听Integrative Physiology Professor Christopher Lowry has spent 19 years studying the impact beneficial microorganisms have on mental health.
听He found that people who grow up in rural areas are more resilient to the physical impacts of stress, and injections of soil-derived microorganisms in animals quell brain inflammation and prevent stress-induced digestive disorders.
听Someday he hopes to develop a 鈥渟tress vaccine.鈥�
Could exposure to microorganisms in the dirt somehow protect us from anxiety, depression and post-traumatic stress disorder? Could our increasingly sterile, urban environments be partly to blame for rising rates of stress-related disease?
For nearly two decades, Integrative Physiology Professor Christopher Lowry has dedicated his career to exploring these once-controversial ideas. Now, with mounting research suggesting he鈥檚 been on the right track all along, he鈥檚 forging ahead with a dream of someday developing a bacterium-based immunization鈥攐r stress vaccine鈥攖o stem the rising tide of mood disorders.
鈥淎s human societies have migrated to urban environments, we have lost touch with a host of bacterial species that play a role in regulating our immune system, and this is helping to fuel an epidemic of inflammatory disease,鈥� says Lowry. 鈥淚 want to know: What are the impacts on mental health?鈥�
Lowry was a research fellow at the University of Bristol in the early 2000s when he began to hear stories about听Mycobacterium vaccae, a rare microorganism discovered in the soil on the shores of Lake Kyoga in Uganda. Scientists were perplexed by the fact that when given vaccines to prevent tuberculosis, lakeshore residents resisted TB better than people who lived elsewhere.
鈥淚t appeared that this microorganism living in the soil had powerful immune-regulating properties that were somehow making the vaccines work better,鈥� he said.
Researchers tried using it as an immune-boosting adjunct to various vaccines, with limited success.听But one trial in lung cancer patients yielded a curious result: While those injected didn鈥檛 live longer, their mood improved.
Lowry set out to find out why.
In April 2007, he published a groundbreaking study听showing that when a preparation of听M. vaccae was injected into mice, it activated brain cells that produce the feel-good chemical serotonin and altered the animals鈥� behavior in a way similar to that of antidepressants.
His peers were skeptical. 鈥淪ome people commented that it must have been an April Fool鈥檚 joke,鈥� he recalls.
But since then, he鈥檚 published an array of studies adding weight to the notion that good bacteria can be good for the mood.
One showed that children raised in a rural environment, surrounded by animals and bacteria-laden dust, grow up to have more stress-resilient immune systems and may be at lower risk of mental illness than pet-free city dwellers.
鈥淚t has already been very well documented that exposure to pets and rural environments during development is beneficial in terms of reducing risk of asthma and allergies later in life," said Lowry. "This study showed for the first time that these exposures are likely to be important for mental health.鈥�
听It鈥檚 exciting to see so many people interested in our relationship with the microbial world.鈥�听鈥揅hristopher Lowry
Another study showed that injections of听M. vaccae prior to a stressful event could prevent a 鈥淧TSD-like鈥� syndrome, fending off stress-induced colitis and making them act less anxious and fearful when stressed again later. Another found that M. vaccae听has a long-lasting anti-inflammatory effect on the brain. That鈥檚 important, because brain inflammation impacts mood-regulating brain chemicals.
While more research is needed, some evidence already suggests that various other strains of bacteria鈥攅ven in the form of oral probiotics鈥攈ave anti-inflammatory effects and may hold potential for alleviating anxiety in humans.
Lowry is now collaborating with the Department of Veterans Affairs on a clinical trial looking at whether听Lactobacillus reuteri听can improve physiological and psychological responses to stressful situations in veterans with PTSD.
Meanwhile, he continues to study M. vaccae, in hopes that someday an M. vaccae-based 鈥渟tress shot鈥� could be given to soldiers or first responders to make their brains and bodies more resilient.
At home, he makes a point of exposing his own children to a healthy dose of dirt, via a front yard vegetable garden and frequent camping trips. He encourages his friends and colleagues to do the same. Only now, they鈥檙e not so skeptical.
鈥淭his idea went from being this novel, turn-your-world upside down concept to something that doesn鈥檛 even surprise people anymore,鈥� he says. 鈥淚t鈥檚 exciting to see so many people interested in our relationship with the microbial world.鈥�
