The purpose of this study is to examine the short term effects (12 Weeks) of Lactobacillus plantarum PS128 (PS128) on Parkinson's disease (PD) symptoms.

This study is designed to examine the extent to which L. plantarum PS128 can improve symptoms in PD patients. L. plantarum PS128 is a psychobiotic that regulates the level of dopamine in specific brain regions. Patients with PD will receive PS128 treatment for 12 weeks. Symptoms of PD will be clinically evaluated before and after the treatment, and the results will be compared.

Inclusion Criteria:

• Between ages of 40-80 years old
• Diagnosed as a patient with Parkinson's disease of modified Hoehn and Yahr Stage between 1 and 2.5 as rated during an "on" period

Exclusion Criteria:

• Patients on antibiotics within the preceding one month
• Patients using of other probiotic products (sachet, capsule or tablet) within the preceding two weeks
• Have current or history of inflammatory bowel disease
• Have history of cancer
• Have undergone surgery of liver, bladder, or gastrointestinal tract
• Known allergy to probiotics
• Patients with comorbid dementia (Mini-Mental State Examination score ≤ 26) or major depression (The Beck Depression Inventory-II score ≥ 29)
• Have received deep brain stimulation
• Patients receiving artificial enteral or intravenous nutrition