I remember my first twinge of excitement and awe when I first heard that a neurologic disease may actually have roots in the gut.
It was in an advance neuroanatomy course in medical school and we were dissecting the basal ganglia discussing Parkinson’s disease. My professor mentioned new research that suggested Parkinson’s may actually originate in the GI tract and migrate up the vagus nerve to the brain!
It shook my foundation of knowledge. From that moment, I understood that, we doctors, know and are taught many things, but nothing is certain and we must keep digging to find answers. That means medicine changes as new data comes to light.
That lecture opened my eyes and my mind to all the “radical” new science out there and desire to keep questioning.
The second thing I discovered that day is that our body is one system and everything in it is interconnected, nothing seems to work in isolation.
What do we know now, years later, about Parkinson’s and the gut? Well, since 2003, when the idea was proposed, the theory has taken off and spurred more research. There are several hypotheses:
1) some type of pathogen travels up the vagus nerve from the intestine
2) the "Lewy bodies" (clumps of the protein alpha synuclein) travel the vagus nerve themselves or induce other proteins to become misshapen
3) bacteria in the gut influences the brain through another mechanism, like inflammation
The origin of Parkinson's is still unclear, but it's enough to flip my world upside down and shifted my black-and-white thinking to a technicolor world of uncertainty. Little did I know then, where this would lead me.
Here’s a recent article from Brain Research that might be of interest: https://www.ncbi.nlm.nih.gov/pubmed/29360467