Tuesday January 22, 2019

Microbes May Be Stirring Up Anxiety And Depression In Obese People

To test the theory, Kahn and colleagues fed mice a high-fat diet and studied their behavior as the animals became obese

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Microbes May Be Stirring Up Anxiety And Depression In Obese People
Microbes May Be Stirring Up Anxiety And Depression In Obese People, Pixabay

Microbes may be helping stir up anxiety and depression in obese people, if results from a new mouse study hold true in humans.

The authors link the effects to how the brain responds to insulin, the hormone that regulates sugar levels in the blood.

The research raises questions about whether changing gut microbes, or changing diet, could help treat these conditions.

Mood, microbes and metabolism

Obesity triggers changes in metabolism — for example, making liver, muscle, fat and other tissues less responsive to insulin. Left untreated, these changes can lead to diabetes.

Obese people also have higher rates of anxiety and depression.

“One could say, ‘Maybe that’s just because they’re obese,’ ” said Harvard Medical School diabetes researcher Ronald Kahn, “but others could say, ‘Maybe there’s a metabolic link.’ ”

“And we asked the question, ‘Maybe the metabolic link is at least partly fueled by the microbiome,’ ” the community of microbes living in a person’s gut, he added.

Those microbes change with diet, and Kahn said different microbes might respond differently to the foods we eat.

To test the theory, Kahn and colleagues fed mice a high-fat diet and studied their behavior as the animals became obese.

They used common tests to gauge anxious and depressed behavior in rodents — for example, how much time the animals spent hiding in a dark box versus exploring a brightly lit area. The more anxious the mouse, the less time it will spend in the light.

Obese mice spent about 25 percent less time in the light than animals on a normal diet, and they scored higher on the other anxiety and depression tests, too.

obesity
obesity, Pixabay

Return to normal

But those differences disappeared when obese mice were given antibiotics, even though their weight didn’t change much.

“That really says there’s probably something about the microbiome,” Kahn said.

The researchers then tested how the animals’ microbiomes affected mice raised in a sterile environment with no microbes of their own.

Bacteria from obese rodents made these germ-free mice more anxious than microbes from normal mice.

But when germ-free mice got microbes from obese animals that had been given antibiotics, they behaved like normal mice.

To see what parts of the brain might be responsible for the effects, the researchers focused on two regions involved in metabolism and responses to rewards. They found these regions were less responsive to insulin in the obese mice compared with normal-weight animals.

Again, antibiotics returned those responses to normal.

The research appears in the journal Molecular Psychiatry.

“It was actually quite a surprise,” Kahn said. “Even though we had seen some effects on metabolism in the rest of the body, I was very surprised how dramatic and how clear the effects were also on the brain and on behavior.”

Into the unknown

That doesn’t mean antibiotics are the cure for depression, Kahn warned. The drugs kill good and bad microbes indiscriminately, and taking the medication unnecessarily can contribute to the rising threat of antibiotic resistance.

Also, what happens in mice does not necessarily happen in humans, he added, or it may happen for only some people. So far, there is not much evidence that probiotics help anxious people.

scale
scale, Pixabay

“The difficulty is, both of these things — depression and obesity — are complicated things that have multiple, multiple factors influencing them,” said mental health researcher Gregory Simon at Kaiser Permanente Washington Health Research Institute, who was not part of the study.

Microbes are likely just one factor, along with environment, genetics, social influences and more, Simon added.

But Kahn said his group’s research raised interesting questions about how food affects our behavior.

“I think now we can get some idea that there are a lot of things that are being metabolized by gut bacteria that could affect brain function,” he said.

And he said there might be ways to change brain function by changing those bacteria, by eating helpful microbes or by eating foods that sustain them.

Also read: Two New Ways To Prevent Cholera: Microbes Fighting Microbes

He and his colleagues are working to figure out exactly which of the hundreds of species of gut bacteria are responsible. At the moment, it’s a mystery. (VOA)

Next Story

Smartphones Using Artificial Intelligence Can Predict User’s Mental Well-Being

At the University of Illinois' Chicago campus, researchers are using crowdsourcing to test their experimental phone app.

