Comparisons of vesicular monoamine transporter type 2 signals in Parkinson's disease and parkinsonism secondary to carbon monoxide poisoning

Parkinson's disease (PD) and carbon monoxide (CO) poisoning demonstrate parkinsonian features related to presynaptic dopaminergic deficits. However, their clinical features and treatment responses are different, indicating other roles of neurotransmitters in symptomatic modulation. In this study, we used ¹⁸F-FP-(+)-DTBZ PET to explore vesicular monoamine transporter type 2 (VMAT2) distributions in 31 patients with PD, 39 patients with CO poisoning and parkinsonian features (n = 39), and 24 age-matched controls. In addition to the disease-specific VMAT2 topographies in PD and CO poisoning, we also constructed feature-specific functional networks. The cardinal features included tremor, rigidity, akinesia, and rapid alternating movements (RAM), and the overall motor severity was scored using Unified Parkinson Disease Rating Scale (UPDRS) and modified Hoehn-Yahr (mH-Y) Scale scores. Our results suggested that a reduction in VMAT2 signals in the caudate, amygdala, and hippocampus were more specific to CO poisoning, while low uptake in the putamen and substantia nigra was more specific to PD. UPDRS and mH-Y scores were related to striatum signals in both groups and hippocampus and raphe in the CO poisoning group. With regards to the cardinal features, the putamen was related to akinesia in both groups. The substantia nigra was related to rigidity in PD, and the caudate and nucleus accumbens were related to akinesia, RAM and rigidity in CO poisoning. Our study enhances the current understanding of different patterns of monoaminergic terminal deficits in patients with CO poisoning and PD.