In May 2017 I wrote about some really exciting research into the probiotic bacteria Lactobacillus reuteri (which is derived from human breast milk) in both PTSD and autism. If you remember, I mentioned that a clinical trial would be conducted on 40 veterans with PTSD. According to clinicaltrials.gov, the study concluded at the end of May.[i] However, the results are not yet available. Stay tuned for those.
Also in 2017, the same team of researchers (headed by Dr. Christopher Lowry) at the University of Colorado-Boulder who conducted that clinical study published a paper[ii] that showed that when mice were injected with a (heat-killed) bacterium called Mycobacterium vaccae and placed with a larger and more aggressive male, “…they exhibited less anxiety or fear-like behaviors and behaved more proactively around their aggressor. They were also 50 percent less likely to suffer stress-induced colitis (as measured by cellular damage to the colon) and showed less system-wide inflammation.” The treated mice also produced more of an enzyme involved in producing serotonin in the brain. The results indicated that mice, at least, essentially can be vaccinated against PTSD.
Yesterday I spotted that this same group have just published another paper in Brain, Behavior and Immunity[iii] in which they examined precisely how M. vaccae produces its anti-anxiety neurological effect. They injected the bacterium into rodents once per week for 3 weeks. Eight days after the last injection, they discovered increased levels of the anti-inflammatory cytokine interleukin-4 in the mice’ hippocampus. This part of the brain is important in learning and memory and a part of the brain’s system of regulating our anxiety levels, fear, and fight-or-flight response. They also found lower than normal levels of a stress-induced protein called alarmin and a higher level of receptors that keep brain inflammation low.[iv] From the paper: “The present findings suggest that M. vaccae enhances immunomodulation in the CNS and mitigates the neuroinflammatory and behavioral effects of stress, which may underpin its capacity to impart a stress resilient phenotype.”
I don’t think it will be long now before targeted probiotics become a mental-health treatment norm.
[iii] Frank, MG, et. al. Immunization with Mycobacterium vaccae induces an anti-inflammatory milieu in the CNS: Attenuation of stress-induced microglial priming, alarmins and anxiety-like behavior. Brain, Behavior, and Immunity. 2018. https://doi.org/10.1016/j.bbi.2018.05.020