Researchers Want to Know If Probiotics Can Affect Mental Health

Scientists have long known that the microbes living in your gut impact your health. More studies are looking at whether using probiotics to alter your gut microbiome can reduce symptoms of mental illness.

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Researchers are learning how the gut affects the brain. Illustration by Brittany England.

Ashley Abramson was 10 years old when she received a diagnosis of anxiety and an obsessive-compulsive disorder. Since then, she’s taken an antidepressant in various forms and doses almost every single day for two decades.

In recent years, though, this mom-writer hybrid from Minneapolis, Minnesota, has shifted toward a more holistic approach.

In addition to her medications, she’s tried herbal and vitamin supplements, chiropractic adjustments, and visits to a naturopath to see if they can also help lessen her symptoms.

And like millions of other people, she’s also used “pricey probiotics,” which she says would run her about $50 a month if she took them every day — which she doesn’t.

While most people may take probiotics to improve their gut health and potentially reduce their risk for gastrointestinal conditions like IBS, more and more people like Abramson are investigating if probiotics can help with their mental health in addition to their gut.

Probiotics have risen in popularity in recent years thanks to studies that have found evidence that “good” bacteria in the gut may be associated with a variety of conditions like type 2 diabetes, obesity, and colon cancer.

Taking probiotics in pill and powdered form are thought to boost your health by altering your gut microbiome, the collection of bacteria, yeasts, and fungi inside your gastrointestinal track.

However, the field is relatively new and researchers are still trying to understand the complex interactions of probiotics with naturally occurring bacteria.

One of the connections they’re trying to understand is how the gut impacts the brain and mental illness.

As researchers learn more about this connection, probiotics are being marketed for better mental health in addition to improved digestive function, lower cholesterol, and weight loss.

The gut may seem to be the last place to treat a mental illness, but experts say that understanding the microbiome may help them find issues, such as inflammation, that can take a toll on the brain.

“It’s an exploding area of research,” said Nicole Beurkens, a licensed psychologist and certified nutrition specialist in Caledonia, Michigan. “The research that’s been done so far really shows a lot of connections between gut health, the gut microbiome, and mental health symptoms.”

This is true not only for anxiety, but also for other mental illnesses such as depression, bipolar disorder, and schizophrenia. Researchers are even looking into whether probiotics can help ease the symptoms of autism.

Probiotics being used to support your brain even have their own name: psychobiotics.

Dr. Asim Shah, professor and executive vice chair in the Menninger Department of Psychiatry and Behavioral Sciences at Baylor College of Medicine, said “there’s a lot of hope that we’ll be able to use probiotics down the road to treat anxiety or depression, maybe even as a first-line treatment.”

Shah said that we’ve known for a while that gut microbes play an important role in keeping us healthy, including protecting us from germs, producing vitamins in our gut, and helping us digest our food.

But in recent years, researchers have turned their attention to the microbial gut-brain connection.

Bacteria in the intestines produce many chemicals, including neurotransmitters such as serotonin, melatonin, and acetylcholine. These may directly impact brain function and mental health and help explain the benefits of probiotics.

One small study published last year in Gastroenterology found that 64 percent of people with mild-to-moderate anxiety or depression who took a daily probiotic for six weeks had fewer depression symptoms during that time. Only 32 percent of people taking an inactive placebo improved.

Brain imaging with functional MRI also showed that people taking the probiotic had changes in areas of the brain involved in mood. The researchers say this suggests that the “probiotic has antidepressive properties.”

Probiotics may also help with other mood disorders. Another preliminary study published earlier this year suggests that daily probiotics — taken alongside regular medication — may reduce manic attacks in people with bipolar disorder.

Ruth Ann Luna, an assistant professor of pathology and immunology at Baylor College of Medicine, said “there’s huge potential for microbially mediated therapies in the treatment of autism, especially gastrointestinal symptoms, but also many of the other core symptoms.”

She and her colleagues are analyzing data right now from a study involving hundreds of children with autism.

One goal of the study is to see if it’s possible to link the microbiome, metabolome, and diet with behaviors or other symptoms of autism spectrum disorder.

If the microbiome is what’s living in your gut, the metabolome is what they’re doing. This collective activity shows up as small biological molecules produced by the microbes.

This kind of intestinal profiling might help doctors decide which patients with autism would benefit from probiotics or other treatments targeting the microbiome.

“While a probiotic may work for 1 out of 10 kids, you have to have a reason to select that one kid over the other nine,” said Luna.

She said scientists have had success using this approach with gastrointestinal disorders in kids to “predict which individuals would respond favorably to a dietary intervention. And we’ve seen potential evidence of that with probiotics, as well.”

Other autism studies are focused on finding microbiome-based treatments. One that’s underway is looking at whether giving children a probiotic for six months improves their autism symptoms.

Some researchers have used fecal transplantation to alter the microbiomes of children with autism spectrum disorder. This involved transferring a stool sample from a donor without autism to the colon of the child with autism.

In this study, researchers “saw improvement in the core symptoms of autism, improvement in quality of life, and a decrease in some of the symptoms commonly associated with autism, both on the behavioral and social side,” said Luna.

Some autism studies have looked at the effects of antibiotics on autism symptoms, something that’s also been tried with schizophrenia. In theory the antibiotics may affect the gut bacteria in a way that could reduce symptoms of mental illnesses.

One doctor reported in 2007 that two patients with schizophrenia saw improvements in their symptoms while taking an antibiotic called minocycline.

Antibiotics may decrease inflammation in the brain, which lessens the symptoms of schizophrenia. Researchers in the relatively new field of autoimmune neurology point to other conditions that look like bipolar disorder, epilepsy, or dementia, but clear up when the immune system is suppressed with drugs.

However, other scientists think that antibiotics alter the microbiome, which affects the immune system and decreases inflammation in the brain.

Most of the research on probiotics and mental health consists of smaller studies, but Shah said these kinds of pilot trials are “promising.”

But he said larger trials are needed in order to show whether probiotics — and which ones — are effective at treating depression and other mental illnesses.

Despite probiotic research being so new, Shah pointed out that the risks of people using probiotics in addition to standard treatments to improve their mental health are low.

Although Shah is clear that probiotics haven’t been proven to replace standard treatments for mental health.

“If your depression is severe, you need to try things which are already proven to be effective, such as cognitive behavioral therapy and antidepressant medications,” said Shah.

Instead, experts like Beurkens use probiotics in addition to standard treatment to hopefully improve symptoms further.

Beurkens said enough research has been done that she’s comfortable using probiotics as part of a treatment plan in her clinical practice with both children and adults.

“My approach as both a clinical psychologist and a nutrition specialist is to use everything that’s available before we look at prescription medications,” said Beurkens.

This includes looking at other factors that can affect mental health such as nutrient deficiencies, lack of exercise, stress, allergies, and thyroid issues.

This holistic approach to mental health works on many levels — your gut, your immune system, your brain — and on the billions of tiny creatures within.

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