Screening for prodromal Parkinson's disease in the general community: a sleep-based approach

Objective/background: Neuroprotective therapy for Parkinson's disease (PD) is most likely to be effective if provided in its prodromal stages. However, identifying prodromal PD is difficult because PD is relatively uncommon, and most markers are nonspecific. Rapid eye movement (REM) sleep behavior disorder (RBD) is by far the strongest clinical marker of prodromal PD, but most patients do not seek out medical attention. Developing an efficient way of diagnosing RBD from the general community may be the most practical method to detect prodromal PD.

Methods: We developed a screening strategy that began with a newspaper advertisement containing a single-question screen for RBD. All screen-positive subjects underwent an interview based on the Innsbruck RBD inventory aimed to optimize the positive predictive value. Those who passed both screens underwent confirmatory polysomnography. The proportion of screened RBD patients who met the International Parkinson and Movement Disorder Society (MDS) criteria for prodromal PD was assessed. A broad array of clinical markers of neurodegeneration was compared between newspaper-screened RBD patients and 130 RBD patients clinically referred to the sleep center.

Results: Of 111 RBD-screen-positive participants, 40 (36%) passed the secondary screen, and 29 underwent full polysomnography. Of these 29 patients, 19 were ultimately proven to have RBD (PPV = 66%), 12 (63%) of whom met the criteria for prodromal PD. Compared to patients referred to the sleep center, newspaper-screened patients had similar age, sex, olfaction, autonomic function, and color vision. However, motor and cognitive assessments were slightly better in newspaper-screened patients.

Conclusions: A multistep screening approach using RBD screening questionnaires and telephone follow-up can efficiently identify prodromal PD in the general community.