Categorized as a neurodegenerative disease, Parkinson’s disease occurs when dopamine producing cells begin to malfunction or die. Although most symptoms manifest as movement disorders, other symptoms such as constipation, depression, memory loss and other non-movement-related symptoms can occur. The symptoms of Parkinson’s disease progress over time and will continually worsen throughout a patient’s life. Symptoms and the rate of disease progression vary greatly between patients, making diagnosis difficult. Parkinson’s disease affects nearly 1 million people in the United States alone and more than 6 million worldwide.
The most likely cause of Parkinson’s disease is a combination of environmental and genetic factors. There is not one source of environmental exposures thathas been linked to the disease, but some research has indicated pesticides and head injuries are associated with higher risk. Certain genetic mutations have been linked to an increased risk of developing Parkinson’s disease.As such, aging is the greatest risk factor in developing Parkinson’s disease. The average age at diagnosis is 60 years, but it is still possible for some to develop the disease at 40 or younger.
Currently, there is no test that can be used to make a definitive diagnosis of Parkinson’s disease. Doctors diagnose Parkinson’s based on a person’s medical history, answers to medical questionnaires and a physical examination. Clinical diagnostic accuracy rests heavily on the expertise and judgment of the physician, making diagnosis in underserviced or developing areas difficult. During the diagnosis process a doctor may order lab or imaging tests to rule out alternative diseases. As with Alzheimer’s, there is a strong push to discover biomarkers capable of detecting Parkinson’s. It is also hypothesized that disease biomarkers will provide information such as risk of developing the disease and progression of those already diagnosed. There are large biomarker discovery initiatives being carried out currently, such as the Parkinson’s Progression Markers Initiative sponsored by the Michael J. Fox Foundation.
Recent studies have shown that biomarkers related to Parkinson’s disease may be present in the breath of patients. The 2013 Tisch et al.study compared the breath of 30 diagnosed Parkinson’s patients with 12 healthy controls. Researchers were able to identify key differences in the composition of exhaled breath from both sample groups and assign characteristic breathprints. The study also tentatively identified 7 compounds that occurred in >75% of both test groups at considerably different average concentrations, pointing to possible biomarkers.Bach et al. were also able to demonstrate a difference in breath composition between patients diagnosed with Parkinson’s and healthy controls at two separate collection sites. The researchers tentatively identified 4 compounds that when compared in unison allowed the differentiation between test groups.
Further research with larger sample populations are required to validate these preliminary findings. There is great potential for an unprecedented diagnostic test using breath analysis. With a better understanding of the metabolites produced from Parkinson’s disease, comes the potential for novel treatment options.
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Tisch, U.; Schlesinger, I.; Ionescu, R.; Nassar, M.; Axelrod, N.; Robertman, D.; Tessler, Y.; Azar, F.; Marmur, A.; Aharon-Peretz, J.; et al. Detection of Alzheimer’s and Parkinson’s Disease from Exhaled Breath Using Nanomaterial-Based Sensors. Nanomedicine2012, 8(1), 43–56.
Bach, J.-P.; Gold, M.; Mengel, D.; Hattesohl, A.; Lubbe, D.; Schmid, S.; Tackenberg, B.; Rieke, J.; Maddula, S.; Baumbach, J. I.; et al. Measuring Compounds in Exhaled Air to Detect Alzheimer’s Disease and Parkinson’s Disease. PLOS ONE2015, 10(7), e0132227.