TIME neuroscience

How Air Pollution Affects Babies in the Womb

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A new study finds evidence that prenatal exposure to common pollutants can contribute to hyperactivity, aggression and more in kids

It makes sense that an expectant mom’s exposure to pollutants in the air can affect her still-growing baby’s lungs and respiratory system. But there’s increasing evidence that such compounds can also harm brain development and contribute to behavioral and cognitive problems later in childhood.

In the latest study on the subject, published in JAMA Psychiatry, researchers for the first time pinpointed exactly which areas of the brain are affected if a baby is exposed to car exhaust and the byproducts of burning home heating oil. These polycyclic aromatic hydrocarbons (PAHs) have previously been linked to developmental delays, lower verbal IQ. signs of anxiety depression and problems with attention. But researchers haven’t been able to identify which areas of the brain are most vulnerable.

MORE: Children Exposed to More Brain-Harming Chemicals Than Ever Before

In this study, they recruited 40 mothers and their children living in the inner city who were participating in an ongoing study of pollution’s effect on development. They were selected because they had low exposure to environmental factors other than PAHs that could affect development, such as tobacco smoke, lead, insecticides and other chemicals. Based on measurements of PAH in their surroundings, about half of the mothers had PAH exposures below the median of those in the larger group, and half had PAH exposures higher than the median.

“The effects were extraordinarily powerful,” says Dr. Bradley Peterson, director of the Institute for the Developing Mind at Children’s Hospital Los Angeles and lead author of the study. “The more prenatal exposure to PAH, the bigger the white matter problems the kids had. And the bigger the white matter problems, the more severe symptoms of ADHD, aggression and slow processing they had on cognitive tasks.”

MORE: Mom’s Exposure to Air Pollution Can Increase Kids’ Behavior Problems

White matter is made up of the fibrous connections between nerve cells and is critical to helping neurons from one part of the brain communicate with their counterparts in other regions, and the babies with the highest exposure to PAH in the womb showed a dramatically lower volume of white matter in the left side of their brains. The entire left hemisphere, from the front to the back, was affected. “You would assume that an environmental exposure brought in by the blood and circulating to the brain would affect both sides of the brain,” says Peterson. “But the adverse effects of PAHs is located on one side; that’s surprising.”

The asymmetrical effect speaks volumes about how PAHs target brain tissue. Like other neurotoxins, they may preferentially seek out actively developing tissue. During gestation, the left side of the brain, which houses language capabilities, may be undergoing more intense structural changes in preparation for birth. This was supported by the fact that in the larger group of children in the study, those who were exposed to PAHs around age five didn’t show the same left-sided bias; in the older children, the pollutants affected both sides equally because the right hemisphere of the brain is undergoing active development at that time as well.

MORE: ADHD Linked to the Air Pregnant Women Breathe

Peterson suspects that the connection between PAHs and later behavioral and cognitive symptoms such as inattention, hyperactivity and slow processing speed may be due to how PAHs disrupt the normal communication between nerves in the left side of the brain and elsewhere.

The problem, he admits, is that moms-to-be can’t easily change where they live or work. And most people aren’t aware of how many PAHs they absorb on a daily basis. There are ways to minimize the risk of exposure, however. Expectant mothers can avoid secondhand smoke, a major source of the compounds. Not directly inhaling exhaust from cars on busy streets or smoke from fireplaces can also help, as can spending as much time as possible in parks or other areas free of burning fuels. It won’t eliminate the risk from living in an inner city and being surrounded by car emissions, but it can help, Peterson says. “Even if you can reduce your exposure from moderately high to moderate levels, it’s going to have a beneficial effect on the developing fetus,” he says.

TIME neuroscience

Your Brain Learns New Words By Seeing Them Not Hearing Them

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To be a really proficient reader, it’s not enough to “hear” words. You also have to see them

We start to talk before we can read, so hearing words, and getting familiar with their sounds, is obviously a critical part of learning a language. But in order to read, and especially in order to read quickly, our brains have to “see” words as well.

At least that’s what Maximilian Riesenhuber, a neuroscientist at Georgetown University Medical Center, and his colleagues found in an intriguing brain-mapping study published in the Journal of Neuroscience. The scientists recruited a small group of college students to learn a set of 150 nonsense words, and they imaged their brains before and after the training.

