dcyphr | Microbiome and mental health in the modern environment


Understanding the physiological cause of mental illnesses has greatly increased. This knowledge combined with the discovery of the microbiome and psychoneuroimmunology has created a new way to study mental health: psychobiotics. The microbiome we have today is much different than past humans, due to our diet, medications, and other environmental factors. The ability of our diets and microbiomes to affect our mental health is a very complex and poorly understood discovery. The potential of psychobiotics to alleviate mental illnesses makes understanding the science very important.

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Affective disorders, anxiety disorders, and psychotic disorders are more than simple stressors, they involve the whole body inflammation and immune health. The microbiome consists of over 100 trillion organisms that affect our bodies. The microbiome can affect diseases of the gut, autoimmune disease, obesity, and alcohol metabolism. Every single person’s microbiome is unique, but healthy people have a lot of the microbiome in common.

The idea that the gut microbiome and brain are connected is based on the hypothalamic-adrenal-pituitary axis. The microbiome may influence the axis in a similar way to stress, which can create inflammatory cascades and an increase in sympathetic nervous activation. Probiotics and antiinflammatories can lessen the inflammation and sympathetic activation. Medication that includes healthy microbes can potentially be used for anti-inflammation, anti-anxiety, or anti-depression medication with much lower side effects than traditional medications.

Studies have shown that rodents' moods can be influenced by probiotics, prebiotics, and fecal transplants. Prebiotics refer to types of fiber that the microbiome can eat. Humans have showed a decrease in negative and obsessive thoughts after a month of probiotic treatment. Prebiotics and pseudocommensals have decreased anxiety in humans. Pseudocommensals are microbes that live in soil and water that can be healthy for human diets, but do not live in the GI tract long term.

In another study, rates of ADHD and autistic spectrum disorders in teenagers were found to decrease if they were given probiotics as infants. The addition of antibiotics with antidepressant medications were more beneficial to the patient than antidepressants alone, found in another study. Differences in the microbiome have been found in people with schizophrenia and anorexia as well.

Though the links between the microbiome and mental health are clear, there are challenges in generating reliable data. For example, a general probiotic supplement may not work well to treat different patients, where it would be more helpful to test them and see which specific microbes their microbiome is missing. 

Food intake is highly variable between people, which can also alter the microbiome. Whole food diets that contain vitamins, minerals, and fatty acids also happen to be higher in fibers and prebiotics. This may explain why whole food diets can be helpful for those with mental illnesses.

One additional area of study includes helminths, which are parasitic worms that live in the gut. Helminths have been studied in some disorders, and may be applicable here due to the role of the helminths in preserving the microbiome. 


More collaborative research should be done in the field of psychobiotics.