Evidence of Gut-to-brain and Brain-to-gut Syndromes


The pathways of mutual influencing between the gut and the brain are strong, and the ‘next wave of research” may involve deliberate microbial interventions as mental health treatments, according to a review of the scientific literature published in the Australian and New Zealand Journal of Psychiatry.

The Australian researchers did a narrative review and found that, “Population surveys show a strong correlation between anxiety, depression, and functional gastrointestinal disorders, contradicting early suspicions that the high prevalence of anxiety and depression in the clinic was mainly due to neurotic health seeking behaviour.”

They also found that this influence was bidirectional and operated through a variety of distinct biological pathways. “Five and 12 year follow-up shows that psychological distress can predict later onset of a functional gastrointestinal disorder and vice versa,” they wrote.

Observations in animal studies suggested that these relationships could potentially lead to effective interventions. “The ability to control rodent temperament and HPA responsiveness with early modification of gastrointestinal flora, and the effects of early stress on the barrier function of the gastrointestinal tract and flora, suggests an ability of both systems to prime each other in early life for later problems,” they wrote. “This hypothesis seems to be supported by a possible protective effect of a probiotic strain of bacteria in a model of early rat psychological trauma.”

Keightley, Philip C., Natasha A. Koloski, and Nicholas J. Talley. “Pathways in Gut-Brain Communication: Evidence for Distinct Gut-to-Brain and Brain-to-Gut Syndromes.” Australian and New Zealand Journal of Psychiatry 49, no. 3 (March 1, 2015): 207–14. doi:10.1177/0004867415569801. (Abstract)


  1. Yes, probiotics help with achieving mental clarity, as well as bolstering immunity. The only thing missing from the equation, here, is the heart. When the gut cools, it in turn cools the heart, and THAT’s what calms the brain activity.

    When the heart has been wounded by chronic betrayal, shaming, etc., it constricts, which leads to chronic rage, grief, despondence, etc. This affects brain activity, thoughts, perception, how we respond to external factors, and even to our own thoughts and actions. With heart constriction, we are likely to feel more guilt, fear, or even victimization, even when we are not really being victimized. That can easily be a perception. The world feels and looks different when your hearts are constricted, darker and more bleak, and also effort-filled.

    But when our hearts are relaxed, open, feeling hope, optimism, and joy, then our thoughts become calmer, more uplifting, and our stress tolerance raises considerably. This is what leads to ease and clarity in life.

    The heart is where consciousness really begins, because what we feel in our hearts is truth, this is our spirit; whereas what we perceive with our brains is simply that, a perception. Often, the brain misguides us with illusions, whereas our hearts guide us honestly, when we learn to trust our hearts and follow its guidance. Our inner guidance is felt in the heart, so it is important to trust this, to know our true path in life.

    So yes, the gut and brain are connected, but through the heart. That’s the vital organ in this equation. When healing from anything, the heart is a good place to start because without addressing heart wounding, healing is limited and temporary. The heart is what most wants to heal, and when it does, the rest falls in line with relative ease.

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  2. So, a “broken heart” should be thought of literally, as well as figuratively. This makes sense to me. For me, the biggest insight or “aha” moment is recognizing that trauma, which originates outside a person, changes one’s biology, and some very effective interventions — e.g., body-based sensorimotor therapy, nutrient therapy — occur at the body level. In some cases, healing at the body level must occur before the individual can benefit from talk therapy or psychosocial support.

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