Before they learned the words, their brains registered them as a jumble of symbols. But after they were trained to give them a meaning, the words looked more like familiar words they used every day, like car, cat or apple.

MORE: Mistakes to Avoid When Learning a Foreign Language

The difference in way the brain treated the words involved “seeing” them rather than sounding them out. The closest analogy would be for adults learning a foreign language based on a completely different alphabet system. Students would have to first learn the new alphabet, assigning sounds to each symbol, and in order to read, they would have to sound out each letter to put words together.

In a person’s native language, such reading occurs in an entirely different way. Instead of taking time to sound out each letter, the brain trains itself to recognize groups of letters it frequently sees together — c-a-r for example — and dedicates a set of neurons in a portion of the brain that activates when these letters appear.

In the functional MRI images of the volunteers’ brains, that’s what Riesenhuber saw. The visual word form area, located in the left side of the visual cortex, is like a dictionary for words, and it stores the visual representation of the letters making up thousands of words. This visual dictionary makes it possible to read at a fast pace rather than laboriously sounding out each letter of each word every time we read. After the participants were trained to learn the meaningless words, this part of their brains was activated.

MORE: An Infant’s Brain Maps Language From Birth, Study Says

“Now we are seeing words as visual objects, and phonetics is not involved any more,” he says. “We recognize the word as a chunk so we go directly from a visual pattern to the word’s meaning, and we don’t detour to the auditory system.”

The idea of a visual dictionary could also help researchers to better understanding reading or learning disorders like dyslexia. More research could reveal whether the visual word form area in people with such disabilities is different in any way, or whether they tend to read via more auditory pathways. “I helps us understand in a general way how the brain learns, the fastest way of learning, and how to build on prior learning,” says Riesenhuber.

TIME Innovation

Five Best Ideas of the Day: March 12

The Aspen Institute is an educational and policy studies organization based in Washington, D.C.

1. Protecting whistleblowers protects national security.

By Mike German at the Brennan Center for Justice

2. Could we treat pain by switching off the region of the brain controlling that feeling?

By the University of Oxford

3. Small businesses are booming in China, and it might save their economy.

By Steven Butler and Ben Halder in Ozy

4. Not so fast: Apps using Apple’s new health technology could require FDA approval. That doesn’t come quick.

By Jonathan M. Gitlin in Ars Technica

5. We might feel better about driving electric cars, but they’re still not good for the environment.

By Bobby Magill in Quartz

The Aspen Institute is an educational and policy studies organization based in Washington, D.C.

TIME Ideas hosts the world's leading voices, providing commentary and expertise on the most compelling events in news, society, and culture. We welcome outside contributions. To submit a piece, email ideas@time.com.

TIME neuroscience

Teen Pot Smokers Have More Memory Damage, Study Says

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Chronic pot smoking may alter the shape of a region in the brain involved in memories

Smoking marijuana as a teenager can harm long-term memory, a new study suggests.

In the new research, published in the journal Hippocampus, researchers at Northwestern University Feinberg School of Medicine looked at 97 people and found that those who smoked marijuana every day for about three years performed worse on long-term memory assessments. A region of their brain associated with long-term memory—the hippocampus—also looked abnormal in an MRI.

“We focused on the brains of young adults who were teenagers when they began abusing cannabis,” says study author Matthew J. Smith, an assistant professor in the department of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine. “We were interested in evaluating whether former cannabis abusers were characterized by differences in brain anatomy and memory performance after a period of abstinence.”

The researchers found that young adults in their 20s who were heavy marijuana smokers in their teenage years scored 18% worse on long-term memory tests that assessed their ability to code, file and recall memories, compared to young adults who had never smoked marijuana. The longer the person’s history of marijuana use, the more the shape of their hippocampus looked altered.

“The generalization we can make is that the greater the differences in the hippocampus shape associated with cannabis, the poorer the participants performed on the memory assessment,” says Smith.

The researchers also looked specifically at marijuana smokers with schizophrenia and found that they scored about 26% worse than the people with the disorder who did not smoke marijuana when they were younger.

According to Smith, components in marijuana can interfere with receptors in the brain that can impair brain chemistry and possibly impact the brain structure. This change, he says, could be what’s causing memory issues.

