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: 

A landslide is imminent and so is its tsunami

An open letter predicts that a massive wall of rock is about to plunge into Barry Arm Fjord in Alaska.

Image source: Christian Zimmerman/USGS/Big Think
Surprising Science
  • A remote area visited by tourists and cruises, and home to fishing villages, is about to be visited by a devastating tsunami.
  • A wall of rock exposed by a receding glacier is about crash into the waters below.
  • Glaciers hold such areas together — and when they're gone, bad stuff can be left behind.

The Barry Glacier gives its name to Alaska's Barry Arm Fjord, and a new open letter forecasts trouble ahead.

Thanks to global warming, the glacier has been retreating, so far removing two-thirds of its support for a steep mile-long slope, or scarp, containing perhaps 500 million cubic meters of material. (Think the Hoover Dam times several hundred.) The slope has been moving slowly since 1957, but scientists say it's become an avalanche waiting to happen, maybe within the next year, and likely within 20. When it does come crashing down into the fjord, it could set in motion a frightening tsunami overwhelming the fjord's normally peaceful waters .

"It could happen anytime, but the risk just goes way up as this glacier recedes," says hydrologist Anna Liljedahl of Woods Hole, one of the signatories to the letter.

The Barry Arm Fjord

Camping on the fjord's Black Sand Beach

Image source: Matt Zimmerman

The Barry Arm Fjord is a stretch of water between the Harriman Fjord and the Port Wills Fjord, located at the northwest corner of the well-known Prince William Sound. It's a beautiful area, home to a few hundred people supporting the local fishing industry, and it's also a popular destination for tourists — its Black Sand Beach is one of Alaska's most scenic — and cruise ships.

Not Alaska’s first watery rodeo, but likely the biggest

Image source: whrc.org

There have been at least two similar events in the state's recent history, though not on such a massive scale. On July 9, 1958, an earthquake nearby caused 40 million cubic yards of rock to suddenly slide 2,000 feet down into Lituya Bay, producing a tsunami whose peak waves reportedly reached 1,720 feet in height. By the time the wall of water reached the mouth of the bay, it was still 75 feet high. At Taan Fjord in 2015, a landslide caused a tsunami that crested at 600 feet. Both of these events thankfully occurred in sparsely populated areas, so few fatalities occurred.

The Barry Arm event will be larger than either of these by far.

"This is an enormous slope — the mass that could fail weighs over a billion tonnes," said geologist Dave Petley, speaking to Earther. "The internal structure of that rock mass, which will determine whether it collapses, is very complex. At the moment we don't know enough about it to be able to forecast its future behavior."

Outside of Alaska, on the west coast of Greenland, a landslide-produced tsunami towered 300 feet high, obliterating a fishing village in its path.

What the letter predicts for Barry Arm Fjord

Moving slowly at first...

Image source: whrc.org

"The effects would be especially severe near where the landslide enters the water at the head of Barry Arm. Additionally, areas of shallow water, or low-lying land near the shore, would be in danger even further from the source. A minor failure may not produce significant impacts beyond the inner parts of the fiord, while a complete failure could be destructive throughout Barry Arm, Harriman Fiord, and parts of Port Wells. Our initial results show complex impacts further from the landslide than Barry Arm, with over 30 foot waves in some distant bays, including Whittier."

The discovery of the impeding landslide began with an observation by the sister of geologist Hig Higman of Ground Truth, an organization in Seldovia, Alaska. Artist Valisa Higman was vacationing in the area and sent her brother some photos of worrying fractures she noticed in the slope, taken while she was on a boat cruising the fjord.

Higman confirmed his sister's hunch via available satellite imagery and, digging deeper, found that between 2009 and 2015 the slope had moved 600 feet downhill, leaving a prominent scar.

Ohio State's Chunli Dai unearthed a connection between the movement and the receding of the Barry Glacier. Comparison of the Barry Arm slope with other similar areas, combined with computer modeling of the possible resulting tsunamis, led to the publication of the group's letter.

While the full group of signatories from 14 organizations and institutions has only been working on the situation for a month, the implications were immediately clear. The signers include experts from Ohio State University, the University of Southern California, and the Anchorage and Fairbanks campuses of the University of Alaska.

Once informed of the open letter's contents, the Alaska's Department of Natural Resources immediately released a warning that "an increasingly likely landslide could generate a wave with devastating effects on fishermen and recreationalists."

How do you prepare for something like this?

Image source: whrc.org

The obvious question is what can be done to prepare for the landslide and tsunami? For one thing, there's more to understand about the upcoming event, and the researchers lay out their plan in the letter:

"To inform and refine hazard mitigation efforts, we would like to pursue several lines of investigation: Detect changes in the slope that might forewarn of a landslide, better understand what could trigger a landslide, and refine tsunami model projections. By mapping the landslide and nearby terrain, both above and below sea level, we can more accurately determine the basic physical dimensions of the landslide. This can be paired with GPS and seismic measurements made over time to see how the slope responds to changes in the glacier and to events like rainstorms and earthquakes. Field and satellite data can support near-real time hazard monitoring, while computer models of landslide and tsunami scenarios can help identify specific places that are most at risk."

In the letter, the authors reached out to those living in and visiting the area, asking, "What specific questions are most important to you?" and "What could be done to reduce the danger to people who want to visit or work in Barry Arm?" They also invited locals to let them know about any changes, including even small rock-falls and landslides.

Your genetics influence how resilient you are to the cold

What makes some people more likely to shiver than others?

KIRILL KUDRYAVTSEV/AFP via Getty Images
Surprising Science

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Harvard study finds perfect blend of fruits and vegetables to lower risk of death

Eating veggies is good for you. Now we can stop debating how much we should eat.

Credit: Pixabay
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