STN-DBS Increases Proactive but Not Retroactive Interference During Verbal Learning in PD.

BACKGROUND Proactive interference (PI) refers to the interference of previously learned materials with new learning and reflects the failure of inhibitory processes in memory. Retroactive interference (RI) refers to the unfavorable effect of new learning on the later recall of previously learned information. Although subthalamic nucleus deep brain stimulation (STN-DBS) does not affect global cognition in Parkinson's disease (PD), it has negative effects on specific aspects of cognition, including verbal fluency and executive inhibitory control of action.To this end, we set to test the acute effect of STN-DBS on PI and RI during verbal learning. METHODS Twenty PD patients with STN-DBS were tested on the California Verbal Learning Test-II using an ON/OFF stimulation design. RESULTS The results showed that stimulation increased PI ON stimulation (P = 0.012) but had no effect on RI (P = 0.816). CONCLUSIONS Our results extend the role of STN to the inhibitory control that is required during memory encoding or recall for prevention of PI. © 2020 International Parkinson and Movement Disorder Society.