Transdermal rivastigmine treatment does not worsen impaired performance of complex motions in patients with Alzheimer's disease

Background: There is a debate about the deterioration of fine motor behavior during treatment with cholinesterase inhibitors. Methods: We used an instrumental motor test, which demands a complex motion series. Thereby we assessed motor function in patients with Alzheimer's disease (AD), in patients with mild cognitive impairment (MCI), and in controls. We also performed this task and a complex reaction time paradigm (CRT) during a six-week open-label safety study using transdermal delivery of the cholinesterase inhibitor rivastigmine. Objectives: To investigate (1) the performance of complex movements during deterioration of cognitive function and (2) the impact of rivastigmine on fine motor behavior and CRT outcomes in AD patients. Results: There were significant differences in the motor test outcomes, particularly when performed with the left non-dominant hand, between controls and patients with AD and MCI. Rivastigmine did not deteriorate assessed fine motor skills and CRT results. Conclusion: Our study shows an impaired carrying out of complex motion series during neurodegeneration associated with cognitive dysfunction. Rivastigmine selectively inhibits the predominant cortical and hippocampal G1 cholinesterase isoform; therefore, hypothetically no deterioration of fine motor behavior appeared during transdermal rivastigmine treatment. We assume that a putative drug-induced increase in speed and attention did not offset a deterioration of motion performance because we found no significant changes in the CRT results.