Two hundred years after the first trial that described Parkinson’s disease, advances are being made to identify its origin. Recently, a group of researchers at the Karolinska Institute in Stockholm discovered that it could originate in the bowels and spread to the brain through the vagus nerve.
Parkinson’s could originate in the bowels and reach the brain through the vagus nerve
Different research has indicated that the gastrointestinal tract could be behind the origin of Parkinson’s. The vagus nerve has great influence on the body and brain. It is the tenth cranial nerve and runs from the brain stem to the abdomen. It is connected to many organs of the digestive, respiratory and cardiac systems. It is a motor nerve, which means that its purpose is to enable muscles to contract and relax. It is also a sensory nerve, which allows us to feel sensations in the areas that it passes through. Another important aspect is its function as a transmitter of the nerve impulses responsible for the automatic activities of many organs. In addition, it facilitates relaxation, promotes feelings of satiety and controls anxiety.
According to the Swedish research, patients who had been operated on to remove the main stem of their vagus nerves were much less likely to develop Parkinson’s (40% less) than those who had not undergone the surgery. They therefore believe that this disease could begin in the bowels and spread to the brain through the vagus nerve.
Although these findings are still preliminary, they may mark the beginning of new research into identifying causative factors with greater certainty. Another important study in this field was conducted by Georgetown University in Washington D.C., which showed that alpha-synuclein, a protein associated with Parkinson’s and other neurodegenerative diseases, is released when an infection occurs in the upper gastrointestinal tract (oesophagus, stomach and duodenum).
The infection could exceed the body’s ability to remove alpha-synuclein. This accumulates in the enteric nervous system (of which the vagus nerve forms part). And it moves from the bowels to the brain. In normal amounts, this protein is a good molecule with a protective function. But repetition of infections in the gastrointestinal tract prevent the body from dealing with high amounts. And these become toxic. This, according to the study, can cause damage to the nervous system and cause Parkinson’s.
Reinforcing the theory that it can start in the bowels is other research by the California Institute of Technology. A connection was found between the bacteria present in the bowels and deterioration of the motor functions that characterise the disease.
If the findings of this research are confirmed, there could be changes in treatments, according to the researchers. Up to now, the emphasis has been on drugs that act on the brain. But if the origin is in the bowels or in the gastrointestinal tract, drugs for this area could be used to treat Parkinson’s.
This research, together with the development of neuroscience, shows that much progress has been made in understanding the origin of this disease, which affects more than 160,000 people in Spain and more than six million worldwide.
It is a complex disorder. It has motor symptoms such as slow movements, tremors, stiffness and postural instability, and non-motor symptoms such as sleep disorders, constipation and visual, respiratory, urinary, cognitive and psychological problems. New treatments enable Parkinson’s sufferers to lead 90% of a normal life.