Nonmotor symptoms in drug-induced parkinsonism and drug-naïve Parkinson disease

Background: The clinical manifestations of drug-induced parkinsonism (DIP) and Parkinson disease (PD) are nearly indistinguishable, making it difficult to differentiate DIP from PD, especially in the early stages. We compared non-motor symptoms between patients with DIP and those with drug-naïve PD in the early stages using the Non Motor Symptoms Scale (NMSS). Methods: We prospectively enrolled 28 patients with DIP, 35 patients with drug-naïve PD, and 32 controls with no history of neurological diseases or related medical problems. We investigated demographic characteristics, medical and drug history, parkinsonian motor symptoms, and non-motor symptoms. We used the NMSS to evaluate non-motor symptoms in all patients. Results: The total NMSS scores were higher in patients with PD than those with DIP, as were the scores for certain domains, including the cardiovascular, sleep/fatigue, urinary, sexual, and miscellaneous domains. When controlling for age and gender, the correlation analysis revealed that scores for urinary symptoms (urgency, frequency and nocturia), sleep disturbances (daytime sleep, restless legs), concentration, taste or smell were significantly associated with PD. Conclusions: Our data suggest that non-motor symptoms, particularly urinary symptoms, excessive daytime sleepiness, restless leg syndrome, attention deficit and hyposmia may be helpful to differentiate between DIP and PD in the early stages.