Decreased and increased cerebral regional homogeneity in early Parkinson's disease.

Regional homogeneity (ReHo), a processed data from resting-state functional magnetic resonance imaging, provides information about spontaneous brain activity in focal areas. Altered ReHo in brain regions has been reported in Parkinson's disease (PD). We compared ReHo of 22 patients with PD in their off-medication state to 25 healthy controls. We observed decreased ReHo in the right primary sensory cortex, the right primary motor cortex and the right middle frontal gyrus in PD patients. Conversely, ReHo was increased in the left inferior parietal lobule, the angular gyrus, the supramarginal gyrus, the middle occipital gyrus and the parahippocampal gyrus. In the right primary sensory cortex, ReHo showed a positive association with disease duration which proposed the low level of ReHo in the early phase of PD. ReHo was decreased in the seven de novo PD patients with disease duration less than 1 year as compared to the control which corresponded to the prediction. In both the off-medication and de novo PD patients, ReHo decreased in the right primary sensory cortex and increased in the angular gyrus as compared to the control. Potential regression of ReHo extrapolated backwards to PD-onset may provide a clue for 'premotor diagnosis'.