title: New Clinical Subtypes of Parkinson Disease and Their Longitudinal Progression: A Prospective Cohort Comparison With Other Phenotypes.
abstract: OBJECTIVE
  There is increasing evidence that Parkinson disease (PD) is heterogeneous in its clinical presentation and prognosis. Defining subtypes of PD is needed to better understand underlying mechanisms, predict disease course, and eventually design more efficient personalized management strategies.
  
  
  OBJECTIVE
  To identify clinical subtypes of PD, compare the prognosis and progression rate between PD phenotypes, and compare the ability to predict prognosis in our subtypes and those from previously published clustering solutions.
  
  
  METHODS
  Prospective cohort study. The cohorts were from 2 movement disorders clinics in Montreal, Quebec, Canada (patients were enrolled during the period from 2005 to 2013). A total of 113 patients with idiopathic PD were enrolled. A comprehensive spectrum of motor and nonmotor features (motor severity, motor complications, motor subtypes, quantitative motor tests, autonomic and psychiatric manifestations, olfaction, color vision, sleep parameters, and neurocognitive testing) were assessed at baseline. After a mean follow-up time of 4.5 years, 76 patients were reassessed. In addition to reanalysis of baseline variables, a global composite outcome was created by merging standardized scores for motor symptoms, motor signs, cognitive function, and other nonmotor manifestations.
  
  
  METHODS
  Changes in the quintiles of the global composite outcome and its components were compared between different subtypes.
  
  
  RESULTS
  The best cluster solution found was based on orthostatic hypotension, mild cognitive impairment, rapid eye movement sleep behavior disorder (RBD), depression, anxiety, and Unified Parkinson's Disease Rating Scale Part II and Part III scores at baseline. Three subtypes were defined as mainly motor/slow progression, diffuse/malignant, and intermediate. Despite similar age and disease duration, patients with the diffuse/malignant phenotype were more likely to have mild cognitive impairment, orthostatic hypotension, and RBD at baseline, and at prospective follow-up, they showed a more rapid progression in cognition (odds ratio [OR], 8.7 [95% CI, 4.0-18.7]; P < .001), other nonmotor symptoms (OR, 10.0 [95% CI, 4.3-23.2]; P < .001), motor signs (OR, 4.1 [95% CI, 1.8-9.1]; P = .001), motor symptoms (OR, 2.9 [95% CI, 1.3-6.2]; P < .01), and the global composite outcome (OR, 8.0 [95% CI, 3.7-17.7]; P < .001).
  
  
  CONCLUSIONS
  It is recommended to screen patients with PD for mild cognitive impairment, orthostatic hypotension, and RBD even at baseline visits. These nonmotor features identify a diffuse/malignant subgroup of patients with PD for whom the most rapid progression rate could be expected.
authors.affiliation: Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Seyed-Mohammad
authors.initials: SM
authors.lastname: Fereshtehnejad
authors.affiliation: Department of Neurology and Neurosurgery, McGill University, Montreal General Hospital, Montreal, Québec, Canada.
authors.forename: Silvia Rios
authors.initials: SR
authors.lastname: Romenets
authors.affiliation: Department of Neurology and Neurosurgery, McGill University, Montreal General Hospital, Montreal, Québec, Canada.
authors.forename: Julius B M
authors.initials: JB
authors.lastname: Anang
authors.affiliation: Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Montréal, Québec, Canada.
authors.forename: Véronique
authors.initials: V
authors.lastname: Latreille
authors.affiliation: Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Montréal, Québec, Canada4Department of Psychology, Université du Québec à Montréal, Montréal, Québec, Canada.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Gagnon
authors.affiliation: Department of Neurology and Neurosurgery, McGill University, Montreal General Hospital, Montreal, Québec, Canada3Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur de Montréal, Montréal, Québec, Canada.
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Postuma
mesh_terms: D000368:Aged; D060825:Cognitive Dysfunction / Q000150:complications / Q000175:diagnosis*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000145:classification / Q000150:complications / Q000175:diagnosis*; D010641:Phenotype; D011379:Prognosis; D011446:Prospective Studies; D020187:REM Sleep Behavior Disorder / Q000150:complications / Q000175:diagnosis*; D012720:Severity of Illness Index