EFFECTS OF PROBIOTICS ON HUMAN RISK-TAKING BEHAVIOR AND ITS UNDERLYING EEG CORRELATES

Decision-making under risk depends on coordinated brain activity and has recently been linked to gut–brain interactions. The gut microbiota knowingly influences cognitive and affective processes. Our previous placebo-controlled studies demonstrated that prolonged probiotic supplementation modulates economic and intertemporal choices. Yet, although neuroimaging evidence implicates altered activation different cortical areas, its underlying electrophysiological mechanisms remain unclear.
Different oscillatory patterns influence decision-making. For example, frontal theta oscillations are an electrophysiological marker of risk-taking; parietal alpha power has a functional relationship with attention and temporal beta power has been associated with cognitive control. This suggests that probiotic-related behavioral changes may be mediated by frequency-specific neural dynamics. Hence, we examined whether probiotics intake modulates oscillatory brain activity.
In a randomized, double-blind, placebo-controlled study, healthy adults (18–35 years) received either probiotics (Ecologic® Barrier) or placebo for 30 days. Preliminary analyses (50 participants; target N = 60) assessed risk-taking was assessed before and after intervention using the Maastricht Gambling Task with concurrent 62-channel EEG. Data were analysed using linear mixed models.
Compared to placebo, the probiotic group showed significantly higher risk-taking (p = 0.028). Regarding gender differences, a trend-level reduction in risk-taking was observed in male participants in the probiotics group (vs. females) (p = 0.076). Resting-state EEG revealed an overall significant decrease in right temporal beta power (p = 0.040) in the probiotics group compared to placebo.
These findings provide preliminary evidence that probiotic supplementation modulates risk-taking behavior and associated EEG markers, advancing a mechanistic account of gut–brain influences on decision-making.