The enteric nervous system (ENS), which is regarded as our second brain, is the part of the autonomic nervous system that controls the digestive tract. Housed along the entire length of the digestive tract, it is made up of more than 100 million neurons. It plays a central role in controlling the regulation of gastrointestinal motility, absorption of nutrients, and control of the intestinal barrier that protects the body from external pathogens.
Braak's hypothesis suggests that the digestive tract could be the starting point for Parkinson's disease. The fact that nearly all patients with Parkinson's disease experience digestive problems and have neuropathological lesions in intrinsic and extrinsic innervation of the gastrointestinal tract suggests that Parkinson's disease also has a gastrointestinal component.
