How is the microbiome associated with Parkinson's disease?

 Michael J. Fox, before he was diagnosed with Parkinson's disease (photo by Alan Light)

Michael J. Fox, before he was diagnosed with Parkinson's disease (photo by Alan Light)

We’ve talked before about what we call the gut-brain axis, the crosstalk between the gut and brain, and it’s effects on autism  and depression. But scientists in Finland have now shown that there is a relationship between bacteria in the gut and Parkinson’s disease. While Parkinson’s disease is a neurodegenerative disease caused by the loss of dopamine producing neurons in the brain that results in the loss of motor functions and tremors, gastrointestinal dysfunction, specifically constipation, is another symptom of the disease and often precedes the loss of motor function in patients.

Even though Parkinson’s disease was first described in 1817 and has been studied for many years, we still do not know what causes the majority of cases of the disease (approximately 5% of cases are a result of genetic mutations).  Because gastrointestinal dysfunction is implicated in the disease, scientists have hypothesized that the microbiome and bacteria in the gut may play a contributing role in the disease. 

Published in the journal Movement Disorders, the researchers in Helsinki have shown that there are variations in specific bacteria in Parkinson’s patients compared to control subjects without the disease. They recruited 72 Parkinson’s patients and the same number of control subjects and compared the bacteria in their fecal samples. They found that specific bacteria, specifically in the Prevotellaceae family, were less abundant in patients who had Parkinson’s disease. Patients who had high levels of Prevotellaceae were unlikely to have the disease. They also found that patients who had higher levels of bacteria in the Enterobacteriaceae family had greater severity of balance impairment and difficulties with their gait. 

While low levels of Prevotellaceae cannot yet be used as an identifier for Parkinson’s disease because it has also been correlated in other conditions like autism and type 1 diabetes, this study shows us that a better understanding of the bacteria in our guts may provide insight into the cause of the disease.  It is important to further investigate the microbiome in association with Parkinson’s as the identification of a biomarker for the disease is critically important. Understanding the role that bacteria in the gut may have in the disease may not only allow us to better identify and diagnose patients, but manipulation of the microbiome prior to the onset of the disease may help prevent or slow disease progression. Countless diseases and conditions are thought to be caused by environmental factors and as we discussed in yesterday's blog, the microbiome may play an important role in these environmental causes of disease.  

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