To describe the prevalence, demographic characteristics, and cognitive function of individuals who believe that selective serotonin reuptake inhibitor (SSRI) use caused or exacerbated symptoms of REM-sleep behavior disorder (RBD) compared to idiopathic RBD (iRBD) in the North American Prodromal Synucleinopathy (NAPS) consortium registry.

REM-sleep behavior disorder (RBD) is characterized by loss of REM-sleep atonia and recurrent dream enactment behavior and often represents a prodromal neurodegenerative syndrome of alpha-synuclein pathology such as Parkinson’s disease or Lewy body dementia. Among patients with RBD, approximately half are noted to be taking a serotonergic antidepressant.  Many patients with RBD indicate that their dream enactment was triggered or exacerbated after they started an SSRI. The exact prevalence of SSRI-induced/exacerbated RBD (5-HT RBD) is not well understood. It is uncertain whether 5-HT RBD is also a prodromal neurodegenerative syndrome, or if individuals with 5-HT RBD are at increased risk for developing neurodegenerative disease in the future.

This is a cross-sectional design to examine prevalence, demographic characteristics, and cognitive function of NAPS participants with 5-HT RBD compared to iRBD. Montreal Cognitive assessment (MoCA) scores were used to measure cognitive function. A Kruskal-Wallis statistical test was performed to compare group means.

Of 294 total participants, 20 identified that an SSRI caused/worsened RBD behaviors. Mean age for the SSRI trigger group was 62.5, 10% were female, and mean MoCA score was 27.3. 159 participants reported never taking an antidepressant. Mean age for this group was 66.9, 10.1% were female, and mean MoCA score was 26.0. There was no significant difference in MoCA scores between the groups.

Our findings of no significant differences in MoCA scores between the 5HT-RBD and iRBD groups suggest that 5HT-RBD may also represent a prodromal neurodegenerative syndrome. Following these groups prospectively will allow for better insight into their neurological progression.