Correlations between dopaminergic dysfunction and abnormal metabolic network activity in REM sleep behavior disorder.

Area of Science:

• Neuroimaging
• Neurology
• Molecular Imaging

Background:

• Idiopathic REM sleep behavior disorder (IRBD) is linked to striatal dopamine transporter (DAT) deficiency.
• Abnormal expression of the Parkinson's disease-related pattern (PDRP) is also observed in IRBD.
• The relationship between DAT deficiency and PDRP expression in IRBD compared to Parkinson's disease (PD) requires further investigation.

Purpose of the Study:

• To investigate the correlations between striatal DAT binding and PDRP expression in IRBD patients.
• To compare these measures between IRBD patients, PD patients, and healthy controls.
• To explore the relationship between dopaminergic dysfunction and network activity patterns.

Main Methods:

• Concurrent positron emission tomography (PET) scans were performed using 11C-CFT for DAT quantification and 18F-FDG for PDRP expression.
• Participants included 37 IRBD patients (further divided into IRBD-RN and IRBD-AB subgroups), 86 PD patients, and 15 age-matched controls.
• Statistical analyses examined group differences and correlations between DAT binding and PDRP scores, considering hemispheric effects.

Main Results:

• Both PD and IRBD-AB groups showed significantly decreased DAT binding and increased PDRP scores compared to controls, while IRBD-RN did not.
• DAT binding varied significantly by hemisphere and group interaction, unlike PDRP expression.
• Significant correlations between DAT binding and PDRP expression were found in IRBD-AB and PD groups, but not in IRBD-RN.

Conclusions:

• IRBD patients exhibit an intermediate state of striatal DAT distribution and PDRP activity between PD patients and healthy controls.
• The observed correlations suggest that dopaminergic denervation alone does not fully explain network activity differences in IRBD and PD.
• Further research is needed to elucidate the complex interplay between dopaminergic pathways and network dysfunction in these conditions.