Introduction High cognitive reserve is associated with milder cognitive and motor deficits in Parkinson's disease (PD). We investigated whether educational status (as a proxy for cognitive reserve) could modulate dual-task (DT) related gait changes after subthalamic nucleus deep brain stimulation (STN-DBS) in PD. Methods DT-related gait changes were assessed in 34 PD patients (age: 60.5 ± 8.7; % female: 44%), before and one year after STN-DBS. Based on walking speed change after DBS, patients were classified into responders (improvement) and non-responders (deterioration) using automated k-means clustering for four DT (i.e. forward and backward counting; semantic and phonemic fluency). Results Patients with high education level improved DT gait performance compared to lower educated patients (p = 0.03). Baseline cognitive performance, disease progression and stimulation efficiency were similar between groups (i.e. responders versus non-responders). Logistic regression showed an association between responders and high level of education for verbal fluency (semantic/phonemic fluency, beta = 3.9/3.4, p = 0.03). No significant changes for any gait parameter were found using all-group analyses. Conclusion Education level is associated with DT-related gait changes in PD one year post-DBS. Subgroup analyses should be considered for highly variable gait outcomes after STN-DBS. With regard to the predominance of motor-cognitive DT performance in everyday life, a high CR could be considered as a favourable inclusion criterion for future DBS candidates.