility for genetic disorders in their children. And for good reason. Eggs are stockpiled from birth, not made anew with each monthly reproductive cycle, so eggs stored for decades until childbearing can develop genetic mutations. The older the mother, the greater the chance of abnormalities that can contribute to conditions such as Down syndrome, especially after age 35. Fathers, on the other hand, constantly make sperm, so their reproductive contribution was supposed to be fresher and free of accumulated DNA damage.

That may not actually be the case, however, according to the latest study in JAMA Psychiatry investigating how advanced paternal age can affect rates of mental illness and school performance in children. After a groundbreaking genetic analysis in 2012 highlighted the surprising number of spontaneous mutations that can occur in the sperm of older men, scientists have been delving into the relationship to better quantify and describe the risk. While some studies confirmed the connection, others failed to find a link.

MORE: Older Fathers Linked to Kids’ Autism and Schizophrenia Risk

In the latest research, Brian D’Onofrio, associate professor of psychological and brain sciences at Indiana University, and his colleagues attempted to address one of the biggest problems with studying the trend. Most of the previous investigations compared younger fathers and their children to different older fathers and their offspring. “That’s comparing apples and oranges,” says D’Onofrio. “We know young fathers and old fathers vary on many things.”

So his team turned to birth registry data from Sweden and compared children born to the same fathers, evaluating the siblings on various mental health and academic measures. The study included 2.6 million children born to 1.4 million fathers.

What they found surprised them – so much so that they spent about two months re-evaluating the data to make sure their numbers were correct. While the previous genetic study found that an older father’s DNA may account for about 15% of autism cases, D’Onofrio’s group found that the increased risk for children of fathers older than 45 years soared to 3.5 times compared to that of younger fathers. Children of older fathers also showed a 13 fold higher risk of developing attention deficit-hyperactivity disorder (ADHD), a 25 times greater chance of getting bipolar disorder, and twice the risk of developing a psychosis. These kids also had doubled risk of having a substance abuse problem and a 60% higher likelihood of getting failing grades in school compared with those with younger fathers.

MORE: Too Old to Be a Dad?

“What this study suggests is that the specific effect of older paternal age may actually be worse than we originally thought,” says D’Onofrio.

The scientists controlled for some of the well-known factors that can account for poor grades and psychoses and mental illnesses, such as the child’s birth order, the mother’s age, the mother’s and father’s education level, their history of psychiatric problems, and their history of criminality. Even after adjusting for these possible effects, they still found a strong correlation between higher rates of mental illness among younger siblings compared with their older ones.

The 2012 genetic study pointed to a possible reason for the higher rates of mental illnesses – because genetic mutations tend to accumulate each time a cell divides, older men may build up more spontaneous, or de novo, changes each time the sperm’s DNA is copied. While a 25-year-old father may pass on an average of 25 mutations to his child, a 40-year-old dad may bequeath each offspring as many as 65; the researchers calculated that the de novo mutation rate doubled with every 16.5 years of the father’s age. In contrast, regardless of her age, a mother tends to pass on about 15 mutations via her eggs.

The findings still need to be repeated by other groups, but the large sample size and the careful way that the researchers designed the study – to analyze the same fathers over time – suggest that the association is significant and worth considering for those who put off having a family. “This study suggests that paternal age does need to be considered as one of many risk factors associated with children’s mental health,” says D’Onofrio.

MORE: Fewer Drugs Being Prescribed to Treat Mental Illness Among Kids

Whether it gains the same amount of weight that maternal age does in family planning decisions isn’t clear yet, but even if it is confirmed, he notes that the correlation doesn’t predict that every child born to an older father will develop a mental illness. Older parents also have protective factors against these disorders, including more maturity and financial and social stability, that can offset some of the effect.

TIME Drugs

Tylenol During Pregnancy Linked to Higher Risk of ADHD

Moms-to-be who relieve pain with acetaminophen may be setting their children up for hyperactivity

Pregnancy is already a fraught time for expectant moms, as more research shows how quickly the foods that women eat, the air they breathe and the compounds to which they are exposed can traverse the placenta and affect their growing child. Now there’s another thing to add to the growing list of agents — including tobacco from cigarettes, mercury from fish, and alcohol — that may affect their babies’ development.

In a study published in JAMA Pediatrics, an international group of researchers led by Dr. Jorn Olsen, at the University of Aarhus, in Denmark, found a strong correlation between acetaminophen (found in common painkillers like Tylenol) use among pregnant women and the rate of attention-deficit/hyperactivity disorder (ADHD) diagnoses and prescriptions for ADHD medications in their children. Overall, moms who used the pain reliever to treat things like headaches or to reduce fevers saw a 37% increased risk in their kids receiving an ADHD diagnosis and a 29% increased risk in the chances that their kids needed ADHD medications compared with moms who didn’t use the over-the-counter medication at all.

(MORE: Majority of Doctors Do Not Follow Treatment Guidelines for ADHD)

Even after the team accounted for factors that could explain the connection, like why the mom needed to take the drug in the first place, the link remained strong, suggesting that there is something specific about the drug, and how it affects fetal development, that might explain the higher risk of behavioral issues.

The findings are especially troubling since more than half of the 64,322 women in the study reported using acetaminophen in the three months prior to the survey. The participants included mothers and singleton children born in Denmark between 1996 and 2002 and registered in the Danish National Birth Cohort, so it included a diverse group of mothers from different social and environmental backgrounds. The study also evaluated hyperactivity on three different levels — from symptom reports by mothers or caregivers, hospital diagnoses and prescriptions to treat ADHD. Higher acetaminophen use among mothers was linked to higher rates of all three outcomes in their children.

