Disease duration-related differences in non-motor symptoms: a study of 616 Chinese Parkinson's disease patients.

The differences in non-motor symptoms (NMS) along with the duration of Parkinson's disease (PD) in Chinese populations remain largely unknown. A total of 616 PD patients consisting of 189 patients with disease duration of less than 2years, 239 patients with duration between 2 and 5years, 122 patients with duration between 5 and 10years, and 66 patients with duration more than 10years from Southwest China were studied. Each patient was assessed using the non-motor symptoms scale (NMSS). The mean affected number of NMS was 8.8±5.8, and the mean total NMSS score was 36.3±33.2. The mean affected number of NMS and the mean total NMSS score increased with the disease progression. The following symptoms became more common and severe with the disease duration: falls due to fainting, fatigue, difficulty falling asleep, restless legs, perceptual problem/hallucination domain (i.e., "hallucinations," "delusions," and "double vision"), gastrointestinal domain (i.e., "dribbling saliva," "swallowing," and "constipation"), urinary domain (i.e., "urgency," "frequency," and "nocturia"), and miscellaneous domain (i.e., "excessive sweating"). However, some symptoms such as mood/apathy pleasure, sexual dysfunction, and others remained stable. NMS are prevalent in all disease duration of the Chinese PD patients. Although the mean affected number of NMS and NMMS score increased with the disease duration, NMS progression is symptom specific.