Bifidobacterium longum 1714 as a translational psychobiotic: modulation of stress, electrophysiology and neurocognition in healthy volunteers

Abstract

The emerging concept of psychobiotics-live microorganisms with a potential mental health benefit-represents a novel approach for the management of stress-related conditions. The majority of studies have focused on animal models. Recent preclinical studies have identified the B. longum 1714 strain as a putative psychobiotic with an impact on stress-related behaviors, physiology and cognitive performance. Whether such preclinical effects could be translated to healthy human volunteers remains unknown. We tested whether psychobiotic consumption could affect the stress response, cognition and brain activity patterns. In a within-participants design, healthy volunteers (N=22) completed cognitive assessments, resting electroencephalography and were exposed to a socially evaluated cold pressor test at baseline, post-placebo and post-psychobiotic. Increases in cortisol output and subjective anxiety in response to the socially evaluated cold pressor test were attenuated. Furthermore, daily reported stress was reduced by psychobiotic consumption. We also observed subtle improvements in hippocampus-dependent visuospatial memory performance, as well as enhanced frontal midline electroencephalographic mobility following psychobiotic consumption. These subtle but clear benefits are in line with the predicted impact from preclinical screening platforms. Our results indicate that consumption of B. longum 1714 is associated with reduced stress and improved memory. Further studies are warranted to evaluate the benefits of this putative psychobiotic in relevant stress-related conditions and to unravel the mechanisms underlying such effects.

Figure 1

The socially evaluated cold pressor test (SECPT) elevated cortisol, and cortisol output and the increase in anxiety were reduced post-1714. (a) Salivary cortisol during socially evaluated cold pressor for each visit. (b) Total cortisol output for each visit, as measured by area under the curve with respect to ground (AUCg) and area under the curve with respect to increase (AUCi). (c) State anxiety (STAI) pre- and post-stressor at each visit. Lower scores indicate lower subjective anxiety. Error bars represent the s.e.m. *P<0.05, **P<0.001. HPA, hypothalamic-pituitary-adrenal.

Figure 2

The probiotic condition was associated with reduced daily stress. (a) Daily stress levels during placebo phase, 1714 phase, and follow-up period. (b) Overall stress, as measured with AUCg and AUCi, during placebo phase, 1714 phase. *P<0.05. AUCg, area under the curve with respect to ground; AUCi, area under the curve with respect to increase.

Figure 3

Total errors on the paired associate learning task. *P<0.05; ^†P<0.01. PAL, Paired Associate Learning test.

Figure 4

Post-1714, Fz mobility was increased and Cz theta power was decreased. (a) Electrode position of Fz, Cz and Pz. (b) EEG mobility at Fz. (c) Theta power at Cz. *P<0.05. EEG, electroencephalogram.