(MORE: Men Diagnosed With Childhood ADHD Struggle More With Jobs, Relationships)

“[The results] are worrisome because more than 50% of the women took acetaminophen; it’s an over-the-counter drug and they can freely buy, and use it at their discretion,” says Dr. Beate Ritz, one of the co-authors and chair of the Department of Epidemiology at the UCLA Fielding School of Public Health. “It’s considered relatively safe, and maybe it’s not.”

Previous studies have raised concerns about acetaminophen; both animal and human works have shown that the drug can interfere with hormone systems, so prenatal exposure may adversely affect development of the brain. Some studies showed the drug hampers the ability of the testes to descend during development as well. “Pregnancy is a very special period,” says Ritz. “Acetaminophen may not harm adults in any other way, but fetal development is special.”

(MORE: New ADHD Guidelines Include Kids as Young as 4)

The latest investigations from the neuroscientists studying developmental and behavioral disorders like autism and ADHD suggest that problems in the connection between different brain regions may contribute to the symptoms of these conditions, and hormone disruptions in utero, triggered by acetaminophen, may unbalance the brain enough to make certain children more vulnerable to autism or hyperactivity later in life.

The results are likely to launch waves of questions about how safe the drug is for pregnant women to take. Kate Langley, a lecturer in the School of Psychology at Cardiff University, in Wales, who wrote an accompanying editorial for the study, cautions that the findings only suggest an association, and do not establish that acetaminophen causes ADHD. “This is an interesting research paper, but it is way too early for it to inform our clinical practice at the moment,” she says.

Some women have a medical need to take acetaminophen, and they should continue to talk to their doctors about this latest risk. But for those who turn to the over-the-counter remedy for less medically urgent needs, such as relieving a headache or the pain of sore muscles, they should have a different kind of discussion with their doctors about the possible risks that the drug poses for their unborn child.

(MORE: Common Painkiller Use May Be Linked to Miscarriage Risk)

Ritz says more studies are needed using different sets of data to confirm and replicate what she and her colleagues found. But she appreciates how difficult it might be for expectant moms, or women who plan on having children soon, to wait for those studies to be completed. “As a scientist, I never want to be alarmist and use one study [to make clinical decisions],” she says. “But as a woman, when I see something like that, I would be worried, and wouldn’t take Tylenol during pregnancy any more.”

She says that women who need to take a pain reliever or need to control their fever should consider other alternatives, such as getting more rest or even gritting through the episode if they are especially worried about what their developing child might be exposed to. If more studies verify the potential harms on developing brains, it might also fall to regulatory agencies like the Food and Drug Administration to rethink the label of acetaminophen and warn users to avoid the medication during pregnancy.

TIME Environmental Health

Children Exposed to More Brain-Harming Chemicals Than Ever Before

A new report finds the number of chemicals contributing to brain disorders in children has doubled since 2006

In recent years, the prevalence of developmental disorders such as autism, attention-deficit/hyperactivity disorder (ADHD) and dyslexia have soared. While greater awareness and more sophisticated diagnoses are partly responsible for the rise, researchers say the changing environment in which youngsters grow up may also be playing a role.

In 2006, scientists from the Harvard School of Public Health and the Icahn School of Medicine at Mount Sinai identified five industrial chemicals responsible for causing harm to the brain — lead, methylmercury, polychlorinated biphenyls (found in electric transformers, motors and capacitors), arsenic (found in soil and water as well as in wood preservatives and pesticides) and toluene (used in processing gasoline as well as in paint thinner, fingernail polish and leather tanning). Exposure to these neurotoxins was associated with changes in neuron development in the fetus as well as among infants, and with lower school performance, delinquent behavior, neurological abnormalities and reduced IQ in school-age children.

(MORE: A Link Between Pesticides and Attention Disorders?)

Now the same researchers have reviewed the literature and found six additional industrial chemicals that can hamper normal brain development. These are manganese, fluoride, chlorpyrifos, dichlorodiphenyltrichloroethane, tetrachloroethylene and polybrominated diphenyl ethers. Manganese, they say, is found in drinking water and can contribute to lower math scores and heightened hyperactivity, while exposure to high levels of fluoride from drinking water can contribute to a seven-point drop in IQ on average. The remaining chemicals, which are found in solvents and pesticides, have been linked to deficits in social development and increased aggressive behaviors.

The research team acknowledges that there isn’t a causal connection between exposure to any single chemical and behavioral or neurological problems — it’s too challenging to isolate the effects of each chemical to come to such conclusions. But they say the growing body of research that is finding links between higher levels of these chemicals in expectant mothers’ blood and urine and brain disorders in their children should raise alarms about how damaging these chemicals can be. The developing brain in particular, they say, is vulnerable to the effects of these chemicals, and in many cases, the changes they trigger are permanent.

“The consequence of such brain damage is impaired [central nervous system] function that lasts a lifetime and might result in reduced intelligence, as expressed in terms of lost IQ points, or disruption in behavior,” they write in their report, which was published in the journal Lancet Neurology.

They point to two barriers to protecting children from such exposures — not enough testing of industrial chemicals and their potential effect on brain development before they are put into widespread use, and the enormous amount of proof that regulatory agencies require in order to put restrictions or limitations on chemicals. Most control of such substances, they note, occurs after negative effects are found among adults; in children, the damage may be more subtle, in the form of lower IQ scores or hyperactivity, that might not be considered pathological or dangerous. “Our very great concern is that children worldwide are being exposed to unrecognized toxic chemicals that are silently eroding intelligence, disrupting behaviors, truncating future achievements and damaging societies, perhaps most seriously in developing countries,” they write. “A new framework of action is needed.”

Your browser, Internet Explorer 8 or below, is out of date. It has known security flaws and may not display all features of this and other websites.

Learn how to update your browser