Investigators have developed a comprehensive questionnaire that assesses the presence of non-motor fluctuations (NMFs) in individuals with Parkinson's disease (PD). To date, 189 participants with PD have been assessed for preliminary data analysis prior to developing the penultimate version. At this time the objectives are to: (i) assess the scale's internal consistency and item-to-total correlations; (ii) assess test-retest reliability; (iii) use factor analysis and reliability measures to guide item reduction; (iv) assess construct validity; and (v) assess the scales ability to discriminate between static non-motor symptoms and non-motor symptoms which fluctuate (vi) estimate the relative distribution of cognitive, psychiatric, autonomic, sleep and sensory NMFs in PD patients with motor fluctuations and their impact on quality of life in Parkinson's disease.

Inclusion Criteria:

• Diagnosed with Idiopathic Parkinson's Disease (according to the United Kingdom Parkinson's Disease Society Brain Bank clinical diagnostic criteria)
• Stage of symptoms is mild, moderate or severe as per the Hoehn & Yahr scale
• Have motor fluctuations
• Have non-motor fluctuations

Exclusion Criteria:

• Atypical Parkinsonism
• Lack of motor fluctuations
• Lack of English language proficiency in either subject or caregiver

Individuals, both men and women, who have been diagnosed with idiopathic Parkinson's Disease and have motor and non-motor fluctuating symptoms are invited to participate in the study. To ensure a representative sample, subjects spanning the disease spectrum will be equally represented in terms of mild, moderate and advanced symptoms of PD.