The study is still preliminary, since its sample size is small and the researchers only looked at one point in time. The hippocampus could also have changed before a young person started heavily using marijuana, the study authors acknowledge, which could make them more susceptible to the memory-related effects. Still, Smith says, the study suggests that smoking as a teen may not be benign for the developing brain.

TIME neuroscience

A Drug Has Been Found That Reverses a Precursor to Alzheimer’s

Researchers now want to proceed to substantial clinical trials

Researchers at John Hopkins University have found that low doses of a drug more commonly used to treat epilepsy can reverse a condition that increases the risk of developing Alzheimer’s disease.

According to statements issued Wednesday, the epilepsy drug, called antiepileptic levetiracetam, calms hyperactivity in the brain — a well-documented symptom of people with amnestic mild cognitive impairment, which is a condition that heightens the possibility of developing Alzheimer’s disease.

The team, lead by neuroscientist Michela Gallagher, now wants to pursue substantial clinical trials.

“What we want to discover now, is whether treatment over a longer time will prevent further cognitive decline and delay or stop progression to Alzheimer’s dementia,” Gallagher said.

The researchers studied 84 people with an average age of 70. Participants received various doses of the drug, as well as a placebo, and the scientists used imaging technology to map brain activity.

TIME neuroscience

Alzheimer’s Protein Found in Young Brains for the First Time

The brain-damaging protein in Alzheimer’s disease may start accumulating as early as in our 20s

For the first time, scientists have found evidence of a protein found in Alzheimer’s disease, called amyloid, in the brains of people as young as 20.

In a report published in the journal Brain, Changiz Geula, a professor at the Cognitive Neurology and Alzheimer’s Disease Center at Northwestern University Feinberg School of Medicine, reveals that the protein—which gradually builds up and forms sticky plaques in the brain in Alzheimer’s disease—starts appearing early in life. Amyloid is normally made by the brain and has important functions; it’s an antioxidant and promotes the brain’s ability to remain adaptable by forming new connections and reinforcing old ones, especially those involving memory. But in some people, the proteins start to clump together with age, forming sticky masses that interfere with normal nerve function. Eventually, these masses kill neurons by starving them of their critical nutrients and their ability to communicate with other cells.

MORE: New Research on Understanding Alzheimer’s

When Geula compared the autopsy brains from normal people between ages 20-66 years, older people without dementia between 70-99 years, and people with Alzheimer’s between 60-95 years, they found evidence of amyloid in a particular part of the brain in all of them. That region isn’t normally studied in Alzheimer’s, but it plays roles in memory and attention.

The results show that the process responsible for causing Alzheimer’s begins as early as in the 20s, and it also pointed to a population of cells that are especially vulnerable to accumulating amyloid—essentially serving as a harbinger of future disease. “There is some characteristic of these neurons that allows amyloid to accumulate there more than in other neurons,” says Geula. “At least in this cell population, the machinery to form aggregates is there.” Reducing the amount of amyloid in the brains of young people might help halt the formation of Alzheimer’s, he says.

MORE: This Alzheimer’s Breakthrough Could Be a Game Changer

Because the study involved autopsy specimens, there’s no way to tell whether those younger individuals would have gone on to develop Alzheimer’s. But they provide a clue about the early steps behind the disease.

They may also shed light on one way to prevent, or at least minimize, the effects of Alzheimer’s. Experts currently believe that the memory-robbing condition occurs when the balance between the production of amyloid and processes that clear the protein from the brain veer out of balance with age. As more amyloid is left in the brain, it tends to become stickier and adhere to other amyloid fragments, eventually forming damaging plaques. Geula believes that even in people with a genetic predisposition to forming these sticky plaques, removing amyloid as early as possible can slow down the progression of the disease. While there aren’t any effective ways to do this yet, there are promising compounds currently being tested in clinical trials. And given Geula’s findings, those studies become even more critical as a way to help more people to treat and even prevent the disease.

MORE: New Test May Predict Alzheimer’s 10 Years Before Diagnosis

The key, as the findings show, is to start early. “If you can get rid of the background [amyloid], then it can’t do anything,” says Geula.

