Understanding the Connection Between the Gut-Brain Axis and Major Depression: A Theoretical Perspective

The theory of neuroinflammation, which is proposed to explain the etiopathogenesis of neuropsychiatric disorders, has a very old history. This theory claims that low-intensity bodily inflammation negatively affects the neuronal system, synaptic neurotransmission is impaired, dysfunction occurs in neurons and glial cells, and because of all these, neuropsychiatric disorders occur. Intestinal microbiota disorder (dysbiosis) is suggested as the source of systemic inflammation. Depression is the disease in which the theory of neuroinflammation is most researched in an experimental environment. The causality between depression and intestinal dysbiosis has not been determined definitively in the studies. Our main goals in this article are to explain how dysbiosis occurs and the effect of civilization on the microbiota, as well as to make a future projection shaped by postmodern living conditions. In order to clarify the concepts, we will draw an analogy between neuroinflammation and a black hole. We will discuss whether we can learn some lessons from this analogy. Finally, we will end our article by making some speculations about the future that awaits humanity. Before we do all this, we will try to briefly explain what neuroinflammation is, its importance and the gut-brain axis.