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Have Researchers Found What Causes Autism, Even How to Prevent It?

3.5 million Americans have ASD today, and the rate has been increasing since the year 2000. Experts aren’t sure why. But a new study offers insights on how autism develops and what might be done to prevent it. 

 

Girl with autism by herself.
A Girl with autism by herself while children nearby play together. Social isolation is typical of ASD

One in 68 children today have autism spectrum disorder (ASD). That equates to about 3.5 million Americans. What’s more, the rate of children born with autism has increased significantly since the year 2000. Prevalence has gone from 6% of all births in 2002 to 15% in 2010. Boys are far more likely than girls to develop autism, and Caucasians more prone than Hispanics or African-Americans.


The condition is typified with speaking later than normal children or having trouble with speech, difficulty grasping abstract concepts, and a lack of social skills. Social anxiety and social immaturity are common as well. This is a wide and varied spectrum, running from those with an ever so slight deficit — some of the strongest minds of Silicon Valley are said to have ASD — to those who are severely disabled.

Experts say the best thing to do with children who are nonverbal at age two or three is to look into early intervention. Most children are diagnosed late, by age four. But autism can be diagnosed as early as 18 months. There is no medical test. The doctor merely evaluates the child through behavior and development assessments. The earlier a child is diagnosed, the better off they are.

Unfortunately, no one knows what causes it or why it has become more prevalent. But a new study may have discovered the origins of autism, and perhaps what can be done to prevent it. Researchers at Baylor College of Medicine hypothesized that the absence of a certain gut bacteria might be causing autism-like behavior in mice.  

Mauro Costa-Mattioli was the senior author of this study. He is a neuroscientist at the college. New findings on the microbiome—thousands of colonies of bacteria which inhabit the gut, suggest that they may have more to do with brain chemistry than we realize. Studies have shown how different kinds of beneficial gut bacteria influence different body systems such as digestion, brain chemistry, the immune system, metabolism, and so many others.

On another front, epidemiological studies show that during pregnancy, maternal obesity increases the risk of ASD. Babies adopt their mother’s microbiome during childbirth. The so-called obesity epidemic, which began to take off in 2000, could explain the rate of autism’s increase, as they have had a similar trajectory. In yet another study, obesity itself was linked to the lack of a crucial gut bacteria. In fact, those with ASD often report chronic gastrointestinal symptoms, which are also common in those whose microbiome has been depleted.

For the Baylor College team to test their theory, researchers fed a number of pregnant mice a high-fat diet several times a day, and another group a normal one. Next, they used gene sequencing to discover what the bacterial composition of each mouse’s gut was. According to first author Shelly Buffington, the two groups had remarkably different microbiomes. She’s a postdoctoral fellow at the university. Buffington said, "The sequencing data was so consistent that by looking at the microbiome of an individual mouse we could predict whether its behavior would be impaired."

Artist’s rendition of helpful gut bacteria. 

60 female mice were fed a high fat diet several times a day. This was the equivalent to eating fast food every day for lunch and dinner. The mice were then bred twice daily. Once born, the offspring stayed with the mother for three weeks. Afterward, they were weaned onto a healthy diet. After a month, the offspring showed behavioral deficits.

Next, the microbiomes of the offspring were tested. Since mice routinely eat each other’s feces, researchers found that impaired mice, who were three weeks old, quickly acquired the gut bacteria of their neighbors by week four, and started to lose their tendency toward social isolation. From there, researchers wondered which bacteria exactly helped normalize social behavior. Fecal-transplant therapy in those who displayed social deficits saw symptoms lessen or evaporate.

Following that, the research team wanted to know exactly which gut bacteria was responsible. To do so, they performed a “whole-genome shotgun sequencing.” They found that gut bacteria was nine times scarcer in mice born to a mother who ate a high-fat diet. Then they identified it, the specific bacteria who absence may cause autism, Lactobacillus reuteri.

 

Model of gut bacteria L. reuteri.

They cultured the bacteria, and introduced it into the water of socially deficient mice. Researchers found that with this single strain, social behavior improved dramatically. Even so, other symptoms such as anxiety were not alleviated. Looking into it further, they found that L. reuteri promoted the production of oxytocin. Known as the bonding hormone, oxytocin plays a major role in humans, helping mothers bond to newborns and men and women to each other, when falling in love. It is also known to play a role in the social behavior associated with autism.

Researchers surmise that the reward system of the brain is where ASD-related social impairment originates. They also believe that restoring the gut bacteria responsible for oxytocin promotion helps to normalize synaptic function in that area of the brain. Though mice are admittedly far different from humans, since it was a human bacterial species that restored the mice, researchers believe that a probiotic therapy may treat neurodevelopmental disorders, such as ASD. Costa-Mattioli said he has a gut feeling about it.

