title: Unraveling the Relationship between Motor Symptoms, Affective States and Contextual Factors in Parkinson's Disease: A Feasibility Study of the Experience Sampling Method.
abstract: BACKGROUND
  In Parkinson's disease (PD), the complex relationship between motor symptoms, affective states, and contextual factors remains to be elucidated. The Experience Sampling Method provides (ESM) a novel approach to this issue. Using a mobile device with a special purpose application (app), motor symptoms, affective states and contextual factors are assessed repeatedly at random moments in the flow of daily life, yielding an intensive time series of symptoms and experience. The aim of this study was to study the feasibility of this method.
  
  
  METHODS
  We studied the feasibility of a five-day period of ESM in PD and its ability to objectify diurnal fluctuations in motor symptom severity and their relation with affect and contextual factors in five PD patients with motor fluctuations.
  
  
  RESULTS
  Participants achieved a high compliance, with 84% of assessment moments completed without disturbance of daily activities. The utility of the device was rated 8 on a 10-point scale. We were able to capture extensive diurnal fluctuations that were not revealed by routine clinical assessment. In addition, we were able to detect clinically relevant associations between motor symptoms, emotional fluctuations and contextual factors at an intra-individual level.
  
  
  CONCLUSIONS
  ESM represents a viable and novel approach to elucidate relationships between motor symptoms, affective states and contextual factors at the level of individual subjects. ESM holds promise for clinical practice and scientific research.
authors.affiliation: Department of Neurology, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: Martijn P G
authors.initials: MP
authors.lastname: Broen
authors.affiliation: Department of Psychiatry and Psychology, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: Vera A M
authors.initials: VA
authors.lastname: Marsman
authors.affiliation: Department of Neurology, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Kuijf
authors.affiliation: Department of Neurology, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Van Oostenbrugge
authors.affiliation: Department of Psychiatry and Psychology, Maastricht University Medical Center, Maastricht, the Netherlands.|King's College London, King's Health Partners, Department of Psychosis Studies, Institute of Psychiatry, London, United Kingdom.
authors.forename: Jim
authors.initials: J
authors.lastname: van Os
authors.affiliation: Department of Psychiatry and Psychology, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: Albert F G
authors.initials: AF
authors.lastname: Leentjens
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D004644:Emotions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology*