Can your gut make you lonely? According to a new study by researchers at the University of California, San Diego, it’s certainly possible, if not probable.
Previous studies have associated gut microbiota with many human traits, including mental health disorders like depression and schizophrenia, personality and psychological aspects, and even social behavior. Now, researchers are delving deeper into the connection between loneliness, wisdom and the microbial diversity of the gut.
Earlier work on the subject has indicated that persons deemed to be wiser are less prone to feel lonely, while those who are lonelier tend to be less wise. In this new study, published in Frontiers in Psychiatry, researchers analyzed fecal samples from 184 participants ranging in age from 28 to 97. The study volunteers also completed self-report-based measures of loneliness, wisdom, compassion, social support and social engagement.
The research team, led by professor of psychiatry Tanya Nguyen, measured each individual’s ecological richness of microbial species, then examined and compared the differences in microbial community composition between individuals.
While identification of the mechanisms that may link loneliness, compassion, wisdom and gut microbial diversity was out of the scope of this paper, the research team did observe that reduced microbial diversity was associated with worse overall physical and mental health. They attribute this, at least in part, to the fact that a more diverse gut microbiota may be inherently stronger, allowing it to better stave off invasion by outside pathogens and promote internal stability.
It’s almost a catch-22.
"It is possible that loneliness may result in decreased stability of the gut microbiome and, consequently, reduced resistance and resilience to stress-related disruptions, leading to downstream physiological effects, such as systemic inflammation," the authors wrote. "Bacterial communities with low alpha-diversity may not manifest overt disease, but they may be less than optimal for preventing disease. Thus, lonely people may be more susceptible to developing different diseases."
This loneliness was stronger in older adults that participated in the study. This could make older adults especially vulnerable to detrimental health effects and disease, which is in line with previous studies and overall convention concerning age-related health declines.
One of the limitations of the current study was the absence of data about individuals’ social networks, in addition to the emergence of COVID-19 and isolation/quarantine guidelines. Still, the researchers said they support the idea that the combination of social interaction, compassion and wisdom could protect against loneliness-related instability in the gut microbiome—thereby warding off disease and other health vulnerabilities in older individuals.
The current study did not record or evaluate individuals’ diet, which is intrinsically linked to their gut microbiome. The research team says that is reason enough alone to conduct a larger, longer study.
"Loneliness may lead to changes in the gut microbiome or, reciprocally, alterations of the gut milieu may predispose an individual to become lonely," said Dilip Jeste, MD, professor of psychiatry and neurosciences at UC San Diego School of Medicine and senior author of the paper. "We need to investigate much more thoroughly to better understand the phenomenon of the gut-brain axis."
Photo: Greater diversity of gut microbes may be associated with greater wisdom or vice versa; similarly, less diversity might mean higher likelihood of being lonely. Credit: UC San Diego Health Sciences