A predictive model of neurodegeneration in idiopathic REM-sleep behavior disorder

Parkinsonism Relat Disord. 2013 Nov;19(11):1009-12. doi: 10.1016/j.parkreldis.2013.07.003. Epub 2013 Jul 26.

Abstract

Objective: To investigate whether Parkinson's disease (PD) and dementia are competing risks in subjects with idiopathic rapid-eye-movement sleep behavior disorder (RBD).

Methods: The number of incidental PD cases observed in 11 longitudinal RBD studies was compared with the corresponding expected number as estimated by a simple mathematical model based on population parameters for PD age-of-onset.

Results: The expected number of incidental PD cases exceeded observed PD cases (p-value < 0.001) but was in agreement with the sum of observed PD cases and observed mild cognitive impairment/dementia cases (p-value = 0.34). Sensitivity analyses confirmed the results.

Conclusion: In the RBD population, PD and dementia cases are competing risks, suggesting that alpha-synuclein pathology occurs simultaneously in substantia nigra and neocortex. This observation has implications for the design and analysis of trials of neuroprotection.

Keywords: Competing risks; Dementia; Lewy body dementia; Mild cognitive impairment; Parkinson's disease; Rapid-eye-movement sleep behavior disorder.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Dementia / diagnosis*
  • Dementia / epidemiology
  • Female
  • Follow-Up Studies
  • Humans
  • Incidental Findings*
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Models, Theoretical*
  • Neurodegenerative Diseases / diagnosis
  • Neurodegenerative Diseases / epidemiology
  • Parkinson Disease / diagnosis*
  • Parkinson Disease / epidemiology
  • Predictive Value of Tests
  • REM Sleep Behavior Disorder / diagnosis*
  • REM Sleep Behavior Disorder / epidemiology