According to the WHO, depression is one of the major causes of disability worldwide. However, the understanding of the disorder remains incomplete. Recently, antibiotic use has been associated with...Show moreAccording to the WHO, depression is one of the major causes of disability worldwide. However, the understanding of the disorder remains incomplete. Recently, antibiotic use has been associated with the onset of mood disorders. It is assumed that microbiota-gut-brain interactions are partly managed by the immune system. Accordingly, this study aimed to clarify the correlations between antibiotic-induced microbial dysbiosis, cognitive reactivity to sad mood (CRSM), and concentration of the antibody secretory immunoglobulin A (sIgA). Participants, which finished an antibiotic treatment within the past three months (n = 47), were compared to control participants (n = 60). Participants’ CRSM was measured using the Leiden Index of Depression Sensitivity (LEIDS-R). Antibody levels of salivary sIgA were investigated by obtaining saliva samples from the participants. Results indicated that antibiotic use was not associated with remarkable differences in sIgA concentration or depression sensitivity, i.e. CRSM. However, based on exploratory observations the preliminary idea of antibiotic use resulting in sex-specific responses was developed and is proposed valuable to be investigated in future research. Moreover, it was examined if antibiotic use can be considered a moderator in the relation between sIgA concentration and CRSM. Antibiotic use did not display a moderating role and CRSM was not predicted by sIgA concentration. The findings within this study were limited by a reduced dataset of sIgA concentrations. Ultimately, in contrast to the hypothesized outcome antibiotic-induced microbial dysbiosis was not associated with a decreased sIgA concentration or increased depression sensitivity of healthy individuals within this study. To clarify the correlation between the microbiota-immune-brain axis, antibiotic use, and mental health future research is needed.Show less
