Wisdom is difficult to define. There are those we know to be wise – Gandalf, Obi-Wan Kenobi, Kermit the Frog – but why they are wise is more challenging to say. Some scholars argue that there is no single, comprehensive definition of wisdom. But what they do know is that one state of existence has the opposite of wisdom: loneliness.
Tanya Nguyen is an assistant professor of psychiatry at the University of California, San Diego. She is very interested in the evidence that people who are considered wiser are less likely to feel lonely, and those who are more lonely are less wise. It also studies the axis of the gut and the brain and how the relationship between the gut microbiome and the brain affects healthy aging.
“We can’t know for sure at this point, but I guess it’s probably both,” Nguyen tells me. This was a cross-sectional study, which means that it can show a connection, but it cannot predict the “direction of the connection”.
“We know that loneliness can lead to other physiological changes in the body, so it is possible that these changes may also include or even be caused by the microbiome,” she says.
“Or, conversely, perhaps the presence of a particular microbiome can change social behavior that leads to loneliness.”
The connection between the gut and behavior
As for how the gut affects itself, most of what we know comes from animals. Research on various animal species, Nguyen explains, shows that microbes can create signals that are used in social interactions and communications. Studies in rodents, for example, suggest that changes in the intestinal microbiota may modulate emotional behavior, including depression and anxiety.
We do not yet have equivalent research on humans, but past research has linked intestinal microbial diversity and composition to certain personality traits and psychosocial constructs. For example, a study published in March 2020 in Journal of Human Microbiome found people who are more social have a more diverse intestinal microbiome, while people who are more anxious have a less diverse intestinal microbiome. But the important thing is that this is an observed association, not a finding of cause and effect.
A study by Nguyen and her colleagues published in the March issue of the journal Limits in psychiatry, is the first to show loneliness and wisdom are related to the microbial diversity and composition of the intestine.
What was found – The team analyzed faecal samples from 184 study participants aged 28 to 97 years, along with their self-reported measures of loneliness, wisdom, compassion, social support, and social engagement. These fecal samples helped the team measure gut microbial diversity.
They were looking for alpha diversity – which is the “ecological wealth” of microbial species in humans – and beta diversity, which are the differences in the microbial community between humans.
“… the aspects of mental health and well-being are very closely related for our physical health. ”
In general, higher levels of wisdom, compassion, social support, and engagement have been found to be associated with more diverse intestinal microbiomes. Meanwhile, loneliness has been associated with reduced microbial diversity, especially among older adults, which suggests that older people are particularly vulnerable to the health consequences of loneliness compared to previous work.
However, “the mechanisms by which loneliness, compassion and wisdom can be linked to gut microbial diversity are unknown,” the team wrote. Other studies have found a link between reduced alpha diversity and poorer physical and mental health, while low microbial diversity has also been linked to conditions such as major depressive disorder.
The study suggests that single people “may be more susceptible to developing various diseases”, while social support, compassion and wisdom can provide “protection against the loneliness-related instability of the intestinal microbiome”.
What next – Can preventing loneliness improve bowel health and in turn help with healthy aging? It is possible. One can increase wisdom through behavioral interventions. This study is a sign that is a smart choice for overall wellness.
“The most important message [of the study] is that the aspects of mental health and well-being are very closely linked to our physical health, ”says Nguyen.
Even seemingly “blurred” concepts, such as loneliness and wisdom, can be related and perhaps even influenced by “hard” biological units. Loneliness contributes to true medical morbidity [even mortality], and the intestinal microbiome may be an important factor in this regard. “
This complex interaction between the gut and the brain, Nguyen says, has been known for centuries. Some of the earliest reports linking the functioning of the gastrointestinal tract and mental health date from the late 18th and early 19th centuries. But the last five years have seen a renaissance in intestinal and brain research due to technological advances in microorganism sequencing.
She then wants to study the intestinal microbiome over time to understand the connections between chicken and eggs here. Does the gut affect behavior, driving loneliness, or does loneliness affect the gut? The answer can help experts understand how they can potentially intervene and develop “therapeutic tools to help improve mental health and aging,” Nguyen said.