Professor Chris Lowry is an Associate Professor of Integrative Physiology and Director of the University of Colorado’s Behavioral Neuroendocrinology Laboratory. He spoke at BRC on Friday about the connection between the gut and the brain and how humans’ microbiome controls it.
What’s a microbiome? When Professor Lowry describes microbiome, he says i
t is essentially the trillions of microorganisms that are living in and on our bodies and some estimates suggest that there are more micro organism cells in and on our bodies than human cells. He said, “to really understand human biology, we need to start thinking of humans as ecosystems.”
Another important definition is “health.” Professor Lowry said that the World Health Organization’s 1948 definition still applies, “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.”
Professor Lowry outlined the two areas he wanted to address in his program: the link between mental health and the microbiome and potential prevention of mental health issues because of this research. Professor Lowry pointed out that the idea of “prevention” for mental health issues is not new. However, not many advances have been made. That search, the search for prevention of mental health disorders is the focus of Professor Lowry’s work.
Where do you start when looking for preventative strategies? Professor Lowry said that he looked at what risk factors there are for psychiatric disorders. Some of those factors are, genetic predisposition, environmental influences, and microbial inputs.
How could microbe inputs (or exposure) have anything to do with mental health? Professor Lowry started by explaining that when you get a cold, for example, you’ve been exposed to a bacteria and the body reacts with something called “sickness behavior.” Sickness behavior can include things like, feeling sluggish, having a fever and maybe having slower cognitive function. You might describe this type of interaction as causing inflammation in the body.
There are however other types of bacteria that do not cause that inflammatory response in the body. They in fact, are anti-inflammatory. These bacteria control or prevent inappropriate inflammation. Professor Lowry explained that if people are not exposed to these anti-inflammatory bacteria in our lives then we may be at risk for an exaggerated or inappropriate levels of inflammation. He called this exaggerated inflammation response, “a failure of immune regulation.” When this failure of the immune system happens, the immune system is unable to terminate inappropriate inflammation.
Professor Lowry said that we should be concerned about inflammation. Conditions related to inflammation have been dramatically increasing since the 1950’s. He said this type of condition includes things like type 1 diabetes, asthma, Crohn’s disease and multiple sclerosis.
This relates to something called the “hygiene hypothesis.” This was proposed by Professor David Strachan of St. George’s University of London. Professor Strachan thought that infections acquired in early childhood may protect against development of allergic diseases. Part of his paper proposed that there was a greater chance that first-born children had allergies (as opposed to children lower in the birth order.) This allergy proposition shows as true when you look at allergy studies at a national level. First-born children have more allergies than younger children in the same family. Professor Strachan believed it was because those first-born children got sick which exposed the younger siblings to the sickness which built up their immune responses.
Professor Lowry said that scientists now think it is a little more nuanced than Professor Strachan’s original hypothesis. He said that environmental bacteria sources also play a pivotal role in how children develop a healthy immune response. So now, scientists believe that factors such as birth order and environmental exposure are important.
Professor Lowry illustrated this by showing the results of a study of three groups of people in Switzerland; Amish farmers (using very few modern farming practices or chemicals); Swiss farmers (using modern farming practices) and Swiss non-farmers. The Amish farmers had 5.25 asthma incidence; the Swiss farmers had 6.8% asthma incidence and the Swiss non-farmers had 11.2% of asthma incidence.
Bringing it back to the incidence of mental health, Professor Lowry showed another large study that showed the incidence of mood disorders followed a similar path as the asthma study- those who live in rural areas have lower over all incidences of mood disorders than people living in urban areas.
Professor Lowry and his team designed a study to test this idea that environmental factors, immune response and inflammation are affected by where people live. He and his team set up a study to look at 20 young healthy German men, average age of 24, that grew up on farms with farm animals in close proximity and compare them to 20 young healthy German men that grew up in cities of over one hundred thousand people and did not own pets.
In the experiment, they brought the young men into the lab and exposed them to the Trier social stress test. (“TSST”) Professor Lowry described this as, “one of the most stressful things that we can do to a human in a research laboratory that’s ethical.”
The TSST made the young men stand up and give a speech about their dream job in front of a camera and a group of scientists sitting in front of the young man (in white lab coats.) The scientists are trained not to smile or to give any type of positive feedback. And the young men know that they are being “evaluated.” This is designed to induce neuroendocrine stress response, a “fight-or-flight” response and also an immune stress response. That third part of the stress response- the immune response- includes inflammation and circulation of inflammatory agents through your body.
What Professor Lowry and his team found was that the young men who had grown up in cities, when exposed to this type of stress test had a massively exaggerated pro-inflammatory immune response compared to those young men that grew up on farms (in the first 15 years of their lives.) Professor Lowry said that the young men who grew up on farms reported that they were very stressed and anxious about the test and the young men who grew up in cities did not voice the same concerns. The results of test in their bodies was very different than what the young men told the research team.
Professor Lowry said that this study showed just one type of pro-inflammatory response in a controlled setting. Individuals who are exposed to stress for prolonged time periods may fail to recover and the body’s inflammatory immune response may increase over time. He believes there is a strong association between physical health and mental health, “particularly in the context of inflammation and particularly in the context of autoimmune disorders.”
Professor Lowry said that this study aligns with studies showing that people with post traumatic stress disorder (“PTSD”) have a much higher incidence of auto-immune disorders, (this includes disorders like inflammatory bowel disease, rheumatoid arthritis, thyroiditis, etc.) Professor Lowry said this suggests that people with a diagnosis of PTSD are not able to shut off inflammatory responses regardless of genetic predisposition.
Professor Lowry went on to say that his colleague, Graham Rook, identified beneficial bacteria that he called “old friends.” These old friends co-evolved with humans and mammals in a way that allows them to interact with human immune systems and induce anti-inflammatory responses. This type of bacteria prevent inappropriate inflammation. That means if you don’t have these “old friend” bacteria in your system, you have a higher risk of developing an inflammatory disease. This type of bacteria also can persist in people for long periods of time. (This is a trait that allows the bacteria to be “successful” in an evolutionary way.) They are also transmissible - people pass these bacteria to others. This is a symbiotic relationship- it is beneficial to both the bacteria and the human host.
After explaining this interaction, Professor Lowry said the goal then is to have a “healthy microbiome.” What does healthy mean? Professor Lowry said that “diversity” is a key to a healthy microbiome. He said to think about it like the way you think of the Amazonian rain forest. The Amazon has incredible diversity when you compare it to a wheat field. Keeping the wheat alive may mean adding fertilizer to the soil, adding minerals or controlling bugs by spraying insecticide. The rain forest gets along without these types of intervention. The Amazon is a healthy ecosystem compared to the wheat field.
How do you get a diverse microbiome? He said he took a picture of his breakfast and it includes lots of plants-
more than 30 types! Why plants? He explained that a spinach plant has over 800 different types of bacteria living inside the plant (you can’t wash them off) because the bacteria in the plant is the plant’s microbiome. So you can get an incredibly diverse sample bacteria when you eat different types of plants.
Diverse is good! And plants are a good way to increase microbiome diversity in your body.
Professor Lowry ended by saying that more studies are focusing on meta-analysis of dietary intervention in mental health treatment. He said that some studies have shown replacing unhealthy diets with healthy foods has decreased depressive symptoms in patients. He believes this is an incredible opportunity for people with mental health disorders and he is continuing his work at the University of Colorado.
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*** This article is a synopsis of the program presented to Boulder Rotary Club. The views and opinions expressed by the presenter do not necessarily reflect the opinions of, policy or position of the Boulder Rotary Club and its members.