This is an open-label study to investigate the effects of the rivastigmine patch on attention and behavior in Parkinson's disease when associated with memory and/or thinking problems. Rivastigmine (also sold under the name Exelon) is an FDA approved medication used for the treatment of mild to moderate Alzheimer's Disease (AD) and memory or thinking problems due to Parkinson's disease. Recently a rivastigmine patch was developed, which has shown similar effectiveness with fewer side effects and increased caregiver preference when compared to capsules. This is an open-label 12 week study where 15 subjects diagnosed with Parkinson's Disease who have mild to moderate memory and/or thinking complaints will be treated with the rivastigmine patch at UCSF. This study also analyzes the mechanism by which the rivastigmine patch works in people with Parkinson's disease and memory and/or thinking problems.