Decision, Vol 12(3), Jul 2025, 216-245; doi:10.1037/dec0000261
In a 6-week randomized, triple-blind, placebo-controlled trial, we investigated the impact of a probiotic intervention on risky choices in healthy adults as well as a potential link between gut microbiota and risky decision-making. Our study explored whether the gut–brain interaction was mediated by gut bacteria or cardiac vagal activity, representing the vagal pathway in the gut–brain axis. Additionally, we examined whether these potential mediations would be moderated by interoceptive accuracy. To assess risky decision-making, the Iowa Gambling Task (IGT; Bechara et al., 1994) and the Balloon Analogue Risk Task (BART; Lejuez et al., 2002) were employed. Interoceptive accuracy was captured with the heartbeat perception task (Dunn et al., 2012; Schandry, 1981). Neither the probiotic intervention nor many of the tested bacteria and cardiac vagal activity predicted risky decision-making. Our data suggest a potential gut–cognition link in healthy adults predominantly via Faecalibacterium prausnitzii and Lactobacillaceae that merits further investigation. This connection was found for risky decision-making in the BART and IGT tasks and was moderated by interoceptive accuracy. Participants with high accuracy in perceiving internal bodily signals while also exhibiting higher numbers of specific bacteria (i.e., F. prausnitzii, Lactobacillaceae) were less inclined to make risky choices. While our results warrant further research concerning the role of Bacillota family of gut bacteria, other recent studies have brought neurotransmitters into play. Future research should consider these possible factors together, scrutinizing psychophysiological mechanisms in risky decision-making. (PsycInfo Database Record (c) 2025 APA, all rights reserved)