Effect of rivastigmine on tremor in patients with Parkinson's disease and dementia.

The purpose of this study was to assess whether rivastigmine, a cholinergic agent, affects tremor features when given to improve cognition in demented Parkinson's disease (PD) patients. Demented PD patients (n = 26; Mini-Mental State Examination score, 13-25; age, 75.2 +/- 4.9 yr) were given rivastigmine (mean dose, 8.0 mg/day) for 12 weeks. They underwent tremor assessment before and during treatment. Global Tremor Score (GTS) was based on eight items specific to tremor in the Unified Parkinson's Disease Rating Scale. Tremor amplitude was also measured using accelerometers during the ON state in both hands in 19 patients. Drug therapy for other PD symptoms was unchanged. The mean group baseline GTS was 1.2 +/- 1.6 points, increasing to 1.6 +/- 2.4 points after treatment (mean increase, 0.4 +/- 1.2 points; P > 0.05). The GTS increased by 3.2 +/- 1.9 points (range, 1-5) in 7 patients (26.9%) and decreased by 1 +/- 0 points in 3 patients (11.5%). Accelerometric assessment showed a significant increase of the average tremor amplitude in the right hand (0.08 +/- 0.03 xg at baseline; 0.12 +/- 0.02 xg at Week 12 of treatment, P = 0.02). Left-hand tremor amplitude did not change. Rivastigmine caused only slight worsening of tremor in demented PD patients, while improving cognition.