Depression and the Microbiome: A Brief Update

A few days ago, the website Psychiatry Advisor, had a very nice review article[i] of our current understanding of probiotics’ effects on depression. I’ve written about this before, obviously, but want to always keep you updated on all the latest.  Besides, this is also a good lead in for my  next post, which I am devoting to leaky gut.

An overall summary:  we continue to be faced with the usual situation in medical science.   Preliminary results look very promising but way more research is need before definitive conclusions can be drawn.

What we do know right now:

1. 1. 1. Major depressive disorder (MDD) is associated with chronic low-grade inflammation.
      2. A 2017 meta-analysis of 82 studies found that those with MDD have increased levels of pro-inflammatory cytokines.  Also, those with MDD also have higher rates of co-morbid inflammatory disorders like rheumatoid arthritis and heart disease.[ii]
      3. Anti-inflammatory drugs like NSAIDS (i.e. ibuprofen, etc.), for example, have proven to be anti-depressive as well.
      4. Depression is highly associated with alterations of the bacterial microbiota.
      5. Studies have shown that the probiotic Bifidobacterium infantis can normalize inflammation that is the result of stress.  (Not many probiotics contain this particular strain, but I did find this one: Align Probiotic Supplement.)
      6. The increase in pro-inflammatory cytokines from stress is known to increase intestinal barrier permeability (i.e. leaky gut). This, in turn, leads to increased levels of toxic bacterial byproducts in the blood, which is also highly inflammatory.  Several probiotics have been shown to normalize this intestinal permeability.  This past week, a study was published that looked at potential treatment for leaky gut, and among the non-pharmaceutical options presented are probiotics (like VSL 3 ) that contain Bifidobacteria and Lactobacilli; prebiotics (that contain FOS and GOS (I use this Jarrow product myself); melatonin (there are several good ones on the market like this NOW product); and NAC (n-acetyl cysteine, like this Jarrow product, which is a powerful antioxidant).[iii]
      7. I mentioned this study in that previous post mentioned above,  but it’s worth repeating. In an 8-week long randomized, double-blind trial of 40 people diagnosed with MDD, half were given the placebo and half were given a fairly low-potentcy probiotic formulation consisting of 2 billion units each of Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium bifidum. Those who received the probiotic had “significantly” decreased depressive scores, and also, improved inflammatory markers and glucose metabolism (lower insulin levels, for example).  The researchers also noted significantly higher blood glutathione levels.  Glutathione is one of the major antioxidants in our bodies, as well as being crucial to normal detoxification.[iv] 
      8. There have been several other clinical trials that have shown similar excellent results.

1. 1. 1. While a few other studies have not shown benefits, this review article correctly  points out that those studies were measuring mood improvement in people not diagnosed with depression.
   1. 1. So, while there is most certainly no medical consensus on dosing, species of bacteria, and so forth, trying probiotics (along with prebiotics and other biome restoring supplements) for depression makes perfect sense.
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      3. [i] https://www.psychiatryadvisor.com/depression-advisor/probiotics-depression-and-the-role-of-inflammation/article/807994/
      4. [ii] Köhler CA, Freitas TH, Maes M, et al. Peripheral cytokine and chemokine alterations in depression: a meta-analysis of 82 studies. Acta Psychiatr Scand. 2017;135(5):373-387.
      5. [iii] Morris, G, Fernandex, BS, Puri, BK, Walker, AJ, Carvalho, AF, Berk, M. Leaky brain in neurological and psychiatric disorders: drivers and consequences.  The Australian and New Zealand Journal of Psychiatry. 2018;52(10):924-948.  doi: 10.1177/0004867418796955.
      6. [iv] Akkasheh G, Kashani-Poor Z, Tajabadi-Ebrahimi M, et al. Clinical and metabolic response to probiotic administration in patients with major depressive disorder: a randomized, double-blind, placebo-controlled trial. Nutrition. 2016;32(3):315-320.