Background and aims: Non-motor symptoms (NMS) are important manifestations of Parkinson's disease (PD) that reduce patients' health-related quality of life. Some NMS may also be caused by age-related changes, or manifested as a psychological reaction to a chronic neurological condition. This case-control study compared the NMS burden among PD patients, healthy controls and hemifacial spasm (HFS) patients. In addition, we determined the NMS that discriminated between PD and non-PD subjects.
Methods: 425 subjects were recruited from a tertiary hospital in Singapore (200 PD patients, 150 healthy controls and 75 HFS patients). NMS burden in subjects was measured using the Non-Motor Symptoms Scale (NMSS).
Results: NMSS total score was significantly higher in PD patients (37.9±2.6) compared to healthy controls (11.2±0.9) (p<0.0001) and HFS patients (18.0±2.1) (p<0.0001). In addition, NMSS total score was significantly higher in HFS patients compared to healthy controls (p = 0.003). PD patients experienced a higher NMS burden than healthy controls in all domains, and a higher NMS burden than HFS patients in all but attention/memory and urinary domains. NMS burden for HFS and healthy controls differed only in the sleep/fatigue and urinary domains. Using stepwise logistic regression, problems of 'constipation', 'restless legs', 'dribbling saliva', 'altered interest in sex' and 'change in taste or smell' were found to have significant discriminative power in differentiating between PD patients and healthy controls and between PD patients and HFS patients.
Conclusion: PD patients experienced a greater overall NMS burden compared to both healthy controls and HFS patients. HFS patients demonstrated a higher NMS burden than controls, and some NMS may be common to chronic neurological conditions while others are more specific to PD. Differentiating patients using NMS domains may help refine the clinical management of NMS in PD patients.