Limbic hypoconnectivity in idiopathic REM sleep behaviour disorder with impulse control disorders

• Published in: Journal of neurology Vol. 268; no. 9; pp. 3371 - 3380
• Main Authors: Marques, Ana, Roquet, Daniel, Matar, Elie, Taylor, Natasha Louise, Pereira, Bruno, O’Callaghan, Claire, Lewis, Simon J. G.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2021; Springer Nature B.V; Springer Verlag
• Subjects: Behavior; Brain research; Cognitive ability; Dopamine; Dopamine receptors; Functional magnetic resonance imaging; Impulsive behavior; Impulsivity; Life Sciences; Measuring techniques; Medical imaging; Medicine; Medicine & Public Health; Morphometry; Neostriatum; Neural networks; Neurodegeneration; Neuroimaging; Neurology; Neurons and Cognition; Neuroradiology; Neurosciences; Obsessive compulsive disorder; Original Communication; Parkinson's disease; Psychology; Questionnaires; Reinforcement; REM sleep; Sleep; Sleep disorders; Structure-function relationships; Substantia grisea; Reward system; REM sleep behaviour disorder; MRI; Impulse control disorders; Parkinson’s disease
• ISSN: 0340-5354; 1432-1459
• DOI: 10.1007/s00415-021-10498-6

Introduction Current neuroimaging research has revealed several brain alterations in idiopathic REM sleep behaviour disorder (iRBD) that mirror and precede those reported in PD. However, none have specifically addressed the presence of changes across the reward system, and their role in the emergence of impulse control disorders (ICDs). We aimed to compare the volumetric and functional connectivity characteristics of the reward system in relation to the psychobehavioral profile of patients with iRBD versus healthy controls and PD patients. Methods Twenty patients with polysomnography confirmed iRBD along with 17 PD patients and 14 healthy controls (HC) underwent structural and functional resting-state brain MRI analysis. Participants completed the questionnaire for impulsive-compulsive disorders in PD (QUIP), the short UPPS-P impulsive behaviour scale, as well as neuropsychological testing of cognitive function. Results A higher percentage of iRBD patients reported hypersexuality, compared to HC and PD ( p  = 0.008). Whole-brain and striatal voxel-based morphometry analyses showed no significant clusters of reduced grey matter volume between groups. However, iRBD compared to HC demonstrated functional hypoconnectivity between the limbic striatum and temporo-occipital regions. Furthermore, the presence of ICDs correlated with hypoconnectivity between the limbic striatum and clusters located in cuneus, lingual and fusiform gyrus. Conclusion Altered functional connectivity between the limbic striatum and posterior cortical regions was associated with increased hypersexuality in iRBD. It is possible that this change may ultimately predispose individuals to the emergence of ICDs when they receive dopaminergic medications, after transitioning to PD.