TIME neuroscience

Three Guys in Austria Have Basically Become Cyborgs After Getting Robotic Hands

The bionic hand allows the patients to perform everyday activities

Robotic hands have been successfully attached to three amputees in Austria, using a new technique that allows the users to control their electronic limbs with their minds.

The operations were completed by using an innovative procedure called bionic reconstruction, which connects prostheses directly to a patient’s nerves, according to a study in British medical journal The Lancet.

The procedure first involves intense cognitive training to prepare the body and mind for the advanced robotic prosthesis, followed by elective amputation and replacement. Once attached, the bionic hand allows all three patients to perform everyday activities, like using kitchen utensils and opening doors.

“So far, bionic reconstruction has only been done in our center in Vienna,” said Professor Oskar Aszmann from the Medical University of Vienna. “However, there are no technical or surgical limitations that would prevent this procedure from being done in centers with similar expertise and resources.”

[Science Daily]

TIME neuroscience

A Simple Skin Test May Detect Alzheimer’s

There’s new hope that the first signs of these brain disorders may lie in the skin

Detecting Alzheimer’s and Parkinson’s diseases as early as possible is critical. But while doctors know that the conditions can start 15 to 20 years before the symptoms appear, there aren’t many reliable ways of pinpointing exactly when that occurs. Now, scientists led by Dr. Ildefonso Rodriguez-Leyva at Central Hospital in University of San Luis Potosi in Mexico report that the skin may hold the clue to such early detection.

MORE Early Warning: Detecting Alzheimer’s in the Blood and Brain Before Memory Loss

In a study that will be presented in April at the American Academy of Neurology’s annual meeting in Washington, D.C., Rodriguez-Leyva found that compared to healthy patients and those with age-related dementia, patients with Alzheimer’s and Parkinson’s diseases had seven times higher levels of an altered form of a protein called tau in skin biopsies, and Parkinson’s patients also showed seven to eight times greater levels of a harmful version of another protein known as alpha-synuclein. Researchers aren’t sure what alpha-synuclein’s role is in the brain, but in Parkinson’s patients, it tends to clump into harmful aggregates that interrupt normal nerve function. Tau is involved in the brain decline associated with Alzheimer’s; as nerve cells die, the normally aligned molecules of tau, which function like railroad tracks to transport nutrients, collapse, twisting into unorganized masses of tangled protein.

“This skin test opens the possibility to see abnormal proteins in the skin before central nervous system symptoms — cognitive or motor deficits — appear,” Rodriguez-Leyva says.

MORE New Research on Understanding Alzheimer’s

Rodriguez-Leyva turned to the skin to look for signs of the altered brain proteins since the skin and brain share a common embryonic origin; while everyone makes the two proteins, those who go on to develop Alzheimer’s or Parkinson’s seem to be especially vulnerable to having them fold in abnormal ways and stick together in damaging masses in the brain. If there were genetic signals dictating these sticky forms of the proteins, he speculated, then those signals might be detectable in the skin as well. “The ectoderm originates the nervous tissue and the skin,” he writes in an email to TIME discussing the study. “Our idea is that they have a similar program of protein expression. Therefore the skin could reflect events taking place in the nervous system.”

MORE New Test May Predict Alzheimer’s 10 Years Before Diagnosis

The study involved only a few dozen patients — 20 with Alzheimer’s, 16 Parkinson’s patients and 17 with age-related dementia, who were compared to 12 healthy controls — so more work needs to be done to confirm the findings. But the results hint that it may be possible to detect these neurodegenerative conditions sooner, and it also provides drug developers with more confidence that targeting abnormal forms of tau and alpha-synuclein may lead to effective treatments.

Read next: America’s Pain Killer Problem is Growing, Federal Data Shows

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TIME Aging

Famed Scientist Oliver Sacks Reveals He Has Terminal Cancer in Soulful Op-Ed

The Music Has Power Awards Benefit
Brad Barket—Getty Images Dr. Oliver Sacks speaks at the Music Has Power Awards Benefit in the Allen Room at the Frederick P. Rose Hall, Home of Jazz at Lincoln Center on Nov. 6, 2006 in New York City.

The neurologist and author writes in the New York Times that he feels "intensely alive" in the face of death

Oliver Sacks, one of the leading public intellectuals of the last half-century, says terminal cancer of the liver has left him with only months to live.

