Probiotics Experiment Shows 'Good Bacteria' Can Help Treat Depression

According to a recent study including 47 volunteers who were having depressive episodes, probiotics - the 'good bacteria' commonly touted to contribute to favorable health responses – may have a role to play in treating depression.

Over the course of a 31-day period, participants who took probiotic supplements in addition to antidepressants exhibited a larger improvement in their depression symptoms than those who took a placebo.

The researchers also detected alterations in the gut flora of those who took the probiotics, including an increase in lactic acid-producing bacteria. However, a four-week follow-up revealed that the levels of these bacteria had dropped over that period.

"It may be that four weeks of treatment is not long enough and that it takes longer for the new composition of the intestinal flora to stabilize," says psychiatrist Anna-Chiara Schaub of the University of Basel in Switzerland.

The study confirms what scientists already know: the gut and the bacteria that live in it play an essential role in our mental health. The researchers also looked at a hitherto unexplored link between sadness and how we absorb other people's emotions.

Certain brain areas handle this processing differently in patients with depression, and this is commonly tested by looking at reactions to facial expressions. The same strategy was used in this research, which used fMRI scans to see how people reacted.

It turns out that probiotics had an effect here as well: individuals who took the 'good' bacteria course had their typically aberrant brain functions return to normal. While the reasons for this aren't fully understood, the early indicators suggest that the medication has a good impact on several aspects of depression.

"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," adds Schaub.

Probiotics' health advantages aren't always evident, and study is ongoing to see if they might do more damage than good. However, based on this limited sample size, it appears that they have at least some promise in the treatment of depression.

However, the researchers are quick to point out that without the antidepressants, the probiotics wouldn't function as a treatment - and that additional research is needed to look at the impact of certain types of live bacteria on much bigger groups of individuals.

Antidepressants are currently provided to about two-thirds of people who do not have a strong long-term response to them. It's likely that probiotics play a significant role in the hunt for more personalized and effective medicines that we haven't discovered yet.

"With additional knowledge of the specific effect of certain bacteria, it may be possible to optimize the selection of bacteria and to use the best mix in order to support treatment for depression," says Schuab.