According to new research involving 47 volunteers who were experiencing depressive episodes, 'good bacteria' which are frequently claimed to lead to positive health responses could play a role in treating depression.
Participants in the study who did take probiotic supplements in addition to antidepressants improved their depressive symptoms more than those who took a placebo over 31 days.
The researchers also noticed changes in the intestinal flora of those who took the probiotics, such as an increase in lactic acid-producing bacteria. However, a four-week follow-up revealed that the levels of these bacteria had decreased again during that time.
The study confirms what scientists already know: the gut and the bacteria that live in it play a significant role in our mental health.
The team also investigated a previously unknown link between depression and how we process the emotions we encounter in others. In this context, research has found that antibiotic-induced changes in the gut microbiota are linked to altered emotional behaviors.
The gut-brain-microbiota axis has been linked to the development of several neurological and psychiatric diseases, including Alzheimer's disease, Parkinson's disease, and an autism spectrum disorder. Any imbalance in the gut microbiota during the emerging adulthood period can set off a chain of events with long-term negative consequences for both physical and mental health.
Certain brain regions handle this processing differently in people with depression, and it's often evaluated by looking at responses to facial expressions. The same approach was used in this study, which used fMRI scans to see how participants responded to neutral or fearful faces.
It turns out that probiotics had an effect here as well: those who followed the path of 'good' bacteria had their normally awry brain processes normalized. While the reasons for this aren't fully understood, the early signs indicate that the treatment affects multiple aspects of depression.
Probiotics' health benefits are far from certain, and research into whether they may cause more harm than good is ongoing. However, based on this small sample size, it appears that they have at least some potential for treating depression.
However, the study's authors are quick to point out that the probiotics would not work as a standalone treatment without the antidepressants - and more research is needed to examine the effects of specific types of live bacteria on much larger groups of people.
Currently, approximately two-thirds of those prescribed antidepressants do not show a significant long-term response. Probiotics may be used in the search for more tailored and effective treatments.