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Students, smartphones
Students walk across a campus in Portland, Oregon. VOA

Could the devices being blamed for teen depression be useful in revealing it?

Studies have linked heavy smartphone use with worsening teen mental health. But as teens spend time on sites like Instagram, Snapchat and YouTube, they also leave digital trails that may offer signs about their mental well-being.

Experts say possible warning signs include changes in writing speed, voice quality, word choice and how often a student stays home from school.

There are more than 1,000 smartphone “biomarkers,” said Dr. Thomas Insel, former head of the National Institute of Mental Health, which is the largest mental health research organization in the world. Insel is a leader in the smartphone psychiatry movement.

Snapchat, smartphones
An image of the Snapchat logo created with Post-it notes is seen in lower Manhattan, New York, May 18, 2016. VOA

Researchers are testing smartphone apps that use artificial intelligence, or AI, to predict depression and possible self-harm. Using smartphones as mental health detectors require permission from users to download an app, and permission could be revoked any time.

Nick Allen, a psychologist at the University of Oregon, has created an app being tested on young people who have attempted suicide. Allen says the biggest barrier is discerning the mental health crisis signals in the information on people’s phones.

Suicide is the second leading cause of death for people between the ages of 10 and 34 in the United States. By 2015, suicide rates among teen boys rose to 14 in every 100,000 and five in every 100,000 people, among girls. A recent study suggested a rise in smartphone use has probably worsened the crisis.

People with mental illness, Insel said, usually get treatment “when they’re in crisis and very late. … We want to have a method to identify the earliest signs.”

Smartphones
iPhones on display at an Apple store in Virginia, USA, April 4, 2016. VOA

If smartphones can become effective predictors, app developers say the goal might be to offer automated text messages and links to assistance, or digital messages to parents, doctors and first responders.

Facebook employs “proactive detection.” Last year, after a suicide was broadcast on Facebook Live, the company trained its AI systems to look for words in online posts that could predict possible self-harm. Friends’ comments expressing concern about the user’s well-being are part of that detection system.

Facebook has helped first responders quickly reach around 3,500 people in the past year. But the company did not offer followup details on those people.

Ongoing research includes a Stanford University study of about 200 teens. Many of them are at risk for depression because of bullying, family issues or other problems. Teens who have been studied since grade school get an experimental phone app that asks them questions about their mood three times a day for two weeks.

Students, smartphones
In this Feb. 26, 2015, file photo, a UCLA campus tour guide leads prospective college-bound high school seniors on a campus tour in Los Angeles. VOA

Laurel Foster, 15, is part of the study. Foster said she is stressed about school and friendships. Depression is common at her San Francisco high school, she said. The smartphone app felt a little like being spied on, she said, but many websites are already following users’ behaviors.

Alyssa Lizarraga, 19, is also part of the study. Lizarraga said she has had depression since high school, and worries about her heavy use of smartphones and social media. She said comparing herself with others online sometimes causes her sadness. But she believes using smartphones to identify mental health problems might help push people to seek early treatment.

At the University of California, Los Angeles, researchers offer online counseling and an experimental phone app to students who show signs of at least minor depression on a test. It is part of a larger effort launched in 2017 by the university to battle depression in its students. About 250 UCLA students agreed to use the app during their first year.

Also Read: Depression In Girls Linked To Higher Use Of Social Media: Study

At the University of Illinois’ Chicago campus, researchers are using crowdsourcing to test their experimental phone app. Nearly 2,000 people have downloaded the app and agreed to let researchers follow typing behaviors. Alex Leow, a professor of psychiatry and bioengineering at the university, helped develop the app.

The study is for people 18 and older, but Leow said it could also be used for children if successful.

Along with studies at universities, technology companies such as Mindstrong and Verily — the tech health division of Google — are testing their own experimental apps. (VOA)