Consumption of fermented milk product with probiotic modulates brain activity

Abstract

Background & aims: Changes in gut microbiota have been reported to alter signaling mechanisms, emotional behavior, and visceral nociceptive reflexes in rodents. However, alteration of the intestinal microbiota with antibiotics or probiotics has not been shown to produce these changes in humans. We investigated whether consumption of a fermented milk product with probiotic (FMPP) for 4 weeks by healthy women altered brain intrinsic connectivity or responses to emotional attention tasks.

Methods: Healthy women with no gastrointestinal or psychiatric symptoms were randomly assigned to groups given FMPP (n = 12), a nonfermented milk product (n = 11, controls), or no intervention (n = 13) twice daily for 4 weeks. The FMPP contained Bifidobacterium animalis subsp Lactis, Streptococcus thermophiles, Lactobacillus bulgaricus, and Lactococcus lactis subsp Lactis. Participants underwent functional magnetic resonance imaging before and after the intervention to measure brain response to an emotional faces attention task and resting brain activity. Multivariate and region of interest analyses were performed.

Results: FMPP intake was associated with reduced task-related response of a distributed functional network (49% cross-block covariance; P = .004) containing affective, viscerosensory, and somatosensory cortices. Alterations in intrinsic activity of resting brain indicated that ingestion of FMPP was associated with changes in midbrain connectivity, which could explain the observed differences in activity during the task.

Conclusions: Four-week intake of an FMPP by healthy women affected activity of brain regions that control central processing of emotion and sensation.

Figure 1

A distributed network of brain regions showing decreases in the FMPP group during the emotional faces attention task is shown in the shaded regions. Three regions of interest selected from the network for study in the resting state are highlighted in pink (insula), green (periaqueductal gray), and blue (somatosensory regions). The change in network strength with intervention is depicted graphically.

Figure 2

Regions showing reduced activity in response to an emotional faces attention task after FMPP intervention are shown, with significant regions demarcated.

Figure 3

A resting-state midbrain centered network has strong positive correlation with midbrain emotional reactivity after No-Intervention, is not engaged after Control, and is negatively correlated with midbrain activity after FMPP. This suggests a shift away from an arousal-based resting-state network and toward a regulatory network. Network regions are depicted in (A) (detailed in Supplementary Tables 4A and B). Red regions show areas that are positively correlated with midbrain activity in the No-Intervention group and negatively correlated in the FMPP group. Green regions are negatively correlated with midbrain activity in the No-Intervention group and are positively correlated in the FMPP group. (B) Correlation of the network with midbrain reactivity by group.