Rapid eye movement (REM) sleep behavior disorder (RBD) increases the risk for mild cognitive impairment (MCI) and subsequent cognitive decline and dementia in patients with Parkinson’s disease (PD), according to a study published in SLEEP.
A neurological assessment, neuropsychological exam, and polysomnography were performed in patients with PD with RBD (n=53), patients with PD without RBD (n=40), and healthy subjects (n=69) to determine the risk for MCI in patients with RBD. Tests assessed episodic learning, attention, language, visuospatial abilities, and executive functions. Additional assessments examined participants’ subjective cognitive decline (SCD).
Patients with PD and RBD demonstrated poorer performance in cognitive assessments compared with healthy subjects and patients with PD but without RBD. There was a nearly 3-fold greater frequency of MCI in the PD and RBD group compared with in patients with PD but without RBD (66% vs 23%; P <.001). Reported SCD was higher in patients with PD with RBD without MCI compared with in patients with PD without RBD and without MCI (89% vs 58%; P =.024).
Although investigators controlled for sex and age and used sex as an independent variable in additional analyses, they noted that they couldn’t “discount potential age or gender effects on some of our results.” An additional limitation to this study was the lack of criteria or methods for specifying or measuring SCD in the PD population.
According to the researchers, the findings suggest more widespread neurodegeneration in patients with both PD and RBD. They believe these patients should receive direct and “targeted medical attention to better detect and monitor impairment and to enable the development of management interventions for cognitive decline and its consequences.”
Jozwiak N, Postuma RB, Montplaisir J, et al. REM sleep behavior disorder and cognitive impairment in Parkinson’s disease. Sleep. 2017;40(8):zsx101.