Evaluation of Autonomic and Cognitive Functions in Patients with Essential Tremor

INTRODUCTION: This study aimed to evaluate autonomic and cognitive functions in patients with essential tremor (ET) and investigate their correlation. METHODS: A total of 38 patients with ET and 35 healthy volunteers were included in the study. Electrophysiological assessment of the autonomic nervous system was performed using the sympathetic skin response (SSR) and RR interval variation analyses. Additionally, cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) for all participants. RESULTS: In the patient group, compared with the control group, median and tibial nerve SSR latencies were greater, and amplitudes were lower in both the upper and lower extremities. SSR latencies were prolonged in several upper- and lower-extremity recordings, and the right tibial SSR amplitude was significantly reduced (p < 0.05); the remaining amplitude differences showed a similar trend without reaching statistical significance. Although RR interval variation was lower in patients than in controls during both rest and deep breathing, no statistically significant difference was detected. MoCA scores were significantly lower in patients than in healthy volunteers. Subgroup analysis revealed that this difference was particularly prominent in visual-spatial/executive functions and language function. No correlation was detected between the SSR, RR interval variation, or MoCA in either the patient or control group. CONCLUSION: Patients with ET demonstrated electrophysiological findings suggestive of altered sympathetic autonomic function, together with lower cognitive performance. However, parasympathetic dysfunction was not demonstrated by analysis of RR interval variation.