Pyridostigmine for the Treatment of Constipation in Parkinson Disease

Change in number of spontaneous bowel movements per week after the study intervention

Participants will keep a Bowel Movement Journal during the four week Screening Phase, from which the pre-intervention average number of spontaneous bowel movements will be calculated. They will again keep a Bowel Movement Journal for the four weeks of the Treatment Phase, from which the postintervention average number of spontaneous bowel movements will be calculated.

Changes from Baseline to the End of Study Visit in the Gastrointestinal Dysfunction Scale in Parkinson's Disease (GIDS-PD)

The Gastrointestinal Dysfunction Scale in Parkinson's Disease (GIDS-PD) is a PD-specific self-administered scale that evaluates various gastrointestinal symptoms including, but not limited to, constipation, and lifestyle factors that impact symptoms such as diet and physical activity. The GIDS-PD score is broken down into 3 subscores: constipation, bowel irritability, and upper GI. There are 12 items, and each item score is calculated by multiplying the frequency score and the severity score. The total score is calculated by adding the scores of items 1-12. The minimum score is 1 and the maximum score is 108. While the GIDS-PD is typically completed based on symptoms over the past six months, the investigator will ask the participant to consider their symptoms over the past one month.

Changes from Baseline to the End of Study Visit in the Cleveland Clinic Constipation Scoring System (CCCSS)

The Cleveland Clinic Constipation Scoring System (CCCSS) is a 0-30 point self-administered scale comprised of eight variables (i.e., frequency, difficulty, completeness, pain, time, assistance, failure and history) quantifying the degree of constipation. A score of 0 is normal while a score of 30 indicates severe constipation. While the CCCSS is typically completed based on symptoms over the past six months, the investigator will ask the participants to consider their symptoms over the past one month.

Changes from Baseline to the End of Study Visit in the MDS-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Parts I-IV

The MDS sponsored revision of the Unified Parkinson's Disease Rating Sale (MDS-UPDRS) was developed to evaluate various aspects of Parkinson's disease including non-motor and motor experiences of daily living and motor complications. It includes a motor evaluation and characterizes the extent and burden of disease across various populations. The MDS-UPDRS is broken down into 4 parts: Part I (non-motor experiences of daily living), Part II (motor experiences of daily living), Part III (motor examination), and Part IV (motor complications).

Changes from Baseline to the End of Study Visit in the International Parkinson and Movement Disorder Society Non-Motor Rating Scale (MDS-NMS)

The International Parkinson and Movement Disorder Society Non-Motor Rating Scale (MDS-NMS) is a revision of the Non-Motor Symptoms Scale (NMSS) and was developed to improve and refine the assessment of non-motor symptoms in Parkinson's disease (PD). This rater completed assessment measures frequency and severity of 13 non-motor domains, over 52 items and covers a range of key non-motor symptoms both PD and treatment related, and in greater depth, compared with the NMSS. The scale also has a new MDS-NMS Non-Motor Fluctuations (NMF) Subscale to assess changes in non-motor symptoms in relation to the timing of antiparkinsonian medications across 8 domains. The MDS-NMS is a valid and reliable rating scale that measures the burden of non-motor symptoms, including non-motor fluctuations, in PD patients.