Kaminsky DA, Grosset DG, Kegler-Ebo DM, et al. - This study was undertaken to investigate variations in lung function that occurred over 12 months in patients on standard Parkinson disease (PD) therapy as part of the observational cohort of an open-label study of inhaled levodopa (CVT-301) in PD. Researchers included a total of 106 patients (81.5%) in the observational cohort on no investigational therapy. Compared with healthy non-smokers of similar age, PD patients had greater declines in FEV₁, and FVC, but not in carbon monoxide. Declines in FEV₁ and FVC with little change in FEV₁ /FVC, and decline in VA and IVC with little change in carbon monoxide/VA, imply these variations were due to decreases in lung volume and are compatible with progressive PD-associated respiratory muscle weakness.