Bacteria of the digestive tract influence the development of Parkinson’s disease
Parkinson’s disease affects nearly 2% of the population over age 65. It is becoming a growing concern as more and more baby boomers advance in age. The condition is characterized by slowing of movement, difficulty walking, gait abnormalities, muscle rigidity and tremor, difficulty of getting out of chair. Consequently, it is classified as a neurodegenerative movement disorder. Some epidemiological researchers link pesticides, toxins and pollution with increased risk of Parkinson’s disease development. At the same time other researchers report protection with increased coffee intake and physical exercise. Genetic predisposition plays small role in Parkinson’s disease with only 10% of the conditions presentation.
There are few processes known to contribute to the neuronal loss of cells within the substantia nigra. These include iron deposition, oxidative stress, mitochondrial damage and accumulation of a protein called alpha-synuclein.
Together with motor symptoms Parkinson’s disease is also characterized by non-motor abnormalities such as loss of the sense of smell, sleep disturbances and digestive complains. There are strong evidence that Parkinson’s disease may originate in the gut with alpha-synuclein accumulations propagate via the vagus nerve from the digestive tract into the brain. Actually the initial degeneration within the brain begins with the cell bodies of the vagus nerve. Furthermore, symptom of constipation, which usually precedes the development of the motor symptoms, just adds weight to this theory.
Gut’s bacteria plays very important role in the digestion of food, formation of nutrients and toxins, regulation of the immune system, maintenance of the blood-brain barrier and communication with our nervous system. It also affects production of serotonin, a neuro-hormone responsible for pain and motility( active movement) within the digestive tract, and for mood.
In recent study (Sampson 2016) the team of researchers examine the role of bacteria in the development Parkinson’s disease. They collected the fecal matter containing bacteria from the patients with Parkinson’s disease and transplanted it to the digestive tract of mice, and compare the results of it to the transfer of fecal matter from healthy patients. The mice with gut bacteria from patients with Parkinson’s disease developed motor abnormalities within 8 weeks. When examining the nerves of the mice researchers found alpha-synuclein aggregations as a result of implanted gut bacteria from Parkinson’s disease donors. That means that gut bacteria can stimulate alpha-synuclein aggregations.
There are many factors that affect quality of the microflora. Antibiotics use provide huge impact. It takes 6 month to restore proper bacteria in digestive tract after using them. By removing some microflora and allowing others to prosper these medications can alter the composition, in either direction – creating a positive environment by removing the offending, pathogenic bacteria, or stimulating a pro-inflammatory environment by damaging the beneficial bacteria.
Pesticides, which are known as rick factor for developing Parkinson’s disease, can damage the composition of the gut bacteria by destroying particular families of microbes. On the other hand, some bacteria are known to be able to breakdown pesticides, potentially protecting us from their toxic effects. It is a great possibility that the change in microflora in patients with PD results in exposure to a larger amount of environmental pollutants and toxins that are usually cleared by the microflora present in the gut of healthy people.
Diet plays a significant role in regulating the composition of the microflora. This is because it provides a source of new bacteria and nutrients for their growth. Prebiotics (which are the fuel for bacteria) contain fiber and indigestible carbohydrates that promote the growth of the healthy bacteria. Additionally, there is strong evidence for the beneficial role of coffee and blueberries and harmful effects of dairy.
These foods provide rich supply of antioxidants and nutrients with anti-inflammatory properties. As a result, they offer protection to the neurons and offset the increase in oxidative stress seen with Parkinson’s disease. But these food also protective because of their influence on the digestive tract. Since the fruits and vegetables are high in fiber they can serve as important source of prebiotics.
Additional factor that influence microflora is the immune system. This is because the function of the immune system influences the bacteria that can colonize the digestive tract. Mood and anxiety and other neurological changes can also influence gastrointestinal function and microflora.
While the research of the relationship between gut bacteria and Parkinson’s disease continues current evidence suggest that microflora may be the root of the problem.
- Sampson T. Gut microbiota regulate motor deficits and neuroinflammation in a model of Parkinson’s disease. Cell. 2016; 167: 1469-1480