A biopsy of the submandibular gland may provide an accurate diagnosis of Parkinson’s disease and dementia with Lewy bodies (DLB), according to a study published March 30 in the Journal of Parkinson’s Disease. If confirmed, the results could improve patient recruitment for clinical trials.
Parkinson’s disease and DLB are widely misdiagnosed. Misdiagnosis may occur in approximately 50% of patients with Parkinson’s disease who are within the first five years of symptom onset, according to the researchers. Between 15% and 25% of neuropathologically defined patients with DLB receive a diagnosis of DLB during life.
“The low diagnostic accuracy, during life, for DLB has made it difficult to conduct effective clinical trials of possibly helpful new drugs,” said Thomas G. Beach, MD, PhD, Head and Senior Scientist at the Civin Laboratory for Neuropathology and Director of the Brain and Body Donation Program at Banner Sun Health Research Institute in Phoenix. “With better diagnostic accuracy, clinical trials would have a higher chance of success and could be done more quickly and at a lesser cost,” Dr. Beach said.
Brain biopsies are highly accurate for detecting Parkinson’s disease and DLB, but they entail a high risk of complications. Previous data suggested a high prevalence of submandibular gland synucleinopathy in patients with Parkinson’s disease. “This new work shows, in autopsies, that the submandibular gland also has the same signature alpha-synuclein pathology in a high proportion of subjects diagnosed during life with DLB,” said Dr. Beach.
Thomas G. Beach, MD, PhD
Dr. Beach and colleagues performed brain necropsies and neuropathologic examinations on elderly subjects with and without CNS Lewy-type pathology who had donated their bodies. The investigators stained submandibular gland sections with an immunohistochemical method to find Lewy-type α-synucleinopathy (LTS). Subjects with Lewy body disorders included 47 with Parkinson’s disease, 28 with DLB, nine with incidental Lewy-body disease, 33 with Alzheimer’s disease with Lewy bodies, and two with progressive supranuclear palsy with Lewy bodies. The 79 control subjects without CNS LTS included 15 with Alzheimer’s disease, 12 with progressive supranuclear palsy, two with corticobasal degeneration, and two with multiple system atrophy.
Submandibular gland LTS was present in 42 of 47 (89%) individuals with Parkinson’s disease, 20 of 28 (71%) people with DLB, four of 33 people with Alzheimer’s disease with Lewy bodies, one of nine people with incidental Lewy-body disease, and none of the 110 controls.
Needle biopsy of the submandibular gland may be useful as diagnostic biomarker or a biomarker of progression in Parkinson’s disease, said the researchers. In addition, the technique may improve diagnostic sensitivity for DLB and be a potential prognostic indicator. “The next step will be to do biopsies of the submandibular gland in living people with DLB to confirm these autopsy results,” Dr. Beach said.
—Erica Robinson