Prevalence and clinical features of non-motor symptoms of essential tremor in Shanghai rural area.

OBJECTIVE: Few studies regarding the epidemiology of essential tremor (ET) and its non-motor symptoms (NMS) have been conducted to date. We thus conducted a door-to-door survey to investigate the ET and its NMS and their clinical manifestations in a rural area of Shanghai, China.

METHODS: We recruited 19,614 residents (≥ 50 years old), living in Malu town, Shanghai. Investigations were divided into two steps. In first step, trained physicians conducted door-to-door surveys and reported probable ET subjects to movement disorder specialists. In the second step, participants with suspected ET had their diagnosis confirmed by movement disorder specialists. We randomly selected 123 subjects from those adults who screened negative for neurological conditions as healthy controls for the study of NMS.

RESULTS: The prevalence of ET in individuals (≥ 50 years old) was 0.306% (PR = 3.06 per 1000). The mini-mental state examination (MMSE) scores were lower in ET patients than in controls (25.81 ± 4.20 vs. 26.63 ± 3.14, P= 0.024). Complaints of restless legs reported by ET patients were significantly higher than those in controls (P < 0.05). In contrast, we did not observe a significant difference for other NMS between ET patients and controls, including olfactory function (P = 0.82), depression (P = 0.94), and rapid eye movement sleep behavior disorder (RBD) (P = 0.71).

CONCLUSIONS: The prevalence of ET in people ≥ 50 years old in a rural area of Shanghai China is low. Prevalence of certain NMSs was higher among participants with ET relative to health controls.