What is Depression?
Depression is a disorder that makes people feel chronically unhappy. It’s the number one disability in the world. Scientists have found many different factors that can cause depression, such as:
- The brain
- How people think
- And things outside of a person’s control
There are many different ways to treat depression, such as medicines and different kinds of therapies. Most people who get treatment feel better, but some people don’t. That’s why scientists are looking for new ways to help people with depression.
The Relationship of the Gut Microbiota And The Brain
The gut microbiota is important for human health. It has been linked to:
- Celiac disease
- Crohn’s disease
- And depression
Studies have also shown that the gut microbiota can affect stress reactivity and mental health.
This means that the gut microbiota can cause someone to be more or less stressed and make someone more or less likely to have mental health problems. There is evidence that transforming the gut microbiota can change someone’s behavior, their stress levels, and their likelihood of having mental health problems.
The gut microbiota may help regulate mental health by communicating with the brain through the gut-brain axis. This system connects the gut and brain and uses neural, hormonal, and immunological signals.
The vagus nerve is thought to be important for this communication, and when it’s cut, the antidepressant effects of probiotics in mice stop working.
Another way the gut and brain communicate is through tryptophan. Tryptophan can be turned into serotonin, but most of it is turned into kynurenine. Kynurenine can be turned into anthranilic acid, kynurenic acid, and quinolinic acid. These two have neuromodulatory properties.
The gut microbiota may also affect mental health by causing systemic inflammation. Systemic inflammation is when inflammation happens throughout the body. This can be caused by the gut microbiota letting microbes and other inflammatory stimulants move across the epithelium. When this happens, it can lead to a leaky gut
Leaky gut is when the gut becomes more permeable, which means that things like microbial products and lipopolysaccharides can get into the blood and activate an inflammatory immune response.
Systemic inflammation from a leaky gut can influence brain function by causing pro-inflammatory cytokines to cross the blood-brain barrier and affect central nervous system function. This might contribute to symptoms of depression.
Psychobiotics are probiotics that can have a positive effect on mental health. Studies have shown that animals and people who take probiotics have better moods and behavior. However, more research is needed to figure out if probiotics can be used to treat depression and if any specific strains of probiotics are more effective.
In this study, we looked at how probiotics might help with depression. We gave probiotics to people who had mild depression, and we looked to see if their symptoms got better.
We looked at whether people with more severe depression responded differently to probiotics than people with mild depression. We also looked at whether probiotics affected people’s moods, and whether this was related to changes in people’s gut bacteria.
The Study Method on Probiotics for Depression
71 people were chosen to take either a probiotic or a placebo every day for 8 weeks. Before and after the 8 weeks, their symptoms and markers of depression were measured, as well as their gut microbiota composition. The participants were also compared on psychological variables and gut microbiota composition to those who weren’t depressed.
The participants in the study all showed an improvement in their symptoms, which suggests that taking probiotics has some positive effect. The people who took probiotics showed a more significant reduction in cognitive reactivity than those who took a placebo. However, the probiotics didn’t seem to change the gut bacteria of the people who were severely depressed.
Probiotics seem to affect a psychological variable that is related to depression. Researchers need to do more work to see if probiotics can be used to improve mental wellbeing and if they can be used together with other treatments.