Abstract

Background High frequency deep brain stimulation of the subthalamic nucleus (STN‐DBS) is a well‐established therapy for Parkinson's disease (PD) motor symptoms, however, its effect on non‐motor symptoms is controversial. Low frequency DBS can improve cognition, but its effects on motor functions are detrimental. Objective Our goal was to evaluate the effect on verbal fluency (VF) of dual frequency STN‐DBS combining high and low frequency (130 + 10 Hz) as compared to 130 Hz or 10 Hz alone and to OFF stimulation. The effect on motor symptoms, working memory, and subjective feelings was also assessed. Methods We used a randomized order of experimental conditions with a double‐blind design to assess the effects of 130 Hz, 10 Hz, and 130 + 10 Hz stimulation as compared to OFF stimulation in 18 PD patients with STN‐DBS. In each condition, participants completed: phonemic and action VF, N‐back task, and visual analogue scales for fatigue and stress level. Motor functions and gait velocity were also assessed. Friedman analysis of variance were conducted to determine whether change scores from baseline OFF stimulation, in our primary (VF) and secondary outcomes measures (motor functions, N‐back task, subjective feelings) were different in the three stimulation conditions. Results VF improved more in the 130 + 10 Hz condition than 130 Hz condition (P = 0.006); there was no difference between 130 + 10 Hz and 10 Hz (P = 0.2) and between 130HZ and 10 Hz (P = 0.6). There was a significant difference among the stimulation conditions for the motor score (χ2(2) = 11.1, P = 0.004), it being worse at 10 Hz than 130 Hz (P = 0.002) and 130 + 10 Hz (P = 0.01). Conclusions Dual frequency STN‐DBS improves phonemic VF while maintaining a beneficial effect on motor signs of PD. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.