Symptoms of Medication Withdrawal in Parkinson's Disease: Considerations for Informed Consent in Patient-Oriented Research.

INTRODUCTION: Dopamine medication withdrawal in Parkinson's disease (PD) is commonly employed in clinical practice and can be required for participation in research studies. When asked to withdraw from medications, participants often enquire as to what symptoms they should expect.
OBJECTIVES: This study sought to improve the informed consent process by identifying patient-reported symptoms when dopamine treatment is withheld. We also sought to provide clinical guidance regarding the extent of these symptoms and consider participant willingness to undergo these assessments.
METHODS: Participants were recruited from community-based PD programs and support groups in Nashville, Tennessee, USA. A patient-based questionnaire determined the frequency and severity of motor and nonmotor symptoms. The questionnaire also assessed whether patients would be willing to abstain from medication at a future date and under what circumstances.
RESULTS: A total of 31/90 participants reported willingness to withdraw from dopaminergic medications for clinical or research purposes. Tremor, walking, and balance were the most common motor symptoms that worsened during this time. Sleep dysfunction, constipation, and tremor were noted as the most severe symptoms. Of note, 10% of participants indicated that they would not be willing to go off medications again, suggesting that a minority of patients find this to be most discomforting. When prompted for a reason why participants would be willing to come off of their medications again, "for clinical purposes" was selected the most.
CONCLUSIONS: Study teams should list these symptoms in the applications to their institutional review board and in the informed consent to provide guidance for participants.