Objective: To determine if deep brain stimulation (DBS) changes cognitive function in Parkinson’s Disease (PD), and if these cognitive changes may relate to gait dysfunction in PD, specifically in freezing of gait (FOG).

Background: Studies suggest a transient change in cognitive function shortly after DBS placement. It is unclear whether worsening cognitive function in the years following DBS placement reflects the natural course of PD progression, or if it may be attributed to the DBS itself. FOG is characterized by a sudden inability to move forward while walking, and may be associated with cognitive dysfunction in PD.

Method: We retrospectively compared pre- and post-operative neuropsychological test scores and the MDS-UPDRS part III scores in 89 patients with PD or PD/ET who received DBS. Scores across timepoints were analyzed with Wilcoxon tests. Simple linear regressions were used to determine relationships between individual neuropsychological tests and MDS-UPDRS Part III scores, at pre- and post-operative timepoints, both on and off PD medications. Analyses were repeated for FOG and no-FOG (NFOG) subgroups.

Results: Assessments of language (FAS, Animals), memory (Digit Span), and anxiety (BAI), showed improvement in function following DBS. While cognitive function assessed by certain tests (Montreal Cognitive Assessment, Digit Span, Matrix Reasoning) were significantly correlated with MDS-UPDRS Part III scores pre-operatively, these same tests were not significantly correlated to motor scores following DBS placement. In the FOG subgroup, there were no pre-operative associations between motor and cognitive function. No post-operative associations in the NFOG subgroup were found. However, in the FOG subgroup, there was a significant post-operative association between motor and fluency scores (semantic and phonemic).

Conclusion: Results from this retrospective analysis show that in general, cognitive and motor function improve following DBS, but the strong association between motor and cognitive function found pre-operatively seems to be decoupled following DBS placement. The opposite is true when PD patients with FOG are assessed separately, as they show emergent associations between motor and cognitive function following DBS placement. Longitudinal follow-up and more sensitive measures are required to parse the connection between cognitive and motor function.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/changes-in-cognitive-function-with-deep-brain-stimulation-in-pd-patients-with-and-without-freezing-of-gait/