The rise of 'psychobiotics'? 'Poop pills' and probiotics could be game changers for mental illness

No area of psychiatry is as hot, or controversial today as the idea of manipulating the gut to alter the mind

Sharon Kirkey, National Post 6 minute read December 17, 2019

The calls started pouring in soon after word spread that Dr. Valerie Taylor was testing fecal microbiota transplantation — transferring poop from one body to another — for bipolar disorder.

The mental health condition is different from depression. It comes with mania, the “up” swings that can make people feel superhuman. “But so many people with depression called wanting to take part in the study we felt we had an obligation to try,” said Taylor, chief of psychiatry at the University of Calgary.

Two years after spearheading the bipolar study, the first of its kind in the world, Taylor has now launched a second study testing fecal transplants in people with depression, as well as a third for depression in people who also have irritable bowel syndrome.

“The literature that we’re on to something has grown,” said Taylor. “But we’re not Goop,” she added, referring to Gwyneth Paltrow’s often airy lifestyle brand. “We want to know if there’s something here or not.”

No area of psychiatry is as hot, or controversial today as the idea of manipulating the gut to alter the mind. The trillions of bacteria living in the human gut have been shown to play a crucial role in gut-brain communication, researchers write in the Canadian Journal of Psychiatry. The hope is that enhancing good gut microbes — whether with probiotics, fecal transplants or capsules filled with donor stool, or by adding sauerkraut or other fermented foods to the diet — may be the answer to intractable depression, the kind conventional treatments can’t touch.

It could also fundamentally alter the way we conceptualize mental illness. “We now think mental illness is essentially a brain illness, and it may be that it isn’t,” Taylor said.

Gastro-intestinal problems are common among people with depression and anxiety, and studies suggest people with depression have a different gut flora than people without. Intestinal bacteria also produce serotonin, dopamine and other brain chemicals that regulate mood.

There are also direct connections via the vagus nerve, which connects nerves in the gastro-intestinal system to those in the brain. Years ago, doctors used to cut away the vagus nerve as a way to treat peptic ulcers. But people who underwent a “vagotomy” showed higher rates of psychiatric illness post surgery.

Recent estimates put the number of bacteria in the human gut at slightly more than the total number of human cells. “The collective genome of these bacterial cells, the gut microbiome, vastly exceed the amount of human DNA present in the body, such that, for every one human gene we have over 100 bacterial genes,” Mary Butler, of University College Cork in Ireland and her co-authors wrote in the psychiatric journal.

We want to know if there’s something here or not

The field is still in its infancy, the authors wrote, and it’s premature to suggest “psychobiotics” or poop transplants are ready to replace standard treatments. For one thing, to be successful, donor bacteria has to attach to the recipient’s gut.

Just how gut bacteria communicate with the brain, and the brain with the gut, isn’t entirely clear, though Taylor suspects the immune part is paramount. Gut bacteria influences the immune system. Stress causes inflammation and inflammation can lead to conditions like gut dysbiosis, which has been linked with altered brain function.

There is some evidence certain probiotics — particularly bifidobacterium and lactobacillus supplements — can improve human moods. Results for anxiety have been mixed, though one small study found fermented, probiotic-containing foods appeared to protect against social anxiety disorder in people with higher-than-normal levels of neuroticism, Butler and her co-authors reported.

Fecal transplants, for their part, have a near 100 per cent success rate in curing antibiotic-resistant Clostridium difficile, a hospital-acquired super bug, and Taylor believes they do a better job at recolonizing the gut than probiotics.

The hope is that enhancing good gut microbes may be the answer to intractable depression. Getty Images

Part of her enthusiasm comes from “really profound” animal studies showing that when stool from depressed humans is transplanted into germ-free mice — mice raised in ultra-sterile environments and free of intestinal bugs — the rodents show depressive-like behaviours.

“Humans aren’t mice and mice aren’t humans,” said Taylor, who moved to Calgary from Toronto’s Women’s College Hospital a year ago to take on the headship of the U of Calgary program. “But there’s clearly a signal.”

The Calgary depression studies will be comparing fecal tablets — poop pills — against a placebo. The bipolar study, still underway in Toronto, involves injecting specially prepared stool from a donor into the recipient’s colon via colonoscopy. It’s a randomized trial: some are injected with donor faces, others re-infused with their own poop.

“We really wanted to look at quite ill individuals and say we’re going to take out the entire gut microbiome and introduce a new one and see if we can recolonize,” Taylor said.

But there are caveats: Stool donors have to be rigorously screened. “It’s easier to donate blood than feces,” Taylor said. One Toronto stool donor program recently reported that, in the first two years of the program, only two of 322 prospective donors — 0.6 per cent — ultimately passed screening.

Can you cause schizophrenia if you gave somebody stool from someone with schizophrenia?

Donors also must have zero history of mental illness, in either themselves or first-degree relatives.

“Can you cause schizophrenia if you gave somebody stool from someone with schizophrenia? We don’t know,” Taylor said. But certainly the mouse studies suggest these behaviours are transferrable.

There are other potential disasters: In June, the U.S. Food and Drug Administration issued an alert and halted all fecal transplants after two immune-compromised people contracted drug-resistant E. coli infections from the same donor. One died.

“In the U.S. there are people doing this in unlicensed and unregulated ways,” Taylor said. In Canada, the fecal matter used in the transplants is considered a “biologic drug,” and regulated like one, by Health Canada.

Taylor is cautious, noting in a recent editorial that charlatans and self-appointed wellness gurus have been all too happy to suggest cleaning out the colon can instantly improve wellbeing. We need to manage the hype, she said. Still, something needs to be done to help people for whom standard treatments provide little relief, or unbearable side effects.

“I would love to be able to show this actually works and that it’s potentially game changing,” Taylor said. “We’re not there yet. But I think we’re getting there.”

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