Relations of clinical symptoms with dopamine transporter imaging in drug-naïve Parkinson's disease

Abstract

Objectives: The aim of the present study was to determine the relations of clinical symptoms with nigrostriatal neuron loss in drug-naïve patients with Parkinson's disease (PD). We examined the severity of motor symptoms and freezing of gait (FOG), falls and overactive bladder (OAB) in PD patients and their relations with striatal dopamine transporter (DAT) binding.

Patients and methods: Thirty-two untreated PD patients (14 men and 18 women with a mean age of 71.4 ± 7.2 years) were included in this study. Clinical assessments were performed by using Unified Parkinson's Disease Rating Scale (UPDRS) and overactive bladder symptom score (OABSS), and striatal dopamine transporter (DAT) binding was measured by¹²³I-FP-CIT SPECT.

Results: The results showed that striatal DAT availability was significantly lower in the high UPDRS motor score group, high akinetic-rigid score group, FOG group, and OAB group than in the low UPDRS motor score group, low akinetic-rigid score group, non-FOG group, and non-OAB group. However, the results also showed that there was no significant difference in striatal DAT availability between the high tremor score group and low tremor score group or between the faller group and non-faller group.

Conclusions: The severity of bradykinesia and axial symptoms and the existence of FOG and OAB in untreated PD patients are related to a decrease in striatal DAT availability. Severity of tremors and occurrence of falls are not related to a decrease in striatal DAT availability. The mechanisms underlying the clinical symptoms of PD involve not only dopaminergic pathways but also non-dopaminergic pathways.

Keywords: Akinetic-Rigid score; Dopamine transporter imaging; Freezing of gait; Overactive bladder symptom score; Parkinson’s disease; Tremor score; Unified Parkinson’s disease rating scale.