RBD persists in Parkinson’s disease patients

By Eleanor McDermid, Senior medwireNews Reporter

Symptoms of rapid eye movement sleep behaviour disorder (RBD) are unlikely to resolve in patients with Parkinson’s disease (PD), show the findings of a 3-year study.

Its prevalence also increased over time, report K Anne Bjørnarå (Drammen Hospital, Norway) and team in the European Journal of Neurology.

At baseline, probable RBD was present in 37 (38%) of 107 PD patients drawn from three outpatient clinics, as judged by at least six “yes” answers out of a possible 13 on the RBD screening questionnaire (RBDSQ).

During follow-up averaging 36.6 months, 77% of patients did not change their diagnosis on the RBDSQ, and just 6% of those with probable RBD at baseline fell below the RBDSQ threshold by the end of the study. But an additional 17% of the whole cohort developed above-threshold symptoms, so that 49% of the 96 patients assessed at the end of follow-up had probable RBD.

“Whether RBD symptoms are too subtle to be detected early in these patients or whether the symptoms emerge as a result of increasing pathology or medication is unknown”, says the team.

RBD symptoms were not associated with age, but were related to disease duration, with patients with probable RBD having had PD for an average of 1.8 years longer than those without RBD.

Probable RBD was more common in men (60%) than women (36%). The researchers say that referral bias may partly account for this, because men are thought to present with more violent RBD symptoms and are therefore more likely than women to be referred to a sleep clinic.

Indeed, in the current study, men reported significantly more “fights” and vigorous motor behaviour during sleep than women.

“It is concluded that [probable] RBD is a persistent feature present in a subgroup of PD patients, supporting the hypothesis of a different underlying pathophysiology in these patients”, say Bjørnarå et al.

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