Change in Non-motor Symptoms in Parkinson's Disease and Essential Tremor Patients: A One-year Follow-up Study

BACKGROUND: Non-motor symptoms (NMS) in Parkinson's disease (PD) differ from those in essential tremor (ET), even before a definitive diagnosis is made. It is not clear whether patient's knowledge of the diagnosis and treatment influence their subsequent reporting of NMS. METHODS: 1 year after a clinical and instrumental diagnosis, we compared the motor impairment (Movement Disorders Society (MDS)-Unified Parkinson's Disease Rating Scale-III) and non-motor symptoms (NMSQuest) in PD (n = 31) and ET (n = 21) patients. RESULTS: PD patients reported more NMS than did the ET patients (p = 0.002). When compared to their baseline report, at follow-up, PD patients reported less nocturia (p = 0.02), sadness (p = 0.01), insomnia (p = 0.02), and restless legs (p = 0.04) and more nausea (p = 0.024), unexplained pain (p = 0.03), weight change (p = 0.009), and daytime sleepiness (p = 0.03). When compared to their baseline report, ET patients reported less loss of interest (p = 0.03), anxiety (p = 0.006), and insomnia (p = 0.02). Differences in reported weight change (p<0.0001) and anxiety (p = 0.001) between PD and ET patients were related to pharmacological side effects or to a reduction in the ET individuals. DISCUSSION: The reporting of NMS is influenced by subjective factors, and might vary with the patient's knowledge of the diagnosis or the effectiveness of treatment.