The Human Brain, Microbiome, and Gene therapy. A Cascade of How One Effects Another.

The studies of the human brain, human microbiome, and gene therapy seem like wildly different topics. By most common convention, they are. However, in the overall view of how a human body works and is maintained, these topics intertwine.

When one begins to study brain disorders, several heavy-hitting diseases come to mind: Huntington’s disease, Dementia, Alzheimer’s, and Tay-Sachs to name a few. These diseases, are all related to genetics in some way, as a person’s genetic makeup often lays the groundwork for predispositions to these diseases, or directly causes the disease. In the case of Huntington’s disease, it is an inherited brain disorder in which brain cells are slowly destroyed. The disease manifests in the patient first with general mood and mental issues, moving on to effect coordination of movement, and eventually causing the patient to be unable to talk. There is no cure for this disease, but some treatments have been formed to help improve the quality of life for the patient. Dementia and Alzheimer’s are often confused for one another due to the fact that they both effect the same subset of humans (geriatric) and have similar looking symptoms. Dementia, however, is a syndrome which combines the symptoms of impacted memory, reduced daily performance, and decreased communication abilities. Alzheimer’s is a type of dementia, which is a neurodegenerative disease which scientists are still studying the cause of. Many speculate that dementia is due to genetic factors, and those with a history of depression, traumatic brain injuries, and or hypertension are at higher risk of obtaining the disease. Tay-Sachs disease is an inherited metabolic disorder where lipids build up in the brain causing cell death. This most often is seen in infants between three to six months of age, and showing loss of skills in body coordination. This later often causes seizures, hearing loss, and death.

Terminal or chronic disorders like those listed above have devastating effects on the people afflicted by them, and all of these are uncurable. Or so we think. Recently, a new scientific technology has been created, coined “CRISPR”, short for Clustered Regularly Interspaced Short Palindromic Repeats. CRISPR is used to effectively edit DNA sequences in a more simple way than ever before, and with it, we may be able to cure such diseases as those previously stated. This topic is highly controversial, because the thought of editing a person’s genome is both dangerous, and possibly unethical. Most opposition for the use of this technology in humans has to do with changing germ-line cells that would propagate into the next generation of people, and thus, our actions now could have very real consequences later. Other arguments against CRISPR’s use has to do with the idea of personality and how genetics helps to shape it. If scientists were to change the building blocks of a person’s body, would they also change who they become mentally?

This brings us to the topic of the brain vs. the mind. A paper by Gabbard G.O. digs down to the point of how the public and how professionals currently think about the mind and the brain. The author argues that they are entwined, which everyone knows intrinsically, but speak differently upon, trying to separate the concept of mind from the anatomical organ found within the skull of a human. Ultimately the author argues that mental disorders are due in-part to anatomical issues within the brain itself, which means that again, genetics has play here. However, answering whether gene therapy in germ-cells is ethical cannot be answered based purely on this basis, as although genetics has a role to play as intrinsic factors, environmental factors also must be taken into account for who a person will some-day become. Environmental factors range from exposure to certain chemicals (via food, inhalation, skin absorption, etc.), to levels of stress incurred during development. The “nature vs. nurture” topic has been brought up time-and-time again to try to explain what ultimately determines a person’s personality and further actions. Do intrinsic motivations shape a person, or does the values a parent passes on to their child shape them? This is also, unfortunately, not easily answered as it turns out that both nature and nurture have to do with how a person will develop, and even further, microbial populations within a person can add to the environmental factors that shape people into who they are.

Microbial populations residing within the human microbiome help shape who a person becomes mentally sounds like a bit of a stretch. That is, until one looks into the forming body of research that shows how much the gut microbiome of a person actually effects the brain. As earlier established, the brain and mind as we know them are intertwined, where the anatomy of the brain shapes the mind, and the mind can eventually change the anatomy of the brain. Interestingly, microbial populations throughout the human body, especially in the lower gastrointestinal tract, can cause changes within the brain’s anatomy. Within the last decade, many scientific studies have linked the human gut microbiome to human behavior via emotions, learning ability, and feelings of satiety. Healthy microbiomes can promote proper brain function, while unhealthy microbiomes can exacerbate genetic predispositions already present in a person. Thus, gut microbiota help effect who a person becomes mentally.

To bring this full circle, the brain, human microbiome, and gene therapy are related in that the human microbiome effects the brain, the brain effects the mind, and the mind shapes who we are as people. Gene therapy promises to change this dynamic with repercussions that we as scientists cannot yet understand, but regardless, it is an exciting time to be alive to see these new developments in the world.