People treated for depression exhibit greater improvements if probiotics are taken with anti-depressants as compared to only taking anti-depressants, a Swedish study has found.
Participants that took probiotics daily for 31 days with their anti-depressants had a greater reduction in their depression scores, higher prevalence of healthy bacteria, especially increased proportions of the Lactobacillus genus bacteria.
The genus of bacteria entered the gut microbiome through the probiotic and is also associated with improved mood scores in participants.
The control group of patients that only took anti-depressants also saw improvements in their gut diversity immediately after the study, but they did not gain Lactobacillus genus bacteria. Healthy bacteria such as Prevotella enterotype bacteria, though present at first, was also reduced four weeks after the study whilst bacteria associated with removal of the anti-depressants became more prevalent.
These findings all highlight the benefits that probiotics contribute to gut health and subsequently, mental health.
Further, researchers observed that when exposed to neutral and fearful expressions, the probiotics group had different brain signaling before and after treatment.
The same reduced signaling is also observed in mentally healthy individuals, suggesting possible mental health improvements linked with probiotics.
However, the control group had the same left and right putamen activation both before and after treatment.
Though this signaling pathway is not well understood, the researchers also observed the same patterns in baseline depressed individuals, indicating a possible link between putamen and depression.
Altogether, 47 participants with bipolar and major depressive disorder completed the study with 21 participants in the probiotics group and 26 individuals as control.
The probiotics the testing group took contained eight common strains including Streptococcus thermophilus, Bifidobacterium breve, Bifidobacterium longum, Bifidobacterium infantis, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus paracasei, and Lactobacillus helveticus, though researchers were not certain of the specific effects of each bacteria.
Researchers also observed that whilst the probiotics group saw increases in the prevalence of beneficial bacteria following treatment, many of these bacterial levels dropped four weeks following treatment, though gut biodiversity was mostly maintained.
“Although the microbiome-gut-brain axis has been the subject of research for a number of years, the exact mechanisms are yet to be fully clarified,” said Schaub.
Whilst she emphasized that probiotics are not suitable as a sole treatment for depression, Schaub highlighted that with more understanding on the functions of the individual bacteria, “it may be possible to optimize the selection of bacteria and to use the best mix in order to support treatment for depression.”
The study was published in Translational Psychiatry on June 3, the journal is a peer-reviewed open-access journal.
