Objective: The aim of current study was to evaluate the volumetry of subcortical structures in Parkinson’s disease (PD) patients with Rapid Eye Movement (REM) Sleep Behavior disorder (PD-RBD) compared to PD patients without RBD and healthy controls.

Background: RBD is a parasomnia observed in up to 60% of PD patients, usually associated with a more severe phenotype, possibly reflecting a more widespread neurodegenerative process. Although the pathophysiology of RBD is restricted to the brainstem, recent clinical evidences suggest a more severe impairment of the mesolimbic system in PD-RBD compared to PD-noRBD.

Methods: Sixty-six participants were included: 22 PD with RBD (PD-RBD); 22 PD without RBD (PD-noRBD) and 22 healthy controls, matched by age and gender (Table 1). RBD was diagnosed by video polysomnographic recording according to the ICSD-3 criteria. Subjects with impulse control disorders, depression or apathy were excluded. Normalized brain structure volumes were measured on T1-weighted-MRI with volBrain software. The following subcortical structures were considered for analysis: brainstem, caudate, putamen, thalamus, globus pallidus, amygdala, nucleus accumbens and hippocampus.

Results: PD patients with RBD showed a smaller volume of the left nucleus accumbens (NAc, 0.2092mm3 versus 0.2333mm3, p=0.036) compared to patients without RBD (Figure 1 and Table 2) as well as a trend for a smaller volume of the left globus pallidus when compared to healthy control (0.8233mm3 versus 0.7655mm3,p=0.05). Interestingly, although none of the included patients was apathetic, a positive correlation was observed between the measure of apathy, as assessed by the Lille Apathy Rating Scale, and the atrophy of the left NAc (r = 0,34, p<0,05).

Conclusions: The present study found a specific atrophy of the left NAc in PD patients with RBD compared to those without RBD. Volumetric reduction of NAc may be paralleled by an increased apathy in PD-RBD patients. This observation supports the notion of a specific impairment of the mesocorticolimbic system in PD patients with RBD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/neurostructural-alterations-associated-with-rapid-eye-movement-sleep-behavior-disorder-in-parkinsons-disease/