The association between restless legs syndrome and premotor symptoms of Parkinson's disease.

Background: Previous studies regarding the association between restless legs syndrome (RLS) and Parkinson's disease (PD) have produced contradictory results. However, the time frame between them has varied across these studies, and also, the longitudinal trajectroy of RLS symptoms has not been considered.
Objective: To investigate if transient or continuous/recurrent RLS identified by questionnaire are associated with the premotor symptoms of PD.
Methods: The study population comprised 16,636 men in the Health Professional Follow-Up Study, who answered questions regarding RLS symptoms in both 2002 and 2008, and were not diagnosed with PD. Outcomes were self-reported constipation, possible REM sleep behavior disorder (pRBD) in 2012 and smell identification test score in 2014.
Results: RLS was associated with increased odds of constipation, but only continuous/recurrent RLS status was associated with higher odds of having pRBD. RLS was not significantly associated with olfactory scores.
Conclusion: In this large-scale longitudinal study, we found moderate associations between the presence of RLS and increased odds of having constipation and pRBD.
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