The purpose of this study is to perform biopsies of one of the glands that make saliva. The biopsied tissue will then be analyzed to see if it has changes that occur in Parkinson's disease. This study will determine whether it is possible to do a second biopsy a few years after a previous biopsy and determine whether there are changes in the biopsy that would allow for analysis of disease progression.

Tissue biopsies documenting the presence and density of Lewy type synucleinopathy (LTS) in living patients with probable Parkinsons disease (PD) would be extremely valuable as a diagnostic test, as a marker of molecular therapeutic target engagement and as a progression marker. Based on recent data from our group with both early and advanced PD patients, we propose to perform a second transcutaneous submandibular gland (SMG) needle core biopsy in 12 patients who have previously been biopsied and had LTS present in their SMG tissue.

Inclusion criteria

1. PD patients ages up to age 85.
2. Previous participation in a SMG biopsy study at Mayo Clinic Arizona with a positive biopsy being reported

Exclusion criteria

1. Evidence for dementia that would preclude the patient from signing informed consent
2. History of bleeding diathesis or hematologic disorders
3. Medically unable to undergo a core needle biopsy of the submandibular gland
4. Prior treatment of the submandibular gland with botulinum toxin injections.
5. History of past or current acute infection or abscess of the submandibular gland.
6. History of past or current neoplastic process within the submandibular gland.
7. History of peripheral neuropathy.