Respiratory changes in Parkinson's disease may be unrelated to dopaminergic dysfunction

OBJECTIVE: To investigate the maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in patients with Parkinson's disease (PD) during the on and off periods of levodopa and to compare with healthy controls. METHODS: Twenty-six patients were analyzed with Hoehn and Yahr scores (2-3) and 26 age and gender matched-controls. Statistical analysis was performed with Student's t-test for paired and independent samples. RESULTS: MIP and MEP values in patients were significantly lower than the values obtained in controls both for off and on stages -excepted for MIP in women (p=0.28). For patients with PD, the studied parameters did not differ between stages on and off, with the exception of MEP in women (p=0.00). CONCLUSIONS: Patients with PD have respiratory pressure lower than controls, even in early stages of the disease, and dopamine replacement has little impact over these respiratory pressures. These findings suggest that respiratory changes in PD may be unrelated to dopaminergic dysfunction.