Sacks, a neurologist and author of books like Awakenings and The Man Who Mistook his Wife for a Hat, revealed his condition in an article about facing death that was published in the New York Times on Thursday.

“It is up to me now to choose how to live out the months that remain to me,” Sacks, 81, writes in the Times. “I have to live in the richest, deepest, most productive way I can.”

He says he will shun politics and nightly news to focus instead on himself, his friends, and his work–an autobiography is set to come out in the spring, and he says he has “several” other books in the works. He writes:

This is not indifference but detachment — I still care deeply about the Middle East, about global warming, about growing inequality, but these are no longer my business; they belong to the future. I rejoice when I meet gifted young people — even the one who biopsied and diagnosed my metastases. I feel the future is in good hands.

I have been increasingly conscious, for the last 10 years or so, of deaths among my contemporaries. My generation is on the way out, and each death I have felt as an abruption, a tearing away of part of myself. There will be no one like us when we are gone, but then there is no one like anyone else, ever. When people die, they cannot be replaced. They leave holes that cannot be filled, for it is the fate — the genetic and neural fate — of every human being to be a unique individual, to find his own path, to live his own life, to die his own death.

Born in the U.K., Sacks has spent most of his career in the United States, where his prolific writing has blended science and literature to best-selling success. Outside of work, he’s been nearly as active. A one-time weightlifting champion with a stint riding with Hell’s Angel’s—according to a 1995 profile in TIME—he says he still swims a mile a day.

The removal of a tumor in his eye left him blind in one eye nine years ago and led to his 2010 book ‘The Mind’s Eye’ that deals in part with his experience with cancer and his inability to recognize faces. But the tumor metastasized, and the author now says the cancer’s spread cannot be stopped.

“I feel intensely alive, and I want and hope in the time that remains to deepen my friendships, to say farewell to those I love, to write more, to travel if I have the strength, to achieve new levels of understanding and insight,” he writes.

Read Oliver Sacks’s story in the New York Times.

Read next: The Secret of Abraham Lincoln’s Success as a Writer?

Listen to the most important stories of the day.

TIME public health

Even More Bad News For Young Football Players

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Former NFL players performed below expectations for their age groups on cognitive assessments

Professional football players who began playing tackle football before age 12 experienced more dramatic cognitive decline as adults than their counterparts who begin playing later in life, found a new study in the journal Neurology. Overall, former NFL players in the study performed below expectations for their age groups on cognitive assessments.

“As a society we need to question whether we should sanction and condone allowing our children at a young age to having their brains be jostled about inside their skulls hundreds of times per season,” says study author Robert A. Stern, a professor at Boston University.

The study tested 42 former NFL players who were experiencing brain function issues on their ability to remember a list of words, solve problems requiring mental flexibility and read and pronounce uncommon words. Athletes who began playing before age 12 performed significantly worse than their late-starting counterparts on all measures.

MORE: The Tragic Risks of American Football

The results challenge a common misconception that young people are likely fine if they aren’t experiencing full-blown concussions or dramatic injuries. Repeated hits sustained by children under 12, even if they’re not traumatic, may also affect the brain’s structure and function, the study suggests.

“For me, the biggest concern in long-term consequences is not concussion, but rather sub-concussive exposure,” says Stern. “We need to continue anything and everything possible to reduce the number of hits.”

Stern describes the findings as “robust” but noted the study’s limitations. For one, focusing solely on NFL players makes it impossible to generalize the findings to all athletes, or even all football players. Still, he says, the notion that tackle football poses the risk of brain damage just makes “logical sense.”

MORE: Football Head Impacts Can Cause Brain Changes Even Without Concussion

The study, released just days before the Super Bowl, adds to a growing body of evidence on the dangers of the sport, particularly for young people. A 2012 Virginia Tech study, for instance, tracked accelerometers in the helmets of youth football players ages 7 and 8 and found that the average player received 107 impacts throughout the course of the season, some at speeds equivalent to a car accident. Parents have responded to the mounting research by questioning whether their kids should play the sport at all. Between 2007 and 2013, the number of children ages 6 to 12 playing tackle football declined by more than 25%.

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