Objectives: Rapid eye movement (REM) sleep behavior disorder (RBD) is frequently found in Parkinson's disease (PD). PD has been classified in different subtypes and it is unknown if RBD occurs more often in one particular subtype.
Methods: Determination of PD subtype by review of clinical history in consecutively diagnosed PD patients with RBD.
Results: We determined the subtype (tremor- or non-tremor-predominant) of PD and the age at onset of parkinsonism and RBD by review of clinical history. PD patients with RBD had mostly the non-tremor-predominant subtype. RBD preceded parkinsonism only when parkinsonism started after the age of 50 years.
Conclusions: A different pattern of neurodegeneration in non-tremor-predominant PD may explain its preferential association with RBD. The neurodegeneration that causes PD might be insufficient to produce RBD before the sixth decade.