Striatal Subregion Analysis Associated with REM Sleep Behavior Disorder in Parkinson's Disease.

BACKGROUND AND PURPOSE: REM sleep behavior disorder (RBD) in Parkinson's disease (PD) is associated with characteristic clinical subtypes and prognosis. In addition, nigrostriatal pathway, the most vulnerable anatomical area in PD, formed neuronal network interplaying with cortical and subcortical structures, and which may cause PD clinical phenotype. We evaluated the regional selectivity of presynaptic striatal dopaminergic denervation associated with RBD in PD. METHODS: We compared two groups (n = 16) of PD patients with and without RBD in terms of specific binding ratios (SBR) in subregions of the striatum, which were measured using positron emission tomography with 18F-FP-CIT. SBRs of the anterior and posterior caudate, ventral striatum, and posterior and ventral putamen regions were measured in more or less affected side, and right or left side, or bilateral sum of the striatum. RESULTS: Age, disease duration, and severity of parkinsonism were not significantly different between groups. Although group differences in all areas were not significant with multiple comparison corrections, SBR of the ventral striatum and anterior caudate in sum of both sides was significantly less in the RBD than in the non-RBD group without correction (p < 0.05). In the right anterior caudate and left ventral striatum, SBR was also lower in the RBD than in the non-RBD group without correction (p < 0.05). Attention function was impaired in the RBD group compared with the non-RBD group (p < 0.05). However, these statistical significances were not definite after correction of multiple comparisons (p > 0.05). CONCLUSIONS: There is a possibility that RBD in early PD may be associated with presynaptic dopaminergic denervation in the ventral striatum and anterior caudate, which may explain decreased attention in our RBD group. RBD in PD may imply a distinct pathological progression. However, further study using large numbers of participants or longitudinal observation is necessary for the statistical conclusion because of small sample size.

Quantified Striatal Dopaminergic Denervation as Predictor for Motor Outcomes in Parkinson's Disease.

Background: A hallmark of Parkinson's disease (PD) is progressive loss of dopamine terminals in the basal ganglia, with clinical symptoms including motor and non-motor manifestations such as bradykinesia, rigidity, and cognitive impairment. Dopamine transporter single-photon emission computed tomography (DaT-SPECT) can be used to assess dopaminergic denervation by detecting loss of striatal dopamine transporters (DaT). Objective: We examined DaT binding scores' (DaTbs) association with motor outcomes in PD and explored its usefulness as a predictor of disease progression. Faster dopaminergic denervation in the basal ganglia was hypothesized to have stronger correlation and predictive value for poor motor outcomes. Methods: Data was analyzed from the Parkinson's Progression Markers Initiative. DaTbs in the putamen and caudate nucleus were correlated with Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) scores for walking and balance difficulties, gait difficulties, and presence of dyskinesias. A predictive model using baseline speed of drop in DaT binding score was performed for each motor outcome. Results: All motor outcomes had mild, significantly negative correlation with DaTbs in the putamen and caudate nucleus, with similar degree of correlation per region. Speed of drop was predictive of only substantial gait difficulties when evaluated in the putamen but not the caudate. Conclusions: These findings suggest that analyzing speed of drop in DaTbs, which occurs early in the motor phase of the disease, may be helpful for predicting clinical outcomes in PD. Longer observation of this cohort may provide further data to investigate DaTbs as a prognostic marker in PD.

Serial changes of I-123 FP-CIT SPECT binding asymmetry in Parkinson's disease: Analysis of the PPMI data.

Background: Dopaminergic denervation and motor symptoms are usually asymmetric at the onset of Parkinson's disease (PD). In this study, we estimated the asymmetry of specific binding ratio (SBR) of I-123 FP-CIT SPECT images during 4-years of follow up, to demonstrate the pattern of serial changes of asymmetry. Methods: Clinical and I-123 FP-CIT SPECT image data of 301 PD patients and 141 normal controls were reviewed from the Parkinson's Progression Markers Initiative cohort. I-123 FP-CIT SPECT images were taken at baseline, 1-, 2-, and 4-year follow up periods for PD patients, and at baseline for normal controls. Asymmetry index were calculated by two methods. Method 1, by using the ratio of absolute difference of right and left SBRs to the average SBR. Method 2, by using the ratio of absolute difference of right and left SBRs to the SBR values of age-matched normal controls. Results: Asymmetry index by method 2 revealed a more significant decrease during the 4-year follow up period, compared with method 1. The baseline asymmetry index of the putamen by method 2 showed significant correlation with the non-dominant putamen SBRs. However, there were no significant correlation with the baseline asymmetry index by method 2 and motor symptoms, cognition, nor autonomic symptoms. Conclusion: We suggest a novel asymmetry index in association to age-matched normal SBR values. This novel index could be adopted in predicting and evaluating the natural course of PD.