A new study from Tufts University suggests that a common gut fungus could subtly influence how the brain reacts to alcohol.
Researchers discovered that an overgrowth of Candida albicans, a fungus commonly present in the digestive tract, triggers inflammation that can reach the brain and affect dopamine signaling, a key pathway involved in reward and motivation. The study, published in mBio, found that the fungus increases levels of prostaglandin E2 (PGE2), an inflammatory molecule that can cross the blood-brain barrier.
“Our study shows how science works — our initial ideas were very wrong,” said Andrew Day, first author of the study and a Ph.D. graduate of the Tufts Graduate School of Biomedical Sciences. “This could be explained by differences in how mice respond to C. albicans compared to humans, differences in fungal strains or we might be seeing a small snapshot of the entire story.”
In mice, higher levels of Candida and PGE2 were linked to lower interest in alcohol. When the researchers blocked PGE2 receptor molecules, the behavior was reversed and the mice began drinking again.
“Our bodies are wired so that our behavior responds to gut microbiota, and this study highlights that fungi are important components of the gut-brain axis,” said Carol Kumamoto, PhD, senior author and professor of molecular biology and microbiology at Tufts. “We think fungal colonization levels in individuals with alcohol use disorder could be impacting host alcohol consumption by influencing interest in drinking — whether it’s affecting how rewarding a drink may be is more of an interpretation.”
Alcohol use disorder affects more than 5% of adults worldwide, and current treatments can be only moderately effective. The researchers say understanding how gut microbes, including fungi, influence behavior could eventually open new avenues for supporting recovery.
This research was supported by the National Institutes of Health, including the National Institute of Allergy and Infectious Diseases and the National Institute on Alcohol Abuse and Alcoholism, as well as the Tufts Initiative on Substance Use and Addiction.