Neuropsychological changes 1-year after subthalamic DBS in PD patients: A prospective controlled study

ObjectiveThis study aimed at investigating the neuropsychological effect of DBS of the Subthalamic Nucleus in patients with advanced Parkinson's disease (PD).MethodsA standardized neuropsychological test battery, assessing reasoning, memory and executive functions, was administered to 27 PD patients who underwent DBS-STN (DBS group) and to a matched control group of 31 PD patients under optimal medical treatment (MED group). Patients were evaluated at baseline and at the end of 1 year.ResultsChange score analysis (T1 minus T0 scores) demonstrated a significant decline in phonemic verbal fluency in the DBS group compared with the MED group (p < 0.005), while there were no significant changes between the two groups for the other cognitive tests. Single cases analysis by means of multivariate normative comparisons revealed that 4 out of 27 DBS patients (15%) showed cognitive deterioration one year post surgery. These patients were significantly more compromised from a motor standpoint (UPDRS, section III) than the 23 DBS PD patients who had no cognitive decline post surgery.ConclusionResults of this prospective controlled-study showed that phonemic verbal fluency declined one year after DBS-STN, while the other cognitive domains did not change significantly. Nevertheless, single case analysis highlighted the fact that a subgroup comprising 15% of DBS-STN patients (4/27) showed significant cognitive decline 1 year after surgery.