Abnormal intrinsic brain activity of the putamen is correlated with dopamine deficiency in idiopathic rapid eye movement sleep behavior disorder.

Objectives: To investigate the changes in spontaneous neuronal activity of the striatum in idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) patients using regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF) analysis. Furthermore, we tested the association between abnormal spontaneous brain activity and dopamine deficit in patients with iRBD.

Methods: Fifteen iRBD patients and 15 matched healthy controls received resting state magnetic resonance imaging (MRI) and neuropsychological assessments. ReHo and ALFF in subregions of the striatum were calculated and compared between groups in a voxel-by-voxel manner. In addition, 15 iRBD patients and seven healthy controls underwent dopamine transporter single photon computed emission tomography (DAT-SPECT) imaging. Correlation analysis was also performed to investigate whether the altered spontaneous brain activity could be correlated with dopamine deficiency in iRBD patients.

Results: We found that iRBD patients, compared with healthy controls, exhibited significantly reduced ReHo in the bilateral putamen. Patients also had significantly decreased tracer uptake in the bilateral putamen and left caudate. In addition, a significantly positive correlation was observed between the mean ReHo value and the tracer uptake ratio in the left putamen of iRBD patients.

Conclusions: We detected abnormal spontaneous brain activity of the bilateral putamen in iRBD patients. These findings could be complementary to the Braak staging model and could help to clarify the pathophysiology of iRBD.