Roughly 60,000 people in the United States are diagnosed with Parkinson’s disease each year, according to the Parkinson’s Disease Foundation. In all, more than 1.5 million people in the United States suffer from the condition. Yet thousands of cases go undetected and diagnosing the disease in the early stages remains challenging.
Early diagnosis of Parkinson’s enables the disease to be treated with drugs such as dopamine agonists and monoamine oxidase type-B inhibitors, which can alleviate the condition’s symptoms and postpone the need to begin levodopa therapy. Nevertheless, early diagnosis of Parkinson’s has remained challenging and misdiagnoses are common.
Two recent studies performed at Rush University Medical Center (Chicago) point to an alternate way of diagnosing the disease: colonic tissue obtained during colonoscopy or flexible sigmoidoscopy might be used to predict who will develop the disease.
From the abstract published in the Movement Disorders journal:
Despite clinicopathological evidence that Parkinson’s disease (PD) may begin in peripheral tissues, identification of premotor Parkinson’s disease is not yet possible. Alpha-synuclein aggregation underlies Parkinson’s disease pathology, and its presence in peripheral tissues may be a reliable disease biomarker. Objective: We sought evidence of alpha-synuclein pathology in colonic tissues before the development of characteristic Parkinson’s disease motor symptoms. Methods: Old colon biopsy samples were available for three subjects with PD. Biopsies were obtained 2-5 years before PD onset. We performed immunohistochemistry studies for the presence of alpha-synuclein and Substance P in these samples. Results: All subjects showed immunostaining for alpha-synuclein (two, five and two years before first motor Parkinson’s disease symptom). No similar alpha-synuclein immunostaining was seen in 23 healthy controls. Staining of samples for substance P suggested colocalization of alpha-synuclein and substance P in perikarya and neurites. Conclusions: This is the first demonstration of alpha-synuclein in colon tissue prior to onset of PD. Additional study is required to determine whether colonic mucosal biopsy may be a biomarker of premotor PD
The scientists examined the tissue samples of people who later developed Parkinson’s disease. The samples were taken several years before the patients showed symptoms of the neurological disorder.
Kathleen M. Shannon, neurologist in the Movement Disorders and Parkinson’s Center at Rush, who was involved in the study, offered the following thought-provoking quote in a statement (emphasis added):
“Recent clinical and pathological evidence supports the notion that Parkinson’s disease may begin in the intestinal wall then spread through the nerves to the brain. Clinical signs of intestinal disease, such as constipation, [may precede] Parkinson’s disease diagnosis by more than a decade. These studies suggest it may one day be possible to use colonic tissue biopsy to predict who will develop motor Parkinson’s disease.”
While the research might ultimately lead to the use of colonoscopy or flexible sigmoidoscopy to diagnose Parkinson’s, the researchers stress the need for more studies to replicate the findings in larger patient populations with Parkinson’s and Parkinson’s-like disorders.
Image (from Wikipedia): Immunohistochemistry for alpha-synuclein shows positive staining (brown) of an intraneural Lewy-body in the Substantia nigra in Parkinson’s disease.