Increased motor activity during rem sleep is linked with dopamine function in idiopathic rem sleep behaviour disorder and Parkinson’s disease

Abstract

Increased motor activity during rapid eye movement (REM) sleep is associated with neurodegenerative disorders such as Parkinson’s disease, Dementia with Lewy bodies, Multiple system atrophy and idiopathic REM sleep behavior disorder (iRBD). Although studies have shown a reduced density of striatal dopamine transporters in idiopathic RBD, it is unclear if the nigrostriatal dopamine system is related to the increased motor activity during sleep in these patients. Therefore, the objective was to investigate if the nigrostriatal dopaminergic system is related to muscle activity during sleep in patients with idiopathic RBD and Parkinson’s disease. 10 patients with iRBD, 20 patients with PD (10 PD + RBD and 10 PD-RBD), and 10 healthy controls were included in the study. All participants were assessed with 123I-FP-CIT single- photon emission computed tomography, neurological examination, and polysomnography. Higher EMG-activity rates were seen in patients with iRBD, PD + RBD and PD-RBD compared with healthy controls. 123I-FP-CIT uptake in striatum was highest in controls, followed by iRBD, and lowest in patients with PD (contralateral to the affected body side). In iRBD patients EMG-activity in submental muscle was correlated to 123I-FP-CIT uptake in striatum. In PD EMG-activity in PD + RBD/PD-RBD was partly associated with dopaminergic treatment. Nigrostriatal dopaminergic function may be related to the pathogenesis of increased muscular activity during REM and NREM in iRBD and PD. This work was supported by the Lundbeck Foundation; the National Foundation for Parkinson’s Disease; Toyota Foundation.