Cortical Domain Deficits Do Not Confer Risk for Cognitive Decline in Deep Brain Stimulation (DBS) for Parkinson’s Disease (PD)
Scott Harcourt1, Jessica Herman1, Aidan Kunju1, Jonathan Jagid1, Corneliu Luca1, Bonnie Levin1, Ihtsham Haq1, Marina Sarno1
1University of Miami Miller School of Medicine
Objective:
Evaluate domain-specific cortical deficits as possible risk factors in motor, medication, mood/adaptivity, and cognitive PD-DBS surgical outcomes.
Background:
Cognitive deficits in PD are well studied; however, DBS risks posed by mild-moderate deficits in semantic fluency, verbal memory storage, and confrontation naming are not as well understood. The current study examined the post-surgical cognitive, mood/adaptivity, and physical (motor, medication intake) PD patient outcomes through pre/post-DBS neuropsychological and neurological evaluations.
Design/Methods:
Forty-seven PD-DBS patients (53.2% Hispanic, 70.2% male, 59.6% Spanish-language) of Mage= 64.3 (SD= 9.3; range 43-84), Mdisease_duration_years= 9.9 (SD= 3.7; range 1-21), Meducation_years= 15.2 (SD= 3.4), underwent pre- and post-DBS (91% bilateral, 87% subthalamic nucleus) neuropsychological evaluations [Mmonths= 11.8 (SD=7.2) post-UPDRS after surgery; Mmonths= 19.6 (SD= 13.0) post-neuropsych after surgery]. Participants were retrospectively stratified into normal, mildly-impaired, and moderately-impaired cognitive ranks by pre-DBS semantic fluency (Animals), naming (BNT), and memory registration (CVLT-3-Recognition) scores. Groups were compared via paired-sample-t-tests of pre- and post-surgery scores at Bonferroni-adjusted alpha=.001.
Results:
Normal-group verbal memory declined significantly [t(16)=3.9, p=.001], but cognition did not significantly change from pre-to-post-DBS in other groups across language, verbal/visual memory, visuospatial function, processing speed, attention, or executive functioning. Mood/adaptivity (BAI, BDI, PDQ-39-SI) and motor (UPDRS-3 pre-DBS/ON-medication versus post-DBS/ON-stimulation/OFF-medication scores) showed no significant change, although post-DBS/ON-stimulation was clearly better than pre-DBS/ON-medication. Non-significant levodopa-equivalent dose (LED) reductions of 37-50% were noted across groups. In sum, three cognitive groups responded similarly across cognitive, mood/adaptivity, motor, and medication measures.
Conclusions:
The current study demonstrates that weaknesses in semantic fluency, naming, or verbal memory pre-DBS are not associated with worsened motor, medication, mood/adaptivity, and cognitive outcomes. Normal, mild, and moderate impairment groups benefitted from LED-reduction while maintaining similar UPDRS function. However, future studies with larger sample sizes are needed to help stratify low-and high-risk patients, and caution should still be exercised when determining DBS candidacy of patients with significant cognitive compromise.