To learn more about ASD click here: 

Radical innovation: Unlocking the future of human invention

Ready to see the future? Nanotronics CEO Matthew Putman talks innovation and the solutions that are right under our noses.

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Your body’s full of stuff you no longer need. Here's a list.

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Quantum particles timed as they tunnel through a solid

A clever new study definitively measures how long it takes for quantum particles to pass through a barrier.

Image source: carlos castilla/Shutterstock
  • Quantum particles can tunnel through seemingly impassable barriers, popping up on the other side.
  • Quantum tunneling is not a new discovery, but there's a lot that's unknown about it.
  • By super-cooling rubidium particles, researchers use their spinning as a magnetic timer.

When it comes to weird behavior, there's nothing quite like the quantum world. On top of that world-class head scratcher entanglement, there's also quantum tunneling — the mysterious process in which particles somehow find their way through what should be impenetrable barriers.

Exactly why or even how quantum tunneling happens is unknown: Do particles just pop over to the other side instantaneously in the same way entangled particles interact? Or do they progressively tunnel through? Previous research has been conflicting.

That quantum tunneling occurs has not been a matter of debate since it was discovered in the 1920s. When IBM famously wrote their name on a nickel substrate using 35 xenon atoms, they used a scanning tunneling microscope to see what they were doing. And tunnel diodes are fast-switching semiconductors that derive their negative resistance from quantum tunneling.

Nonetheless, "Quantum tunneling is one of the most puzzling of quantum phenomena," says Aephraim Steinberg of the Quantum Information Science Program at Canadian Institute for Advanced Research in Toronto to Live Science. Speaking with Scientific American he explains, "It's as though the particle dug a tunnel under the hill and appeared on the other."

Steinberg is a co-author of a study just published in the journal Nature that presents a series of clever experiments that allowed researchers to measure the amount of time it takes tunneling particles to find their way through a barrier. "And it is fantastic that we're now able to actually study it in this way."

Frozen rubidium atoms

Image source: Viktoriia Debopre/Shutterstock/Big Think

One of the difficulties in ascertaining the time it takes for tunneling to occur is knowing precisely when it's begun and when it's finished. The authors of the new study solved this by devising a system based on particles' precession.

Subatomic particles all have magnetic qualities, and they spin, or "precess," like a top when they encounter an external magnetic field. With this in mind, the authors of the study decided to construct a barrier with a magnetic field, causing any particles passing through it to precess as they did so. They wouldn't precess before entering the field or after, so by observing and timing the duration of the particles' precession, the researchers could definitively identify the length of time it took them to tunnel through the barrier.

To construct their barrier, the scientists cooled about 8,000 rubidium atoms to a billionth of a degree above absolute zero. In this state, they form a Bose-Einstein condensate, AKA the fifth-known form of matter. When in this state, atoms slow down and can be clumped together rather than flying around independently at high speeds. (We've written before about a Bose-Einstein experiment in space.)

Using a laser, the researchers pusehd about 2,000 rubidium atoms together in a barrier about 1.3 micrometers thick, endowing it with a pseudo-magnetic field. Compared to a single rubidium atom, this is a very thick wall, comparable to a half a mile deep if you yourself were a foot thick.

With the wall prepared, a second laser nudged individual rubidium atoms toward it. Most of the atoms simply bounced off the barrier, but about 3% of them went right through as hoped. Precise measurement of their precession produced the result: It took them 0.61 milliseconds to get through.

Reactions to the study

Scientists not involved in the research find its results compelling.

"This is a beautiful experiment," according to Igor Litvinyuk of Griffith University in Australia. "Just to do it is a heroic effort." Drew Alton of Augustana University, in South Dakota tells Live Science, "The experiment is a breathtaking technical achievement."

What makes the researchers' results so exceptional is their unambiguity. Says Chad Orzel at Union College in New York, "Their experiment is ingeniously constructed to make it difficult to interpret as anything other than what they say." He calls the research, "one of the best examples you'll see of a thought experiment made real." Litvinyuk agrees: "I see no holes in this."

As for the researchers themselves, enhancements to their experimental apparatus are underway to help them learn more. "We're working on a new measurement where we make the barrier thicker," Steinberg said. In addition, there's also the interesting question of whether or not that 0.61-millisecond trip occurs at a steady rate: "It will be very interesting to see if the atoms' speed is constant or not."

Self-driving cars to race for $1.5 million at Indianapolis Motor Speedway ​

So far, 30 student teams have entered the Indy Autonomous Challenge, scheduled for October 2021.

Illustration of cockpit of a self-driving car

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  • The Indy Autonomous Challenge will task student teams with developing self-driving software for race cars.
  • The competition requires cars to complete 20 laps within 25 minutes, meaning cars would need to average about 110 mph.
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Mind & Brain

The dangers of the chemical imbalance theory of depression

A new Harvard study finds that the language you use affects patient outcome.

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