Parkinson's disease - could it really all start in your gut?

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Parkinson's disease affects around one in 500 people - somewhere near 127,000 people in the UK. The majority of people with Parkinson's are over the age of 50, but it does happen in younger people. The main symptoms are shaking, rigidity, slow movement and difficulty walking. As well as these, people with Parkinson's often feel tired, and may experience pain, depression and constipation. Symptoms vary between people, and the speed of onset of the condition is different between different people. 

People with Parkinson's begin to lose nerve cells in the midbrain, resulting in a lack of dopamine, a chemical that allows nerves to signal to each other in the brain. The reason these cells die is not known, but it involves the build up of proteins into aggregates within the cells. One of these proteins, alpha-synuclein, is thought to be one of the main culprits in Parkinson's disease, as well as various rarer conditions. 

Parkinson's is currently incurable. Current treatments involve giving extra dopamine or using drugs to simulate dopamine binding, but these gradually become less effective over time. 

Findings publishing in the journal Cell may have finally shed some light on this common yet mysterious condition, and it's not what you might think! In their experiment two groups of mice that over produce alpha-synuclein, and therefore are genetically susceptible to developing Parkinson's, were kept in different conditions. One group were kept in sterile conditions, and had no bacteria living in their gut. The other group was kept normally. The scientists found that only the animals living with bacteria went on to develop the disease. This prompted the question, "are the gut microbes in Parkinson's sufferers different from those in healthy people?". Further experiments showed that mice transplanted with gut bacteria from people with Parkinson's developed more symptoms than mice transplanted with gut bacteria from healthy people. 

So what does this mean for Parkinson's patients? Dr Timothy Sampson, one of the researchers behind this paper said:

"This was the 'eureka' moment, the mice were genetically identical, the only difference was the presence or absence of gut microbiota. Now we are quite confident that gut bacteria regulate, and are even required for, the symptoms of Parkinson's disease".

This is the first time a solid link between bacteria in the gut and Parkinson's has been shown, and opens up whole new avenues for management and treatment. Scientists hope that drugs to modify the bacteria in the gut, or even probiotics, could eventually become new and better therapies for this disease.