Imagine trying to navigate a maze when some of the pathways are blocked or disconnected. That’s similar to what happens in the brains of patients with isolated rapid eye movement sleep behavior disorder (iRBD). In this study, researchers used resting-state functional MRI to examine the brain networks of 21 iRBD patients and 22 healthy controls. They discovered alterations in the topological properties of the occipital lobe, which is associated with attention impairment. The patients exhibited lower scores in various cognitive and motor function tests compared to the controls. Further analysis using graph theory revealed a decrease in network global efficiency, network local efficiency, and nodal efficiency in certain brain regions. Functional connectivities between nodes in the occipital lobe were also reduced. Interestingly, there was a correlation between attention scores and nodal efficiency in the right middle occipital gyrus. These findings shed light on the disrupted brain network topology and functional connectivity underlying iRBD and provide valuable insights into its pathophysiological mechanisms. To explore more about this fascinating research, check out the full article.

PurposeThis study investigates the topological properties of brain functional networks in patients with isolated rapid eye movement sleep behavior disorder (iRBD).Participants and MethodsA total of 21 patients with iRBD (iRBD group) and 22 healthy controls (HCs) were evaluated using resting-state functional MRI (rs-fMRI) and neuropsychological measures in cognitive and motor function. Data from rs-fMRI were analyzed using graph theory, which included small-world properties, network efficiency, network local efficiency, nodal shortest path, node efficiency, and network connectivity, as well as the relationship between behavioral characteristics and altered brain topological features.ResultsRey-Osterrieth complex figure test (ROCFT-copy), symbol digital modalities test (SDMT), auditory verbal learning test (AVLT)-N1, AVLT-N2, AVLT-N3, and AVLT-N1-3 scores were significantly lower in patients with iRBD than in HC (P < 0.05), while trail making test A (TMT-A), TMT-B, and Unified Parkinson’s Disease Rating Scale Part-III (UPDRS-III) scores were higher in patients with iRBD (P < 0.05). Compared with the HCs, patients with iRBD had no difference in the small-world attributes (P > 0.05). However, there was a significant decrease in network global efficiency (P = 0.0052) and network local efficiency (P = 0.0146), while an increase in characteristic path length (P = 0.0071). There was lower nodal efficiency in occipital gyrus and nodal shortest path in frontal, parietal, temporal lobe, and cingulate gyrus. Functional connectivities were decreased between the nodes of occipital with the regions where they had declined nodal shortest path. There was a positive correlation between TMT-A scores and the nodal efficiency of the right middle occipital gyrus (R = 0.602, P = 0.014).ConclusionThese results suggest that abnormal behaviors may be associated with disrupted brain network topology and functional connectivity in patients with iRBD and also provide novel insights to understand pathophysiological mechanisms in iRBD.

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