Quantitative assessment of non-motor fluctuations in Parkinson’s disease using the Non-Motor Symptoms Scale (NMSS)

Data on frequency, severity and correlations of NMS with motor complications are only available for a limited number of NMS. The NMS Scale (NMSS) is a validated tool to assess a broad range of NMS, which has not been used in NMS fluctuations. We assessed fluctuations of a broad range of non-motor symptom (NMS) for a 1-month time period in fluctuating Parkinson’s disease (PD) in a multicenter cross-sectional study using the NMSS assessing NMS in motor On (NMSS_On) and Off state (NMSS_Off) combined with clinical NMS and motor function scoring in 100 fluctuating PD patients. ΔNMSS_On/Off was defined as the differences of NMSS scores between On and Off. Complete NMSS datasets were available from 73 patients (53 % men; age: 68.2 ± 9.7 years) with mean total NMSS score in On state of 41.5 ± 37.6 and in Off state of 75.6 ± 42.3 (P < 0.001). Scores were higher in Off compared to On state for all domains except for domain “perceptual problems/hallucinations” (P = 0.608). Clinimetric properties of the NMSS were similar to those reported previously for NMS assessments independent of motor oscillations. NMSS_On, NMSS_Off and ΔNMSS_On/Off showed weak to moderate correlations with demographics, indicators of motor symptom severity as well as with other measures of NMS, depression and quality of life. Correlations of NMSS items/domains with independent measures of related constructs were weak to moderate. In conclusion, when assessed with the NMSS, a broad range of NMS fluctuate with motor oscillations, but these fluctuations do neither correlate with motor function nor with measures of disease progression.