Objective: To assess apathy and its relationship with cognitive functions in PD patients with and without Rapid Eye Movement Sleep Behavior Disorder (RBD).

Background: Apathy is a frequent neuropsychiatric feature in Parkinson’s disease (PD), that may precede the onset of motor symptoms. Indeed, apathy was found to be common in idiopathic REM sleep behavior disorder (RBD)(1), a condition that often heralds PD. Up to 60% of PD patients has RBD, wich may be associated with an increased frequency of psychobehavioral symptoms (2). However, no study has assessed whether PD-RBD patients are more apathetic than PD-noRBD.

Methods: Fifty-four consecutive non-demented PD patients with videopolysomnographically-confirmed RBD (36M, mean age:65.6±6.7yrs., mean disease duration: 7.9±4.7 yrs.) and 27 age- and sex-matched PD patients without RBD (18M, mean age:63.0±8.7, mean disease duration 6.4±3.8) underwent to an extensive clinical and neuropsychological evaluation including apathy using the Lille Apathy Rating Scale (LARS), depression with the Hospital Anxiety and Depression Scale, a broad spectrum of cognitive functions as well as motor and non-motor features. Results were adjusted for variables known to be associated to apathy in PD, namely age, sex, disease severity and duration, dopaminergic treatment dose, Mild Cognitive Impairment (MCI) and depression.

Results: The two groups were comparable in terms of clinico-demographical variables, namely severity and duration of PD, levodopa daily dose, MCI or in any cognitive measures except for visuospatial (p=0.03) and visuoconstructive (p=0.01) habilities. A total of 12/54 (22%) PD-RBD patients showed moderate to severe apathy (LARS score >-16) compared to only 1/27 (3.7%) of PD-noRBD patients (p=0.03). After controlling for confounder factors, PD-RBD had a lower total LARS score (p=0.048, 95% IC:0.03-8.78) and particularly a reduced Initiative (p=0.015, 95% IC 0.18-1.64) and a reduced Novelty seeking (p=0.003, 95% IC 0.41-2.01). Analysis of LARS subdomains revealed that PD-RBD were impaired in Intellectual curiosity (p=0.05, 95%IC 0.001-1.16) and Action initiation (p=0.015, 95% IC0.16-146) compared to PD-noRBD.

Conclusions: Apathy appears to be strongly associated to RBD in PD patients, perhaps paralleled by a more severe impairment in the dopaminergic mesolimbic pathway involved in motivation and reward. Further studies are warranted in order to explore the neurobiological bases of this association.

References: 1. Barber, T. R. et al. Apathy in rapid eye movement sleep behaviour disorder is common and under-recognized. Eur J Neurol. 2018;25(3):469-e32. 2. Fantini M. L. et al. Increased risk of impulse control symptoms in Parkinson’s disease with REM sleep behaviour disorder. J. Neurol. Neurosurg. Psychiatry (2015) 86, 174–179.

« Back to 2018 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/apathy-in-parkinsons-disease-is-associated-with-rem-sleep-behavior-disorder/