Prior to this study, it was generally believed that there was only one type of Parkinson’s disease. However, their work revealed that there are actually two major strains of the disease that can leave patients susceptible to a wide range of symptoms.
“Until now, many people have viewed the disease as relatively homogenous and defined it based on the classical movement disorders,” said researcher Per Borghammer. “But at the same time, we’ve been puzzled about why there was such a big difference between patient symptoms. With this new knowledge, the different symptoms make more sense and this is also the perspective in which future research should be viewed.”
Identifying the two disease strains
For the study, the participants included both Parkinson’s patients and those at an increased risk of the disease. Each group experienced an initial round of MRI and PET scans, and every few years they were reevaluated to see how Parkinson’s develops and spreads.
Based on the findings, the researchers theorize that there are two main types of Parkinson’s disease that start in different places in the body and can result in different bodily symptoms. While nerve deterioration eventually happens in both forms of the disease, how the participants got there was very different based on the variant they had.
“For some patients, the disease starts in the intestines and spreads from there to the brain through neural connections. For others, the disease starts in the brain and spreads to the intestines and other organs such as the heart,” Borghammer said.
With this information, it’s no surprise that patients experience such a wide range of symptoms that are all related back to Parkinson’s. The researchers explained that this can be especially tricky for patients who have the variant that originates in the brain because the symptoms may not be apparent until the disease has already progressed.
“This variant of the disease is probably relatively symptom-free until the movement disorder symptoms appear and the patient is diagnosed with Parkinson’s,” Borghammer said. “By then the patient has already lost more than half of the dopamine system, and it will therefore be more difficult to find patients early enough to be able to slow the disease.”
Improving treatment options
The researchers say these findings are very promising and could lead to the development of more specific Parkinson’s treatment options that can be better suited to patients’ individual needs.
“Previous studies have indicated that there could be more than one type of Parkinson’s, but this has not been demonstrated clearly until this study, which was specifically designed to clarify this question,” said Borghammer. “We now have knowledge that offers hope for better and more targeted treatments of people who are affected by Parkinson’s disease in the future.”