Sleep medicine | 2019
Longitudinal study of striatal aromatic l-amino acid decarboxylase activity in patients with idiopathic rapid eye movement sleep behavior disorder.
Abstract
STUDY OBJECTIVES\nTo determine if nigrostriatal dopaminergic system function, evaluated by aromatic l-amino acid decarboxylase (AADC) activity using 6-[18F]fluoro-meta-tyrosine brain positron emission tomography (FMT-PET) can accurately and efficiently identify idiopathic rapid-eye-movement behavior disorder (IRBD) individuals at risk for conversion to a clinical diagnosis of Parkinson s disease (PD) or dementia with Lewy bodies (DLB).\n\n\nMETHODS\nWe assessed prospectively striatal aromatic l-amino acid decarboxylase activity using FMT brain PET imaging in IRBD patients who were followed systematically every 1-3 months for 1-10 years. IRBD patients (n\xa0=\xa027) were enrolled in this prospective cohort study starting in 2009. Those who underwent follow-up scans between January 2011 and September 2014 (n\xa0=\xa024) were analyzed in the present study.\n\n\nRESULTS\nOf the 24 IRBD patients with baseline and follow-up FMT-PET scans, 11 (45.8%) developed PD (n\xa0=\xa06) or DLB (n\xa0=\xa05). Compared to IRBD patients who were still disease-free, those who developed PD (n\xa0=\xa05) or DLB with parkinsonism (n\xa0=\xa01) had significantly reduced bilateral putaminal FMT uptake during the follow-up. Furthermore, the rate of FMT decline between baseline and follow-up scans was higher in all converted patients, even for those with DLB without parkinsonism, than in IRBD patients who remained disease-free.\n\n\nCONCLUSIONS\nFMT-PET, which represents a dynamic change in AADC activity over time, may also be a useful predictor for the risk of conversion to PD or DLB over short-term clinical follow-up periods, or when testing neuroprotective and restorative strategies in the prodromal phases of PD or DLB.